Dictionary of Aviation by mrbenugwe

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Dictionary of
   second edition

  David Crocker

A & C Black   London
             Originally published by Peter Collin Publishing
                 as Dictionary of Aeronautical English

                      First edition published 1999
      Second edition published 2005 by Bloomsbury Publishing Plc

                           Reprinted 2007 by
                       A&C Black Publishers Ltd
                   38 Soho Square, London W1D 3HB

   Copyright © David Crocker and Peter Collin Publishing Ltd. 1999
  Revisions and additional material © A&C Black Publishers Ltd 2007

           All rights reserved. No part of this publication may
         be reproduced in any form or by any means without the
                prior written permission of the publishers.

       A CIP record for this book is available from the British Library

                         eISBN-13: 978-1-4081-0226-8

                  Text Production and Proofreading
     Katy McAdam, Sandra Anderson, Heather Bateman, Emma Harris

This book is produced using paper that is made from wood grown in managed,
 sustainable forests. It is natural, renewable and recyclable. The logging and
  manufacturing processes conform to the environmental regulations of the
                                 country of origin.

                  Text processed and typeset by A&C Black
                      Printed in Spain by GraphyCems
English is the universal language of communication used in civil aviation. This
dictionary provides the basic vocabulary of terms used by pilots, cabin staff,
maintenance crews, ground staff and travellers worldwide. The terms are those used
in everyday work on aircraft, and cover parts of the aircraft, manipulating the
aircraft on the ground and in the air, instructions to passengers, conversations with
air traffic control, weather, emergencies, etc.

Unlike conventional aeronautical dictionaries, the Dictionary of Aviation defines
vocabulary often found in conjunction with the purely technical terms as well as the
technical terms themselves. Simple explanations are presented in simple language,
making the dictionary ideal for those working towards a private or commercial
pilot’s licence, as well as trainee maintenance engineers and more experienced
professionals. We also give examples to show how the words are used in context.

We have selected quotations from various specialised magazines to show the words
and phrases as they are used in real-life situations. The supplements at the back give
further information in the form of tables.

We are particularly grateful to the staff at Qatar Aeronautical College for their help
in the production of the first edition of this dictionary. Thanks are also due to
Stephen Copeland and Gavin Rowden for specialist advice and helpful suggestions
during the preparation of this new edition.

The information contained in this dictionary is not to be regarded as a substitute for
formal training in a given discipline.
Pronunciation Guide
The following symbols have been used to show the pronunciation of the main
words in the dictionary.

Stress is indicated by a main stress mark ( ) and a secondary stress mark ( ) .
Note that these are only guides, as the stress of the word changes according to its
position in the sentence.

            Vowels                      Consonants
                        back            b            buck
            ɑ           harm            d            dead
            ɒ           stop            ð            other
            a          type            d            jump
            aυ          how             f            fare
            aə         hire                         gold
            aυə         hour            h            head
            ɔ           course          j            yellow
            ɔ          annoy           k            cab
            e           head            l            leave
            eə          fair            m            mix
            e          make            n            nil
            eυ          go              ŋ            sing
                        word            p            print
            i           keep            r            rest
            i           happy           s            save
            ə           about           ʃ            shop
                       fit             t            take
            ə          near            tʃ           change
            u           annual          θ            theft
            u           pool            v            value
            υ           book            w            work
            υə          tour            x            loch
                        shut                         measure
                                        z            zone
                                                   able / eb(ə)l/ adjective skilful and
AAIB                                               able

AAIB abbreviation Air Accident Inves-
tigation Branch                                    competent to be able to to have the

AARA abbreviation air to air refuelling            power, knowledge, skill or strength to
area                                               do something Is she able to carry this
                                                   heavy suitcase?
abbreviate /ə bri viet/ verb to

                                                   able-bodied / eb(ə)l bɒdid/ adjec-

shorten a word or a text Air Traffic               tive referring to a person who has no
Control is usually abbreviated to ATC.             physical disabilities Physically disad-
  abbreviated weather report a short-              vantaged as well as able-bodied people
ened weather report                                can gain a PPL.
abbreviation /ə bri vi eʃ(ə)n/ noun

                                                   abnormal / b nɔ m(ə)l/ adjective
                             |   |

the short form of a word or text Aero-             not normal
nautical charts use abbreviations and
                                                   abnormality / bnɔ m lti/ noun

symbols. Km is the abbreviation for                                                |

                                                   something that is not normal, expected
                                                   or correct, and is therefore possibly
       COMMENT: Abbreviations can cause            worrying Any abnormality in engine
       confusion. They may range from those        performance should be checked.
       which have a very specific meaning as
                                                   abnormal load / b nɔ m(ə)l ləυd/
                                                   abnormal load

       defined by an authoritative body, to                                    |

       others which may come about                 noun a load which is heavier than nor-
       because of personal usage in note-          mal
       making,      etc.    ICAO     approved      abort / ə bɔ t/ verb 1. to stop some-


       abbreviations may differ from those
       used in JARs. AC can mean
                                                   thing taking place They had to abort
       ‘alternating current’ or ‘altocumulus’.     the landing because of a violent storm
       CPL is generally taken to mean              2. to end something before it has fin-
       Commercial Pilot’s Licence but the          ished
       ICAO definition is Current Flight Plan.     absolute / bsəlu t/ adjective com-

       Advances       in   technology     have     plete, total absolute necessity some-
       significantly increased the number of
       abbreviations with which pilots and         thing that you cannot manage without
       engineers       must     be     familiar.   under any circumstances        absolute
       Abbreviations in this dictionary include    silence a condition in which no sound
       those     with    generally    accepted     of any kind can be heard
       definitions and others with specific        absolute ceiling / bsəlu t si lŋ /
                                                   absolute ceiling

       ICAO definitions.                           noun the maximum height above sea
ability /ə blti/ noun the power,                 level at which an aircraft can maintain


knowledge or skill needed to do some-              horizontal flight
                                                   absolute humidity / bsəlu t hju
                                                   absolute humidity

thing Strength is the ability of a mate-                                                 |

rial to support a load. he has great                mdəti/ noun the vapour concentration
ability he has good skills or is very              or mass of water in a given quantity of
clever                                             air
absolute pressure                                         2
                pressure / bsəlu t                            metres per second per second. Abbrevi-
absolute pressure

 preʃə/ noun a unit of force per unit of                      ation g
area without comparison to other pres-                                                 /ək selə rɒmtə/

                                                              accelerometer                   |   |

sure Aircraft show absolute pressure                          noun an instrument that measures an
in inches of mercury on the inlet mani-                       aircraft’s acceleration
fold pressure gauge.                                          accept /ək sept/ verb 1. to be able to


absolute value / bsəlu t v lju /
absolute value

                                                              take or receive       Some units accept
noun the size or value of a number                            electrical inputs from the autopilot. 2.
regardless of its sign     The absolute                       to take or receive something when it is
value of –64.32 is 64.32.                                     given to you She accepted the award
absolute zero / bsəlu t zərəυ/                               on behalf of the whole crew. to accept
absolute zero

noun the lowest temperature possible,                         a gift, to accept a prize to take a prize
0 °K, or –273.15 °C                                           which is handed to you 3. to be willing
                                                              to receive or admit something          to
absorb /əb zɔ b/ verb to take in


                                                              accept the blame to be willing to admit
Warm air absorbs moisture more easily                         that you were the person who caused
than cold air. Our bodies absorb oxy-                         something bad to happen The airline
gen. to absorb information to under-                          accepted the blame for the loss of their
stand and remember something Only                             baggage. to accept responsibility to
a few passengers absorb the pre-depar-                        be willing to be answerable for some-
ture safety information.                                      thing The copilot accepted responsi-
absorption /əb zɔ pʃən/ noun the

                                          |                   bility for the incident.
act of taking something in There is                           acceptable /ək septəb(ə)l/ adjective


absorption of energy by the tyre when                         allowed or approved of, although it may
the aircraft lands.                                           not be perfect       acceptable level of

AC abbreviation 1. alternating current                        safety a good enough standard of safety
2. altocumulus (ICAO)                                           acceptable limits the limits generally

ACARS abbreviation airborne com-                              regarded as correct there must be a
munication, addressing and reporting                          continuous flow of clean oil at an
system                                                        acceptable temperature the tempera-
                                                              ture of the oil must be within given
ACAS / ek s/ abbreviation airborne

                                                              maximum and minimum figures
collision avoidance system
                                                              acceptance /ək septəns/ noun 1.

ACC                                                                                       |

ACC abbreviation area control centre                          willingness to believe something or
accelerate /ək seləret/ verb to

                                              |               agree to something There is a growing
increase speed      After start-up, the                       acceptance that safety is the main pri-
engine accelerates up to idling speed.                        ority. 2. willingness to do or use some-
The aircraft accelerated down the run-                        thing acceptance of new technology
way and took off. Opposite decelerate                         willingness to use new technology
                      /ək selə reʃ(ə)n/                      accepted /ək septd/ adjective


                                                  |   |                               |

noun 1. the act of increasing the speed                       believed or recognised It is accepted
of something or of going faster. Oppo-                        that incorrect use of English played a
site deceleration (NOTE: Acceleration                         part in the accident. It is generally
can be felt as an aircraft begins its take-                   accepted that flying is one of the safest
off run.) 2. a force that pulls outwards                      forms of transport.
and is caused by a change in direction                        access / kses/ noun a way to find or

rather than a change in speed Acceler-                        get at something to gain access to to
ation forces can be felt during aerobatic                     manage to enter a place         access to
manoeuvres.                                                   information the means to get at,
acceleration due to earth’s gravity

acceleration due to earth’s                                   retrieve and use information í verb to
gravity noun the pulling force exerted                        find and use to access data, to access
on a body by the Earth. It has an inter-                      information to find, retrieve and use
national standard value of 9.80665                            data or information
                                                   3                                                according to
accessibility / ək ses blti/ noun                   to one of the passengers and is carried

                                 |       |

the ease with which something can be                   on the same aircraft. unaccompanied
reached or found Accessibility of com-                 accompany /ə k mp(ə)ni/ verb to


ponents and equipment during servic-                   go together with something else
ing enables work to be done more                       Engine failure is sometimes accompa-
quickly.                                               nied by fire. Mr Smith was accompa-
accessible /ək sesb(ə)l/ adjective                    nied by his wife and children on the


easy to get at It is a good idea to have               flight to New York Mr Smith’s wife
a set of emergency charts in an accessi-               and children were with him on the flight
ble place in the cockpit. Instruments                  accomplish /ə k mplʃ/ verb (in for-


which need resetting in flight must be                 mal technical texts) to do something
accessible to the crew.                                Feathering is accomplished by moving
accessory /ək sesəri/ noun a system

                     |                                 the pilot’s control lever. Retraction of
or piece of equipment of secondary                     the undercarriage is accomplished by
importance      a camera with several                  electrical power.      to accomplish a
accessories í adjective of secondary                   task to successfully finish doing some-
importance There are many accessory                    thing demanding        She was the first
systems which need engine power to                     woman to accomplish the feat in a sin-
operate them – pumps, generators,                      gle-engined aircraft.
magnetos, etc. (NOTE: The noun acces-                  accomplishment /ə k mplʃmənt/


sory is not connected with the noun                    noun 1. an achievement Charles Lind-
access or the verb to access.)                         bergh’s flight across the Atlantic in May
access panel / kses p n(ə)l/
access panel

                                                       1927 was a great accomplishment. 2.
noun a part of the aircraft skin which                 (in physics) work done Power is meas-
can be easily removed so internal com-                 ured by units of accomplishment corre-
ponents can be inspected                               lated with time.
accident / ksd(ə)nt/ noun 1.                          accordance /ə kɔ d(ə)ns/ noun in
accident                                               accordance


something which happens which seems                    accordance with in agreement with or
to have no cause it was an accident                    following something such as rules,
nobody planned that it should happen or                instructions or laws      Fuels must be
deliberately caused it to happen by                    used in accordance with instructions.
accident by chance we met by acci-                     in accordance with Buys Ballot’s Law
dent we met by chance 2. an unfortu-                   as described by Buys Ballot’s Law
nate or harmful event, something caus-                     ‘…use full heat whenever carburettor
ing damage       An accident must be                       heat is applied, partial hot air should only
reported.     The flight attendant was                     be used if an intake temperature gauge is
injured in the accident.                                   fitted and only then in accordance with
    ‘Mr Skidmore lost both arms in an                      the Flight Manual or Pilot’s Operating
    accident while serving in the army as a                Handbook’ [Civil Aviation Authority,
    young man, and is believed to be the first             General Aviation Safety Sense Leaflet]
    pilot in the UK – and possibly the world –         accordingly / ə kɔ dŋli/ adverb as


    to go solo with two artificial arms’ [Pilot]       needed Check for increasing manifold
accidental / ks dent(ə)l/ adjective

                             |                         pressure and reduce power accordingly.
1. happening by accident, not deliberate               according to /ə kɔ dŋ tu / preposi-
                                                       according to


or planned There is a safety device to                 tion 1. as determined by or in relation to
prevent accidental retraction of the                      The force exerted by the pilot on the
undercarriage. 2. relating to an acci-                 control column will vary according to a
dent, or happening as a result of an acci-             number of factors. 2. as written or said
dent We were told of his accidental                    by somebody else According to the
death.                                                 copilot, engine vibration was detected
                         /ə k mp(ə)nid/

accompanied                          |                 in engine number one. 3. in agreement
adjective found together with accom-                   with something, e.g. instructions, etc.
panied luggage luggage which belongs                   according to instructions exactly as
account                                        4
said in the instructions according to              modern navigational equipment is
requirements as required                           much greater than older systems.
account /ə kaυnt/ noun                             accurate / kjυrət / adjective 1. cor-
account                                            accurate

                   |              to take
something into account to remember                 rect Skill in accurate flying can only
something and consider it carefully                be achieved by practice.          accurate
When planning a flight, wind speed and             results results which are exactly correct
direction must be taken into account.              2. precise This watch is very accurate.
In the event of an in-flight emergency,            ACFT

                                                   ACFT abbreviation aircraft
the aircraft should be landed at the
                                                   achieve /ə tʃi v/ verb 1. to manage to

nearest suitably equipped airport, tak-                                         |

ing into account fuel available. on no             do something demanding In order to
account under no circumstances, never              achieve a safe landing in a crosswind,
  On no account should anybody fly an              the correct techniques must be used. 2.
aircraft without carrying out pre-flight           to obtain In wind shear conditions, a
checks.                                            fly-by-wire system allows the pilot to
                                                   achieve maximum lift by pulling hard
account for /ə kaυnt fə/ verb 1. to
account for

                                                   back on the stick without risk of a stall.
make up or constitute Kevlar and car-
                                                   achievement /ə tʃi vmənt/ noun

bon fibre account for a large percentage                                                  |

of the materials used in modern air-               something difficult that somebody suc-
craft. 2. to provide the main reason for           ceeds in doing and feels proud about
something High humidity accounted                  For most trainee pilots, making their
for the longer take-off run.                       first solo flight is a great achievement.
                                                   acid / sd/ noun a chemical sub-

accrete /ə kri t/ verb to increase in


amount by slow external addition, to               stance which reacts with a base to form
accumulate ice accretes on the rotor               a salt sulphuric acid (H2SO4) (NOTE:
ice builds up on the rotor                         An acid turns a litmus indicator red and
accretion /ə kri ʃ(ə)n/ noun increase

                                                   has a sour taste.)
                                                   acidity /ə sdti/ noun having an acid

or accumulation by slow external addi-                                  |

tion Ice accretion can cause loss of lift          content the acidity of a substance the
and significantly increase the weight of           amount of acid in a substance
the aircraft.                                      acid-proof / sd pru f/ adjective

accumulate /ə kju mjυlet/ verb to                 able to resist the harmful effects of an


collect and increase Due to katabatic              acid
effects, cold air flows downwards and              acid test / sd test/ noun a difficult
                                                   acid test

accumulates over low ground.                       or exacting test of worth or quality A
accumulation /ə kju mjυ leʃ(ə)n/

                                       |   |       pilot’s ability to react appropriately in
noun the collection and increase of                an emergency situation is the acid test
something       Fire in a toilet could             of his or her professionalism.
present difficulties due to the confined           ACMS

                                                   ACMS noun a computer which records
space and possible smoke accumula-                 information from various aircraft sys-
tion.                                              tems during flight. Full form aircraft
accumulator /ə kju mjυletə/ noun

                                   |               condition monitoring system
1. a device for storing energy in hydrau-          ACN

                                                   ACN abbreviation aircraft classifica-
lic systems An accumulator is fitted to            tion number
store hydraulic fluid. 2. an electric cir-
                                                   acoustic /ə ku stk/ adjective refer-

cuit in a calculator or computer, in                                                |

which the results of arithmetical and              ring to sound
                                                   acoustic ear muffs /ə ku stk ə
                                                   acoustic ear muffs

logical operations are formed                                                                    |

accuracy / kjυrəsi/ noun 1. the
                                                    m fs/ plural noun coverings to protect
state of being correct to check for                the ears from loud noise. Also called
accuracy to make certain that the result           ear protectors, ear defenders
                                                   acquire /ə kwaə/ verb to buy or oth-

is correct 2. the ability to find, hit or                                   |

show things correctly The accuracy of              erwise obtain                        to acquire a new air-
                                             5                                     adapt
craft Speed control is used to acquire           active runway / ktv r nwe/
                                                 active runway

and maintain a selected airspeed.                noun a runway that is being used
acquisition / kw zʃ(ə)n/ noun

                                                  ‘…never cross an active runway without
the act of buying or otherwise obtaining          permission from the tower: there may be
   Each computer checks data acquisi-             more than one active runway’ [Civil
tion.      The image of the airline               Aviation Authority, General Aviation
improved after the acquisition of the             Safety Sense Leaflet]
new aircraft.                                    activity / k tvti/ noun a movement


acronym / krənm/ noun a word

                                                 or action of some kind Sunspot activ-
which is made up of the initial letters of       ity can affect the amount of solar radia-
a name, and is pronounced as a word              tion.
NASA is the acronym for National Aer-            actual / ktʃuəl/ adjective real The

onautics and Space Administration.               actual path of the aircraft over the
VASI is the acronym for visual                   ground is called its track, which may
approach slope indicator.                        not be the same as the desired course.
act / kt/ verb 1. to behave in a partic-

                                                 actually / ktʃuəli/ adverb in fact, in

ular way       The crew must act with            reality      The design is such that,
authority. 2. to take the role of Moun-          although the aircraft loses altitude rap-
tain ranges act as a barrier. The gov-           idly, it does not actually stall.
ernor spill valve also acts as a safety
                                                 actuate / ktʃu et/ verb 1. to move a

relief valve. 3. to act on to produce an                                 |

effect Bending and twisting forces act           device or a part The fore and aft move-
on a propeller. Gravity acts vertically          ment of the control column actuates the
downwards.                                       elevators. 2. to switch on a system or a
                                                 piece of equipment, or put it into opera-
acting / ktŋ / adjective temporarily

                                                 tion A lever actuates the fire deluge
taking on the responsibilities of some-          system. 3. to put a procedure into action
body Captain Smith will be acting                   Receipt of the distress signal will
Chief Flying Instructor while Captain            actuate the support facilities at the air-
White is absent from work.                       port.
action / kʃən/ noun 1. something

                                                 actuation / ktʃυ eʃ(ə)n/ noun 1.


done or to be done to take action to             the act of making a device or a part
so something If there is a risk of colli-        move electrical actuation the use of
sion, the crew should take the appropri-         an electric motor to make something
ate action. 2. an effect                         move mechanical actuation the use
activate / ktvet/ verb to make a

                                                 of a mechanical part such as a rod, arm
system or a piece of equipment or a pro-         or lever to make something move 2. a
cedure start to work or to operate The           movement made by a device or part
system is activated by the pilot or copi-        actuator / ktʃυetə/ noun a device

lot. The sounding of the alarm will              which changes electrical or hydraulic
activate emergency procedures.                   energy into mechanical motion The
activation / kt veʃ(ə)n/ noun the

                                                 actuator control is sensitive to engine
act of making something start to work            rpm. Actuators are classified as either
or to operate        Activation may be           linear or rotary.
mechanical or electrical.                        AD

                                                 AD abbreviation airworthiness direc-
active / ktv/ adjective 1. live, in

action or use the system is active the           A/D

                                                 A/D abbreviation aerodrome
system is on and working 2. not passive          ADA

   in a secondary radar system, the              ADA abbreviation advisory airspace
                                                 adapt /ə d pt/ verb 1. to change or

target is active in a secondary radar                            |

system the target transmits a signal             modify for special use The turboprop
while in a primary radar system it does          engine is often used in transport air-
not 3. active Cb clouds developing               craft and can be adapted for use in sin-
cumulonimbus clouds                              gle-engine aircraft. 2. to change to suit
adaptation                                  6
new conditions Crew flying long-haul            adhere /əd hə/ verb to stick as if


routes have to adapt to time changes.           glued Clear ice adheres strongly to
adaptation / d p teʃ(ə)n/ noun 1.              airframes.


the act of changing or modifying some-          adhesive / əd hi sv / noun glue í


thing for special use Doppler VOR is            adjective having the sticking quality of
an adaptation of VOR to reduce errors           glue adhesive tape Adhesive bond-
caused by location. 2. adjustment to            ing of aluminium parts is widely
new conditions        Adaptation to time        employed.
changes when travelling west to east            ADI /edi a/ abbreviation attitude


takes time.                                     direction indicator or attitude director
adapter /ə d ptə/ noun 1. a piece of

             |                                  indicator
equipment or device which allows a              adiabatic / də b tk/ adjective 1.


change or modification a ‘T’ piece              referring to processes through which
adapter a device for connecting two             heat cannot be lost or gained 2. refer-
inputs to one output or vice versa 2. a         ring to a change in temperature in a
device that allows two incompatible             mass of air, which occurs when the air
devices to be connected                         is compressed or expanded by an
ADC / e di si / abbreviation air data

                                                increase or decrease in atmospheric
computer                                        pressure and does not involve the air
add / d/ verb 1. to put figures together        losing heat to, or gaining heat from, its

to form a sum, to make a total Add the          surroundings
two numbers together to find the sum. 2.        adiabatic                                           compression
                                                adiabatic compression

to put together to make a larger group or       /  dəb tk kəm preʃ(ə)n/ noun                  |

a group with different properties               compression caused by atmospheric
There are only nine chairs, add another         factors, which makes descending air
one. A substance is added to the fuel           warm up
to clean fuel injectors.                        adiabatic cooling / dəb tk
                                                adiabatic cooling

addition /ə dʃ(ə)n/ noun 1. a mathe-            ku lŋ/ noun a process in which


matical operation consisting in putting         ascending air is cooled by a decrease in
numbers together         Addition is nor-       atmospheric pressure without heat
mally taught before subtraction, multi-         transfer
plication and division. The addition            adiabatic expansion / dəb tk
                                                adiabatic expansion

sign is +. 2. the act of adding something       k sp nʃ(ə)n/ noun expansion caused

  With the addition of methanol, the tur-       by atmospheric factors, which makes
bine inlet temperature is restored. 3.          ascending air cool down Cooling by
in addition also in addition to as              adiabatic expansion may result in cloud
well as                                         formation.
additional /ə dʃ(ə)nəl/ adjective

                                                adiabatic heating / diə b tk
                                                adiabatic heating

added or extra                                   hi tŋ/ noun a process in which
additive / dtv/ noun a chemical

                                                descending air is heated by an increase
substance, often liquid, added to               in atmospheric pressure without heat
another substance to give it extra quali-       transfer
ties Additives are used in engine oils          adjacent /ə d es(ə)nt/ adjective


to prolong the life of the engine. Anti-        next to or near      Fire extinguishers
icing additives are used in radiator            should be positioned adjacent to the
coolants.                                       aircraft during all ground-running
adequate / dkwət/ adjective

enough, sufficient        The compressor        adjust /ə d st/ verb to change and


must provide an adequate airflow                improve the position or setting of a
through the engine.        adequate fuel        piece of equipment The pilot adjusts
enough fuel                                     the throttle or propeller controls. to
ADF abbreviation automatic direction

                                                adjust the seat to move the seat into a
finder                                          position suitable for yourself        to
                                            7                                               advice
adjust the volume to increase or                advanced      /əd vɑ nst/ adjective


decrease the volume to improve the              modern and sophisticated The A340 is
sound quality                                   an advanced type of aircraft.
adjustable / ə d stəb(ə)l/ adjective

                                                 ‘…a Seattle-based modification company
designed to be adjusted An adjustable            specializing in advanced winglet designs
stop on the throttle control ensures a           is developing a lightweight winglet for
positive idling speed.                           the Boeing 747 200F’ [Flight
adjustment /ə d stmənt/ noun 1. a

                                                 International 1–7 May 1996]
                                                advantage /əd vɑ ntd / noun a

change to improve the setting, position                                     |

or operation of something A slight              good or beneficial factor The multi-
adjustment to the seat will make it much        wheel combination has the advantage
more comfortable to sit in. 2. the act of       of smaller and lighter undercarriage
changing something to improve its set-          structures. to take advantage of to
ting or position       Maximum system           get benefit from a situation to take
pressure is often controlled by adjust-         advantage of favourable winds to use
ment of the main engine-driven pump.            tailwinds to increase ground speed and
admit /əd mt/ verb to allow to enter

                                                thus save time and money. Opposite
Cold air can be admitted to the cabin           disadvantage
                                                advantageous            / dvən ted əs/

through adjustable louvres or shutters.                                                 |

adopt /ə dɒpt/ verb to choose to use

                                                adjective better     the most advanta-
something as standard equipment or to           geous the best The minimum time path
make it standard procedure A policy of          is the most advantageous for economy.
                                                advect /əd vekt / verb to move in a

no smoking on all flights has been                                  |

adopted by many airlines.         widely        horizontal direction due to convection
adopted now in standard use with many           Dispersal of hill fog takes place when
companies, institutions and organisa-           surface heating lifts the cloud base or
tions                                           drier air is advected.
adoption /ə dɒpʃən/ noun the act of             advection /əd vekʃ(ə)n/ noun the


using something as standard equipment           movement of air in a horizontal direc-
or making it standard procedure In              tion
spite of the adoption of the axial flow         advection fog /əd vekʃ(ə)n fɒ /
                                                advection fog


type compressor, some engines retain            noun fog which forms when warmer
the centrifugal type.                           moist air moves over a colder surface
ADR abbreviation accident data                  advent / dvent/ noun an arrival,
ADR                                             advent

recorder                                        especially of something very important
ADS abbreviation automatic depend-

                                                  With the advent of satellite navigation
ent surveillance                                systems, pilots of light aircraft have a
ADT abbreviation approved departure
                                                more accurate means of knowing their
time                                            position.
                                                adverse / dv s/ adjective 1. bad or

advance /əd vɑ ns/ noun 1. a change


that improves something enormous                poor Only in extremely adverse condi-
advances in aircraft design great               tions should the crew evacuate the air-
progress or developments in aircraft            craft. adverse handling characteris-
design 2. in advance of ahead of                tics aspects of an aircraft’s handling
The Gulf region is three hours in               which are poor 2. acting or going
advance of GMT. í verb 1. to move for-          against you
                                                adverse yaw / dv s jɔ / noun yaw
                                                adverse yaw

wards, or move something forwards
the throttle lever is advanced the              caused by aileron drag, in the opposite
throttle lever is moved forwards 2. to          direction to the direction of the intended
make something happen at an earlier             turn
                                                advice /əd vas/ noun useful or help-

time to advance the ignition to adjust                          |

the timing of the ignition so that the          ful information          The instructor’s
spark occurs earlier                            advice was of great help to the student
advisability                                            8
pilot. (NOTE: Advice has no plural                          aerial / eəriəl/ adjective 1. happening

form.)                                                      in the air 2. done by an aircraft in flight
advisability /əd vazə blti/ noun                           noun a device to send or receive radio

                                        |       |

the advisability of something whether                       or TV signals Ice-covering reduces
something is a good idea or not Flying                      the effectiveness of aerials. (NOTE: The
manuals often contain guidance on the                       US English word with this meaning is
advisability of flying with a cold.                         antenna.)
                                                            aerial display / eəriəl ds ple/ noun
                                                            aerial display

advisable /əd vazəb(ə)l/ adjective

recommended, suggested It is advisa-                        a display of flying skills and aircraft
ble to check the condition of the tyres                     performance
                                                            aerial photography / eəriəl fə
                                                            aerial photography

after each landing.                                                                                       |

advise /əd vaz/ verb 1. to inform, to

                                                             tɒ rəfi/ noun photography done from
notify     The flight deck advised the                      an aircraft in the air
                                                            aero- /eərəυ/ prefix 1. referring to the

cabin crew that descent would start in
20 minutes. 2. to recommend, to sug-                        air aerodynamic 2. referring to air-
gest Because of the bad weather, the                        craft aero-engine aero-tow
instructor advised the trainee pilot not                    aerobatic / eərə b tk/ adjective


to fly. to advise against to recom-                         referring to aerobatics Loops and rolls
mend or to suggest that something                           are aerobatic manoeuvres.
should not be done                                          aerobatic aircraft / eərəb tk
                                                            aerobatic aircraft

advisory /əd vaz(ə)ri/ adjective giv-                       eəkrɑ ft/ noun an aircraft which is


ing advice and information                                  designed to perform aerobatics
advisory airspace /əd vaz(ə)ri
advisory airspace

                                                    |           COMMENT: One of the most famous
 eəspes/ noun airspace containing                              competition aerobatic aircraft is the
advisory routes in which air traffic con-                       Pitts Special which first flew in 1944.
trol provide an advisory service but not                    aerobatic display / eərəb tk ds
                                                            aerobatic display


full control. Abbreviation ADA                               ple/ noun a demonstration, often pub-
advisory route /əd vaz(ə)ri ru t/                          lic, of piloting skill and aircraft per-
advisory route


noun a published route for which there                      formance
                                                            aerobatics / eərəυ b tks/ noun the

is an advisory service. Abbreviation                                                    |

ADR                                                         art of performing spectacular controlled
advisory service

advisory        service /əd vaz(ə)ri               |
                                                            movements in a flying aircraft for the
 s vs/ noun a service in which Air                         purposes of entertainment or competi-
Traffic Control provides advice and                         tion The Russian pilot gave a great
information to assist a pilot in the safe                   display of aerobatics.
                                                            aerobatic team / eərə b tk ti m/
                                                            aerobatic team

conduct of a flight                                                                         |


AEEC abbreviation airlines electronic                       noun a team of pilots and aircraft who
engineering committee                                       perform aerobatics
                                                            aerodrome / eərədrəυm/ noun any

aerate / eəret/ verb to put a gas,

                                                            area of land or water designed for the
especially carbon dioxide or air, into a                    taking off and landing of aircraft Air-
liquid so that bubbles are formed Aer-                      ports and military air bases or stations
ated fuel causes problems. Opposite de-                     are types of aerodrome.        All aero-
                                                            dromes are marked on charts. Abbrevi-
aeration /eə reʃ(ə)n/ noun the act of

                            |                               ation A/D disused aerodrome an aer-
putting a gas, especially carbon dioxide                    odrome which is no longer in use for the
or air, into a liquid The purpose of the                    purpose of taking off and landing aero-
booster pump is to prevent fuel aera-                       planes
tion. Opposite de-aeration                                  aerodrome boundaries

                                                            aerodrome                       boundaries
aerator /eə retə/ noun a device to put                     / eərədrəυm baυnd(ə)riz/ plural noun


a gas – especially carbon dioxide or air                    the physical or geographical limits of an
– into a liquid. Opposite de-aerator                        aerodrome
                                                                       9                                                              aeronautics
aerodrome       circuit / eərədrəυm                                        aero-engine / eərəυ end n/ noun
aerodrome circuit                                                          aero-engine

 s kt/ noun the pattern and direction                                     an engine used in aircraft Most piston
of aircraft movement in the air around                                     aero-engines are cooled by air.
the aerodrome                                                              aerofoil / eərəυfɔl/ noun a surface

aerodrome QFE / eərədrəυm kju
aerodrome QFE

                                                                           which is shaped to produce more lift
ef i / noun the barometric pressure set-                                   than drag when moved through the air
ting at which the altimeter reads zero                                     Wings, ailerons, elevators, fins and pro-
when the aircraft is on the runway                                         pellers are all examples of aerofoils.
aerodrome QNH / eərədrəυm kju                                              (NOTE: The US English word is airfoil.)
aerodrome QNH

en etʃ/ noun the barometric pressure                                      aeronautical           / eərə nɔ tk(ə)l/


setting at which the altimeter reads aer-                                  adjective referring to aeronautics
odrome elevation when the aircraft is on                                   aeronautical           chart       / eərə
                                                                           aeronautical chart


the runway                                                                  nɔ tk(ə)l tʃɑ t/ noun a map used in
aerodrome surveillance moni-
aerodrome surveillance monitoring indicator

                                                                           air navigation which may include topo-
toring  indicator / eərədrəυm                                              graphic features, hazards and obstruc-
 s veləns mɒntərŋ ndketə/                                            tions, navigational aids and routes, des-
noun same as airport surface detec-                                        ignated airspace and airports
tion equipment                                                             aeronautical
                                                                           aeronautical engineer

aerodrome                                     traffic           zone       / eərənɔ tk(ə)l end  nə/ noun an
aerodrome traffic zone


/ eərədrəυm tr fk zəυn/ noun an                                           engineer who specialises in the design
area of protected airspace around an                                       of aircraft
aerodrome, which pilots need permis-                                       aeronautical
                                                                           aeronautical engineering

sion to enter or to move in. Abbrevia-                                     / eərəυnɔ tk(ə)l end  nərŋ/ noun                       |

tion ATZ                                                                   the science or study of the design of air-
aerodynamic / eərəυda n mk/

                                                            |              craft
adjective 1. referring to the way in                                       aeronautical
                                                                           aeronautical fixed service

                                                                                                                          fixed                   service
which objects are affected when they                                       / eərənɔ tk(ə)l fkst s vs/ noun a
move through the atmosphere 2. refer-                                      radio communications service between
ring to a smooth rounded shape which                                       fixed points that is designed to enable
moves easily through the air aerody-                                       aircraft to travel safely. Abbreviation
namic design a streamlined shape that                                      AFS
enables something to move easily                                           aeronautical fixed telecommu-
                                                                           aeronautical fixed telecommunication network

through the air                                                            nication network / eərənɔ tk(ə)l
aerodynamic braking / eərəυ                                                 fkst telikəmju n keʃ(ə)n netw k/
aerodynamic braking


dan mk brekŋ/ noun the braking                                         noun a ground-based network of tele-
effect of drag                                                             printers that transmits flight plans and
aerodynamic          forces / eərəυ
aerodynamic forces

                                                                           similar data between control centres.
dan mk fɔ sz/ noun the forces of                                        Abbreviation AFTN
the air which act on an aircraft in flight                                 aeronautical information circu-
                                                                           aeronautical information circular

aerodynamic resistance / eərəυ                                             lar / eərənɔ tk(ə)l nfə meʃ(ə)n
aerodynamic resistance


dan mk r zstəns/ noun same as         |                                 s kjυlə/ noun a notice issued by an
drag                                                                       aviation authority in which information
aerodynamics / eərəυda n mks/                                            is given about administrative, technical,


noun the science that deals with the                                       safety or operational matters
                                                                           Aeronautical Information Publi-
                                                                           Aeronautical Information Publication

interaction of moving objects with the
atmosphere Aerodynamics is one of                                          cation noun a document issued by a
the major areas of study for a trainee                                     state in which information is given
pilot.                                                                     about aviation in that country. Abbrevi-
aerodyne / eərəυdan/ noun an air-                                         ation AIP

                                                                           aeronautics / eərə nɔ tks/ noun 1.

craft that is heavier than air and whose                                                                                      |

lift in flight results from forces caused                                  the science of aircraft design, construc-
by its motion through the air, e.g. a                                      tion and operation 2. the theory and
plane or helicopter                                                        practice of aircraft navigation
aeroneurosis                                             10
                                    / eərəυnjυ rəυss/        after / ɑ ftə/ adjective positioned
aeroneurosis                                                  after

aeroneurosis                                  |

noun anxiety and fatigue in airline                           closer to the rear of an aircraft í adverb
pilots as a result of long periods of fly-                    closer to the rear of an aircraft
ing                                                           afterburner / ɑ ftəb nə/ noun a

aeroplane / eərəplen/ noun a
                                                              system that injects fuel into the hot
power-driven, heavier-than-air craft                          exhaust gases of a jet engine in order to
with fixed wings (NOTE: Many people                           increase thrust
                                                              AFTN abbreviation aeronautical fixed

use the words aeroplane and aircraft
as if they had exactly the same mean-                         telecommunication network
                                                              agent / ed ənt/ noun 1. a chemical

ing. However, aeroplanes, hot-air bal-
loons, helicopters, airships and gliders                      substance which causes a change If
are all aircraft. The US English is air-                      de-icing fluid is used as an anti-icing
plane.)                                                       agent it should be sprayed onto the air-
aeroplane performance

aeroplane                              performance            craft before the onset of icing. extin-
/ eərəplen    pə fɔ məns/ noun a
                                                              guishing agent a substance used to put
description in figures of what a plane                        out fires 2. a person who represents a
can do, including, e.g., its speed, rate of                   company or arranges something for a
climb, and the length of its take-off run                     company the agent for British Air-
                                                              ways a travel agent
aerostat / eərəυst t/ noun a hot-air

                                                              aggregate /         r ət/ noun the total

or gas-filled aircraft, e.g. an airship or                    obtained by adding The aggregate of
balloon                                                       the capacity of all the fuel tanks is 50
aero-tow / eərə təυ/ noun a tech-

                                |                             gallons. í verb to add or come together
nique of using a powered aircraft to pull                     to form a mass or total Ice crystals
a glider into the air An aero-tow to                          aggregate to form snowflakes.
2,000 feet costs $25.                                         AGL abbreviation above ground level

                                                              agree /ə ri / verb 1. to have the same

AFCS abbreviation automatic flight


control system                                                idea or opinion about something The

AFDS abbreviation autopilot flight                            crew agreed with the findings of the
director system                                               investigation. 2. to come to an under-
                                                              standing After hours of discussion, the
affect /ə fekt/ verb to have an influ-

                                                              cabin staff agreed to call off the planned
ence on something, or cause a change in                       strike.
something Humidity and air density                            agreed /ə ri d/ adjective generally


are factors which affect the output of the                    accepted The millibar is an agreed
engine. Compare effect                                        unit of pressure.

AFI abbreviation assistant flying                             agreement /ə ri mənt/ noun 1. the


instructor                                                    state of having the same idea or opinion

AFIC abbreviation assistant flying                            as somebody we are in agreement we
instructor course                                             agree 2. a document in which the things
AFIS                                                          that two or more people or organisa-
AFIS abbreviation aerodrome flight                            tions have agreed to do are written
information service                                           down Regional Air Navigation Agree-

AFS abbreviation aeronautical fixed                           ments
service                                                       ahead /ə hed/ adverb in front look


aft /ɑ ft/ adjective towards the rear part                    ahead look some distance in front of

of the aircraft The rear part of the                          you straight ahead directly in front
                                                              ahead of /ə hed əv/ preposition 1. in
                                                              ahead of

fuselage is called the aft section. aft                                                 |

cabin the passenger compartment at the                        front of Air ahead of a cold front is
back of the aircraft í adverb rearwards                       warmer than air behind a cold front. 2.
or backwards to move the control                              in advance of or at an earlier time than
column aft to move the control column                           The flight from Paris arrived 10 min-
backwards. Opposite fore, forward                             utes ahead of schedule.
                                                11                                                aircraft
AHRS noun a sensor which provides                    airborne weather radar / eəbɔ n
AHRS                                                 airborne weather radar

information on the pitch, bank and                    weθə redɑ / noun a radar installation
heading of an aircraft. Full form atti-              in an aircraft to give the flight crew
tude heading reference system                        information about the weather along
AI abbreviation attitude indicator
                                                     their route. Abbreviation AWR
                                                     air-breathing engine / eə bri θŋ
                                                     air-breathing engine

AIAA abbreviation area of intense air

activity                                              end n/ an engine that burns a mixture
AIC abbreviation aeronautical informa-
AIC                                                  of liquid fuel and air (NOTE: There are
                                                     four types of air-breathing engine: turbo
tion circular
                                                     jet, turbo prop, turbofan and ramjet.)
aid /ed/ noun something which helps

                                                     air bridge / eə brd / noun a link pro-
                                                     air bridge

somebody do something í verb to help                 vided by aircraft that carry people and
   Computers can aid students in their               supplies between two places, especially
studies.                                             in situations where travel by land is not
AIDS /edz/ abbreviation 1. airborne

integrated data system 2. aircraft inte-             Airbus / eəb s/ a trademark for a

grated data system                                   large passenger jet aircraft manufac-
aileron / elərɒn/ noun a horizontal

                                                     tured by aerospace companies from dif-
control surface hinged to the main-                  ferent European countries working
plane, which enables an aeroplane to                 together
bank or roll By rotating the yoke the                air conditioner / eə kən dʃ(ə)nə/
                                                     air conditioner


ailerons are moved and the aircraft rolls            noun a device which filters and cools
into a turn. (NOTE: The word comes                   the air in a room or in an aircraft In
from the French ‘aile’, meaning ‘wing’.)             order to obtain maximum engine power,
aim /em/ noun a goal or objective A

                                                     the air conditioner should be switched
100% safe operation is the aim of all                off for take-off.
airline companies. í verb to intend or to            air conditioning /eə kən dʃ(ə)nŋ/
                                                     air conditioning


try to do something we aim to suc-                   noun a system for controlling the tem-
ceed we intend to succeed                            perature of the air in a building or in an
AIP abbreviation Aeronautical Infor-

mation Publication                                   air-cooled / eə ku ld/ adjective

air /eə/ noun the mixture of gases

                                                     cooled by means of a flow of air air-
which forms the Earth’s atmosphere                   cooled engines piston aero-engines
Air enters the cabin through an inlet.               cooled by air, not water
AIRAC abbreviation aeronautical                      air corridor / eə kɒrdɔ / noun a
AIRAC                                                air corridor

information regulation and control                   route that aircraft must take through an
Air  Accident    Investigation
Air Accident Investigation Branch

                                                     area in which flying is restricted
Branch / eər  ksd(ə)nt n vest    |       |        aircraft / eəkrɑ ft/ noun a machine

   eʃ(ə)n brɑ ntʃ/ noun the depart-                 that is able to travel through the air
ment of the CAA of the United King-                  Aeroplanes, gliders, balloons, airships,
dom responsible for establishing the                 helicopters, etc., are all aircraft. Abbre-
cause of accidents. Abbreviation AAIB                viation ACFT (NOTE: Aircraft has no
airborne / eəbɔ n / adjective lifted                 plural form.)

and kept in the air by aerodynamic                   aircraft classification number
                                                     aircraft classification number

forces      Shortly after the aircraft               / eəkrɑ ft kl sf keʃ(ə)n n mbə/

becomes airborne, the undercarriage is               noun a number expressing the relative
retracted.                                           effect of an aircraft on a pavement for a
airborne installation / eəbɔ n                       specified sub-grade strength. Abbrevia-
airborne installation

 nstə leʃ(ə)n/ noun a radio device in
                                                     tion CAN
                                                     aircraft condition monitoring

an aircraft which operates in conjunc-
tion with a ground installation The                  system / eəkrɑ ft kən dʃ(ə)n                |

airborne installation comprises an                    mɒnt(ə)rŋ sstəm / noun full form
antenna, receiver and indicator(s).                  of ACMS
aircraft configuration                                   12
aircraft configuration / eəkrɑ ft                             spark plug a spark plug with a space
aircraft configuration

kən f ə reʃ(ə)n/ noun a particular
              |             |                                 between the electrodes, across which
combination of moveable parts such as                         the spark jumps
flaps and landing gear that affects the                       air intake / eə ntek/ noun the front
                                                              air intake

aerodynamics of the aircraft                                  part of a jet engine where air enters
aircraft                        proximity   hazard            air lane / eə len/ noun a regular route
aircraft proximity hazard                                     air lane

/ eəkrɑ ft prɒk smti h zəd/ noun
                                 |                            that aeroplanes fly along
same as airprox                                               airline / eəlan/ noun a company

aircraft stability / eəkrɑ ft stə
aircraft stability

                                                     |        which manages air transport services
 bləti/ noun the tendency of an aircraft                     for passengers or goods Which airline
to return to its original attitude after                      is she working for, Air France or Air
being deflected                                               Canada? Most airlines do not allow
aircrew / eəkru / noun the pilot, nav-                        passengers to smoke during flight.

                                                              airliner / eəlanə/ noun an aeroplane

igator and other crew members of an
aircraft                                                      designed to carry large numbers of pas-
air cushion vehicle / eə kυʃ(ə)n                              sengers Concorde is the world’s fast-
air cushion vehicle

 vi k(ə)l/ noun same as hovercraft                           est airliner.
                                                              airline representative / eəlan
                                                              airline representative

air data computer / eə detə kəm
air data computer

                                                               repr zentətv/ noun a person who

 pju tə/ noun an electronic device                                              |

which provides information such as air                        acts on behalf of an airline, or a person
temperature, airspeed and static pres-                        who works for an airline Passengers
sure. Abbreviation ADC                                        should assemble in the departure
air density / eə densəti/ noun the
air density                                                   lounge where an airline representative
density of the atmosphere                                     will meet them.
                                                              airline security area / eəlan s
                                                              airline security area

airfield / eəfi ld/ noun an area of land
airfield                                                                                                  |

                                                               kjυərti eəriə/ noun an area in which
given over to runways, taxiways and                           measures are taken by an airline to
aprons When the pressure setting on                           ensure the safety of people and property
the altimeter is set to 1013.25 millibars,
                                                              Airline     Transport      Pilot’s
                                                              Airline Transport Pilot’s Licence

the pressure altitude of the airfield is
known as QNE.                                                 Licence / eəlan tr nspɔ t paləts
                                                               las(ə)ns/ noun the licence that a per-
air filter / eə fltə / noun a device to
air filter

                                                              son must have to be the pilot-in-com-
filter solid particles out of the air in                      mand or co-pilot of a public transport
engine and ventilation systems                                aircraft. Abbreviation ATPL
airflow / eəfləυ/ noun 1. the move-

                                                              airman / eəmən/ noun a person who

ment of air over the aircraft as it travels                   is a member of a country’s Air Force
through the atmosphere 2. a current of
                                                              airmanship / eəmənʃp/ noun all-

air flowing through or past an object or
body The compressor must provide an                           round skill in piloting an aircraft which
adequate airflow through the engine.                          includes academic knowledge, com-
                                                              mon sense, quick reactions, awareness,
airfoil / eərfɔl/ noun US same as

                                                              experience, consideration for other peo-
aerofoil                                                      ple and property Keeping a careful
airframe / eəfrem/ noun the body of

                                                              lookout for other aircraft in the circuit
the aircraft without the engines, instru-                     is good airmanship.
ments and internal fittings The air-                           ‘I was always told by my airmanship
frame has to be built to very specific                         instructor, in an emergency, to find the
requirements.                                                  largest piece of asphalt with the biggest
airframe icing / eəfrem asŋ/
airframe icing

                                                               fire trucks’ [INTER PILOT]
noun ice that forms on the aircraft struc-                    air mass / eə m s/ noun a very large
                                                              air mass

ture as opposed to on components such                         mass of air in the atmosphere in which
as carburettors                                               the temperature is almost constant and
air gap / eə         p/ noun a space
air gap

                                                              which is divided from another mass by
between two things        air gap type                        a front Air masses are divided into two
                                                      13                                       air taxi
types according to source region, and                      airship is classified as a lighter-than-
these are known as polar and tropical                      air craft.
air masses.                                                airshow / eəʃəυ/ noun a public dis-

airpark / eəpɑ k/ noun a small air-

                                                           play of aircraft in flight and on the
port, usually found near a business or                     ground, held at an airfield
industrial centre                                          airside / eəsad/ noun the part of an

airplane / eəplen / US same as aero-                      airport where the aircraft take off and

plane                                                      land, load, or unload
air pocket / eəpɒkt/ noun a small                         air sock / eə sɒk/ noun same as wind-
                                                           air sock
air pocket

area where the air is less dense or where                  sock
                                                           airspace / eəspes/ noun the part of

there is a downward air current, and
which makes an aircraft lose height                        the atmosphere that is above a particular
suddenly                                                   geographical area and is subject to the
air pollution /eə pə lu ʃ(ə)n/ noun                        laws of a particular country or control-
air pollution


pollution of the air by gas, smoke, ash,                   ling authority The Korean 747 flew
etc. Solid particles in the air include                    into Soviet airspace and was shot down.
                                                           airspeed / eəspi d/ noun the speed of

dust, sand, volcanic ash and atmos-
pheric pollution. Also called atmos-                       the aircraft relative to the air around it
pheric pollution                                           Maintain a constant airspeed on final
airport / eəpɔ t/ noun a civil aero-
                                                           airspeed         indicator / eəspi d
                                                           airspeed indicator

drome designed for the take-off and
landing of passenger-carrying aircraft                      ndketə/ noun a primary cockpit or
for the general public and/or cargo air-                   flight deck instrument which shows the
craft London Heathrow is one of the                        pilot the speed of the aircraft in relation
busiest airports in the world. Abbrevia-                   to the air around it Airspeed is shown
tion A/P                                                   in knots on the airspeed indicator.
airport authority / eəpɔ t ɔ θɒrti/
airport authority

                                                           Abbreviation ASI
noun the organisation responsible for                          COMMENT: The position of the pitot
the running of an airport                                      tube and the attitude of an aircraft can
                                                               affect the accuracy of the airspeed
airport security officer / eəpɔ t s
airport security officer

                                                               indicator.     Aircraft       operating
 kjυərti ɒfsə/ noun a person                                 handbooks usually have a table to
employed by an airport authority to                            help pilots calculate calibrated
check passengers and baggage for ille-                         airspeed (CAS).
gal substances or devices, e.g. drugs,                     air station / eə steʃ(ə)n/ noun a
                                                           air station

guns                                                       small airfield with facilities for the
airport surface detection equip-
airport surface detection equipment

                                                           maintenance of aircraft
ment / eəpɔ t s fs d tekʃ(ə)n          |       |
                                                           airstream / eəstri m/ noun the flow

 kwpmənt/ noun short-range radar                          of air caused by the movement of the
equipment that scans the surface area of                   aircraft through the air Pressure is
an airport and tracks the movement of                      built up inside the pitot tube by the air-
aircraft and other vehicles on the                         stream.
                                                               COMMENT: Unlike airflow, airstream
airprox / eəprɒks/ noun a situation in

                                                               does not refer to the movement of air
which aircraft are too close to one                            around    the    airframe  and    its
another in an area of airspace and there                       aerodynamic effect.
is the possibility of danger to them.                      airstrip / eəstrp/ noun a place for air-

Also called aircraft proximity hazard                      craft to take off and land that has no
air-sea rescue / eə si reskju /
air-sea rescue

                                                           facilities and is often temporary
noun a rescue at sea in which aircraft,                    air taxi / eə t ksi/ noun a small com-
                                                           air taxi

especially helicopters, are used                           mercial aircraft used for short flights
airship / eəʃp/ noun a powered, gas-

                                                           between places not on a regular airline
filled balloon which can be steered An                     route
air terminal                                   14
air terminal / eə t mn(ə)l/ noun 1.                      Instrument Flight Rules (IFR), but it
air terminal

an airport building with a range of facil-                also provides a service to aircraft
ities where passengers check in before                    using Visual Flight Rules (VFR).
                                                          Ground control is for aircraft taxiing to
boarding their plane and where they                       and from runways. The tower controls
arrive when their plane lands 2. a build-                 aircraft around an airport, clearing
ing in a city for receiving passengers                    them for take-off or landing. Departure
who are being transported to or from an                   and approach controls monitor and
airport by train or bus                                   control aircraft around the airport, and
                                                          en route centres control traffic
air terrorism / eə terərz(ə)m /
air terrorism

                                                          between airports.
noun violent actions that aim to frighten
                                                    air traffic controller / eə tr fk
                                                    air traffic controller

or kill passengers, disrupt air services,
or damage or destroy aircraft in an                 kən trəυlə/ noun a person who works

attempt to achieve a political objective            in air traffic control and whose main
air-tight / eə tat/ adjective closed or
                                                    task is to ensure correct separation of
sealed so that air cannot get in or out             aircraft in all phases of flight The air
                                                    traffic controller approved the emer-
air-to-air / eətə eə/ adjective between

                                                    gency landing. Abbreviation ATC.
one airborne aircraft and another air-              controller
to-air communications           air-to-air
                                                    air traffic movements / eə tr fk
                                                    air traffic movements

communications           communications
between one airborne aircraft and                    mu vmənts/ plural noun the number
another                                             of aircraft taking off and landing an
                                                    increase in air traffic movements
air to air refuelling area / eə tə eə
air to air refuelling area

                                                    airway / eəwe/ noun an area of the

ri fju əlŋ eəriə/ noun an area of air-

space in which tanker aircraft are per-             sky, usually rectangular in cross-sec-
mitted to refuel other aircraft in flight.          tion, along which civil aircraft fly from
Abbreviation AARA                                   place to place Airways provide a high
                                                    degree of safety by ensuring adequate
air-to-ground visibility / eə tə
air-to-ground visibility

                                                    separation between aircraft. Aircraft
   raυnd vz blti/ noun a descrip-

                                                    inside an airway are controlled by ATC.
tion of how easily seen an object on the            (NOTE: Airways are usually 10 nm wide
ground is from the air Glare caused by              with a centreline joining navigational
reflection of sunlight from the top of a            beacons.)
layer of fog or haze can seriously
                                                    Airways / eəwez/ noun a commer-

reduce the air-to-ground visibility.
                                                    cial company operating flights (NOTE:
air-to-surface / eə tə s fs/ adjec-

                                                    Usually used in the names of compa-
tive directed from a flying aircraft to a
                                                    nies, e.g. British Airways, South African
point on the ground
air traffic / eə tr fk/ noun aircraft
air traffic

                                                    airworthiness / eə w ðinəs/ noun

operating in the air or on the airport sur-                                      |

face Students practising circuit flying             the state of an aircraft with regard to
need to keep a very careful lookout                 whether it can fly safely, as determined
especially at times when there is a lot of          by a national certifying authority
                                                    airworthiness directive

air traffic.                                        airworthiness directive noun a
air traffic control / eə tr fk kən
air traffic control

                                                    regulation issued by an aviation author-
 trəυl/ noun a service that oversees and            ity when a problem has been identified
guides the movements of aircraft and                with a particular aircraft part. Abbrevi-
provides for the safe and efficient flow            ation AD
                                                    airworthy / eəw ði/ adjective meet-

of air traffic Controllers in the tower
provide an air traffic control service for          ing the standards of a national certify-
aircraft in the air around the airfield.            ing authority It is the pilot’s responsi-
Abbreviation ATC                                    bility to ensure that the aircraft is
    COMMENT : Air Traffic Control’s main
                                                    AIS abbreviation aeronautical informa-

    function is to maintain separation
    between aircraft operating within               tion services
                                               15                                             allowance
aisle /al/ noun a long passageway                  out of alignment not aligned as it

between the seats in the passenger cabin            should be
                                                    alkaline / lkəlan/ noun a substance

of an airliner aisle seat a seat which is
by an aisle, as opposed to a window seat            with a pH value of more than 7
alarm /ə lɑ m/ noun 1. fear or worry                alleviate /ə li viet/ verb to reduce or
alarm                                               alleviate


If the ammeter shows a high level of                lessen the harmful effect of something
charge after start-up, it is quite normal           Anti-icing additives are available to
and no cause for alarm. 2. a warning                alleviate the problem of icing.
                                                    alleviation /ə li vi eʃ(ə)n/ noun a

sound or light In the event of fire or                                            |       |

overheat, the control unit will produce             reduction or lessening of the harmful
an alarm. í verb to frighten or worry               effect of something        Deep, regular
Severe turbulence may alarm passen-                 breathing may provide some alleviation
gers.                                               from stress.
alert /ə l t/ adjective fully awake,                allocate / ləket/ verb to provide
alert                                               allocate


watchful and ready to deal with any sit-            something particular for a given pur-
uation The crew must be alert at all                pose Special seats are allocated to
times to the possibility of hijacking,              mothers with small children.
                                                    allocation / lə keʃ(ə)n/ noun the

bombs and stowaways. í noun a signal,                                                 |

warning everyone to be alert to be on               provision of something particular for a
the alert to be watchful and ready for              given purpose At the check-in desk,
anything that may happen í verb to                  airline staff are responsible for the allo-
warn It is the cabin staff ’s responsibil-          cation of seats to passengers.         fre-
ity to alert the flight crew if they see            quency allocation the frequency or
smoke coming from an engine.                        range of radio frequencies set aside for
                                                    a particular use The frequency alloca-
alight /ə lat/ adjective on fire

                                                    tion for VOR is 108–117.975 MHz.

Although the passenger thought he had
                                                    allow /ə laυ/ verb to enable, to permit

extinguished his cigarette, it was still                          |

alight when he threw it into the waste              or to authorise An engine should be
disposal bin. í verb (formal) 1. (of peo-           run at low rpm after flight to allow
ple) to leave or get off an aeroplane At            engine components to cool.           Addi-
some airports, passengers alight onto               tional fuel is carried to allow for hold-
the apron when they leave the aircraft.             ing en route.        Passengers are not
2. (of aircraft) to land An aeroplane               allowed to smoke on some aeroplanes.
                                                    allowable /ə laυəb(ə)l/ adjective per-

may not fly over a city below such a                                      |

height as would allow it to alight in the           mitted or authorised maximum allow-
event of an engine failure.                         able weight maximum allowable tyre
align /ə lan/ verb 1. to position along

                                                    allowance /ə laυəns/ noun 1. consid-
            |                                       allowance

an axis or line The nose wheel must be                                        |

aligned in a fore and aft direction dur-            eration for possibilities or changing cir-
ing retraction. 2. to set in a correct posi-        cumstances to make allowances for
tion in relation to something else                  to take into account When estimating
Aligned white marks on the wheel and                flight duration, make allowances for
tyre indicate that there is no creep.               taxiing time. 2. something such as
                                                    money given at regular intervals or for a
alignment /ə lanmənt/ noun 1.

                                                    specific purpose a travel allowance to
position in relation to an axis or a line           cover hotel and restaurant bills. 3. the
to check the alignment of something                 amount of something that somebody is
to make sure it is in the correct position          allowed to have
relative to an axis or line to maintain                 ‘…with many four and six seat aircraft, it
alignment with the runway to keep                       is not possible to fill all the seats, use the
the aircraft on the imaginary extended                  maximum baggage allowance, fill all the
centre line of the runway 2. correct                    fuel tanks and remain within the approved
position in relation to something else                  centre of gravity limits’ [Civil Aviation
alloy                                           16
    Authority, General Aviation Safety Sense         a valve.      an alternative means of
    Leaflet]                                         doing something another or different
alloy / lɔ/ noun a mixture of metals
                                                     way of doing something í noun another
        an alloy of aluminium and lithium            choice or possibility In some emer-
                                                     gency situations the pilot may have no
aloft /ə lɒft/ adjective up in the air


                                                     alternative but to force-land the aircraft
alter / ɔ ltə/ verb to change, modify or

                                                     as soon as possible.
adjust If there is a risk of collision,              alternator / ɔ ltənetə/ noun a type

alter course to the right. If the rate of            of generator designed to produce AC
descent is too low, alter the throttle set-          power
ting accordingly. The rudder linkage
                                                     altimeter / ltmi tə/ noun a radio

was altered to comply with certification
requirements.                                        instrument for measuring vertical dis-
                                                     tance or altitude altimeter check a
alteration / ɔ ltə reʃ(ə)n/ noun 1. a

                                                     routine check to ensure that the altime-
change, modification or adjustment It                ter pressure setting is correct altime-
was discovered that alterations had                  ter display the display of altitude infor-
been made to the log book. As a result               mation, which can be given in analogue
of the accident, alterations were made               or digital form. pointer
to the design of the carburettor heat sys-
                                                     altitude / lttju d/ noun the vertical

tem. 2. the act of making changes, mod-
ifications or adjustments         heading            distance between an aircraft, or a point
alteration the act of making of heading              or a level, and mean sea-level to lose
corrections                                          altitude to descend from higher to
                                                     lower altitude cabin altitude the arti-
alternate adjective /ɔ l t nət/ 1.

                                                     ficial altitude created in the cabin by
every other A, c, e, and g are alternate             pressurisation
letters, as are b, d, f, h, etc. alternate
                                                     alto- / ltəυ/ prefix at a moderate or

days every other day There are out-
                                                     high altitude
ward flights on alternate days, i.e. on
                                                     altocumulus / ltəυ kju mjυləs/

Mondays, Wednesdays and Fridays. 2.                                                     |

US same as alternative í noun /ɔ l          |
                                                     noun small white cumulus clouds
 t nət/ an aerodrome of second choice                which form as a layer at moderate alti-
to be used if the aircraft cannot be                 tude, usually meaning fair weather.
landed at the aerodrome of first choice              Compare stratocumulus
                                                     altostratus / ltəυ strɑ təs/ noun a

because of bad weather, etc. The point                                              |

of no return is calculated before depar-             uniform layer cloud at moderate alti-
ture to cover the chance that both the               tude
terminal airfield and its alternate                  aluminium / lə mniəm/ noun a


become unavailable during flight. í                  strong, light metal used in the construc-
verb / ɔ ltənet/ to happen in turns                 tion of aircraft (NOTE: The US English is
Captain Smith and Captain Jones                      aluminum.)
alternate as CFI on a daily rota each                      COMMENT: In recent years, aluminium
captain has one day on duty as CFI fol-                    has been increasingly replaced by the
lowed by a day off, on which the other                     use of composite materials in the
captain acts as CFI                                        construction of different types of
alternating current / ɔ ltənetŋ                          aircraft, from small home-built light
alternating current

                                                           aircraft to transport aircraft such as the
 k rənt/ noun an electric current which                    Airbus A320.
reverses its direction at regular intervals
                                                     aluminum /ə lu mnəm/ noun US

    Resistance to alternating current                                      |

remains almost constant and is inde-                 same as aluminium
pendent of frequency. Abbreviation AC                AMA abbreviation approach monitor-

alternative /ɔ l t nətv/ adjective                  ing aid


                                                     amber / mbə/ adjective an orange or

referring to another or a second possi-
bility A turbine bypass, in the form of              yellow colour An amber light flashes
an alternative exhaust duct is fitted with           on the instrument panel. (NOTE: Amber
                                             17                                 analogue
is often used to describe the colour of           ample / mpəl/ adjective plenty of

the yellow light in traffic signals.)             During the course you will have ample
ambient / mbiənt/ adjective refer-                opportunity to demonstrate your skill.

ring to the surrounding atmospheric               ample time plenty of time
conditions Fresh ambient air is routed            amplification / mplf keʃ(ə)n/


into the cabin. ambient temperature               noun the act of increasing the strength
the temperature outside the aircraft              of an electrical signal Amplification of
ambient pressure / mbiənt
ambient pressure

                                                  the signal increases the volume.
 preʃə/ noun the pressure outside the             amplifier / mplfaə/ noun an elec-

aircraft                                          tronic device for increasing the strength
ambiguity / mb ju ti/ noun

                               |                  of an electrical signal If the power
something heard or seen which can be              supply from the amplifier to the gauge
understood in more than one way, thus             fails, the needle slowly falls to zero.
resulting in possible confusion         to        amplify / mplfa/ verb to increase

avoid ambiguity to avoid misunder-                the strength of an electrical signal An
standing or confusion Correct use of              electric current is amplified and then
R/T phraseology avoids ambiguity.                 transmitted. (NOTE: amplifies – ampli-
ambiguous / m b juəs/ adjective

                           |                      fying – amplified)
able to be understood in more than one            amplitude / mpltju d/ noun the

way It is important that R/T transmis-            maximum variation of a vibration or
sions are not ambiguous.                          oscillation from the position of equilib-
AMD abbreviation amendment

                                                  rium to calculate fuel required, multi-
amend /ə mend/ verb to change,

                   |                              ply the duration of the flight by the con-
update, improve or correct something              sumption of the engine at the required
he amended the entry in his log book              power
he corrected or changed the entry in his          AMS abbreviation aeronautical mobile

log book                                          service
amendment /ə mendmənt / noun a

                                                  AMSL abbreviation above mean sea

change, updating, improvement or cor-             level
rection made, e.g., to a document or
                                                  AMSS abbreviation automatic mes-

procedure       When a terminal aero-
drome forecast requires amendment,                sage switching system
                                                  anabatic / nə b tk/ adjective

the amended forecast is indicated by                                     |

inserting AMD after TAF.                          referring to a warm flow of air travel-
ammeter / mi tə/ noun an instru-
                                                  ling up a hillside or mountainside.
ment for measuring amperes in order to            Compare katabatic
                                                  anabatic wind / nəb tk wnd/
                                                  anabatic wind

give the strength of an electric current
The centre-zero ammeter tells the pilot           noun a wind current, caused by solar
the status of the aircraft battery.               heating of the land, that rises up a south-
amp / mp/ abbreviation ampere
                                                  facing mountainside           South-facing
                                                  slopes are most suitable for the ana-
amperage / mpərd / noun the

                                                  batic wind. Compare katabatic wind
strength of an electric current expressed
                                                  analog / nəlɒ / adjective same as

in amperes Measuring the amperage
of a motor can give a rough estimate of           analogue
                                                  analogous /ə n lə əs/ adjective

the load on the motor.                                               |

ampere / mpeə/ noun a unit of elec-               similar or comparable to Isobars are

tric current equal to one volt flowing            analogous to contour lines.
                                                  analogue / nəlɒ / adjective 1. rep-

through an impedance of one ohm a
13-amp fuse Current flow is measured              resenting a quantity or signal that varies
in amperes. Abbreviation amp                      continuously by means of a physical
ampere hours number of amperes per                apparatus such as a dial and pointer
hour      Battery capacity is rated in            The electronic centralised aircraft mon-
ampere hours.                                     itor (ECAM) does not have analogue
analyse                                     18
presentation of engine information. 2.           aneroid switch / nərɔd swtʃ/
                                                 aneroid switch

analogue display (on a clock) a tradi-           noun a switch operated by an aneroid
tional hands and face display on a clock         capsule
or dial. Compare digital display
                                                 angle / ŋ əl/ noun the difference in

analyse / nəlaz/, analyze verb to

                                                 direction between two lines or surfaces
break down into parts and study very             measured in degrees
closely to analyse fuel to separate
                                                 angle of attack / ŋ (ə)l əv ə t k/
                                                 angle of attack


fuel into its different parts to find out        noun the angle formed between the rel-
what it consists of to analyse a chart           ative airflow and the chord line of the
to examine a chart in detail                     aerofoil
analysis /ə n ləss / noun breaking

                                                     COMMENT: The angle of attack is

down a substance into its parts in order             related to the flight path of the aircraft,
to study them closely At a crash site,               not to the angle the wing makes with
samples of materials are removed for                 the horizontal. If the angle of attack
analysis. (NOTE: The plural form is anal-            becomes too great, the smooth airflow
yses /ə n lsi z/ .)|    chart analysis              over the upper surface of the wing will
careful study of charts                              break down. If no corrective action is
                                                     taken by the pilot, there will be a
anchor / ŋkə/ noun a device con-

                                                     sudden loss of lift and the aircraft will
nected to and dropped from a boat in                 stall.
order to prevent the boat from moving            angle of incidence / ŋ (ə)l əv
                                                 angle of incidence

in the water í verb to drop an anchor to          nsd(ə)ns/ noun the angle formed
prevent the boat from moving                     between the chord-line of the main-
anemograph /ə nemə rɑ f/ noun

                            |                    plane and the horizontal when the air-
an instrument which maintains a contin-          craft is in the rigging position
uous recording of wind direction and             angle of inclination / ŋ (ə)l əv
                                                 angle of inclination

speed on a graph The anemograph                   nkl neʃ(ə)n/ noun the angle formed

gives a continuous recording of wind             between a sloping path or surface and a
velocity which is displayed on a chart           reference point or line which is either
and reveals gusts, squalls and lulls.            horizontal or vertical      Between any
anemometer / n mɒmtə/ noun an

                                |                two meridians there is an angle of incli-
instrument, usually attached to a build-         nation one to the other which varies
ing, with three or four ‘cups’ which             with latitude.
rotate with the wind thus providing              angular / ŋ jυlə/ adjective refer-

wind-speed information The strength              ring to or forming an angle The angu-
of the wind can be seen by the speed             lar difference between the direction of
with which the anemometer rotates.               magnetic north and compass north is
aneroid / nərɔd / adjective not con-            called variation.

taining or using liquid                          anneal /ə ni l/ verb to heat and allow


aneroid barometer / nərɔd bə                    to cool slowly in order to strengthen
aneroid barometer


 rɒmtə/ noun a barometer which uses             Sheet and plate magnesium are
an aneroid capsule to sense atmospheric          annealed at the rolling mill.
                                                 annotate / nətet/ verb to add notes

pressure changes
                               / nərɔd          to an existing document, book, chart,
aneroid capsule

aneroid         capsule
 k psju l/ noun a thin flexible cylin-           etc. He annotated his report after he
drical box, usually made of metal,               was asked to give the exact time of the
which has most of the air removed from           incident. Variation is annotated east
it and which expands and contracts with          or west according to the direction of
changes in atmospheric pressure The              change.
                                                 annotation / nə teʃ(ə)n/ noun the

aneroid capsule in the barometer is                                           |

connected to a system of levers which            act of adding notes to a document,
operate a pointer.                               book, chart, etc., or the notes added
                                              19                                              anti-icing fluid
announce /ə naυns/ verb to state                       Hypoxia is a lack of sufficient oxygen,


something publicly or officially Brit-                 the symptoms of which are sometimes
                                                       difficult to detect.
ish Airways announce the departure of
                                                   antenna / n tenə/ noun US same as

flight BA152 to New York.                                                        |

announcement              / ə naυnsmənt/           aerial


                                                   anti- / nti/ prefix against, opposing

noun a public statement The captain
made a public address (PA) system                  anti-icing                  anticlockwise              anti-corro-
announcement asking passengers to                  sion
remain seated.                                     anticipate / n tspet/ verb to real-


annual / njuəl/ adjective 1. happen-

                                                   ise what is likely happen and do what is
ing once a year annual inspection an               necessary in readiness during take-
inspection that happens once a year 2.             offs, pilots should anticipate an
over a period of one year Overload                 engine failure pilots should think
operations should not exceed 5% of                 ahead and be ready to act immediately
annual departures.                                 if an engine fails during take-off
annular / njυlə/ adjective shaped                  anticipation / n ts peʃ(ə)n/ noun
annular                                            anticipation

                                                                                         |        |

like a ring                                        a state in which you realise what is
annunciation /ən nsi eʃ(ə)n/ noun

                                                   likely to happen and do what is neces-
an announcement or indication on the               sary in readiness
                                                   anticipation of landmarks / n
                                                   anticipation of landmarks

annunciator panel failure annuncia-                                                                                 |

tion signals on the annunciator panel               tspeʃ(ə)n əv l ndmɑ ks/ noun the
indicating the failure of a system                 action of watching out for landmarks,
annunciator /ə n nsietə/ noun a

                                                   which you know from flight planning
device which gives off a sound or light            should be visible at a particular stage of
to indicate which of several electrical            a flight
                                                   anticlockwise          / nti klɒkwaz/

circuits is active      An annunciator                                                                |

panel may contain a precise warning.               adjective, adverb referring to a circular
anode / nəυd/ noun a positive pole
                                                   movement in the opposite direction to
or electrode The positive connector of             the hands of a clock Turn the nut anti-
a battery is usually called the anode              clockwise to loosen it. Opposite clock-
and is indicated by the sign +.                    wise
                                                                       / nti kə l (ə)n/

anodise / nədaz/, anodize verb to
                                                   anti-collision                                             |

coat or cover by using electrolysis                adjective helping to prevent collisions
                                                   anti-collision light / nti kə
                                                   anti-collision light

Anti-corrosion treatment includes the                                                                               |

anodizing of aluminium parts.                       l (ə)n lat/ noun a flashing white light
anomalous /ə nɒmələs/ adjective

                                                   on an aircraft
                                                   anti-corrosion / nti kə rəυ (ə)n/

referring to something unusual, unex-                                                                     |

pected or otherwise departing from                 adjective protecting against corrosion,
what is the normal order or range an               especially rust                           an anti-corrosion
anomalous instrument reading an                    treatment
unusual instrument reading which may               anticyclone / nti sakləυn/ noun


require further investigation                      an area of high atmospheric pressure,
anomaly /ə nɒməli/ noun something                  usually associated with fine dry weather


unusual, unexpected or otherwise not               in summer and fog in winter Winds
within the normal order or range Any               circulate round an anticyclone clock-
anomalies in the localiser will be                 wise in the northern hemisphere and
detected during calibration.                       anticlockwise in the southern hemi-
anoxia / nɒksiə / noun a state in

                                                   anti-icing / nti asŋ/ adjective

which no oxygen reaches the body tis-
sues, resulting in death. hypoxia                  preventing icing anti-icing additive
                                                   anti-icing fluid / nti asŋ flu d/
                                                   anti-icing fluid

    COMMENT: Anoxia is a complete lack
    of oxygen and can, of course, be fatal.        noun a fluid which prevents icing
anti-skid                                    20
anti-skid / nti          skd/ adjective          applicable /ə plkəb(ə)l/ adjective 1.
anti-skid                                         applicable


designed to prevent skidding                      relevant or appropriate rule 24 is not
anvil / nvl/ noun a metal block
                                                  applicable in this case rule 24 cannot
which ends in a point, has a rounded              be used in this case 2. suitable, neces-
bottom and a flat top, and on which               sary, appropriate Emergency systems
horseshoes, etc., are made A cumulo-              are checked when applicable.
                                                  application / pl keʃ(ə)n/ noun 1.

nimbus cloud has a characteristic anvil                                              |

shape.                                            a formal request, often on paper, for
anvil cloud / nvl klaυd/ noun a
anvil cloud
                                                  employment application form a form
cloud, usually a large dark thunder-              to be filled out by a person looking for a
cloud, which has the shape of an anvil            job, and sent back to the organisation
A/P                                               offering the job 2. the act of putting a
A/P abbreviation 1. airport 2. autopilot          substance onto something the appli-
apart /ə pɑ t/ adverb separated from

              |                                   cation of a coat of paint the covering
one another The jets were only 200                of something with a coat of paint 3. the
feet apart, vertically.                           act of using something, e.g. an ability,
aperture / pətʃə/ noun an opening
                                                  to carry out a task When an accident
   Any aperture or cut-out in the fuse-           occurs, the application of knowledge
lage structure must be specially                  and skills is important.
                                                  apply /ə pla/ verb 1. to apply for a

strengthened.                                                    |


APHAZ abbreviation aircraft proxim-               job to formally ask for employment
ity hazard                                        He applied for the post of chief engineer
APP                                               but was not successful. 2. to put on to
APP abbreviation 1. approach 2.                   apply a coat of paint Apply a plaster
approach control                                  to the skin. 3. to use something to carry
apparent /ə p rənt/ adjective 1.

                          |                       out a task Apply the same method as
obvious, clear      It became apparent            in the example. 4. to be relevant or relate
that carbon monoxide was entering the             to The rules which apply to the meas-
cabin.     from the above, it will be             urement of wind velocities on isobaric
apparent that … from the above, it                charts apply equally to contour charts.
will be clear that … 2. seeming or                (NOTE: applying – applied)
appearing to be an apparent failure of            appreciable /ə pri ʃəb(ə)l/ adjective


the system The ILS showed an appar-               1. possible to measure   Appreciable
ent deflection to the right.                      weakening may be permitted without
appear /ə pə/ verb 1. to come into

                  |                               risk of failure. 2. considerable, large in
view Another aircraft appeared on the             size or amount there is an apprecia-
radar screen. 2. to seem to be                    ble difference between statute miles
Although air may appear to be still, it is        and nautical miles there is a big differ-
in fact, moving.                                  ence between statute miles and nautical
appearance /ə pərəns/ noun 1. an

                                                  appreciate /ə pri ʃiet/ verb 1. to

instance of being seen or coming into                                    |

view The appearance of the passen-                understand or recognise the importance
ger on the flight deck surprised the              or significance of something The map
crew. 2. the way something looks It               reader is in a position to appreciate the
may be difficult to recognise a particu-          relative values of the features seen on
lar stretch of coast in an area simply by         the ground. 2. to increase in value The
its appearance.                                   value of the building has appreciated by
appendix /ə pendks/ noun a section

                                                  100% in 10 years. Opposite depreciate
containing additional information,                3. to be thankful or grateful for some-
often found at the end of a book, etc.            thing     The student appreciated the
Charts are reproduced as an appendix              extra help given by the instructor.
                                                  appreciation /ə pri ʃi eʃ(ə)n/ noun

to the map section. (NOTE: The plural                                            |       |

form is appendices.)                              1. understanding It is essential to have
                                                 21                                                   APRX
an appreciation of the basic gas laws. 2.             approach to land, the aircraft reduces
an increase in value There has been an                speed and height
appreciation of 100% in the value of the              appropriate /ə prəυpriət / adjective


building in 10 years. Opposite depreci-               suitable or needed           appropriate
ation 3. thankfulness, gratitude After                action the action that is needed to deal
gaining her private pilot’s licence, the              with the situation
newly-qualified pilot showed her appre-               appropriately

                                                                                 /ə prəυpriətli/

ciation by sending a letter of thanks to              adverb in a way that it is suitable or nec-
her instructor.                                       essary to adjust the mixture appro-
approach /ə prəυtʃ/ noun 1. a path

                          |                           priately to adjust the mixture to suit the
towards something The approach to                     conditions
the terminal was blocked by an over-                  approval /ə pru v(ə)l/ noun permis-


turned lorry. 2. the descent of an air-               sion or agreement with the captain’s
craft towards the place where it intends              approval with the permission of the
to land. Abbreviation APP 3. a way of                 captain to meet with the approval to
achieving or doing something to take                  be approved by The management’s
a different approach to a situation to                plans for restructuring the airline met
deal with or to manage a situation in a               with the approval of the shareholders.
different way í verb 1. to move nearer                approve /ə pru v/ verb 1. to allow or


in place or time to something The air-                agree to something The air traffic con-
craft is approaching a danger area.                   troller approved the emergency land-
nightfall is approaching it will soon be              ing. 2. to approve of to believe some-
dark 2. to have a particular mental atti-             thing to be right or good           Nearly
tude towards something                 He             everybody approved of the new colour
approaches his studies with great                     scheme for the furnishings.             he
enthusiasm. 3. to speak to or get in                  doesn’t approve of women being air-
touch with somebody            You must               line pilots he believes that it is wrong
approach the chief flying instructor                  for women to be airline pilots
regarding your request for a week’s hol-
                                                      approx /ə prɒks/ same as approxi-

iday.                                                                 |

                                                      mate, approximately
approach control /ə prəυtʃ kən
approach control

                                                      approximate                         /ə
                                  |          |        approximate

 trəυl/ noun a control station in an air

traffic control centre that guides an air-             prɒksmət/ not exact, around or about
craft while it is making its approach                   an approximate distance of 60 nm
                                                      about 60 nautical miles í verb /ə                  |

approach monitoring aid /ə
approach monitoring aid

                                                       prɒksmet/ to be close to, to be
 prəυtʃ mɒntərŋ ed/ noun an                        around (NOTE: Approximate can be
instrument or system that helps an air                shortened to approx or APRX (ICAO).)
traffic controller to track the position              approximately

                                                                             /ə prɒksmətli/

and movements of an aircraft during its               adverb not exactly, around or about
approach. Abbreviation AMA                            Approximately 2,000 people work in the
approach path /ə prəυtʃ pɑ θ/
approach path

                              |                       airport. (NOTE: Approximately can be
noun the course taken by the aircraft in              shortened to approx or APRX (ICAO).)
preparation for landing                               approximation /ə prɒks meʃ(ə)n/

                                                                                      |           |
approach plate

approach plate noun a document                        noun a calculation which is not exact
issued by an aviation authority which                 but near enough, a rough estimate an
provides detailed information about                   approximation of aircraft height a
how to land at a given airport in very                rough estimate of aircraft height
poor visibility                                       apron / eprən / noun an area of tar-

approach to land /ə prəυtʃ tə                         mac, concrete, etc., outside a hangar for
approach to land


 l nd/ noun the final stage of the flight             parking aircraft (NOTE: The US term is
when the aircraft is manoeuvred into                  ramp.)
                                                      APRX abbreviation (ICAO) 1. approxi-

position, relative to the landing area, in
preparation for landing           on the              mate 2. approximately
APU                                           22
APU abbreviation auxiliary power unit

                                                   tional standard atmosphere. 2. a verbal
aquaplaning / kwəplenŋ/ noun
                                                   disagreement to have an argument to
sliding in an uncontrolled way over a              disagree openly and verbally with
thin layer of water on the runway                  somebody The investigation revealed
Aquaplaning is caused by a layer of                that there had been an argument
water between the tyre and the runway.             between the commander and the copilot
                                                   about the advisability of continuing
arbitrary      / ɑ btrəri/

                              adjective            with the final approach to land. 3. a rea-
decided by chance rather than by care-             son One of the arguments in favour of
ful logical thought, happening without             building the new terminal is the
planning or at random       The statute            increase in opportunities of employ-
mile is an arbitrary unit of measure-              ment for the local residents.
ment. (NOTE: The nautical mile is not an
                                                   arid / rd / adjective very dry arid

arbitrary unit: it is based on calculations
which have a wider use. See arc.)                  terrain desert an arid, sub-tropical
                                                   climate a hot, dry climate
arc /ɑ k/ noun part of the circumfer-

                                                   arise /ə raz/ verb to come into being,

ence of a circle A nautical mile is the                          |

length of an arc on the Earth’s surface            to happen, to show up or to appear
subtended by an angle of one minute at             Should any problems arise, report back
the centre of the Earth. í verb to jump            to me immediately. (NOTE: arising –
across a gap The spark arcs from one               arose – arisen)
                                                   arm /ɑ m/ noun 1. a device similar in

electrode to another. The condenser
prevents spark plugs from arcing. gap              function to a human arm, operating as a
Arctic / ɑ ktk/ adjective referring to
                                                   lever 2. the horizontal distance from a
the area around the North Pole cold                reference point to the centre of gravity
Arctic air cold air from the Arctic the            The principle of the arm is used in
Arctic Circle a parallel running round             weight and balance calculations for an
the Earth at latitude 66°32N, to the               aircraft. í verb to make ready for action
north of which lies the Arctic region í            or use Door-mounted escape slides
noun      the Arctic the area of the               are armed before flight.
                                                   armature / ɑ mətʃə/ noun the rotat-

Earth’s surface around the North Pole,
north of the Arctic Circle The aircraft            ing coils of an electric motor or dynamo
flew over the Arctic.                                 Secondary windings are wound over
area / eəriə / noun 1. a defined part of
                                                   the primary windings and the whole
a surface 2. a region area forecasts a             assembly is known as an armature.
                                                   ARR abbreviation arrival

weather forecast for a region rather
                                                   arrange /ə rend / verb 1. to organ-

than, e.g., an aerodrome                                                     |

area control service / eəriə kən                   ise, to plan and prepare to arrange a
area control service


 trəυl s vs/ noun a unit that provides            meeting 2. to put in special position
air traffic control services to flights            Charts should be numbered and
within the area for which it is responsi-          arranged in order of use. A series of
ble                                                dipoles are arranged in a circle.
area navigation / eəriə n v                       arrangement /ə rend mənt/ noun
area navigation

   eʃ(ə)n/ a method of navigation that            1. a plan The arrangements for the
permits aircraft to operate on any                 VIPs are being handled by the public
desired flight path within the area cov-           relations department. 2. the relative
ered by ground-based navigational aids,            positions of a number of different parts
self-contained navigational aids or a                The diagram shows a simple arrange-
combination of the two. Abbreviation               ment of pistons, cylinders and pipes.
                                                   array /ə re/ noun an arrangement of

RNAV                                                                 |

argument / ɑ jυmənt/ noun 1. a                     antennas The localiser antenna array

factor QNH is the pressure at station              is very wide.
                                                   arrest /ə rest/ verb 1. to stop or to pre-

level reduced to sea level using argu-                                   |

ments of station height and an interna-            vent something from happening to
                                                     23                                          assess
arrest the spread of a fire to stop the                   forced, precipitation is mostly light and
fire spreading 2. to hold somebody for                    occasionally moderate.
breaking the law He was arrested at                       ascertain / sə ten/ verb to find


the airport. í noun the act of holding                    out, to make certain During pre-flight
somebody for breaking the law His                         checks, control surfaces should be
arrest was unexpected.                                    moved by hand to ascertain that they
arrester /ə restə/ noun a device or

                                         |                have full and free movement.
substance which prevents or stops                         ASDE abbreviation airport surface

something from happening                                  detection equipment
arrival /ə rav(ə)l/ noun the act of

                                                          ASI abbreviation airspeed indicator

reaching somewhere. Abbreviation                          ASMI abbreviation aerodrome surface

ARR Gulf Air announce the arrival                         movement indicator
of flight GF147 from Abu Dhabi
                                                          aspect / spekt/ noun 1. a part of a

flight GF147 from Abu Dhabi has just
landed                                                    problem or subject Vertical motion is
                                                          an important aspect of meteorology.
arrivals /ə rav(ə)lz/ noun the part of

                                                          safety aspects matters related to safety
an airport that deals with passengers                     2. the view from a particular position
who are arriving                                          The aspect of the runway on final
arrive /ə rav/ verb to reach some-

                                                          approach helps the pilot to judge height
where the flight from Tokyo arrived                       and progress.
at 8.30 the flight from Tokyo landed at                   aspect ratio / spekt reʃiəυ/ noun
                                                          aspect ratio

8.30                                                      the ratio of the length of an aircraft’s
arrow / rəυ/ noun a painted or

                                                          wing to the average distance between
printed sign which points to something                    the front and back edge of the wing
  Non-return valves are marked with an                    (NOTE: Aircraft that operate at low
arrow which shows the direction of                        speeds, for example gliders, need a
flow.                                                     high aspect ratio and have long narrow
arrow convention / rəυ kən
arrow convention

                                                 |        wings. Supersonic aircraft need a low
 venʃ(ə)n/ noun an agreed method of                       aspect ratio, which is created by swing-
using arrows when drawing wind trian-                     ing the wings back.)
gles                                                      asphyxiation           /əs fksi eʃ(ə)n/

                                                                                         |   |

article / ɑ tk(ə)l/ noun an object, an

                                                          noun unconsciousness or death caused
item loose articles things which may                      by lack of oxygen Fire may result in
move during flight and cause problems                     the cabin being filled by smoke causing
artificial / ɑ t fʃ(ə)l/ adjective not                  asphyxiation.


                                                          ASR / e es ɑ / abbreviation 1. airport

natural, made by humans The small
needle indicates cabin altitude or the                    surveillance radar 2. altimeter setting
artificial altitude created by the pres-                  region
surisation system.                                        assemble /ə semb(ə)l/ verb 1. to put


artificial horizon / ɑ tfʃ(ə)l hə
artificial horizon

                                                 |        a number of parts together The parts
 raz(ə)n/ noun an instrument that dis-                   are made in different countries but the
plays the degree of pitch or bank of an                   plane is assembled in France. 2. to
aircraft relative to the horizon                          gather together       Passengers should
ascend / ə send / verb to rise, to go or                  assemble in the departure lounge where


move upwards Hot air ascends. in                          an airline representative will meet
ascending order in order of number or                     them.
                                                          assembly /ə sembli/ noun 1. some-

rank with the smallest or less important                                         |

at the bottom and the largest or more                     thing that is made up of smaller parts 2.
important at the top. Opposite descend                    the act of putting parts together to make
ascent /ə sent/ noun a rise, a slow                       a whole Final assembly of the A320


upward movement the forced ascent                         takes place in France.
                                                          assess /ə ses/ verb to check, estimate

of air over high ground In a stable                                      |

atmosphere where the ascent of air is                     or find out Cabin crew must assess if
assessment                                    24
their exits are usable. to assess a sit-           that the return flight from the point of no
uation to consider all aspects of a situ-          return to A is made on three engines,
ation                                              calculate the distance from D to the
assessment /ə sesmənt/ noun a

                                                   point of no return. 3. to take on, to
judgement on a situation based on care-            undertake the duties of somebody The
ful thought The captain’s assessment               copilot assumed control of the aircraft
of factors such as aircraft damage, pas-           after the captain was taken ill during
senger-load, fire, etc., will affect the           the flight. 4. to take a particular bodily
decision on whether to evacuate the                position      The correct technique of
aeroplane or not.                                  using the escape slides is to assume a
                                                   sitting position.
assign /ə san/ verb to set apart


                                                   assumption /ə s mpʃ(ə)n/ noun an

beforehand or allocate for a specific                                              |

purpose assigned seats seats selected              understanding or belief The one-in-
beforehand for particular people Crew              sixty rule is based on the assumption
sit in their assigned seats. Individual            that one nautical mile subtends an
carriers assign codes to aircraft.                 angle of one (at a distance of 60 nauti-
                                                   cal miles).
assist /ə sst/ verb to help If you


                                                   asymmetric / s metrk/, asym-

have any difficulty, cabin staff will                                                      |

assist you. When evacuating the air-               metrical / s metrk(ə)l/ adjective

craft, hand signals by cabin staff assist          not identical or equal on each side of an
in directing passengers to the exits.              imaginary central dividing line. Oppo-
power                                              site symmetric
assistance /ə sst(ə)ns/ noun help                 asymmetric flight / smetrk
                                                   asymmetric flight


to require assistance to need help If               flat/ noun a condition in which one
a pilot requires assistance, they should           engine, displaced from the aircraft’s
contact ATC. to provide assistance to              centre-line is not working
give help                                          asymmetric power / smetrk
                                                   asymmetric power

associate /ə səυsiet/ verb to come                 paυə/ noun power on one side of the


with or be linked to something else                aircraft’s centre line only
Turbulence is often associated with                asynchronous /ə sŋkrənəs/ adjec-


strong winds. The airport authority                tive 1. not happening at the same time or
has to overcome a lot of problems asso-            rate An asynchronous orbit is a 24-
ciated with its plans to build a new ter-          hour orbit which enables a satellite to
minal.                                             remain overhead one part of the Earth’s
association /ə səυsi eʃ(ə)n/ noun

                                  |       |        surface. 2. not in frequency or phase
1. a group of people who organise                  asynchronous computer /e
                                                   asynchronous computer


themselves into an official body with               sŋkrənəs kəm pju tə/ noun a com-

common objectives and a code of con-               puter which does not process informa-
duct British Air Line Pilots Associa-              tion according to the internal clock
tion. 2. in association with together
                                                   ATA / e ti e/ abbreviation actual

with Rain-ice occurs only rarely over
the British Isles and is usually found in          time of arrival
                                                   ATC / e ti si / abbreviation 1. air

association with warm fronts.
assume /ə sju m/ verb 1. to take as

                                                   traffic control 2. air traffic controller

true before there is proof I assume                ATCC abbreviation air traffic control
that she’s ill because she’s not at work           centre
today – but I may be wrong. 2. to sup-             ATCRU

                                                   ATCRU abbreviation air traffic control
pose for our studies we will assume                radar unit
that the earth is a perfect sphere we
                                                   ATD / e ti di / abbreviation actual

know that the Earth is not a perfect
sphere but it helps if we accept, for the          time of departure

time being, that it is assuming (that)             ATFM abbreviation air traffic flow
accepting or supposing that Assuming               management
                                                                       25                                                  attenuate
ATIS abbreviation Automatic Terminal                                        ATPL abbreviation Airline Transport
ATIS                                                                        ATPL

Information Service                                                         Pilot’s Licence
ATM / e ti em/ abbreviation air traf-                                      ATS abbreviation air traffic services
ATM                                                                         ATS

fic management                                                              ATSU abbreviation air traffic service

atmosphere / tməsfə/ noun 1. a                                             unit

                                                                            attach /ə t tʃ/ verb to join or fix

mixture of gases in a mass surrounding                                                             |

the earth The surrounding atmosphere                                        something to something           The ice
moves with the earth. 2. a unit of meas-                                    detector is attached to the fuselage.
urement of pressure                                                         attachment /ə t tʃmənt/ noun 1.


       COMMENT: The main gases found in                                     the act of joining or fixing something to
       the atmosphere are nitrogen and                                      something The attachment of winglets
       oxygen. The atmosphere contains less                                 improved the handling characteristics
       than 1% carbon dioxide and argon,                                    of the aeroplane. 2. an accessory which
       and also traces of hydrogen, helium,                                 can be attached The video camera is
       krypton, neon, ozone and xenon.
                                                                            sold with a number of attachments
atmospheric / tməs ferk/ adjec-

                                                      |                     including a carrying strap and a battery
tive referring to the atmosphere                                            pack.
atmospheric density                                                         attachment point /ə t tʃmənt
                                                                            attachment point


                                                                            pɔnt/ noun a place on the airframe
atmospheric attenuation

atmospheric                                           attenuation
/  tməsferk ə tenju eiʃ(ə)n/ noun
                              |               |                             where something such as an engine is
the weakening of a radio signal as it                                       attached by means of bolts Additional
passes through the air                                                      strength is required for the power plant
atmospheric pollution

atmospheric                                               pollution         attachment points.
   tməsferk pə lu ʃ(ə)n/ noun same                                         attain /ə ten/ verb to reach, to achieve

/                                 |

as air pollution Solid particles in the                                     something, often with difficulty       In
air include dust, sand, volcanic ash and                                    order to attain a fuller understanding of
atmospheric pollution.                                                      gas turbines, it is essential to know
atmospheric pressure

atmospheric                                               pressure          something about basic gas laws.
   tməsferk preʃə/ noun normal air                                         attempt /ə tempt/ noun a try Any

/                                                                                                      |

pressure on the surface of the earth                                        attempt to increase range by applying
atmospheric refraction                                                      more power is of little or no benefit. í
atmospheric                                               refraction        verb to try      He attempted to land
/   tməsferk      r fr kʃən/      noun
                                                                            despite the poor visibility but then

change in direction of waves due to var-
                                                                            decided to divert to another airfield
iations in temperature, pressure and
                                                                            where he landed safely.
humidity, particularly at lower altitudes
                                                                            attendant /ə tendənt/ adjective

atom / təm/ noun the smallest
atom                                                                                                               |

                                                                            accompanying something else Fuel
amount of a substance which can take                                        spillage and attendant fire risk must be
part in a chemical reaction An atom                                         minimised. attendant problems asso-
consists of a nucleus and electrons.                                        ciated problems í noun a person
atomic /ə tɒmk/ adjective referring

                                                                            employed to help members of the pub-
to atoms atomic structure of matter                                         lic
the structure of materials and sub-                                         attention /ə tenʃən/ noun the ability


stances at their smallest level                                             or power to concentrate on something
atomisation / təma zeʃn/, atomi-

                                                  |                         The crew’s attention is alerted by an
zation / təma zeʃ(ə)n/ noun the     |                                     automatic display. attention please
reduction of liquids to a fine spray The                                    listen carefully to what will be said
fuel achieves fine atomisation under                                        pay attention listen to the speaker and
pressure.                                                                   concentrate on what is being said
atomise / təmaz/, atomize verb to                                          attenuate /ə tenjuet/ verb to lose
atomise                                                                     attenuate


reduce liquids to a fine spray The fuel                                     power or strength A wave becomes
must be atomised or vaporised to com-                                       attenuated or loses strength as range
bine with the air to permit combustion.                                     increases.
attenuation                                             26
attenuation /ə tenju eʃ(ə)n/ noun                           something      The attraction of flying

                                                |   |

loss of strength Atmospheric attenua-                        was the factor which made him decide
tion is negligible until the upper end of                    to train as a pilot.
the UHF band when it increases rapidly                       attractive /ə tr ktv/ adjective 1.


to limit the highest usable frequency to                     referring to something you feel you
about 10 GHz.                                                would like to have After long talks, the
attenuative /ə tenjuətv/ adjective

                                            |                prospective buyer made a financially
becoming weaker Rain has an attenu-                          attractive offer for the aircraft. 2. nice
ative effect.                                                to look at
attitude / ttju d/ noun 1. the posi-

                                                             ATZ abbreviation aerodrome traffic

tion of the aircraft in the air in relation                  zone
to the horizon Angle of attack will                          audible / ɔ db(ə)l/ adjective possible

vary with changes in engine speed and                        to hear      The fire detection system
aircraft attitude. nose down attitude                        should contain an audible warning
the attitude of the aircraft when the nose                   device.
is at a lower level than the tail 2. a way
                                                             audio / ɔ diəυ/ noun an audible sound

of thinking and feeling about or of
behaving towards something or some-                          or sound signal The diagram shows an
body he has an excellent attitude                            amplitude modulation case where the
towards his training programme he is                         lower frequency of the audio is about
positive and motivated in his training                       300 Hertz.
                                                             augment /ɔ ment/ verb to make

programme                                                                            |

attitude heading reference sys-
attitude heading reference system
                                                             larger by adding something The sea
tem / ttju d hedŋ ref(ə)rəns                               breeze may augment the up-slope
 sstəm/ noun full form of AHRS                              motion of an anabatic wind.
                indicator / ttju d                          aural / ɔ rəl/ adjective referring to

attitude indicator

 ndketə/ noun a flight instrument                         hearing The aural and visual alerts
that gives the pilot information about                       will continue until the crew take action
the position of the aircraft in the air in                   to cancel them. (NOTE: Aural is some-
relation to the horizon In light air-                        times pronounced / aυrəl/ to show the
craft, the attitude indicator is situated                    difference with oral.)
on the instrument panel, directly in                         authorise / ɔ θəraz/, authorize verb

front of the pilot. pitch, bank                              to allow officially, to give permission
    COMMENT : The attitude indicator is                      A signature is required to authorise the
    sometimes referred to as the ‘artificial                 repair.
    horizon’. In instrument flight training,
                                                             authorised / ɔ θərazd/, authorized

    the attitude indicator is the primary
    reference instrument. It is positioned                   adjective officially allowed, permitted
    on the instrument panel directly in front                Aircraft with a maximum authorised
    of the pilot.                                            weight of 12,500 lb or less.            an
attract / ə tr kt/ verb 1. to cause to

                                                             authorized person a person who has
draw near If two magnets, with unlike                        been given power to act and perform
poles are brought together, they will                        particular tasks or duties
                                                             authoritative /ɔ θɒrtətv/ adjec-

attract each other. to attract atten-                                                    |

tion to behave in such a way that people                     tive in the manner of somebody with
will notice you 2. to cause people to                        authority, in a commanding way crew
want to have or do something                                 must act in an authoritative manner
attraction /ə tr kʃən/ noun 1. a

                                                             crew must give firm instructions or
force that draws things towards some-                        orders
                                                             authority /ɔ θɒrti/ noun 1. com-

thing The strength of the magnetic                                               |

force will depend, amongst other                             plete control or power over something
things, on the magnitude of attraction at                    While boarding, the captain has the
the magnetic source. 2. a quality that                       authority to ask an unruly passenger to
causes people to want to have or do                          leave the aircraft. 2. an official or gov-
                                                                            27                                                      average
ernment body with the power to make                                              gives pilots the current weather, runway
decisions                                                                        in use, etc. Students listen to the ATIS
auto- /ɔ təυ / prefix automatic or auto-                                         to practise their language skills. Abbre-

mated                                                                            viation ATIS
autogiro / ɔ təυ d arəυ/ noun an                                                automation / ɔ tə meʃ(ə)n/ noun

aircraft that uses a propeller to produce                                        the automatic operation or automatic
forward motion and has an unpowered                                              control of a piece of equipment, a proc-
horizontal rotor for lift and stability                                          ess, or a system         Automation has
autoland / ɔ təυl nd/ abbreviation
                                                                                 speeded up baggage handling. Auto-
automatic landing                                                                mation of throttle control has removed
automate / ɔ təmet/ verb to make
automate                                                                         the need for pilots to monitor airspeed
e.g. a device or procedure automatic                                             so closely. It is possible that the alter-
automated systems systems which                                                  nate source might provide a reduced
have been made less dependent on                                                 level of automation.
                                                                                 autopilot / ɔ təυpalət / noun a sys-

direct human control or management
automatic / ɔ tə m tk/ adjective 1.

                                                                                 tem which automatically stabilises an
done without needing to think In the                                             aircraft about its three axes, restores the
early stages of training, student pilots                                         original flight path following an upset
have to think about the use of the flying                                        and, in some systems, causes the air-
controls, but after a while these actions                                        craft to follow a preselected airspeed,
become automatic. 2. which works by                                              altitude or heading. Full form auto-
itself without the need of an operator                                           matic pilot. Abbreviation A/P
                                                                                 auxiliary /ɔ zliəri/ adjective sec-

The normal activation method is auto-                                                                       |

matic.                                                                           ondary, which is used when necessary
automatic dependent surveil-
automatic dependent surveillance
                                                                                 to help or substitute for something else
lance / ɔ təm tk d pendənt sə                                                  auxiliary gearbox /ɔ zliəri ə
                                                                                 auxiliary gearbox

                                                                                                                                |         |
                                                      |                 |

 veləns/ an electronic surveillance sys-                                         bɒks/ noun a gear box which allows
tem that uses data that aircraft provide                                         main engine power to be used for sec-
automatically via a datalink and is able                                         ondary systems
                                                                                 auxiliary power unit /ɔ zliəri
                                                                                 auxiliary power unit

to identify and track the aircraft                                                                                                   |

automatic direction finder

                                         direction             finder             paυə ju nt/ noun a small jet engine
/ ɔ təmetd da rekʃ(ə)n fandə/             |
                                                                                 used to generate electrical power for
noun a radio navigation instrument that                                          air-conditioning, etc., when the aircraft
receives signals from non-directional                                            is parked on the ground. Abbreviation
radio beacons The needle on the ADF                                              APU
indicator points toward the selected                                             auxiliary rotor /ɔ        zliəri rəυtə/
                                                                                 auxiliary rotor


radio signal. Abbreviation ADF                                                   noun the tail rotor of a helicopter
automatic landing / ɔ təm tk                                                    availability /ə velə blti/ noun the
automatic landing                                                                availability

                                                                                                                |       |

 landŋ/ noun automatic flight control                                           fact of being available The status of an
system capable of landing an aircraft                                            airport is determined by the availability
‘hands-off.’ Abbreviation autoland                                               of suitable navigation aids.
automatic                                mixture              control            available /ə veləb(ə)l/ adjective
automatic mixture control


/ ɔ təm tk mkstʃə kən trəυl/ noun                       |
                                                                                 ready for immediate use On a multi-
a subsystem in a piston engine which                                             engine aircraft, all the fuel must be
adjusts the flow of fuel to balance                                              available for use by any engine.
changes in air density                                                           average / v(ə)rd / adjective refer-

automatic        pilot     / ɔ təm tk
automatic pilot

                                                                                 ring to an average For load sheet pur-
 palət/ noun full form of autopilot                                             poses, an average weight of the passen-
Automatic Terminal Information
Automatic Terminal Information Service

                                                                                 gers and crew members may be used. í
Service / ɔ təm tk t mn(ə)l                                                    noun the total divided by the number of
 nfə meʃ(ə)n s vs / noun a record-
                  |                                                              items added The average of 1, 5, 9, 10
ing of information played continuously                                           and 15 is 8 (1+5+9+10+15 = 40 ÷ 5 =
on a specified radio frequency which                                             8). í verb to reach a particular figure as
avert                                                          28
an average Brake temperatures aver-                                 pilot should be aware of the positions of
age around 500°C during normal oper-                                all other aircraft in the circuit.
ations.                                                             awareness /ə weənəs/ noun the


avert /ə v t/ verb to avoid To avert

                           |                                        state of being aware or conscious of
a collision, he changed direction.                                  something safety awareness the state
AVGAS / v s/ abbreviation avia-                                     of being familiar with and prepared for

tion gasoline                                                       any situation in which safety is impor-
aviation / evi eʃ(ə)n/ noun flying

                                                                    AWR abbreviation airborne weather

an aircraft Wind speeds in aviation are
usually given in knots.                                             radar
aviation gasoline / evieʃ(ə)n                                     axial / ksiəl/ adjective referring to an
aviation gasoline

    səli n/ noun fuel used in piston-                               axis
engined aircraft. Abbreviation AVGAS                                axial flow compressor / ksiəl
                                                                    axial flow compressor

aviation law / evi eʃ(ə)n lɔ / noun                               fləυ kəm presə/ noun a compressor in
aviation law


the laws relating to flying                                         which the flow of air is along the longi-
aviation routine weather report
aviation routine weather report
                                                                    tudinal axis of the engine In spite of
/ evieʃ(ə)n ru ti n weθə r pɔ t/                        |
                                                                    the adoption of the axial flow type com-
noun a weather report issued regularly                              pressor, some engine retain the centrif-
at intervals of an hour or half an hour                             ugal type.
                                                                    axis / kss/ noun 1. an imaginary

describing weather conditions at an air-
port. Abbreviation METAR                                            line around which a body rotates The
aviator / evietə/ noun a person who
                                                                    Earth rotates around its own axis. An
flies aircraft                                                      aircraft moves around three axes – ver-
                                                                    tical, longitudinal and lateral. pitch,
avionics / evi ɒnks/ noun elec-


                                                                    roll, yaw 2. a horizontal or vertical scale
tronic communication, navigation, and                               on a graph, often referred to as the X
flight-control equipment of an aircraft                             axis, the horizontal axis, and the Y axis,
The trainee engineer is doing an avion-                             the vertical axis The plot shows the
ics course. Full form aviation elec-                                effect of airspeed on lift with airspeed
tronics                                                             shown on the horizontal axis and lift on
avoid /ə vɔd/ verb 1. to prevent

                                                                    the vertical axis. (NOTE: The plural form
something from happening She just                                   is axes.)
managed to avoid an accident. 2. to                                 axle / ksəl/ noun a shaft on which a

keep away from something Avoid fly-                                 wheel is mounted Unequal tyre-pres-
ing close to any person or vessel.                                  sures, where two wheels are mounted on
Cumulonimbus clouds and thunder-                                    the same axle, will result in one tyre
storms should be avoided by as great a                              carrying a greater share of the load
distance as possible.                                               than the other. (NOTE: The wheel either
avoidance /ə vɔd(ə)ns/ noun an act

                                                                    turns round the axle or is fixed to the
of avoiding something avoidance of                                  axle.)
thunderstorms is recommended it is
                                                                    azimuth / zməθ/ noun the horizon-

recommended to keep away from thun-
                                                                    tal angle or direction of a compass bear-
                                                                    ing Where precision approach radar
await /ə wet/ verb to wait for Await

                                                                    is installed, the controller can inform
instructions from the flight deck.                                  the pilot if they depart from either the
aware /ə weə/ adjective knowing and

                                   |                                extended centre-line in azimuth or
being conscious of something       The                              height or both.
back /b k / verb (of the wind) to               free There is an accompanied bag-

change direction in an anticlockwise            gage allowance of 18 kilos.
                                                baggage          handling / b d
                                                baggage handling

direction. Opposite veer
backup / b k p/ adjective, noun a
                                                 h ndlŋ/ noun the process by which
second or third system, instrument or           passengers’ baggage is loaded onto an
computer disk available to be used if the       aircraft, or unloaded and moved to the
first one fails The backup system or            airport terminal
                                                balance / b ləns/ noun 1. a state in

the backup failed as well. Backup gen-
erators are driven by the engine.               which weight, force or importance are
                                                evenly distributed The propelling noz-
backward / b kwəd / adjective

                                                zle size is extremely important and must
directed towards the back a backward            be designed to obtain the correct bal-
movement                                        ance of pressure, temperature and
backwards / b kwədz/ adverb

                                                thrust. 2. the act of staying steady í
towards the back Unlike most aircraft,          verb 1. to be opposite and equal in
the C130 can move backwards using its           weight, force or importance to some-
own power. (NOTE: The US English is             thing else The pressure exerted by the
backward.)                                      weight of the atmosphere above the
backwash / b kwɒʃ/ noun a back-
                                                level of the bowl balances a column of
ward flow of air produced by an aircraft        mercury in the tube. 2. to stay steady,
propeller or jet engine                         especially when resting on the centre of
baffle / b f(ə)l/ noun a metal plate for

preventing the free movement of sound            ‘…balance refers to the location of the
                                                 centre of gravity along the longitudinal
or liquids Integral fuel tanks can be            axis of the aeroplane’ [Civil Aviation
strengthened by fitting baffle plates.           Authority, General Aviation Safety Sense
baggage / b d / noun luggage,

cases and bags which you take with you          ball /bɔ l/ noun in an inclinometer, the

when travelling One passenger had a             round object which indicates if a turn is
huge amount of baggage. She lost one            coordinated to step on the ball to cor-
piece of baggage. (NOTE: The word lug-          rect a skid or a slip by putting pressure
gage is also used in British English.)          on the rudder on the side to which the
baggage hall an area where arriving             ball in an inclinometer has moved dur-
passengers pick up their baggage                ing a turn. If the ball has moved to the
carry-on baggage small bags of lim-             left, the turn can be corrected by putting
ited size and weight that passengers are        pressure on the left rudder, and vice
allowed to take with them into the cabin        versa.
of an aircraft                                  balloon /bə lu n/ noun a large bag


baggage allowance / b d ə
baggage allowance

                                            |   inflatable with hot air or gas to provide
 laυəns/ noun the weight of baggage             lift, but without power Balloons are
each air passenger is allowed to take           sent into the upper atmosphere to col-
BALPA                                        30
lect information useful to meteorolo-             can be a dangerous barrier to flight. 2.
gists.                                            something that prevents a person from
BALPA / b lpə/ abbreviation British               making progress His medical prob-

Air Line Pilots Association                       lems were a barrier to his successful
band /b nd / noun 1. a narrow strip
                                                  completion of the course.
                                                  base /bes/ noun the bottom part or

A jet stream is a narrow band of high-
altitude strong winds. 2. a range of              lowest part í verb to develop or develop
numbers or frequencies between two                something from something else The
limits within a radio system                      operation of the auxiliary power unit is
bandwidth / b ndwdθ/ noun the
                                                  based on the gas turbine engine. The
width of a band of radio frequencies              principle of vapour cycle cooling is
The sharp setting means the bandwidth             based upon the ability of a refrigerant
is reduced to one kilohertz to minimise           to absorb heat.
                                                  base leg / bes le / noun the part of
                                                  base leg

noise or interference.
bank /b ŋk/ verb (of an aircraft) to
                                                  the airfield traffic circuit flown at
rotate or roll around its longitudinal            approximately 90° to the direction of
axis to a particular angle Stresses are           landing, followed by the final approach.
increased when the aircraft banks, turns                 leg
                                                  basic / besk/ adjective referring to

or pulls out of a dive. í noun (of an air-
craft) a rotating or rolling movement             the most important but often simplest
around its longitudinal axis to a particu-        part of something, from which every-
lar angle An attitude indicator gives             thing else is derived This chapter pro-
the pilot pitch and bank information.             vides a basic understanding from which
bar /bɑ / noun 1. a long, straight, rigid         the study of meteorology can develop.

piece of metal The part is made from              basic principle a central or fundamen-
a solid bar of aluminium. 2. (in meteor-          tal idea or theory
                                                  basic area navigation / besk
                                                  basic area navigation

ology) a unit of atmospheric pressure
equal to 1,000 millibars. millibar                 eəriə n v eʃ(ə)n/ noun a standard

barograph / b rə rɑ f/ noun an                    of performance for navigation that

instrument for measuring and recording            requires an aircraft to remain within 5
atmospheric pressure The most com-                nautical miles of the centreline of its
mon type of barograph is that which uti-          course for 95% of the time
                                                  basis / bess/ noun the central and

lises an aneroid capsule mechanically
connected to a pen.                               most important part of something from
barometer /bə rɒmtə/ noun an                     which everything else is derived The


instrument for measuring the atmos-               basis of air navigation is the triangle of
pheric pressure                                   velocities. (NOTE: The plural form is
barometric /b rə metrk/ adjective

                                                  bat /b t/ noun an object shaped like a

referring to a barometer barometric
pressure atmospheric pressure as indi-            table-tennis bat used by a person on the
cated by a barometer                              ground to guide an aircraft when it is
barometric tendency

                              tendency            taxiing or parking
/ b rəmetrk      tendənsi/ noun the              batsman / b tsmən / noun some-

amount of change in pressure with                 body who uses a pair of bats to guide an
increase in altitude                              aircraft when it is taxiing or parking
barrel roll / b r(ə)l rəυl/ noun a                battery / b t(ə)ri/ noun a chemical
barrel roll                                       battery

manoeuvre in which an aircraft turns              device that produces electrical current
completely over sideways while flying             This piece of equipment is powered by 2
along                                             batteries. charger
barrier / b riə/ noun 1. something                bay /be/ noun 1. a space or area in the
barrier                                           bay

such as a wall that prevents the move-            structure of an aeroplane where equip-
ment of something else Elevation of               ment can be located To avoid damage
the ground over which the aircraft flies          to the wheel bay, the nose wheel must be
                                              31                                  beware
aligned in a fore and aft direction dur-           first necessary to convert the relative
ing retraction. 2. a part of the coast that        bearing to a true bearing and then cal-
curves inwards the Bay of Bengal                   culate the reciprocal. 2. a device con-
bayonet fitting / beənt ftŋ/
bayonet fitting
                                                   taining steel balls or needles which
noun a means of attaching something to             allows free rotation of one component
something, in which an object with two             around another
                                                   Beaufort scale / bəυfət skel/ noun
                                                   Beaufort scale

side pins is inserted into a L-shaped slot
in another object on some light-bulbs              scale from 1–12 used to refer to the
Magnetic chip detectors are of the bay-            strength of wind Wind speeds can be
onet type fitting and can be removed               estimated by using the Beaufort scale of
and replaced very quickly.                         wind force.
                                                   belly flop / beli flɒp/ noun same as
                                                   belly flop

beacon / bi kən / noun a light or radio

signal for navigational purposes If the            belly landing
                                                   belly landing / beli l ndŋ/ noun
                                                   belly landing

aircraft turns towards the beacon, sig-
nal strength will increase.                        an emergency landing of an aircraft
beam /bi m/ noun 1. a long thick
                                                   when the wheels have not come down
                                                   belt /belt/ noun 1. a long, relatively

metal bar used as a support A beam is
designed with a breaking load of 12                narrow area high-pressure belt long
tons but when a three ton load is                  narrow area of high pressure precipi-
applied repeatedly, the beam may fail.             tation belt a long narrow area of rain,
2. a shaft of light or radiation travelling        snow or hail rain belt long narrow
in one direction, as from a car’s head-            area where rain falls The cirrus cloud
lights The electron gun produces a                 can be 900 miles ahead of the surface
stream of fast-moving electrons and                front with a rain belt as wide as 200
focuses them into a narrow beam.                   miles. 2. a loop of strong material con-
                                                   necting two pulleys or wheels, one driv-
                                    / bi m
beam sharpening

beam           sharpening                          ing the other
 ʃɑ pənŋ/ noun the process of making
                                                   belt-driven / belt drv(ə)n/ adjec-

a radio or light beam narrower Any
system employing beam sharpening is                tive (of a wheel) moved by a belt linked
vulnerable to side lobe generation at              to another wheel which, in turn, is
the transmitter.                                   moved by a motor or an engine Air-
                                                   craft generators are belt-driven or
bear /beə/ verb 1. to carry or to hold

The undercarriage has to bear the
                                                   belt-driven        generator / belt
                                                   belt-driven generator

weight of the aircraft on the ground.
rain-bearing cloud a cloud carrying                 drv(ə)n d enəretə/ noun a genera-
moisture which can fall as rain 2. to              tor whose pulley is turned by a belt
bear something in mind to keep in                  attached to an engine-driven pulley
                                                   bend /bend/ noun a curve í verb to

mind it should be borne in mind it
should be remembered           bearing in          curve from a straight shape (NOTE:
mind considering         Bearing in mind           bending – bent)         to bend down-
that she hadn’t flown for three weeks,             wards to curve down from a horizontal
the student pilot’s landings were very             position to bend upwards to curve up
good. 3. to be able to deal with some-             from a horizontal position The wings
thing without becoming distressed or               support the weight of the aircraft and
annoyed       He can’t bear the noise.             they bend upwards in flight.
                                                   bending load / bendŋ ləυd/ noun a
                                                   bending load

(NOTE: bearing – bore – borne) he
can’t bear the heat the heat is too                load that causes a structure to bend
much for him                                       Bernoulli’s principle /b nu li z
                                                   Bernoulli’s principle


bearing / beərŋ/ noun 1. the angle,

                                                    prnsp(ə)l/ noun ‘ lift
                                                   beware /b weə/ verb to be careful or

measured in a clockwise direction, of a                                    |

distant point, relative to a reference             to watch out for Beware of carburettor
direction To plot a position line from             icing. Beware of other aircraft in the
the non-directional radio beacon, it is            circuit.
beyond                                          32
beyond /b jɒnd/ preposition further                 caused by the difference between geo-


away than The radio horizon extends                  metric and effective pitch
beyond the visible horizon.            it is         blade twist / bled twst / noun 1. a
                                                     blade twist

beyond his understanding he cannot                   reduction in propeller blade angle from
understand it at all, it is too difficult for        root to tip 2. the unwanted variation in
him to understand                                    propeller blade pitch from root to tip
bi- /ba/ prefix 1. two 2. twice                     caused by aerodynamic loads

biannual /ba njuəl/ adjective hap-                  blank /bl ŋk/ adjective 1. with noth-
biannual                                             blank


pening two times a year           biannual           ing written, printed or drawn on it a
inspection an inspection done twice                  blank sheet of paper a blank form a
every year                                           form without the details filled in 2. (of a
bill /bl/ noun US same as note noun 4
                                                     TV, computer or video screen) with
                                                     nothing appearing on it           When he
bimetallic / bame t lk/ adjective

                                                     returned to his computer, the screen was
made of two metals                                   blank.
bimetallic         strip / bamet lk
bimetallic strip

                                                     bleed air / bli d eə/ noun compressed
                                                     bleed air

 strp/ noun a strip made of two sepa-               air from the engine compressor used for
rate metals with different rates of                  cabin pressurisation or to drive other
expansion, joined together side by side              services        Bleed air from the right
so that when the strip is heated, it bends           engine can power items normally pow-
and makes, or breaks, electrical contact             ered by the left engine.
  Circuit breakers use a bimetallic strip
                                                     bleed screw / bli d skru / noun a
                                                     bleed screw

as the sensing element.
                                                     small screw in highest point of a
binary / banəri/ adjective referring to

                                                     hydraulic system to allow for the
a number system used in computers that               removal of air or vapour
only uses the digits 0 and 1 Logic
                                                     blind transmission / bland tr nz
                                                     blind transmission

gates work with binary data. Comput-                                                               |

ers only process binary information.                  mʃ(ə)n/ noun a transmission from one
                                                     station to another in a situation where
biplane / baplen/, bi-plane noun an

                                                     two-way communication cannot be
old aeroplane design with two pairs of               established but where it is believed that
wings, one above the other Most of the               the called station is able to receive the
aircraft used in the 1914–18 war were                transmission
                                                     block /blɒk/ noun a large mass of

bird strike / b d strak/ noun a col-
bird strike

                                                     something í verb 1. to prevent some-
lision between a bird or birds and an air-           thing such as a fluid from passing freely
craft that is flying                                 through a pipe or channel At high alti-
black box / bl k bɒks/ noun same
black box

                                                     tude, any water condensing out of the
as flight data recorder ( NOTE: It is                fuel could freeze and block the filters. 2.
often called the black box, although it              to prevent a course of action The gov-
is not black.)                                       ernment blocked attempts to prevent the
blade /bled/ noun a flattened part of a

                                                     building of the new airport.
propeller or rotor blade tip the end of              blockage / blɒkd / noun 1. a collec-

the blade furthest from the centre of                tion of something blocking a pipe, nar-
rotation turbine blade a flat part in a              row channel, filter, etc. Ice crystals
turbine, which has an aerodynamic                    may form to cause a blockage of the fuel
effect on the air                                    filter. 2. the state of being blocked The
blade angle / bled ŋ (ə)l/ noun
blade angle

                                                     blockage was caused by ice.
the angle between the blade axis and the             blow /bləυ/ noun 1. an impact a blow

axis of rotation With a variable pitch               on the head 2. a disappointment The
propeller, the blade angle may be                    news of her failure in the examination
changed in flight.                                   was a severe blow. í verb 1. (of the wind
blade slip / bled slp/ noun a loss of
blade slip

                                                     or air) to move The sea breeze may
propulsive power from a propeller                    blow almost parallel to the coast. 2. (of
                                             33                                       boot
a fuse) to break, as it should, when the          boil /bɔl/ verb to heat a liquid until it

circuit is overloaded (NOTE: blowing –            reaches a temperature at which it
blew – blown)                                     changes into gas          Water boils at
blow-back / bləυ b k/ noun a sud-

                                                  100°C. boiling point the temperature
den movement of fluid in the opposite             at which a liquid changes into gas The
direction to the general flow A sudden            boiling point of water is 100°C.
release of pressure may cause a blow-             bolt /bəυlt / noun 1. a metal rod with a

back.                                             head, which screws into a nut The two
blower / bləυə/ noun a device for

                                                  halves of the wheel are held together by
blowing air      Air for combustion is            bolts. 2. bolt of lightning one electri-
obtained from a blower.                           cal discharge of lightning í verb to
board /bɔ d/ noun 1. a flat, square or

                                                  attach with a bolt Aircraft wheels are
rectangular piece of wood or other                constructed in two halves which are
material 2. on board on an aircraft               bolted together.
The flight plan records the callsign and
                                                  bond /bɒnd / noun the power that

the number of people on board. í verb
to get on to an aircraft In an emer-              holds surfaces together, when they are
gency, many passengers only remember              joined using heat, cold, chemicals or
the entrance by which they boarded the            glue      The de-icing boot breaks the
aircraft.                                         bond between the ice and the outer skin.
                                                  í verb to join surfaces together nor-
boarding gate / bɔ dŋ et/ noun
boarding gate

                                                  mally using heat, cold, chemicals or
the door through which passengers                 glue The skin is bonded to the internal
leave the terminal building to get on to
                                                  members by the redux process.
an aircraft Boarding gates 1 – 10 are
                                                  boom /bu m/ noun in some aircraft, a

on the left.
boarding pass / bɔ dŋ pɑ s/ noun
boarding pass
                                                  spar that connects the tail to the fuse-
a temporary pass, issued at the check-in          lage
                                                  boost / bu st/ noun an increase or

desk, which allows the holder to board
the aircraft Boarding passes must be              improvement The improvement in a
shown at the gate. (NOTE: The plural              country’s economy often gives a boost
form is boarding passes.)                         to the airline industry. í verb 1. to make
boarding steps / bɔ dŋ steps/ plu-               or to help something increase An oil
boarding steps

ral noun stairs used by passengers and            pump boosts engine oil pressure. 2. to
crew to get on board an aircraft Pas-             increase The instructor’s comments
sengers had to wait in the aircraft for 15        boosted the student pilot’s confidence.
minutes before the boarding steps were            booster / bu stə/ noun a device

put in position.                                  which increases the force or amount of
boarding time / bɔ dŋ tam / noun
boarding time

the time when passengers are due to
                                                  booster pump / bu stə p mp/ noun
                                                  booster pump

board the aircraft Boarding time is at
13.30 hrs.                                        a centrifugal pump often positioned at
                                                  the lowest point of a liquid fuel tank to
body / bɒdi/ noun 1. the whole of a

                                                  ensure positive pressure in the supply
person or an animal 2. the main part of           lines to the engine Fuel is fed through
a person, but not the arms or legs 3. the         a filter and a booster pump. The pur-
main part of an aeroplane, system, text,          pose of the booster pump is to prevent
etc. The body of an aircraft is also
                                                  fuel aeration.
called the ‘airframe’. A flow-control
                                                  boot / bu t/ noun one of a set of flat,

valve consists of a body and a floating
valve. 4. a large mass of liquid or gas           flexible tubes bonded to the leading
body of air a large quantity of air               edge or wings and other surfaces which,
behaving in a particular way 5. an                when pressurised with fluid, break up
object     Acceleration is the rate of            ice The boots on the leading edge of
change of velocity of a body.                     the wings were damaged by hail.
bottleneck                                    34
bottleneck / bɒt(ə)lnek/ noun a                      round brackets the printing symbol (

buildup of air traffic causing delays in           ) used to separate words in a sentence,
taking off or landing                              or within a text square brackets the
bound /baυnd/ adjective bound for
                                                   printing symbol [ ] used to enclose
on the way to an aircraft bound for                some types of text
                                                   brake /brek/ noun a device for stop-

Paris the Copenhagen-bound flight
the flight on the way to Copenhagen                ping a vehicle or a machine parking
outward bound leaving home, espe-                  brake a brake used to prevent the air-
cially for another country                         craft moving after it has come to a stop
boundary / baυnd(ə)ri/ noun a phys-                í verb to slow down or to stop by press-

ical or imaginary limit between two                ing the brakes He had to brake hard
areas The boundary between two air                 after landing in order to turn off at the
masses is called the frontal surface.              correct taxiway. (NOTE: braking –
boundary layer / baυnd(ə)ri leə/
boundary layer

                                                   brake drum / brek dr m/ noun a
                                                   brake drum

noun the layer of fluid next to the sur-
face over which it is flowing and,                 round hollow part of the brake mecha-
because of friction, travelling more               nism, which is attached to the wheel
slowly than layers further from the sur-           and against which the brake shoes rub,
face                                               thus preventing the wheel from turning
                                                   braking / brekŋ/ noun the act of

bowser / baυzə/ noun a mobile fuel

tank for refuelling aircraft It is impor-          putting on the brakes to slow down or to
tant to prevent the possibility of an elec-        stop í adjective slowing down the
tric spark by earthing the aircraft and            braking effect of drag action
the bowser.                                        breaking load / brekŋ ləυd/ noun
                                                   breaking load

Boyle’s Law / bɔlz lɔ / noun a sci-               a load capable of being supported
Boyle’s Law

entific principle that states that the vol-        before a structure breaks
ume of a given mass of gas, whose tem-             breather / bri ðə/ noun 1. a pipe con-

perature is maintained constant, is                necting the crankshaft to the atmos-
inversely proportional to the gas pres-            phere to prevent build-up of crankcase
sure                                               pressure 2. a short rest (informal ) to
brace /bres/ verb 1. to strengthen a              take a breather to have a short break,

construction using cross-members                   to relax before starting again
and/or wires Early aircraft were of the            breeze /bri z/ noun a gentle wind

braced type of construction. 2. to take a          especially near the coast There’s no
protective body position in preparation            wind, not even a breeze. land breeze
for a crash landing The cabin-crew                 a light wind which blows from the land
will repeat the ‘brace’ order and brace            towards the sea Land and sea breezes
themselves.      to brace yourself to              occur in coastal areas. sea breeze a
quickly prepare yourself mentally and              gentle wind which blows from the sea
physically for what is shortly to happen           towards the land The strength of the
brace position / bres pə zʃ(ə)n/                 sea breeze decreases with height.
brace position


noun the position that a person is rec-            brief /bri f/ adjective short

ommended to adopt before impact in a               visit a visit that lasts only short time
crash, protecting the head with the arms           brief letter a letter containing only a
and bringing the legs up underneath the            few words í noun general instructions
chest                                              to enable somebody to perform their
bracket / br kt/ noun 1. a metal

                                                   duties The inspector’s brief is to find
support, often triangular or L-shaped              out as much as possible about the
component bracket a metal device to                causes of accidents. í verb to give basic
attach and support a component 2. a                information to somebody Before take-
range of frequencies within a band of              off, cabin crew must brief passengers on
radio frequencies Terminal VOR is in               the location and use of emergency exits
the frequency bracket 108–112 MHz. 3.              and life jackets.
                                             35                                     bulkhead
briefing / bri fŋ/ noun a short meet-            because of heat or force Overheating

ing to enable instructions and basic              will make the battery plates buckle.
information to be given                           buffet / b ft/ noun a shaking move-

British Isles / brtʃ alz/ plural               ment of the aircraft caused by the break-
British Isles

noun the islands which make up Great              down of the airflow over the upper sur-
Britain and Ireland The climate of the            face of the wing Large aircraft use a
British Isles is affected by the Atlantic         stick shaker to supplement the natural
Ocean.                                            stall warning of buffet. í verb to push
British thermal unit / brtʃ
British thermal unit
                                                  around with great force, as by water or
 θ m(ə)l/ noun the amount of heat                 wind The storm buffeted the coast.
needed to raise the temperature of one            The aircraft was buffeted by strong
pound of water by one degree Fahren-              crosswinds as it made its final approach
heit. Abbreviation Btu                            to land.
                                                         COMMENT: Buffet is a warning to the
brittle / brt(ə)l/ adjective having a

                                                         pilot that the smooth airflow over the
tendency to break easily, like thin glass                wing is breaking down and that he
   Absorption of oxygen and nitrogen                     should take corrective action to
from the air at temperatures above                       prevent a stall.
1,000° F makes titanium brittle.
                                                  buffeting / b f(ə)tŋ/ noun an irregu-


BRNAV abbreviation basic area navi-               lar shaking of a part or the whole of an
gation                                            aircraft during flight, usually caused by
broad /brɔ d/ adjective 1. very wide

                                                  strong winds
a broad river 2. wide or general Three            buffet speed / b ft spi d/ noun the
                                                  buffet speed

broad categories of aircraft are consid-          speed at which buffet is first noticed
ered – rotary wing aircraft, light single-
                                                  bug /b / noun a fault in computer

engine aircraft and twin-engine air-
craft. Opposite narrow                            software which causes the program to
                                                  operate incorrectly
broadcast / brɔ dkɑ st/ verb to

                                                  build up / bld p/ verb to form by
                                                  build up

transmit, often to a large number of peo-
ple, a radio signal or message which              accumulation In icing conditions, ice
requires no answer The cabin crew                 builds up on the leading edges. built-
can use the public address system to              up (NOTE: building up – built up)
                                                  build-up / bld    p/ noun a gradual

broadcast messages to passengers only.
(NOTE: broadcasting – broadcast) í                accumulation       a build-up of static
noun a transmission of information                electricity
relating to air navigation that is not            built-up / blt p/ adjective built-

addressed to a specific station or sta-           up area an area which is full of houses,
tions                                             shops, offices, and other buildings, and
broadly / brɔ dli/ adverb widely or

                                                  with very little open space
generally broadly speaking gener-                 bulb /b lb/ noun 1. a glass ball inside

ally speaking                                     a lamp that gives electric light If a
brush /br ʃ/ noun 1. a tool that has

                                                  lamp does not work, the bulb may need
lengths of hair or wire fixed into a han-         replacing. 2. something shaped like a
dle and is mainly used for painting or            lamp bulb The most common type of
cleaning 2. a small, replaceable block of         hygrometer is the wet and dry bulb ther-
carbon which rubs against the surface             mometer arrangement.
of a commutator in a generator or elec-           bulkhead / b lkhed/ noun a dividing

tric motor At high altitude, the air              partition across the structure of the
becomes drier and this causes a greatly           fuselage separating one compartment
increased rate of wear on the brushes.            from another for reasons of safety or
buckle / b k(ə)l/ noun a metal part of

                                                  strength A fireproof bulkhead is pro-
a belt used for joining the two ends              vided to separate the cool area of the
together í verb to bend out of shape              engine from the hot area.
bulletin                                     36
bulletin / bυltn/ noun a short report           power supply to various pieces of

or information on a situation news                equipment Complex busbars are thick
bulletin weather bulletin A terminal              metal strips or rods to which input and
aerodrome forecast bulletin may consist           output connections are made.
of forecasts for one or more aero-                button / b t(ə)n/ noun a little round

dromes.                                           disc which you push to operate some-
BUMF ‘ mnemonic

                                                  thing, e.g. to ring a bell
burble / b b(ə)l/ noun a break in the

                                                  Buys Ballot’s Law / baz b ləts
                                                  Buys Ballot’s Law

flow of air around an aircraft’s wing,             lɔ / noun a rule for identifying low
which leads to turbulence                         pressure areas, based on the Coriolis
burst /b st/ noun 1. a minor explo-

sion caused by increased pressure The
                                                         COMMENT:        In     the     northern
risk of tyre burst through overheating is                hemisphere, if the wind is blowing from
increased by hard application of the                     behind you, the low pressure area is to
brakes. 2. a very short period of activity               the left, while in the southern
followed by no activity The ground                       hemisphere it is to the right.
installation transmits a code in two
                                                  buzz /b z/ verb to fly low in an aircraft

short bursts. burst of energy a very
short period of energy í verb to explode          over people or buildings, or to fly across
because of increased pressure or punc-            the path of other aircraft
ture Metal debris on the runway may               bypass / bapɑ s/ noun 1. an alterna-

cause a tyre to burst. (NOTE: bursting –          tive pipe, channel, etc.       A turbine
burst)                                            bypass in the form of an alternative
busbar / b sbɑ / noun an electrical

                                                  exhaust duct is fitted with a valve. 2.
conductor used to carry a particular              same as shunt
C symbol 1. Celsius 2. centigrade                cable / keb(ə)l/ noun 1. thick metal
C                                                cable

CAA abbreviation Civil Aviation
                                                 wire control cables thick metal wire
Authority                                        linking the pilot’s cockpit controls to
cabin / k bn/ noun a passenger com-
                                                 control surfaces such as the elevators
partment in an aircraft Air enters at            and ailerons 2. a thick metal wire used
the front of the cabin and leaves at the         for electrical connections          Earth
rear.                                            return is by cable to the negative pole of
                                                 the battery.
cabin       attendant / k bn ə
cabin attendant

                                                 cabotage / k bətɑ / noun the right
                                             |   cabotage

 tendənt/ noun member of the flight
crew who looks after passengers, serves          of a country to operate internal air traf-
food, etc. If you need something, press          fic with its own airlines and not those of
the call button and a cabin attendant            other countries
                                                 calculate / k lkjυlet / verb to find

will respond within a few minutes. Also
called flight attendant                          out an answer to a problem by working
cabin compressor and blower
cabin compressor and blower system
                                                 with numbers The total flight fuel can
system / k bn kəm presə ən          |
                                                 be calculated by multiplying the time of
 bləυə sstəm/ noun part of the air              the flight by kilograms of fuel per hour.
                                                 calculation / k lkjυ leʃ(ə)n/ noun

conditioning system for the cabin                                                         |

cabin crew / k bn kru / noun air-
cabin crew
                                                 an act of finding out an answer to a
line staff who are in direct contact with        problem by working with numbers
                                                 calculation                    of       fuel   required
                                                 calculation of fuel required

the passengers and whose in-flight
responsibilities include: ensuring cor-          / k lkjυleʃ(ə)n əv fju əl r kwaəd/          |

rect seating arrangements, serving food          noun an arithmetic estimation of fuel
and attending to the general well-being          needed by using time, distance and fuel-
of passengers, etc.                              consumption factors
                                                 calculator / k lkjυletə/ noun an

cabin environment noun the condi-
cabin environment

tions inside the aircraft cabin, including       electronic machine for making calcula-
the temperature, the space, the colour           tions Students are not allowed to use
scheme, the seating arrangements, etc.           calculators in the examination.
cabin pressure / k bn preʃə/                    calibrate / k lbret/ verb to adjust
cabin pressure

noun the pressure of air inside the cabin        the scale or graduations on a measuring
which allows people to breathe nor-              instrument or gauge The international
mally at high altitudes                          standard atmosphere is used to cali-
cabin pressurisation / k bn
cabin pressurisation
                                                 brate pressure altimeters.
 preʃəra zeʃ(ə)n/ noun the mainte-             calibrated airspeed / k lbretd
                                                 calibrated airspeed


nance of an acceptable atmospheric                eəspi d/ noun indicated airspeed cor-
pressure in an aircraft while flying at          rected for instrumentation and installa-
high altitude At 35,000 ft (feet) pas-           tion errors. Abbreviation CAS
                                                 calibration / k l breʃ(ə)n/ noun

sengers can breathe freely because of                                                |

cabin pressurisation.                            the adjusting of the scale or graduations
call button                                  38
on a measuring instrument or gauge                the nose of an aircraft and designed to
The international standard atmosphere             increase its horizontal stability
is used for the calibration of instru-            candela / k n di lə/ noun the SI unit


ments.                                            of brightness of a light The red and
call button / kɔ l b t(ə)n/ noun a                green wing tip navigation lights must be
call button

button, often on the arm of a passenger           at least 5 candela. ( NOTE: It is usually
seat, which can be pushed when you                written cd with figures.)
need help from an attendant                       candle power / k nd(ə)l paυə/
                                                  candle power

callsign / kɔ lsan/ noun a series of
                                                  noun a unit to measure the brightness of
words and/or letters and/or numbers               a light       Estimation of visibility is
used to identify an aircraft or station           achieved by noting the distances at
The aircraft’s callsign is ‘College 23’.          which lights of a known candle power
VOR stations transmit a two or three              can be observed.
                                                  canopy / k nəpi/ noun 1. a transpar-

letter aural Morse callsign.
calorie / k ləri/ noun the amount of
                                                  ent cover, typically on some fighters,
heat required to raise the temperature of         light aircraft and gliders, designed to
1 gram of water by 1°C, equal to 4.186            slide backwards and forwards or hinge
joules      After 2 calories have been            upwards to allow pilots to enter or leave
released the temperature will have risen          an aircraft 2. a covering to protect peo-
2 degrees i.e. to 0°C, and so the freezing        ple in a life raft The canopy should be
process ceases temporarily. Abbrevia-             erected to provide protection from the
tion cal                                          weather.
                                                  cantilever / k ntli və/ noun a beam

calorific / k lə rfk/ adjective refer-

                                                  fixed and supported at one end only

ring to calories calorific value the              The mainplanes or wings are of canti-
heat produced by the complete burning             lever design.
of a given amount of fuel The calorific
                                                  cap /k p/ noun a top or lid

value of a fuel is an expression of the                                                  the
heat or energy content released during            exhaust valve cap
                                                  CAP abbreviation Civil Aviation Pub-

cam /k m/ noun an oval or egg-
                                                  capability / kepə blti/ noun the

shaped wheel which, when rotating,                                         |

converts circular motion into recipro-            capacity or ability to do something
cating motion In a piston engine, the             the flare has a day and night capabil-
shape of each cam is designed to give             ity the flare is effective in daylight and
the correct amount of opening to the              in the dark
valve.                                             ‘France has a large capability in the areas
CAMFAX / k mf ks/ noun the civil
                                                   of commercial aviation training and
                                                   simulation’ [Civil Aviation Training]
aviation meteorological facsimile net-
                                                  capable / kepəb(ə)l/ adjective com-

                                                  petent, having an ability Aircraft used
camplate / k mplet/ noun a rotat-

                                                  in aerobatics must be capable of with-
ing or non-rotating plate with cams on it         standing the extra loads imposed on the
   The fuel pump consists of a rotor              airframe by the manoeuvres. In most
assembly fitted with several plungers,            modern multi-engine jet transport air-
the ends of which bear onto a non-rotat-          craft, each fuel tank is capable of feed-
ing camplate.                                     ing any engine. a capable person a
camshaft / k mʃɑ ft/ noun a rotat-

                                                  person who works well
ing shaft carrying cams, which opens              capacitance /kə p stəns/ noun the


and closes valves in a piston engine As           ability of a system of conductors and
the camshaft rotates, the cam will trans-         insulators to store an electrical charge
mit a lifting force.                              when there is a positive discharge
canard / k nɑ d/ noun a projection

                                                  between the conductors If the supply
similar to a small wing fitted close to           frequency is low, the voltage has more
                                               39                                        cardioid
time to build up a larger charge, or                compounds and is found in various
capacitance. (NOTE: Capacitance is                  forms, e.g. as diamonds or charcoal 2. a
measured in farads and can either be a              black material with good electrical
fixed amount or variable amount.)                   properties
capacitive /kə p stv/ adjective                   carbon brush / kɑ bən br ʃ/ noun a
capacitive                                          carbon brush


referring to the ability of a system of             small, replaceable, carbon block found
conductors and insulators to store an               in electric motors, generators and alter-
electrical charge Overspeed is usually              nators, which provides the passage of
a fault in the constant speed drive unit            electric current
which causes the generator to over-                 carbon deposits / kɑ bən d
                                                    carbon deposits


speed and damage the capacitive loads                pɒztz/ plural noun residues of burnt
on the aircraft.                                    oil deposited in the combustion cham-
capacitor /kə p stə/ noun a system

                                                    ber, etc., in the course of the combus-
of conductors and insulators which                  tion process Carbon deposits on a
store electrical charge (NOTE: A capaci-            spark-plug electrode may cause misfir-
tor is used in a circuit to store energy for        ing.
a short while.)
                                                    carbon dioxide / kɑ bən da
                                                    carbon dioxide

capacity /kə p sti/ noun 1. the abil-
capacity                                                                                            |

                                                     ɒksad/ noun a colourless, odourless,
ity to do something easily Energy is                non-toxic gas found in the atmosphere,
the capacity for performing work. 2. the            and also used in fire extinguishers and
amount of something which a container               fizzy drinks Carbon dioxide can be
can hold Each cylinder has a capacity               solidified at low temperature to produce
of 0.5 litres.    battery capacity the              dry ice. Symbol CO 2
amount of electrical energy a battery
                                                    carbon fibre / kɑ bən fabə/ noun a
                                                    carbon fibre

can store and deliver expressed in
ampere hours 3. the ability of an ATC               thin, light and very strong strand of pure
system, in a given area, to provide a               carbon which can be combined with
normal service, expressed in numbers                other materials to make them stronger
                                                    carbon monoxide / kɑ bən mə
                                                    carbon monoxide

of aircraft                                                                                         |

 ‘…a 500 to 600 seat ultra-high capacity             nɒksad/ noun a colourless but poi-
 type aircraft is now being studied by              sonous gas from incomplete combus-
 Airbus Industrie and Boeing’ [Flight               tion found in the exhausts of spark igni-
 International 1–7 May 1996]                        tion engines. Symbol CO
capillary /kə pləri/ noun a very fine              carburation / kɑ bju reʃ(ə)n/ noun

                       |                                                         |

or narrow tube                                      the process of mixing fuel with air in a
capillary action /kə pləri
capillary action

                                                    carburettor Carburation must ensure
capillary flow /kə pləri fləυ/ noun the
                                                    that rapid and complete burning will
action by which a liquid rises up a nar-            take place within the cylinder.
                                                    carburettor / kɑ bə retə/ noun a

row tube                                                                     |

capsule / k psju l/ noun a small                    device for mixing air with fuel in the

closed container                                    right quantities before combustion
captain / k ptn/ noun the person in
                                                    Most carburettors are installed so that
charge of an aircraft      The captain              they are in a warm position.
                                                    carburettor heat / kɑ bə retə hi t/
                                                    carburettor heat

asked all passengers to remain seated                                                |

until the aircraft had come to a stop.              noun a system for keeping the carburet-
captive / k ptv/ adjective not free to             tor and associated components free of

move                                                ice
captive balloon / k ptv bə lu n/                   carburettor icing / kɑ bəretə
                                                    carburettor icing
captive balloon


noun a balloon which, when in flight, is             asŋ/ noun a process by which, under
attached to the ground by a long cable              particular conditions, ice forms in the
carbon / kɑ bən/ noun 1. a non-
                                                    venturi tube of the carburettor
                                                    cardioid / kɑ diɔd/ adjective shaped

metallic element, which is a component
of living matter and organic chemical               like a heart The cardioid polar dia-
carousel                                    40
gram of the magnetic field around a              crash which destroyed their house was
bar-magnet.                                      a catastrophe for them.
carousel / k rə sel/ noun a rotating             catastrophic / k tə strɒfk/ adjec-
carousel                                         catastrophic

                   |                                                     |

platform from where arriving passen-             tive terrible, disastrous     In a cata-
gers can pick up their baggage Bag-              strophic accident where many persons
gage from flight AC123 is on carousel            may be disabled, those who show signs
No 4.                                            of life should be rescued first.
carriage / k rd / noun the act of               categorise / k t əraz/, catego-
carriage                                         categorise

carrying Regulations require the car-            rize verb to put into groups, classes or
riage of life-rafts when flying over             categories Figure 2 categorises the
water.                                           types of wave by frequency band. Air-
carrier / k riə/ noun 1. a person or             craft can be categorised by weight,

organisation that carries people or              number of engines, role, etc.
goods from one place to another Indi-            category / k t (ə)ri/ noun an offi-

vidual carriers assign codes to aircraft.        cial class or group Load factors vary
2. a frame or bag in which objects can           depending on the category of aircraft.
be carried                                       cathode / k θəυd/ noun a negative

carrier wave / k riə wev / noun a
carrier wave

                                                 electrode or terminal The cathode is a
radio signal that is transmitted continu-        metal cylinder fitted with an internal
ously at a constant amplitude and fre-           heater.
quency       Amplitude modulation has            cathode ray tube / k θəυd re
                                                 cathode ray tube

only one pair of usable sidebands each            tju b/ noun a high-vacuum tube in
at about one sixth of the signal strength        which cathode rays produce an image
of the carrier.                                  on a screen such as a TV screen Elec-
carry / k ri/ verb to take somebody or

                                                 tronic indicating systems show engine
something from one place to another              indications, systems monitoring and
The aircraft was carrying 120 passen-            crew alerting functions on one or more
gers. (NOTE: carrying – carried)                 cathode ray tubes or liquid crystal dis-
cartridge / kɑ trd / noun a remova-

                                                 plays mounted in the instrument panel.
ble unit for an air filter Cabin air fil-        Abbreviation CRT
ters normally consist of a casing, hous-         cause /kɔ z/ noun something that

ing a replaceable filter cartridge.              makes something else happen, a reason
CAS abbreviation 1. calibrated air-

                                                    If the ammeter shows a high state of
speed 2. controlled airspace                     charge after start up, it is quite normal
case /kes/ noun 1. an outer covering,           and no cause for alarm. í verb to make

housing or jacket         Cooling air is         something happen Air in the fuel line
directed through passages in the engine          can cause an engine to flame-out or
case to control engine case tempera-             stop.
ture. 2. an example, situation or circum-        caution / kɔ ʃ(ə)n/ noun 1. advice or

stance In some special cases, e.g. for           a warning to be careful If a problem
landing and take-off, wind directions            occurs in the spoiler system, a master
are measured from magnetic north.                caution light illuminates. 2. care Pro-
casing / kesŋ/ noun a cover that               ceed with caution.

encloses a piece of equipment, etc.              cavitation / k v teʃ(ə)n/ noun the


Annular and outer air casing form a              formation of vapour-filled cavities or
tunnel around the spine of the engine.           holes in liquids and gases, caused by
CAT /k t / abbreviation clear air turbu-         low pressure or high speed Most res-

lence                                            ervoirs are pressurised to provide a
catastrophe /kə t strəfi/ noun a                 positive fluid pressure at the pump inlet


very bad event or accident, a disaster           and thus prevent cavitation and the for-
the recent air catastrophe off the Nova          mation of bubbles.
                                                 cavity / k vti/ noun a hole De-

Scotia coast.      Although the family
were not at home when it happened, the           icing fluid flows into the cavity in the
                                             41                                  centrifuge
distributor panels before passing                 throughout the area controlled by the
through the porous steel outer skin.              ECAC
CB abbreviation cumulonimbus                      centralise / sentrəlaz/, centralize
CB                                                centralise

cc / si si / abbreviation cubic centi-            verb to put into the centre or into the

metres                                            middle position The operating jack
cd symbol candela
                                                  centralises the control surface after the
CDI abbreviation course deviation indi-
CDI                                               turn.
                                                  Central Standard Time / sentrəl
                                                  Central Standard Time

cease /si s/ verb to stop If fuel, oxy-
                                                   st ndəd tam/ noun the time zone of
gen or heat is removed from the fire tri-         the east-central part of the USA and
angle, combustion will cease.                     Canada, 6 hours behind GMT
                                                  centre / sentə/ noun 1. the middle

ceiling / si lŋ/ noun 1. the highest

point 2. the greatest pressure height that        The plane of the great circle passes
can be reached The aircraft has a ceil-           through the centre of a sphere. centre
ing of 50,000 ft.                                 of a circle mid-point of a circle, point in
celestial /sə lestiəl/ adjective refer-

                                                  the middle of a circle 2. a main building
ring to the sky celestial navigation              or office Area Forecasting Centre í
                                                  verb to move to a central position
navigation by using the stars in the sky
                                                  Centre the control column. (NOTE: cen-
cell /sel/ noun 1. a system of positive

                                                  tred – centring; the US English is cen-
and negative plates for storage of elec-          tered – centering.)
tricity that form a battery A battery is
                                                  centre fix / sentə fks/ noun same as
                                                  centre fix

a device which converts chemical
energy into electrical energy and is              self-positioning
                                                  centreline / sentəlan/ noun a

made up of a number of cells. 2. the cen-
tral part of a thunder cloud The life             painted or imaginary line running along
cycle of the thunderstorm cell ends               the centre of the runway (NOTE: It is also
when the downdraughts have spread                 written centre line; written centerline
throughout the cloud.                             in US English.)
Celsius / selsiəs/ noun a scale for               centre of gravity / sentə əv
Celsius                                           centre of gravity

measuring temperature in which water                r vti/ noun the point at which a
freezes at 0° and boils at 100°. Symbol           body can be balanced Distribution of
C. Compare Fahrenheit                             the tanks and the fuel in the tanks is
center / sentə/ noun, verb US same as             vital in maintaining the aircraft centre

centre                                            of gravity and trim. Abbreviation CG
centerline / sentəlan/ noun US

                                                      COMMENT: If the centre of gravity is
same as centreline                                    outside the limits, the aircraft may be
                                                      difficult or impossible to control.
centigrade / sent red/ noun a

                                                  centrifugal / sentr fju (ə)l, sen

scale for measuring temperature in                                           |                  |

which water freezes at 0° and boils at             trfjυ (ə)l/ adjective moving away
100°. Symbol C. Compare Fahrenheit                from the centre The blades must be
centimetre / sentmi tə/ noun a                   strong enough to carry the centrifugal

measure of length that is equal to one            loads due to rotation at high speed.
hundredth of a metre (NOTE: 2.54 cm =             centrifugal force / sentrfju (ə)l
                                                  centrifugal force

1 inch.)                                           fɔ s/ noun outward force caused by
central / sentrəl/ adjective located in           turning motion

the centre or in the middle The control           centrifuge / sentrfju d / noun a

knob is moved from the central position.          device which uses centrifugal force to
Central Flow Management Unit
Central Flow Management Unit

                                                  separate or remove liquids í verb to
(Brussels)    / sentr(ə)l fləυ                    separate liquids by using centrifugal
 m nd mənt        ju nt    br s(ə)lz/           force     The rotating vanes of the
noun a central agency in Brussels that is         breather centrifuge the oil from the
responsible for air traffic management            mist.
centripetal                                                42
                   / sentr pi t(ə)l, sen                       defects, is absorbed by the chalk thus

centripetal                                |           |

 trpt(ə)l/ adjective moving towards                           indicating their positions.
the centre                                                      chamber / tʃembə/ noun a small

centripetal force /sen trpt(ə)l                               enclosed compartment
centripetal force


 fɔ s/ noun inward, centre-seeking                              chandelle /ʃ n del/ noun a steep


force working in opposition to centrifu-                        climbing turn in which an aircraft
gal force The magnitude of the cen-                             almost stalls as it uses momentum to
tripetal force varies with the square of                        increase its rate of climb
the wind speed. In a turn, lift provides                        channel / tʃ n(ə)l/ noun a special

the centripetal force.                                          frequency band for the transmission of
certain / s t(ə)n/ adjective 1. partic-

                                                                radio signals The system operates on
ular, some in certain areas at cer-                             VHF communications between 118 and
tain times        under certain circum-                         135.95 MHz giving 360 channels at 50
stances 2. sure There are certain to be                         kHz spacing.
horizontal differences in the mean tem-                         character / k rktə/ noun 1. a qual-

perature of a layer. to make certain                            ity or set of qualities which make some-
to make sure Make certain that the                              thing different and separate from some-
parking brake is on before doing engine                         thing else       The circulation of the
run-up checks.                                                  atmosphere is zonal in character. 2. an
certificate noun /sə tfkət/ an offi-

                                                                individual letter, number or symbol
cial document which states that particu-                        used in printing and writing
lar facts are true í verb /sə tfket/ to     |
                                                                characterise / k rktəraz/, char-

award or give a certificate aircraft                            acterize verb to be characterised by
which are certificated for flight air-                          to have qualities or features which make
craft which have the necessary paper-                           it different and separate from other
work to be authorised to fly                                    things The stratosphere is character-
certificate of airworthiness /sə
certificate of airworthiness

                                                       |        ised by a temperature structure which is
 tfkət əv eəw ðnəs/ noun a docu-                             steady or increases with height.
ment issued by an aviation authority                            characteristic

                                                                characteristic           / k rktə rstk/

stating that an aircraft meets specific                         adjective typical of a class or group of
safety and performance requirements                             things a characteristic feature a nor-
that allow it to be used in service An                          mal feature of the thing in question í
authorised person may require produc-                           noun a feature or quality making some-
tion of the Certificate of Airworthiness.                       thing different or separate from some-
Abbreviation C of A                                             thing else Air masses have distinct
certification /sə tf keʃ(ə)n/ noun

                               |       |                        characteristics which can be used to
the process of giving certificates The                          separate them on a chart. handling
inferential method of ice detection is                          characteristics features of an aircraft
used on flight trials for certification of                      that make it different from other aircraft
aircraft.                                                       when handling it summer character-
certify / s tfa/ verb to authorise or                         istics climatic conditions which are typ-

permit the use of something The air-                            ical of summertime
craft is certified for aerobatic flight.                        charge /tʃɑ d / noun 1. an amount of


CFI abbreviation chief flying instructor                        electricity Friction causes a charge of

CFMU abbreviation Central Flow                                  static electricity. The battery was so
Management Unit                                                 old, it would not take a charge. a high
                                                                level of charge a high amount of elec-
CFRP abbreviation carbon fibre rein-                            tricity 2. money demanded or paid for
forced plastic                                                  the providing of a service overnight
chalk /tʃɔ k/ noun a soft white lime-

                                                                parking is free of charge it costs noth-
stone rock that may be used in powder                           ing to park overnight í verb 1. to pass
form or as a shaped stick for writing                           electrical current through something
with      Oil, which is trapped in the                          and thereby make it electrically active
                                                 43                                     circuit
An installed battery becomes fully                    made by a chemical process a chemi-
charged by the aircraft generator.                    cal such as anti-ice for propellers
charged particles atmospheric parti-                  chemistry / kemstri/ noun 1. the

cles which have either a positive or neg-             science of chemical substances and
ative electrical charge 2. to take money              their reactions 2. the nature of some-
for a service We do not charge for                    thing The basic chemistry of fire can
overnight parking.                                    be illustrated by the three sides of a tri-
charger / tʃɑ d ə/ noun                               angle representing fuel, oxygen and

charger device for putting an electrical              heat.
charge into a battery. turbocharger                   chief /tʃi f/ adjective most important,

chart /tʃɑ t/ noun a map for naviga-
                                                      main      the chief factors the most
tional purposes significant weather                   important factors
                                                      chief flying instructor / tʃi f
                                                      chief flying instructor

chart a weather chart with important
weather information marked on it                       flaŋ n str ktə / noun the senior rank

chase plane / tʃes plen/ noun an
chase plane
                                                      of flying instructor. Abbreviation CFI
                                                      chock /tʃɒk/ noun a wooden or metal

aircraft whose role is to escort another
aircraft or to photograph it                          device placed in front of the wheels of a
                                                      parked aircraft to prevent it from mov-
check /tʃek/ noun an examination to

                                                      ing The accident happened because
make certain that something is as it                  the chocks had been removed before the
should be safety check A check was                    engine was started.
made on the undercarriage and air-
                                                      choke /tʃəυk/ noun a valve in a carbu-

frame after the pilot reported a heavy
landing. run í verb to examine some-                  rettor, which controls the amount of air
thing in order to find out if it is correct           combining with fuel í verb 1. to block a
  It is the pilot’s responsibility to check           tube, etc., making a liquid unable to
that the aircraft is airworthy.                       move a choked nozzle a blocked or
                                                      partly-blocked nozzle 2. to stop breath-
    ‘European Union (EU) airports may be              ing because you have inhaled water or
    empowered to carry out safety checks on           smoke
    foreign airlines’ [Flight International 1–
                                                      choke tube /tʃəυk tju b/ noun same
                                                      choke tube

    7 May 1996]
                                                      as venturi Increase in rpm increases
check in / tʃek n/ verb to register by
check in

                                                      the speed of air passing through the
giving in your ticket, showing your                   choke tube or venturi.
passport and giving your baggage at an
                                                      chopper / tʃɒpə/ (informal ) noun

airline desk before a flight Passengers
should check in two hours before depar-               same as helicopter í verb to transport
ture.                                                 something or somebody by helicopter,
                                                      or to travel by helicopter
check-in / tʃek n/ noun an airline

                                                      chord /kɔ d/ noun the shortest dis-

desk where passengers register before a               tance between the leading and trailing
flight The check-in is on the first floor.            edges of an airfoil
   check-in time time at which passen-
                                                      chute /ʃu t/ noun same as parachute

gers should check in
               counter / tʃek n
check-in counter

check-in                                              circle / s k(ə)l/ noun a line forming a

 kaυntə/, check-in desk noun counter                  round shape, or a round shape formed
where passengers check in                             by objects or people They stood in a
checklist / tʃeklst/ noun a list of

                                                      circle on the tarmac.     great circle
items, often in booklet form, to be                   direction an imaginary circle on the
checked in a given sequence Before                    surface of the Earth which lies in a
every flight, the pilot should perform                plane passing through the centre of the
pre-flight checks using a checklist.                  Earth
chemical / kemk(ə)l/ adjective                       circuit / s kt/ noun 1. a complete
chemical                                              circuit

referring to chemistry       a chemical               route around which an electrical current
reaction í noun a substance used in or                can flow 2. the pattern of take-off,
circuit board                               44
climb-out, turn onto crosswind leg, turn         equal to one 360th part of the circum-
onto downwind leg, turn onto base leg,           ference of a circle is called one degree.
turn onto final approach and landing             circumstance / s k mstns/ noun a

When carrying out practice landings at           condition which affects something in a
an aerodrome, the pilot should keep a            given situation       in some circum-
sharp lookout for other aircraft in the          stances, under certain circumstances
circuit.                                         in some particular situations
circuit board / s kt bɔ d/ noun an              cirro- /srəυ/ prefix high altitude, i.e.
circuit board

insulating board which holds compo-              above 20,000 feet
nents connected into an electrical cir-          cirrocumulus / srəυ kju mjυləs/


cuit                                             noun a layer of broken cloud at about
circuit-breaker / s kt brekə/

                                                 20,000 feet
noun a small protective device in the            cirrostratus / srəυ strɑ təs/ noun a


circuit which blows or breaks before a           layer cloud at about 20,000 feet
dangerous overload of current arises             cirrus / srəs/ noun a high cloud in a

circuitry / s ktri/ noun a system of

                                                 mass of separate clouds which are
electrical circuits In an anti-skid brak-        formed of ice crystals
ing system, circuitry is employed which          Civil Aviation Authority / svl
                                                 Civil Aviation Authority

can detect individual wheel decelera-             evi eʃ(ə)n ɔ θɒrəti/ noun the
                                                                  |           |

tion.                                            organisation which licences operators,
circular / s kjυlə/ adjective shaped

                                                 aircraft and employees for non-military,
like a circle       Anodes are circular          especially commercial aviation. Abbre-
plates with centre holes. semi-circu-            viation CAA
lar shaped like a half-circle í noun a           Civil Aviation Publication / svl
                                                 Civil Aviation Publication

document distributed to a large number            evi eʃ(ə)n p blkeʃ(ə)n/ noun a

of people an aeronautical information            book, etc., published by the Civil Avia-
circular                                         tion Authority, each publication having
circular slide rule / s kjυlə slad              its own reference number The proce-
circular slide rule

 ru l/ noun a calculating device on              dure for obtaining a bearing can be
which all manner of conversions and              found in CAP 413. Abbreviation CAP
complex calculations can be made to                     COMMENT:       CAA (Civil Aviation
assist in flight planning                               Authority) publications are referred to
                                                        as CAPs and each has a reference
circulate / s kjυlet/ verb to move

                                                        number      for   identification:   the
round in such a way as to arrive at the                 procedure for obtaining a bearing is
point of departure Water circulates                     described in CAP 413.
via the radiator and pump through to
                                                 clad /kl d/ verb to protect by covering

the engine block itself.
                                                   Alloys can be protected from corro-
circulation / s kjυ leʃ(ə)n/ noun

                                                 sion by cladding the exposed surface
the act of moving round in such a way            with a thin layer of aluminium.
as to arrive at the point of departure           clamshell door / kl mʃel dɔ / noun
                                                 clamshell door

The general circulation is indicated by          the hinged part of a thrust reverser
the arrows. cyclonic circulation the             Clamshell doors are hydraulically or
circulation of air which, if viewed from         pneumatically opened, and direct the
above, is anticlockwise in the northern          exhaust gases forwards to produce
hemisphere and clockwise in the south-           reverse thrust.
ern hemisphere
                                                 classification / kl sf keʃ(ə)n/

circulatory / s kjυ let(ə)ri/ adjec-
circulatory                                                                               |

                                                 noun the act of putting things into
tive moving around a circuit a self-             groups or classes because they possess
contained re-circulatory oil system              particular common features Classifi-
circumference /sə k mf(ə)rəns/

                               |                 cation of aircraft consists of a multi-
noun the distance around the edge of a           level diagram with each category
circle The angle subtended by an arc             divided into sub-categories.     A full
                                                     45                                climatic zone
classification of layer cloud is given in                     perhaps a misunderstood radio call.
the table.                                                    The Pan Am aircraft had been asked
                                                              by the controller, who was unable to
classify / kl sfa/ verb to group

                                                              see either aircraft due to low cloud,
items so that those with similar charac-                      ‘Are you clear of the runway?’ The
teristics are in the same group Precip-                       KLM aircraft had already commenced
itation is classified as light, moderate                      the take-off roll without clearance. It is
or heavy according to its rate of fall.                       possible that the KLM pilot mistook the
The weather associated with visibility                        call to the other aircraft thinking that he
                                                              was ‘clear to take off’.
reductions by particles suspended in the
                                                          clear air turbulence / klər eə
                                                          clear air turbulence

atmosphere is classified either as fog,
mist, haze, or smoke.                                      t bjυləns/ noun turbulence encoun-
clear /klə/ adjective 1. referring to
                                                          tered in air where no cloud is present
conditions in which it is easy to see, e.g.               (NOTE: CAT is often associated with the
with no cloud or fog a clear sky a sky                    jet stream.)
                                                          clearance / klərəns / noun 1. a space

with no cloud a clear winter night a
night with no fog, mist or other condi-                   made to allow for the movement of
tions which might impair visibility 2.                    hardware relative to other hardware
possible to easily see through 3. with                    clearance between rocker arm and
nothing blocking the way clear run-                       valve tip 2. official permission Obtain
way, the runway is clear nothing is on                    clearance for IFR flight. 3. the disap-
the runway keep the exits clear do                        pearance of something unwanted, often
not put anything and do not stand in                      rain, fog or snow Low temperatures
front of the exits 4. away from 5. easy to                caused a delay in the clearance of fog.
hear clear of cloud either above or                       clearance limit / klərəns lmt/
                                                          clearance limit

below cloud        keep clear (of) keep                   the point to which an aircraft is allowed
away (from) 6. easy to understand The                     to proceed when granted an air traffic
explanation is very clear. 7. understood                  control clearance
8. understood        is it clear? do you                  clear ice / klər as/ noun ice which
                                                          clear ice

understand? í verb 1. to remove a                         is glass-like rather than white
blockage or some other unwanted effect
                                                          clear pass / klə pɑ s/ noun an
                                                          clear pass

which prevents a system from working
correctly A heater element is fitted to                   exam result which is in no doubt
                                                          clear to land / klə tə l nd/ noun
                                                          clear to land

clear the detector of ice. 2. to disappear
   In winter frost and fog are slow to                    air traffic control permission to land
clear. 3. to make sure that it is all right               climate / klamət/ noun weather con-

to do something clear it with the CFI                     ditions particular to a given area Med-
make sure that the CFI agrees with the                    iterranean climate tropical climate
request 4. to officially ask people to                    temperate climate a type of climate
quickly leave a given area or place to                    which is neither very hot in summer nor
clear the building to quickly leave the                   very cold in winter. continental
building                                                  climatic /kla m tk/ adjective refer-


    ‘…the principles of weight and balance                ring to climate or weather conditions
    should have been learned by all pilots                particular to a given area The aircraft
    during their initial training, but it is clear        forward speed and altitude as well as
    that, afterwards, some forget’ [Civil                 climatic conditions will influence the
    Aviation Authority, General Aviation                  value of thrust.
    Safety Sense Leaflet]
                                                          climatic zone /kla m tk zəυn/
                                                          climatic zone


    COMMENT: On 27th March 1977 two                       noun one of the eight areas of the Earth
    Boeing 747s collided on the runway at
    Los Rodeos airport Tenerife in poor                   which have distinct climates
    visibility, resulting in 575 deaths. A                    COMMENT: The climatic zones are: the
    KLM 747 commenced take-off while a                        two polar regions (Arctic and
    Pan Am 747 was still taxiing towards it                   Antarctic); the boreal zone in the
    on the same runway. There was clear-                      northern hemisphere, south of the
    ly a breakdown in communications,                         Arctic; two temperate zones, one in
climatology                                     46
       the northern hemisphere and one in                  layer of broken cloud at about 20,000
       the   southern     hemisphere;    two               feet; cirrostratus, layer cloud at about
       subtropical zones, including the                    20,000 feet; cirrus, cloud made of ice
       deserts; and the equatorial zone which              crystals at 25,000 – 40,000 feet
       has a damp tropical climate.                        appearing as hair-like formations;
                                                           cumulonimbus, cloud formed as a
climatology /klamə tɒləd i/ noun

                                                           towering mass and often associated
the science of the study of climate                        with thunderstorms; cumulus, cloud
Although pilots do not need to be                          formed in rounded masses with a flat
experts in climatology, they should have                   base at low altitude, resulting from up
a good understanding of the factors                        currents of air; nimbostratus, thick
which produce changes in the weather.                      dark layer cloud at low altitude from
                                                           which rain or snow often falls (nimbus
climb /klam/ noun the act of increas-

                                                           = rain cloud); stratocirrus, cloud
ing altitude by use of power Fine pitch                    similar to cirrostratus but more
enables full engine speed to be used                       compact; stratocumulus, a layer of
during take-off and climb. Opposite                        connected small clouds at low altitude.
descent í verb to increase altitude by               cloud base / klaυd bes/ noun the
                                                     cloud base

use of power After take-off, the air-                bottom part of a layer of cloud In gen-
craft climbed to 5,000 ft. Opposite                  eral, the lower the cloud base, the less
descend                                              heat is lost by the earth.
climb-out / klam aυt/ noun a flight

                                                     cloud ceiling / klaυd si lŋ/ noun
                                                     cloud ceiling

after take-off from 35 feet to 1,500 feet            the height above the ground or water of
during which undercarriage and flaps                 the base of the lowest layer of cloud
are retracted Turn right after climb-
                                                     cloud group / klaυd ru p/ noun a
                                                     cloud group

                                                     collection of different cloud types
clockwise / klɒkwaz/ adjective,

                                                     which have similarities, e.g. stratus
adverb describing a circular movement                clouds
in the same direction as the hands of a              cm

clock a clockwise direction The rel-                 cm abbreviation centimetre
                                                     co- /kəυ/ prefix together

ative bearing indicated is measured                                                  co-axial
clockwise from the nose of the aircraft.             having the same axis co-located hav-
Opposite anticlockwise                               ing the same location
clog /klɒ / verb to prevent movement                 coalesce / kəυə les/ verb to join

of fluid through a pipe, etc., because of            together to form a large mass or number
a build-up of solid matter Most filters                The moisture in the air coalesces into
allow unfiltered fluid to pass to the sys-           large water droplets.
tem when the filter becomes clogged.                 coalescence / kəυə les(ə)ns/ noun


close /kləυz/ verb to shut Close the                 the act of joining together to form a

door.                                                larger mass or number Coalescence of
closure / kləυ ə/ noun the act of clos-
                                                     water vapour in the atmosphere forms
ing or shutting The voltage regulator                larger droplets of water.
                                                     coast /kəυst/ noun an area where the

is turned on by the closure of the gener-
ator control relay.                                  land meets the sea Valentia is situated
cloud /klaυd/ noun a mass of water
                                                     on the coast of south west Ireland.
                                                     coastal / kəυst(ə)l/ adjective refer-

vapour or ice particles in the sky that
can produce rain                                     ring to the coast coastal area an area
       COMMENT : The most important types
                                                     near a coast Land and sea breezes
       of    cloud   are    the   following:         occur in coastal areas.
                                                     coastal refraction / kəυst(ə)l r
                                                     coastal refraction

       altocumulus, cloud formed at about                                                             |

       12,000 feet as a layer of rounded              fr kʃən/ noun change in direction of
       mass with a level base; altostratus,          waves when a signal crosses a coastline
       cloud formed as a continuous layer            from sea to land
       between 6,000 and 20,000 feet usually
                                                     coastline / kəυstlan/ noun the out-

       allowing the sun or moon to be seen
       from the surface; cirrocumulus, a             line of a coast seen from a distance or
                                                   47                                        collapse
on a map It is normally easy to iden-                   coefficient / kəυ fʃ(ə)nt/ noun a


tify a coastline or island.                             mathematical quantity placed before
coat /kəυt/ noun a thin covering of a                   and multiplying another

substance such as paint The coats of                    C of A abbreviation certificate of air-
                                                        C of A

paint on a large aircraft significantly                 worthiness
increase its weight. í verb to cover with               C of G abbreviation centre of gravity
                                                        C of G

a thin layer of a substance such as paint               coil /kɔl/ noun a device consisting of

    Metals are coated for protection                    coiled wire for converting low voltage
against corrosion.                                      to high voltage A voltage coil is con-
coating / kəυtŋ/ noun 1. a thin layer

                                                        nected across the generator.
of a substance There are two coatings                   coiled wire / kɔld waə/ noun a
                                                        coiled wire

on the inside of CRT screens. 2. the act                length of wire twisted round and round
of covering with a thin layer of a sub-                   A coiled wire connects the terminal to
stance                                                  earth.
cock /kɒk/ noun a manually controlled

                                                        coincide / kəυn sad/ verb to hap-


valve or tap to control the flow of a liq-              pen at the same time and/or in the same
uid It is necessary to have a master                    place When the aircraft heading is
cock for each engine.                                   directly into wind or down wind, track
cockpit / kɒkpt/ noun the forward

                                                        and heading coincide.
area in an aircraft from where the air-                 coincident /kəυ nsdənt/ adjective


craft is controlled by the pilot In the                 happening at the same place or at the
case of an in-flight oil loss, a warning                same time The Earth’s true north and
indicator will light in the cockpit.                    magnetic north poles are not coinci-
 ‘…in the cockpit of the future there will              dent.
 be two animals, a pilot and a dog. The                 col /kɒl/ noun an area of slack pressure

 pilot will be there to feed the dog, and the           gradient between two centres of high or
 dog will be there to bite the pilot if he tries
 to touch anything’ [NYT News Service]
                                                        low pressure      The persistence and
                                                        movement of cols are governed by the
code /kəυd/ noun 1. a system of num-

                                                        movement of the adjacent pressure sys-
bers, letters or symbols used to repre-                 tems.
sent language which has to be learned                   cold front /kəυld fr nt/ noun an
                                                        cold front

and decoded in order for the receiver to                advancing mass of cold air, moving
understand the meaning 2. a series of                   under and lifting warmer air A cold
pulses by which an aircraft transponder                 front brought rainy, windy conditions to
replies to a signal from the ground                     the country.
codeshare / kəυdʃeə/ noun code-

                                                        collapse /kə l ps/ noun a sudden


share deal an agreement between air-                    and complete fall the collapse of a
lines regarding connecting flights The                  company the end of the existence of the
two airlines have entered into a code-                  company í verb 1. to fall suddenly and
share deal for flights between Dubai                    completely The magnetic field will
and Bangkok.                                            reach a maximum in one direction, col-
codeshare partner / kəυdʃeə
codeshare partner

                                                        lapse to zero and reach a maximum in
 pɑ tnə/ noun an airline which has an                   the opposite direction. 2. to fold or to
agreement with another airline regard-                  close suddenly and unintentionally
ing connecting flights                                  the undercarriage collapsed (of an
codesharing / kəυdʃeərŋ/ noun 1.                       apparatus) the undercarriage could not

a procedure which allows travellers to                  support the aircraft and broke or
use connecting flights between one air-                 retracted on its own 3. to faint the
line and another partner airline for                    passenger collapsed the passenger fell
worldwide destinations 2. an arrange-                   and became semi- or fully unconscious
ment by which two airlines sell seats on                because of some medical problem
the same flight using their own flight                         ‘…as the aeroplane slid off the runway,
numbers                                                        the left landing gear collapsed’ [Pilot]
collect                                       48
collect /kə lekt/ verb 1. to gather over           combustion /kəm b stʃən/ noun
collect                                            combustion

                  |                                                                                 |

a period of time Any given object will             burning, especially that which takes
usually collect ice more quickly at high           place in an engine The heat generated
speed. 2. to take something or to pick             by combustion is considerable.
something up from a place                          combustion chamber

                                                   combustion            chamber / kəm                      |

collection /kə lekʃən/ noun 1. a                    b stʃ(ə)n tʃembə/ noun the part of


number of things brought together a                the cylinder in a piston engine where
collection of vintage aircraft 2. an act of        the ignition of the fuel/air mixture takes
being collected by somebody            The         place
documents are in the office awaiting               combustor /kəm b stə/ noun the


collection.                                        part of a jet or gas-turbine engine that
collide /kə lad/ verb to bump or to

                                                   burns fuel to produce power. It consists
crash into something The aircraft left             of the fuel injection system, the igniter,
the runway and collided with a fire                and the combustion chamber.
                                                   command /kə mɑ nd/ noun an order

collision /kə l (ə)n/ noun a crash

                                                      the command to evacuate the order
between two objects, two vehicles, etc.            to leave the aircraft in an emergency
   If there is a risk of collision, alter          in command having responsibility for
course to the right. collision avoid-              and authority over í verb to order some-
ance the prevention of collisions by tak-          thing to be done The captain com-
ing measures beforehand to ensure that             manded the evacuation of the aircraft.
they do not happen
                                                   commander /kə mɑ ndə/ noun a

column / kɒləm/ noun 1. a body of
column                                                                                      |

                                                   pilot in control of, and responsible for,
fluid or solid with a tall, narrow shape           the aircraft and its contents during flight
Torricelli first demonstrated that the             time the commander of an aircraft
atmosphere has weight by showing that              the member of the flight crew specified
it can support a column of liquid. 2. a            by the operator as being the commander
vertical section of a table in a document
                                                   commence /kə mens/ verb to start to

   Column four of the table shows the                                               |

totals of the other three columns.                 do something commence the evacua-
                                                   tion start getting people out of the air-
combat / kɒmb t/ verb to fight

against     Fire extinguishers are pro-
                                                   commercial /kə m ʃ(ə)l/ adjective

vided to combat fire.                                                                   |

                                                   referring to a business activity com-
combat                           / kɒmb t
combat aircraft

                 aircraft                          mercial aviation flying as a business
 eəkrɑ ft/ noun aircraft designed for              enterprise
                                                   commercial aircraft /kə m ʃ(ə)l
                                                   commercial aircraft

                       / kɒmb neʃ(ə)n/

combination                               |

                                                    eəkrɑ ft/ noun aircraft used to carry

noun two or more things brought
                                                   cargo or passengers for payment
together to form one The combination
                                                   Commercial Pilot’s Licence /kə
                                                   Commercial Pilot’s Licence

of wind direction and wind speed is                                                                         |

called velocity.                                    m ʃ(ə)l paləts las(ə)ns/ noun the
combine /kəm ban/ verb to bring

                                                   licence that a person requires to be
two or more things together to make                pilot-in-command of public transport
one The stabilising channels for ailer-            aircraft certified for single-pilot opera-
ons and elevators are combined.                    tions. Abbreviation CPL
                                                   common sense / kɒmən sens/
                                                   common sense

Thrust and lift combine to overcome
drag and gravity.                                  noun ordinary good sense You should

combustible             /kəm b stəb(ə)l/
                                                   use your common sense as well as fol-
adjective burning or igniting easily               low the rules if a passenger feels
combustible       materials materials              unwell.
                                                   comms /kɒmz/ abbreviation commu-

which will catch fire easily, e.g. wood,
paper, etc.                                        nications
                                                49                                     compensate
communicate /kə mju nket/ verb                     ance comparable to that of stainless


to make contact with somebody in order               steel.
                                                     comparator /kəm p rətə/ noun a

to pass information The cabin attend-                                          |

ants should communicate with the cap-                device to compare two things          The
tain.                                                autopilot comparator monitors the

communication                /kə mju n
                                 |          |
                                                     operation of the elevator and aileron
 keʃ(ə)n/ noun the act of passing infor-            channels.
                                                     compare /kəm peə/ verb to find the

mation to somebody usually, but not                                    |

always, by using language Two meth-                  similarities and dissimilarities between
ods of communication are available to                two or more things When the chart is
crew members – language and hand                     properly orientated, it is easier to com-
signals.                                             pare the distance between landmarks
                                                     on the ground with their corresponding
communication link /kə mju n
communication link

                                 |          |

                                                     distances on the chart. An aneroid
 keʃ(ə)n lŋk/ noun a telephone or                  barometer is small compared with a
radio connection, as between the                     mercury barometer. (NOTE: Compare
ground crew and flight deck while an                 with is regarded by some as better
aircraft is preparing for departure                  usage than compare to.)
                             /kə mju n

communications                   |          |
                                                     comparison /kəm p rs(ə)n/ noun

 keʃ(ə)nz/ plural noun a system of

                                                     a statement expressing the differences
passing information satellite commu-                 and similarities between two or more
nications VHF communications are                     things A table showing a comparison
allocated the frequency bracket 118–                 of fixed points on various temperature
137 MHz. Abbreviation comms                          scales is given on page three.
commutator / kɒmjutetə/ noun a                                              /kəm pɑ tmənt /



device containing metal bars connected               noun a small space or area in a structure
to the coils of a generator to produce               for a particular purpose engine com-
electrical current As the power output               partment crew compartment the area
required is DC not AC, a commutator is               reserved for crew
fixed at one end of the armature.                    compass / k mpəs/ noun an instru-

compact /kəm p kt/ adjective

                     |                               ment usually with a magnetic needle
small, close together, or not taking                 which always points to the magnetic
much space The annular system, as                    north
used on modern aircraft, provides a                  compass           bearing      / k mpəs
                                                     compass bearing

compact system, and, for the same out-                beərŋ/ noun a direction or position
put and mass flow, a shorter system. í               relative to a fixed point measured in
verb 1. to make smaller or more dense                degrees on a compass
by pressing 2. to compress, by driving               compatibility

                                                                            /kəm p t blti/
                                                                                        |       |

over with heavy machinery When tax-                  noun the ability of a component to oper-
iing on grass, aircraft wheels compact               ate successfully with other components
the earth as the aircraft moves over it.                Problems of compatibility caused the
compaction /kəm p kʃ(ə)n/ noun

                             |                       computerised system to malfunction.
the act of pressing things together to               compatible /kəm p tb(ə)l/ adjec-


form one, or of compressing something                tive referring to a component or system
to make it hard The speed of impact                  which can be used with a different com-
when the aircraft passes through a                   ponent or system without causing any
snowstorm causes compaction of snow-                 problems           Computer software
flakes into a solid mass on leading                  designed for one particular system may
edges and air-intakes.                               not be compatible with other systems.
                       / kɒmp(ə)rəb(ə)l/             compensate / kɒmpənset/ verb 1.


adjective possible to compare equally                to make up for the loss of something
with something else Titanium is non-                 The floor covering may be designed to
magnetic and has an electrical resist-               compensate for temperature, pressuri-
compensation                                 50
sation and bending loads. The fall in             an aircraft after completion of de-icing
air temperature increases the air den-            operations.
sity and so compensates to some extent            complex / kɒmpleks/ adjective com-

for the loss of the thrust due to atmos-          plicated and therefore possibly difficult
pheric pressure. 2. to give money to a            to understand Of all the pre-departure
person or organisation to make up for a           activities, route planning is one of the
physical or financial loss The money              most complex. í noun 1. a whole made
offered by the company did not compen-            up of many different parts a cumulo-
sate for the injuries she received in the         nimbus cloud complex a collection of
accident.                                         cumulonimbus clouds forming a system
compensation / kɒmpən seʃ(ə)n/

                                  |               2. a building made up of many different
noun money paid to an individual or               parts the terminal three complex the
organisation to replace or make up for            main building and associated buildings
physical or financial loss The com-               which together make up terminal three
pany paid out $2 million in compensa-             complexity /kəm pleksti/ noun the


tion to the families of those who lost            condition of being complex, or a com-
their lives in the tragedy.                       plication Up-to-date design does not
compilation / kɒmp leʃ(ə)n/ noun                necessarily mean structural complexity.


the putting together of suitable informa-         complicate / kɒmplket/ verb to

tion The manual is a compilation of               make more difficult Map reading is
materials used by each of the instruc-            often complicated by seasonal varia-
tors.                                             tions.
compile /kəm pal/ verb to put                    complicated / kɒmplketd/ adjec-
compile                                           complicated


together a number of pieces of informa-           tive not easy to understand
tion Aviation routine weather reports             complication / kɒmpl keʃ(ə)n/


are compiled half-hourly or hourly at             noun a difficulty or problem The com-
fixed times.                                      plication with the Mercator’s projection
complement / kɒmplment/ verb to

                                                  is that great circle directions must be
fit in with and improve the performance           converted to rhumb line directions by
of something Ultra-sonic detection is             the application of conversion angle
used to complement other methods of               before they can be plotted.
flaw detection.                                   comply /kəm pla/ verb to be or do


complementary                    / kɒmpl         what is required by an instruction or law


 ment(ə)ri/ adjective the fact of fitting            Equipment and furnishings of modern
in with and improving the performance             jet transports must comply with safety
of something SSR is complementary                 regulations. Passengers must comply
to the primary radars used by ATC.                with the no-smoking signs. (NOTE: com-
complete /kəm pli t/ adjective 1.

                                                  plying – complied)
                                                  component /kəm pəυnənt/ noun 1.

containing all the parts it should contain                                    |

  The centre section can be constructed           a part of an aircraft, aircraft system or
either as a complete unit or as two sep-          piece of equipment        The undercar-
arate units. 2. absolute and total í verb         riage is made up of a number of differ-
1. to finish or make whole            The         ent components. 2. one part of a force
number of revolutions for the crank-              such as wind which consists of a
shaft to complete a full cycle is always          number of different parts 3. a substance
two. complete the work to continue                which forms part of a compound
until the work is finished 2. to fill in          compose /kəm pəυz/ verb to make


information complete the flight plan              something from a number of parts The
to fill in the required information in the        atmosphere is composed of a mixture of
flight plan                                       gases.
completion /kəm pli ʃ(ə)n/ noun the               composite / kɒmpəzt/ adjective
completion                                        composite


satisfactory finishing of a task It is            referring to something made up of a
important to carry out an inspection of           number of different parts composite
                                                       51                                concentration
material The flight crew route flight                       compression /kəm preʃ(ə)n/ noun


plan is a composite document which                          an act or instance of putting pressure on
serves as a navigation log. í noun a                        something
lightweight but very strong man-made                        compression stroke

                                                            compression            stroke       /kəm     |

material used in aircraft manufacturing                      preʃ(ə)n strəυk/ noun the stage of an
  To make a composite it is necessary to                    internal combustion cycle when the
combine the reinforcing glass fibres                        fuel/air mixture comes under pressure
with special glue or resin. (NOTE: The                      from the upward-moving piston
word composite was originally an
                                                            compressive /kəm presv/ adjec-

adjective, but through frequent usage                                                        |

the term composite material has been                        tive referring to forces caused by pres-
shortened to composite.)
                                                            sure on a surface A strut is designed to
                                                            withstand compressive loads.
  ‘Canadian Aerospace Group (CAG) is
                                                            compressive load /kəm presv
                                                            compressive load

  working with Pratt & Whitney Canada on                                                             |

  a turboprop-powered version of its                         ləυd/ noun a load caused by forces act-
  Windeagle all-composite light aircraft’                   ing in opposite directions towards each
  [Flight International 16–22 July 1997]                    other
                                                            compressive stress /kəm presv
                                                            compressive stress

    COMMENT: Composites are used in                                                                  |

    the construction of many modern                          stres/ noun the resistance of a body to
    aircraft, from gliders to aircraft such as              crushing by two forces acting towards
    the Airbus A320, because they are                       each other along the same straight line
    strong and lighter than metals.
                                                            compressor /kəm presə/ noun a


composition / kɒmpə zʃ(ə)n/ noun

                                                            device such as a pump to compress air,
the make-up or structure of something                       in order to increase pressure A shaft
composition of the atmosphere the                           connects the turbine to the compressor.
combination of gases which make up                              axial
the atmosphere                                              comprise /kəm praz/ verb to be

compound / kɒmpaυnd/ adjective

                                                            made of (NOTE: The correct use of com-
referring to something made up of two                       prise is often disputed. Some people
or more parts or substances í noun a                        regard it as a synonym for the verb
substance made up of two or more com-                       consist of, while others believe it
ponents     A chemical compound has                         should be used in an opposite sense: a
qualities that are different from those of                  tank, pipes, a filter, a pump and a car-
the substances from which it is made.                       burettor comprise the fuel system. It is
Advances in sealing compounds have                          sometimes used in its passive form: the
now made fuel tanks less liable to leaks.                   fuel system is comprised of a number of
compound                   wound           generator
compound wound generator

                                                            different parts.)
/ kɒmpaυnd     wu nd d enəretə/                            concentrate / kɒnsəntret/ verb 1.

noun a generator which consists of a                        to collect in a particular place rather
number of windings                                          than spread around Most of the mass
compress /kəm pres/ verb to put

                                                            of air is concentrated at the lowest lev-
under pressure thereby reducing vol-                        els of the atmosphere. 2. to give atten-
ume Pressure is created when a fluid                        tion and thought to something in partic-
is compressed.                                              ular     This chapter concentrates on
compressibility /kəmpresə blti/                           charts. to concentrate hard to give


noun the natural ability of a substance                     all one’s thought and attention to some-
to change volume when under varying                         thing
pressures In systems using very high                        concentration / kɒnsən treʃ(ə)n/


pressure, the compressibility of the liq-                   noun 1. the fact of being collected in a
uid becomes important.                                      particular place rather than spread
compressible           /kəm presəb(ə)l/

                                       |                    around The maximum concentration
adjective referring to something that                       of ozone is between 20 and 25 km above
can be compressed Air is compressi-                         the Earth’s surface. 2. the act of giving
ble, but water is not.                                      attention and thought to something In
concentric                                     52
the early stages of training, instrument            the atmosphere is cooled until moisture
flying requires great concentration on              begins to condense on the surface.
the part of the student pilot.                      Opposite evaporate 2. to remove
concentric /kɒn sentrk/ adjective

                                                    unnecessary parts from a text to make it
having the same centre concentric                   shorter The synoptic code condenses
circles circles of different diameters but          information without loss of sense.
                                                    condenser /kən densə/ noun an

with the same centre point                                                           |

concept / kɒnsept/ noun an idea or
                                                    electrical capacitor       The condenser
abstract principle The concept of open              prevents spark plugs from arcing.
                                                    condition /kən dʃ(ə)n/ noun 1. the

skies is not one with which everybody                                    |

agrees.      a complicated concept an               present state of something although
idea or series of ideas or principles               the aircraft is old, it is in good condi-
which are difficult to understand                   tion the aircraft is old but well cared for
concern / kən s n/ noun 1. serious

                                                    2. the state of the surrounding atmos-
interest a matter for concern some-                 phere In a high relative humidity con-
thing which must be taken very seri-                dition, the evaporation rate is low.
ously 2. responsibility Attention to the            abnormal weather conditions unusual
welfare of passengers is the concern of             or unfavourable weather            adverse
the cabin crew. Safety is everybody’s               weather conditions bad weather 3. cir-
concern. this is no concern of ours                 cumstances 4. something on which
this is nothing to do with us í verb 1. to          another thing depends on condition
cause somebody to feel worried this                 that only if the flight will depart on
report concerns me enormously I am                  condition that the weather improves
not at all happy about this report 2. to be         the flight will depart only if the weather
about or to be the subject of If there is           improves
                                                    conducive /kən dju sv/ adjective

serious vibration, the crew should shut                                      |

down the engine concerned.             this         favourable, which allows something to
report concerns me this report is about             happen more easily Atmospheric con-
me 3. to be of interest and relevance to            ditions conducive to the formation of
  the regulations concern all employ-               ice are detected and these operate a
ees the regulations apply to all employ-            warning system.
ees                                                   ‘…when refuelling, ensure the aircraft is
    ‘…the correct storage and handling of             properly earthed. The very low humidity
    cargo and especially dangerous goods is           on a crisp, cold day can be conducive to a
    an area which is of considerable concern          build-up of static electricity’ [Civil
    to the Federation’ [INTER PILOT]                  Aviation Authority, General Aviation
                                                      Safety Sense Leaflet]
concrete / kɒŋkri t/ noun a sub-

                                                    conduct /kən d kt/ noun / kɒnd kt/

stance made of cement, sand and water                                |

used in the construction of buildings,              1. a manner or way of doing something
roads, etc. Rock, sand and concrete                   The captain is responsible for the safe
reflect only 10–20% of radiation.                   conduct of the flight. 2. behaviour The
                                                    investigation found that the flight
condensation / kɒnden seʃ(ə)n/

                                                    attendant’s conduct was unacceptable.
noun the process by which vapour                    í verb 1. to organise and do something;
changes into liquid If the air becomes              to carry out Crew will conduct area
saturated, further cooling results in               checks. Security conducted a search
condensation. Opposite evaporation                  of the building. 2. to allow something
condensation         trail / kɒnden
condensation trail

                                           |        such as electricity, heat etc. to pass
 seʃ(ə)n trel/ noun same as vapour                through Water conducts electricity.
trail                                               conduction /kən d kʃən/ noun the


condense /kən dens/ verb 1. to

                         |                          process by which heat or electricity
change from vapour to liquid form                   passes through a substance Heat is
The most common type of hygrometer is               transferred to the layer of air next to the
one in which a surface in contact with              Earth’s surface by conduction.
                                                     53                                                       connection
conductive /kən d ktv / adjective                        conform /kən fɔ m/ verb to corre-
conductive                                                conform

                                     |                                            |

referring to the ability of a substance to                spond to required standards        Fuels
allow heat or electricity to pass through                 must conform to strict requirements.
  Steel is a conductive material. Land                    to conform to regulations to do what is
masses are less conductive than water.                    required by rules and regulations
conductivity / kɒnd k tvti/ noun                        conformal /kən fɔ m(ə)l/ adjective


the ability of a material to allow heat or                representing angles, bearings, etc., cor-
electricity to pass through Because of                    rectly    Lambert’s conformal projec-
the poor conductivity of air, heat is                     tion
transferred from the Earth’s surface                      congestion /kən d estʃən/ noun a


upwards by convection.                                    situation where there are too many peo-
conductor /kən d ktə/ noun a sub-                         ple or vehicles in a confined space for


stance through which heat or electricity                  them to be able to move freely When
can pass Water and steel are good                         leaving the aircraft in an emergency, to
conductors.                                               avoid congestion, passengers should be
                                                          directed to move away from exits
cone /kəυn/ noun a solid body with a

base in the shape of a circle, and with
                                                          conic / kɒnk/ adjective based on the

sides which narrow to a point, or any
object which has that shape                               shape of a cone conic projection the
                                                          standard two-dimensional representa-
configuration /kən f jə reʃ(ə)n/

                                         |       |
                                                          tion of the earth
noun the pattern or way in which things
                                                          conical / kɒnk(ə)l/ adjective shaped

are arranged configuration of an air-
craft’s fuel tank system the way in                       like a cone The nose of Concorde has
which the tanks are laid out                              a conical shape.
                                                          conjunction /kən d ŋkʃən/ noun

confine /kən fan/ verb 1. to limit to a

                                                          in conjunction with working or operat-

particular area Cooling is confined to
                                                          ing together with Built-up areas, used
the air in contact with the ground. The                   in conjunction with other features such
damage was confined to a small area. 2.                   as rivers, railways and coastlines which
to limit to a given subject the report                    are near them, are more easily identi-
confines itself to the incident of 3rd                    fied.
January the report deliberately does
                                                          connect / kə nekt / verb to join Bat-

not mention anything other than the                                           |

incident of the 3rd January                               teries are sometimes connected in
                                                          series. A cockpit lever is connected to
confined /kən fand/ adjective lim-

                                                          a needle valve in the float chamber.
ited, small a confined space a small
                                                          connecting flight /kə nektŋ flat /
                                                          connecting flight

defined space which does not allow free                                                               |

movement                                                  noun a second aircraft which a passen-
                                                          ger should arrive on time to catch, and
confirm /kən f m/ verb to agree that

                                                          which will take him or her to the final
something is correct, or to repeat it to                  destination Instead of flying direct to
remove any uncertainty The attitude                       London, take the flight to Amsterdam
indicator shows that the aircraft is in a                 and then take a connecting flight to
nose down attitude and the increasing                     London Heathrow.
airspeed confirms that the aircraft is not
                                                          connecting rod /kə nektŋ rɒd/
                                                          connecting rod

in level flight. Can you confirm that                                                                     |

                                                          noun an engine part that connects the
the instructor was flying the aircraft at
the time of the collision? VHF and/or                     piston to the crankshaft
                                                          connection /kə nekʃən/ noun 1. the

UHF radio aids confirm ADF bearings.                                                  |

                                                          point at which things are joined There
       COMMENT: Cross-checking of certain                 is an electrical connection to the bat-
       flight instruments is used to confirm
       readings from other instruments, e.g.              tery. 2. a link or feature that makes
       the airspeed indicator and vertical                things interdependent There is a con-
       speed       indicator confirm      pitch           nection between temperature change
       information from the attitude indicator.           and altitude. 3. the process of catching
connector                                     54
a second aircraft to arrive at a final des-        distance a long distance considera-
tination Follow the ‘Flight Connec-                ble force a lot of force
tion’ signs.                                       consideration /kən sdə reʃ(ə)n/

                                                                                                 |              |

connector /kə nektə/ noun a device

                  |                                noun 1. something important to remem-
which connects two or more things A                ber and to think carefully about to
connector is used to connect two                   take into consideration to remember
lengths of wire together.        Standard          to include when thinking about some-
connectors consist of a metal coupling             thing, solving a problem or making a
with a rubber sandwich joint.                      calculation 2. thoughtfulness, respect
consecutive /kən sekjυtv/ adjec-                  to show consideration for other peo-


tive following one another without a               ple and property to show respect for
break 4, 5 and 6 are three consecutive             what belongs to other people
numbers. a period of 28 consecutive                consist /kən sst/ verb to consist of


days 28 days following immediately                 to be made up of Layer cloud names
one after the other                                consist of a prefix, according to height
consequence / kɒnskwəns/ noun                     of base, and a suffix according to shape.

the result of an action The accident                 to consist in to mean, to be
was a consequence of the pilot’s                   consistent /kən sstənt/ adjective


actions. as a consequence as a result              always reacting or behaving in the same
consequent / kɒnskwənt/ adjec-

                                                   way Human hair responds in a con-
tive resulting      As temperature rises,          sistent manner to changes in the rela-
there will be a consequent increase in             tive humidity.      consistent perform-
the volume of the gas.                             ance performance which maintains a
consequently             / kɒnskwəntli/           particular standard

adverb therefore, as a result She was              consolidate /kən sɒldet/ verb to


late, consequently she missed the start            make more solid or strong revision of
of the examination.                                the subject helps to consolidate it
conserve /kən s v/ verb to avoid                   revision of the subject helps to set it


using unnecessarily          Release the           more firmly in the memory
brakes when necessary and conserve                 consolidation /kən sɒl deʃ(ə)n/

                                                                                                     |      |

main system pressure.         to conserve          noun 1. a process by which something
energy to use only as much energy as               is made more solid or strong 2. the
you really need to conserve fuel to                grouping of goods together for ship-
use as little fuel as possible                     ment
consider / kən sdə / verb to think

                                                   constant / kɒnstənt / adjective

carefully about something If the air-              unchanging the temperature of the
craft is low on fuel, the commander                gas remains constant the temperature
should consider diverting to the nearest           of the gas stays the same constant
suitable airport.                                  pressure pressure which stays the same
 ‘…many purchasers of flight simulators            constant speed drive unit

                                                   constant                    speed                     drive      unit
 would argue that, when considering the
                                                   / kɒnstənt spi d drav ju nt/ noun
 major manufacturers, there is little to
 choose between them’ [Civil Aviation              a device fitted to aircraft with constant
 Training]                                         speed propellers. Abbreviation CSDU
                                                   constant speed propeller

considerable /kən sd(ə)rəb(ə)l/
                                                   constant                        speed                   propeller
                                                   / kɒnstənt spi d prə pelə/ noun a pro-

adjective a lot of, quite large     The                                                      |

required range of trim change is consid-           peller with a control system which auto-
erable. (NOTE: Considerable does not               matically adjusts pitch to maintain
mean that something should be                      selected rpm
                                                   constant speed unit / kɒnstənt
                                                   constant speed unit

thought about, as the meaning for the
verb consider might suggest.) a con-                spi d ju nt/ noun a device that auto-
siderable amount of fuel a lot of fuel,            matically keeps a propeller at a speed
a large amount of fuel a considerable              set by the pilot. Abbreviation CSU
                                                 55                                 contaminate
constituent /kən sttjυənt/ noun                      engines, which in turn consume fuel. 2.


any one of the various parts that make                to eat
up a whole Water, whether in the form                                        /kən s mpʃ(ə)n/

                                                      consumption                    |

of vapour, liquid or ice, is a very impor-            noun 1. the amount used up in a given
tant constituent of the atmosphere.                   time Fuel consumption is higher in
constitute / kɒnsttju t/ verb to
                                                      bigger, more powerful engines. 2. the
make up, to form Oxygen and nitro-                    process of using up fuel or other
gen together constitute most of the                   resources 3. the amount eaten 4. the act
atmosphere.                                           of eating
                                                      contact / kɒnt kt/ noun 1. touch in

constrain /kən stren/ verb 1. to pre-


vent somebody from being completely                   contact with touching The air in con-
free or from doing something they want                tact with the Earth’s surface cools. 2.
to do The airline was constrained in                  to be in contact with to communicate
its purchase of new aircraft by lack of               with e.g. by telephone or radio to be
financial resources. 2. to force some-                in visual contact to see to make con-
body to do something Lack of finan-                   tact to communicate to lose contact
cial resources constrained the airline to             to stop communicating ATC lost con-
cancel the purchase of new aircraft.                  tact with the aircraft. 3. a person who
                                                      can be contacted in order to get some-
constraint /kən strent/ noun some-

                                                      thing done        I have a contact in
thing that reduces freedom of action                  Madrid who can help I know some-
The number of landings per 24-hour                    body in Madrid who can help 4. an elec-
period is subject to constraint.                      trical connection Dirty contacts were
constrict /kən strkt / verb to make

                 |                                    the cause of the problem. í verb to get
something narrower, especially to make                in touch with somebody e.g. by radio or
the flow of gas or liquid more difficult              telephone The captain couldn’t con-
by narrowing the passage through                      tact ATC.
which it flows In the carburettor ven-                                              / kɒnt kt
                                                      contact breaker

                                                      contact         breaker
turi, the flow of air is constricted.                  brekə/ noun a mechanically operated
constriction /kən strkʃən/ noun                      switch which is timed to break the pri-


the act of constricting, or a place where             mary circuit when maximum current is
something is particularly narrow A                    flowing
thermometer has a constriction in the                 contact flight / kɒnt kt flat/ noun
                                                      contact flight

base of the tube between the bulb and                 a method of navigation for aircraft in
the beginning of the scale.                           which the pilot or crew use no naviga-
construct /kən str kt/ verb 1. to put

                                                      tional aids, but find their way by
together The table on page 4 can be                   observing visible features of the ground
                                                                                    / kɒnt kt
                                                      contact number

used to construct the low level forecast              contact         number
for the route. 2. to build to construct                n mbə/ noun a telephone number
an aircraft to manufacture or build an                where information can be obtained
aircraft Wings are constructed of light               contain / kən ten/ verb to hold, to


alloy pressed ribs and an outer skin.                 have inside Most clouds contain some
construction /kən str kʃən/ noun                      super-cooled water droplets.         The


1. the act of putting things together, or             booklet contains details of the airline’s
the way in which something is put                     flight schedule.
together The basic construction of the                container /kən tenə/ noun a box,


lead-acid cell consists of a positive                 bottle, etc., which holds something else
electrode and negative electrode. 2. a                   A smouldering fire in a waste con-
building      The construction of the                 tainer could become very active due to
home-built aircraft took two years.                   pressure changes during ascent.
consume /kən sju m/ verb 1. to use                    contaminate /kən t mnet/ verb
consume                                               contaminate

                     |                                                          |

up in a given time Drag must be over-                 to make something impure, harmful or
come with thrust, which requires                      dangerous If contaminated air enters
contaminated fuel                                        56
the cabin, the dump valve can be                              contour / kɒntυə/ noun the shape of

opened.                                                       something
                                   /kən                       contour chart / kɒntυə tʃɑ t/ noun
contaminated fuel

contaminated             fuel
                                                              contour chart


 t mnetd fju əl/ noun fuel which                           chart which shows areas of high and
contains an unwanted substance, such                          low ground
as water, and is therefore dangerous to                       contour          gradient       / kɒntυə
                                                              contour gradient

use                                                              rediənt/ noun steepness of change
                             /kən t m                        in elevation

contamination                                |       |

 neʃ(ə)n/ noun a process by which a                          contour line / kɒntυə lan/ noun a
                                                              contour line

liquid, gas or object is made unusable                        line on a map or chart joining points of
because impurities or foreign matter are                      equal elevation
allowed into or onto it contamination                         contract /kən tr kt/ verb to become


of air air pollution fuel contamina-                          smaller in volume Liquids will expand
tion a situation in which fuel becomes                        or contract as a result of temperature
unusable because an unwanted sub-                             changes. Opposite expand
stance such as water gets into it                             contraction /kən tr kʃən/ noun the


nuclear contamination damage done                             decrease in volume of a substance
to an object, person or substance                             brought about by cooling Due to con-
because of contact with nuclear radia-                        traction, the length of a mercury column
tion                                                          shortens. Opposite expansion
content / kɒntent/ noun the amount

                                                              contrail / kɒntrel/ noun same as

of a substance that is contained within                       vapour trail
something, often expressed as a per-                          contrast / kɒntrɑ st / noun 1. the

centage The stratosphere is a layer in                        amount of light and dark in something
which the water vapour content is low.                        seen Contrast and colour enable a
   the moisture content of the atmos-                         pilot to identify ground features. 2. the
phere the amount of water vapour in the                       difference between two things There
air                                                           is an enormous contrast between the
continent / kɒntnənt/ noun one of

                                                              performance of the two aircraft. in
the seven great land masses of the Earth                      contrast to when compared with Air
  the continent of Europe                                     at altitude is cold in contrast to air at
    COMMENT : The seven continents are:                       the surface.
                                                              contribute /kən trbju t/ verb to

    Asia, Africa, North America, South                                               |

    America, Australia, Europe and                            give or provide as part of the whole
    Antarctica.                                               Exhaust gases contribute to engine
continental / kɒnt nent(ə)l/ adjec-                          power.      although the weather was


tive referring to a continent                                 bad, pilot error contributed to the
continental climate

continental                                climate            accident pilot error was partly respon-
/ kɒntnent(ə)l     klamət/ noun the                         sible for the accident
                                                              contribution         / kɒntr bju ʃ(ə)n/

type of climate found in areas where                                                             |

there is no effect from the sea                               noun 1. the part that something plays in
                                                              making or causing something The dif-
contingency /kən tnd ənsi/ noun


                                                              ferences in the effect of solar radiation
something which might happen in the                           on land and sea make the biggest con-
future and therefore must be planned                          tribution to weather and climate. 2. the
for                                                           act of contributing or something, espe-
contingency reserve fuel /kən
contingency reserve fuel

                                                     |        cially money, that is given or provided
 tnd ənsi r z v fju əl/ noun fuel
                                                              contributor /kən trbjυtə/ noun a


which would only be used in an unusual                        person or thing that contributes to
situation such as a diversion                                 something       There are other factors
continuity / kɒnt nju ti/ noun con-

                               |                              which cause the division of the lower
tinuing continuity of precipitation                           atmosphere into two layers but the
continuing rain, snow or hail                                 ozone effect is a major contributor.
                                                  57                                               conventional
control / kən trəυl/ noun 1. the                       control tower /kən trəυl           taυə/
control                                                control tower

                      |                                                                                 |

authority or ability to direct somebody                noun a tall building on an airfield from
or something 2. crowd control the                      which air-traffic controllers organise
management of the movements of large                   incoming and outgoing aircraft by
numbers of people 3. checking or exam-                 speaking to their pilots by radio
ining í verb to direct, to manage or to                control zone /kən trəυl zəυn / noun
                                                       control zone


make a machine, system, procedure,                     a designated ATC area. Abbreviation
etc., work in the correct way The pur-                 CTR
pose of the centrifugal switch is to con-              convection /kən vekʃ(ə)n/ noun the


trol the starting and ignition circuits.               process by which hot air rises and cool
(NOTE: The word control in English is                  air descends Heat is transferred from
used in a different way to similar words               the Earth’s surface upwards largely by
in other languages. In English, the verb               convection.
check is more often used to mean ‘look
                                                       convective /kən vektv/ adjective


at and verify’ while control is used in
                                                       referring to convection, or something
the sense of ‘to make something work                   which is affected by the vertical circula-
in a particular way’: the yoke and rud-                tion of air        convective movement
der pedals are used to control the                     movement caused by warm air rising
movement of the aircraft. Note also:                   and cool air descending
controlling – controlled.)
                                                       convective clouds /kən vektv
                                                       convective clouds

control area /kən trəυl eəriə/ noun
control area                                                                                                |

                                                        klaυdz/ plural noun clouds formed as a
the airspace above a particular area on                result of warm moist air rising and con-
the ground, which is controlled by a                   densing at altitude
particular authority. Abbreviation CTA                 convenience /kən vi niəns/ noun 1.


control column /kən trəυl kɒləm/
control column

                                      |                personal comfort and benefit Reading
noun the main hand control used by the                 lights are provided for passengers’ con-
pilot to control the aircraft in roll and              venience. at your convenience when
pitch                                                  it is least troublesome for you 2. ease of
controlled airspace /kən trəυld
controlled airspace

                                                       understanding        For convenience we
 eəspes/ noun airspace which is gov-                  will assume that the Earth is round. 3.
erned by rules and regulations which                   usefulness, or easiness to use
                                                       convenient /kən vi niənt/ adjective

pilots must comply with. Abbreviation                                              |

CAS                                                    1. useful The circular slide rule has a
                                                       convenient scale for converting weights
controller /kən trəυlə/ noun 1. a


                                                       and volumes. 2. suitable and unlikely to
device which ensures that something                    cause problems We must arrange a
operates in the correct way the propel-                convenient time and place for the meet-
ler speed controller 2. a person who                   ing.
manages systems to ensure the smooth
                                                       convention /kən venʃən/ noun 1. an

operation of procedures                                                        |

                                                       idea which because of long usage has
controls /kən trəυlz/ plural noun

                                                       become normal and accepted By con-
manual or automatic devices that are                   vention, wind direction is the direction
used to control a machine, a system,                   from which the wind blows. 2. a meeting
etc., or to make a machine, a system,                  involving large numbers of people and
etc., work in a correct way the pilot at               long discussions in order to arrive at an
the controls of the aircraft the pilot                 agreed course of action often outlined
who is operating the flying controls                   in a public statement the Tokyo Con-
                             / kən trəυl               vention
control surfaces

control        surfaces                       |

 s fsz/ plural noun moveable aero-                   conventional           /kən venʃ(ə)n(ə)l/


foils, usually on the wings and tail-                  adjective usual or familiar to most peo-
plane, which can be operated from the                  ple Every pilot must know the conven-
cockpit by the pilot, thus changing air-               tional symbols used for depicting the
craft attitude                                         various ground features on charts.
converge                                      58
converge /kən v d / verb to come                   cause to become less hot The airflow


together at a particular point Meridi-             is used to cool the oil. air-cooled
ans converge towards the poles. air-               coolant / ku lənt/ noun a substance,

craft on converging courses aircraft on            usually liquid, used to cool something
courses which may eventually be too                such as an engine radiator coolant
close to each other if no corrective               The coolant is sprayed into the combus-
action is taken. Opposite diverge                  tion chamber inlet.
convergence /kən v d əns/ noun                     cooler / ku lə/ noun a device for cool-
convergence                                        cooler


the fact of coming together at a particu-          ing A self-contained system, consist-
lar point The inter-tropical conver-               ing of an oil tank, pump, filter, cooler,
gence zone is the zone in which the                and oil jets, lubricates the auxiliary
trade winds from the two hemispheres               power unit.
approach each other. There is conver-              cooling / ku lŋ/ noun the action of

gence of meridians of longitude at the             making something cool the cooling of
north and south poles. Opposite diver-             the oil by the airflow í adjective reduc-
gence                                              ing the temperature of something
converse / kɒnv s/ noun the oppo-

                                                   cooling medium a substance which
site The converse of port is starboard.            reduces the temperature of another sub-
   warm air rises – the converse is also           stance or material
true in other words, cool air descends             coordinate /kəυ ɔ dnət/ verb 1. to


conversion /kən v ʃ(ə)n/ noun 1. a

                               |                   bring together the various parts of a pro-
change to a different system or set of             cedure or plan to ensure that the opera-
rules The conversion of km into nm is              tion works correctly It is the task of
not difficult. 2.    conversion course             air traffic controllers to coordinate the
flying training which enables and qual-            movement of traffic in and out of a ter-
ifies a pilot to fly a different aircraft          minal. 2. to make different parts of the
type                                               body work well together During a
convert /kən v t/ verb to change to a              hover, helicopter pilots must be able to


different system or set of rules to con-           coordinate movements of both hands
vert km into nm How do you convert                 and feet.
                                                   coordinated flight /kəυ ɔ dnetd
                                                   coordinated flight

degrees C into degrees F?                                                                   |

converter /kən v tə/ noun a device

                                                    flat/ noun flight, especially during
which alters the form of something A               turns, in which the horizontal and verti-
backup converter converts the alternat-            cal forces acting on the aircraft are in
ing current power into direct current.             balance In coordinated flight, the ball
convertible /kən v təb(ə)l/ adjec-

                                                   in the turn coordinator will be in the
tive possible to change easily, e.g. to fit
in with a new system or set of standards               COMMENT: The ball in the balance
   The statute mile, unlike the nautical               indicator of the turn coordinator shows
                                                       the pilot if the aircraft is in coordinated
mile, is not readily convertible into                  flight or if it is slipping or skidding.
terms of angular measurements.                         When the ball moves to the left the
convey /kən ve/ verb to carry or

                   |                                   pilot should apply left rudder pedal
move from one place to another A                       pressure, if the ball moves to the right,
large number of tubes convey the cool-                 the pilot should apply right rudder
ing medium through the matrix. Buses                   pedal pressure.
                                                   Coordinated                  Universal       Time
                                                   Coordinated Universal Time

are used to convey passengers from the
aircraft to the terminal building. to              /kəυ ɔ dnetd ju n v s(ə)l tam/
                                                                 |                      |

convey information to pass informa-                noun time used in aviation based on the
tion from one person to another, or from           24-hour clock format. GMT
one place to another                               coordinates /kəυ ɔ dnəts/ plural


cool /ku l/ adjective a little cold cool

                                                   noun values used to locate a point on a
weather weather which is not hot,                  graph or a map The airfield can be
warm nor very cold í verb to become or             seen on the map at coordinates B:12.
                                                 59                                           corrode
coordination        /kəυ ɔ d neʃ(ə)n/               tified airspeed is indicated airspeed

                               |       |

noun 1. the process of bringing together              corrected for instrumentation and
the various parts of a procedure or plan              installation error. 2. to mark answers
to ensure that it works correctly A res-              right or wrong, as in an examination
cue coordination centre is set up to con-             The instructor has corrected the stu-
trol the emergency. 2. the ability to use             dents’ examination papers.
different parts of the body together well             correction /kə rekʃ(ə)n/ noun 1. an


   A pilot must have good hand/eye                    adjustment or change made to some-
coordination.                                         thing to make it correct 2. the use of a
cope /kəυp/ verb to manage to do                      mathematical formula for adjusting a

something, often with some difficulty                 known inaccuracy of calculation In
In heavy rainstorms, the windscreen                   applying this correction the reading is
wipers may not be able to cope. The                   converted to that which would occur at
aircraft structure must be able to cope               mean sea level. 3. an alteration on, e.g.
with increased loads caused by turning                a test answer, which provides the right
movement.                                             answer in place of the wrong answer
copilot / kəυpalət/, co-pilot noun a
                                                      given I made several corrections to
licensed pilot who is second in com-                  the text.
                                                      corrective /kə rektv/ adjective

mand to the captain of an aircraft The                                            |

copilot landed the aircraft.                          referring to something designed to cor-
copter / kɒptə/ noun same as heli-
                                                      corrective         action /kə rektv
                                                      corrective action

copter (informal )                                                                             |

cord /kɔ d/ noun a strong thread, usu-
                                                          kʃən/ noun action taken to put a situ-
ally of nylon Tyres are of pure rubber                ation right If the pilot realises that the
and are either cord-strengthened or                   plane is too high on the approach, he or
reinforced. (NOTE: Cord is used to rein-              she should take corrective action imme-
force tyres.)                                         diately.
                                                      correlate / kɒrəlet/ verb to measure

core /kɔ / noun the central part, the

heart of something The primary wind-                  something against something else in
ings consist of heavy gauge wire                      order to form a relationship between the
mounted on a soft iron core. the core                 two Power is measured not by the
of a problem the central, most funda-                 amount of work done, but by units of
mental part of a problem                              accomplishment correlated with time.
                                                      correlation / kɒrə leʃ(ə)n/ noun a

Coriolis force / kɒri əυls fɔ s/
Coriolis force


noun force which accelerates the move-
                                                      measurable and predictable relationship
ment of a rotating mass perpendicular                    At a given speed, there is a correlation
to its motion and towards the axis of                 between time and distance.
                                                      correspond / kɒr spɒnd/ verb 1. to

rotation The Coriolis force explains                                                  |

why wind patterns are clockwise in the                fit with or have a direct relationship
northern hemisphere and anti-clock-                   with Movements of the control sur-
wise in the southern hemisphere.                      faces correspond to movements of the
                                                      pilots flying controls. 2. to be similar to
       COMMENT: The Coriolis force acts at a
       right angle to wind direction and is              In the interests of passenger comfort,
       directly proportional to wind speed. It        the ideal cabin conditions to maintain
       is named after G. G. Coriolis, a French        would be those corresponding to sea
       engineer who died in 1843.                     level.
                                                      corridor / kɒrdɔ / noun same as air

correct /kə rekt / adjective right


correct tyre pressure the pressure at                 corridor
                                                      corrode /kə rəυd/ verb 1. to destroy

which the tyres should be maintained í                                    |

verb 1. to adjust in order to make right              by a slow chemical process such as rust
   A servo-motor fitted in the elevator                 The sulphur and water content of tur-
trim system will automatically correct                bine fuels tend to corrode the compo-
for loads. Calibrated airspeed or rec-                nents of the fuel and combustion sys-
corrosion                                                          60
tems. 2. to be destroyed by a slow                                      course to change direction or to follow
chemical process such a rust Alumin-                                    a different route 2. a formal period of
ium will not corrode easily.                                            study a meteorology course 3. contin-
corrosion /kə rəυ (ə)n/ noun the                                        uing time in the course of the brief-


destruction of a material by chemical                                   ing during the briefing
processes     Aluminium has a high                                      course correction / kɔ s kə
                                                                        course correction


resistance to corrosion. anti-corro-                                     rekʃ(ə)n/ noun same as heading cor-
sion                                                                    rection
corrosion protection /kə rəυ (ə)n
corrosion protection

                                                                        course deviation indicator / kɔ s
                                                                        course deviation indicator

prə tekʃən/ noun action and/or meas-

                                                                         di vi eʃ(ə)n ndketə/ noun a nee-

ures taken to prevent corrosion such as                                 dle in an omni-bearing indicator
rust                                                                    which indicates if an aircraft is on a
corrosive /kə rəυsv/ adjective caus-

                                                                        selected course. Abbreviation CDI
ing corrosion Sulphuric acid is very
                                                                        cover / k və/ verb 1. to include e.g.

cosine / kəυ san/ noun a trigono-

                                                                        the complete extent of a period of time
metric function defined as the length of                                or the whole of a particular area The
the side adjacent to an angle in a right-                               restriction covers the period from 4th-
angled triangle divided by the length of                                8th July. the area covered by the
the hypotenuse. Abbreviation cos                                        forecast the area which the forecast
                                                                        deals with 2. to deal with a subject, as in
counter / kaυntə/ verb to act against

                                                                        a text The subject of central warning
something so as to remove or reduce its                                 systems is covered in the systems book.
effect For level flight, lift must counter                              3. to be completely over something so
the force of gravity. Some people find                                  as to hide what is underneath The area
that swallowing hard counters the                                       is covered in snow. í noun something
effects of changes in pressure.                                         which goes over something else com-
counter- /kaυntə/ prefix against

                                                                        pletely cloud cover the amount of
counterclockwise                 / kaυntə

                                                               |        cloud snow cover a situation in which
 klɒkwaz/ adjective, adverb US same                                    there is a layer of snow on top of the
as anticlockwise                                                        earth so that the earth cannot be seen
counter-rotating                                  propellers
counter-rotating propellers

                                                                        coverage / k v(ə)rd / noun 1. the

/ kaυntə rəυ tetŋ prə peləz/ plural
                              |               |
                                                                        amount of space or time given to a sub-
noun propellers which turn in opposite                                  ject, an event, etc. More complete cov-
directions (NOTE: They are also called                                  erage of the one-in-sixty rule is given in
contra-rotating propellers.)                                            the plotting section of these notes. 2. the
couple / k p(ə)l/ noun two of some-

                                                                        area within which a radar unit can
thing a couple of minutes two or                                        detect objects glidepath coverage
three minutes í verb 1. to connect or to                                localiser coverage
join, often mechanically The auxiliary
                                                                        cowl /kaυl/ noun a covering usually

power unit is a self-contained unit
which normally consists of a small gas                                  made up of hinged or removable panels
turbine engine which is coupled to a                                      cowl flap a removable or hinged panel
gearbox. 2. to combine Pilot error,                                     of a cowl       Further cooling can be
coupled with poor weather conditions,                                   obtained by the use of controllable cowl
resulted in an accident.                                                flaps which regulate the amount of air
                                                                        flowing across the cylinders.
coupling / k plŋ/ noun a joining or

                                                                        cowling / kaυlŋ / noun a covering

connecting component When not in
use, the coupling is sealed by a dust                                   usually made up of hinged or removable
cap.                                                                    panels Access to the engine compart-
course /kɔ s/ noun 1. an imaginary
                                                                        ment is normally via hinged cowling
line across the surface of the Earth                                    panels.

which must be followed in order to                                      CPL abbreviation Commercial Pilot’s
arrive at the destination      to alter                                 Licence
                                              61                             cross-pointer indicator
crab /kr b/ noun a manoeuvre in                    marks on the wheel and tyre indicate

which an aircraft is steered slightly into         that there is no creep.
a crosswind to compensate for flying               crest /krest/ noun the top of a moun-

slightly off course í verb to steer an air-        tain or wave Wind speeds increase
craft slightly into a crosswind to com-            with height, the speed of the wind at the
pensate for flying slightly off course             crest of a mountain or wave being the
craft /krɑ ft/ noun 1. a boat, etc., for           greatest.

carrying people or goods on water 2. an            crew /kru / noun two or more people

aircraft or spacecraft for carrying peo-           who have responsibility for flight oper-
ple or goods in the air or in space An             ations
airship is classified as a lighter-than-
                                                   criteria /kra təriə/ ‘ criterion

air craft.

                                                   criterion /kra təriən/ noun a stand-

crankcase / kr ŋkkes/ noun the

part of the engine that houses the crank-          ard by which you define, decide or
shaft and also usually the oil pump Oil            judge something (NOTE: The plural form
                                                   is criteria.) the criterion for promo-
passages in the crankcase allow lubri-
cating oil to pass through.                        tion is seniority senior staff will be pro-
                                                   moted first
crankshaft / kr ŋkʃɑ ft/ noun the

                                                   critical / krtk(ə)l/ adjective 1.

part of a piston engine connecting the
pistons, via the connecting rods, to the           extremely important, essential Tem-
flywheel and gearbox          Rpm is the           perature and oil pressure are critical to
number of revolutions per minute that              any type of system. 2. at which an
the engine crankshaft is making.                   important change occurs As the angle
                                                   of attack is increased, it reaches the
crash /kr ʃ/ noun an accident that

                                                   critical point when the airflow over the
causes damage í verb to have an acci-              upper surface of the wing begins to
dent or collision that causes damage               break down.
The aircraft crashed into the sea.
                                                   cross /krɒs/ verb 1. to get from one

crash-dive / kr ʃ dav/ verb to

                                                   side of an area to another to cross the
move downwards quickly through the                 Atlantic to go from one side of the
air front first and crash, or cause an air-        Atlantic to the other 2. to go across each
craft to do this                                   other at an angle Meridians intersect
crash-land / kr ʃ l nd/ verb to

                                                   at the poles and cross the equator at
land heavily without using the under-              right angles.
carriage, so that the aircraft is damaged          cross-check / krɒs tʃek/ noun veri-

  The aircraft crash-landed short of the           fication, making certain í verb to verify
runway.                                            or make certain       Cross-check doors
crash-landing / kr ʃ l ndŋ/ noun

                                                   closed and locked and escape slides
an act of landing an aircraft heavily,             armed. (NOTE: This word is often used
sometimes without the undercarriage                in brief messages from one crew mem-
The crash-landing did not damage the               ber to another, as from the pilot to cabin
aircraft as much as the pilot expected.            staff, to confirm that an action has been
create /kri et/ verb to make, to pro-

                                                   carried out.)
                                                   cross-country / krɒs k ntri/ noun

duce The velocity and pressure of the
exhaust gas create the thrust in the tur-          a flight during which the student pilot
bojet engine.                                      must demonstrate navigation skills
creep /kri p/ noun 1. a process of
                                                   the qualifying cross-country flight for
weakening and slow damage to some-                 the PPL
                                                   cross-pointer indicator / krɒs
                                                   cross-pointer indicator

thing Creep is a particular feature of
components which are subjected to                   pɔntə ndketə/ noun a display
operation at high temperatures. 2. a               with crossing horizontal and vertical
slight movement of a tyre on a wheel               bars to indicate aircraft position in rela-
caused by landing          Aligned white           tion to the glideslope
cross-section                                        62
cross-section / krɒs sekʃən/ noun                         required speed from top of climb to top

a view of an object seen as if cut                        of descent usually giving fuel economy
through The diagram is a cross-sec-                       and long engine life Cruising power is
tion of a turbojet engine.                                about 2,300 rpm.
crosswind / krɒswnd/ noun a sur-                         cruising speed / kru zŋ spi d/,
                                                          cruising speed

face wind which blows at an angle to                      cruise speed noun the speed selected
the landing or take-off heading On                        from top of climb to top of descent, usu-
some aircraft, crosswind take-offs                        ally giving fuel economy and long
should be made with full aileron deflec-                  engine life The cruising speed is 110
tion in the direction from which the                      knots.
wind is blowing.                                          cruising weight / kru zŋ wet/
                                                          cruising weight

      COMMENT : A crosswind landing is one                noun the weight of an aircraft in flight,
      of the most difficult exercises for a               consisting of its weight when empty, the
      student pilot. The final approach is                weight of its payload, and the weight of
      usually made with the aircraft yawed                the fuel that it has left
      into wind, while tracking the extended
                                                          crush /kr ʃ/ verb to damage by pres-

      runway centreline. Just before
      touchdown, the pilot aligns the aircraft            sure Excessive load on the beam may
      with the direction of flight using the              crush the core.
      rudder pedals. Correct timing for the               crystal / krstəl/ noun a regular geo-

      alignment and accurate airspeed are                 metric shape formed by minerals, or as
      required to achieve positive contact                water freezes
      with the runway surface otherwise the
                                                          CSDU abbreviation constant speed

      aircraft may depart the runway to one
      side.                                               drive unit
                                                          CSU abbreviation constant speed unit

crosswind                               / krɒs
crosswind component

                          component              |

 wnd kəm pəυnənt/ noun that part of                      CTA abbreviation control area


the wind force acting at an angle to the                  CTOT

                                                          CTOT abbreviation calculated take-off
direction of flight                                       time
crosswind leg / krɒswnd le /                             CTR /kən trəυl/ abbreviation control
crosswind leg


noun part of the airfield traffic circuit                 zone
flown at approximately 90° to the direc-                  cubic / kju bk/ adjective measured

tion of take off and climb out, followed                  in volume, by multiplying length, depth
by the downwind leg                                       and width cubic centimetres (cc) the
CRT / si ɑ ti / abbreviation cathode

                                                          usual unit used to measure the capacity
ray tube                                                  of an internal-combustion engine The
cruise /kru z/ noun the main part of                      engine has a capacity of 2,000cc.

the flight between top of climb after                     Abbreviation cc        cubic foot, cubic
take-off and descent for landing í verb                   inch, cubic metre, cubic yard the vol-
to fly the main part of the flight between                ume of a cube whose edge measures
top of climb after take-off and descent                   one foot, inch, metre or yard, respec-
for landing We are cruising at 500 kt.                    tively
   Cruising speed, cruising power and                     cumuliform / kju məlfɔ m/ adjec-

cruising altitude are selected to give                    tive which develop vertically cumuli-
maximum engine efficiency and prolong                     form clouds such as cumulonimbus
engine life.                                              cumulonimbus

                                                                                     / kju mjυləυ |

cruising                         / kru zŋ                 nmbəs/ noun a dark, low cumulus –
cruising altitude

   lttju d/, cruising level noun the                     type of cloud associated with thunder-
altitude at which most of a flight is                     storms A cumulonimbus has a charac-
flown en route to a destination, from top                 teristic anvil shape. Abbreviation CB
of climb to top of descent Our cruis-                     cumulus / kju mjυləs/ noun big,

ing altitude will be 35,000 feet.                         fluffy, white or grey cloud heaped or
cruising power / kru zŋ paυə/
cruising power

                                                          piled up, which develops at low altitude
noun engine power used to give                               Cumulus clouds may develop because
                                             63                               cylindrical
of thermal activity resulting from the            process of formation, development and
warming of the surface. Grey cumulus              decay of a thunderstorm
often develop into cumulonimbus.                  cyclic / sklk, saklk/, cyclical

altocumulus, stratocumulus                        / sklk(ə)l/ adjective referring to or
cumulus       cloud / kju mjυləs
cumulus cloud

                                                  happening in a cycle Off-shore and
klaυd/ noun clouds which form only in             on-shore wind patterns are cyclic.
an unstable atmosphere and, as the                cyclone / sakləυn/ noun a system of

name suggests, often build vertically for         winds rotating inwards to an area of low
great distances. Also called heap cloud           barometric pressure These areas of
current / k rənt/ adjective present,

                                                  low pressure are called hurricanes in
actual, happening at the moment cur-              the Atlantic Ocean, cyclones in the
rent weather conditions present                   Indian Ocean and Bay of Bengal, and
weather conditions current position               typhoons in the China Sea. Also called
the position now í noun 1. an electrical          low, depression
supply      alternating current     direct        cyclonic /sa klɒnk/ adjective refer-


current 2. flow                                   ring to air movement, which turns in the
curvature / k vətʃə/ noun a curved

                                                  same direction as the Earth and which,
shape      curvature of the earth the             when seen from above, is anticlockwise
curving of the Earth’s surface due to the         in the northern hemisphere and clock-
spherical form of the Earth                       wise in the southern hemisphere In
customary / k stəməri/ adjective

                                                  winter the sub-tropical high retreats
normal or usual It is customary for the           and gives way to cyclonic pressure pat-
senior cabin supervisor to introduce              terns which produce cool unsettled con-
herself to passengers at the start of a           ditions with rain at times.
flight.                                           cylinder / slndə/ noun a device

customs / k stəmz/ noun an official

                                                  shaped like a tube, in which a piston
department of government concerned                moves Smaller aircraft have a static
with movement of people and freight               hydraulic system similar to a car, with a
across national borders customs aer-              master cylinder and individual brake
odrome an aerodrome, usually near a               cylinders at each wheel.         cylinder
border or coast, with customs facilities          block the casing containing the cylin-
customs duty / k stəmz dju ti/                    ders in a internal combustion engine
customs duty

noun same as import duty the duty                 cylinder head the removable top part of
payable on a carton of cigarettes                 a piston engine cylinder containing
cycle / sak(ə)l/ noun a series of                plugs, inlet and exhaust connections

actions which end at the same point as            and valves
                                                  cylindrical /s lndrk(ə)l/ adjective

they begin With the piston engine, the                               |

cycle is intermittent, whereas in the gas         with the shape of a cylinder The mod-
turbine, each process is continuous.              ern jet engine is basically cylindrical in
life cycle of the thunderstorm cell the           shape.
D abbreviation danger area

                                            dangerous to the flight of the aircraft.
DA abbreviation danger area
                                            Abbreviation D, DA
                                            danger zone / dend ə zəυn/ noun
                                            danger zone

DAAIS abbreviation danger area activ-
ity information service                     an area where danger exists
                                            data / detə/ noun 1. information

DACS abbreviation danger area cross-

ing service                                 made up of numbers, characters and
DADC                                        symbols often stored on a computer in
DADC abbreviation digital air data          such a way that it can be processed
computer                                    Airspeed information is supplied from
DADS abbreviation digital air data sys-

                                            an air data computer. meteorological
tem                                         data information about weather condi-
DALR abbreviation dry adiabatic lapse       tions stored on a computer 2. informa-

rate                                        tion. recorder
damage / d md / noun harm that is          datum / detəm/ noun a reference or

caused to something If the tempera-         base point of a scale or measurement,
ture rises it can cause serious damage      e.g. mean sea level
to the engine. í verb to cause harm to      datum shift trim system / detəm
                                            datum shift trim system

something Small stones around the           ʃft trm sstəm/ noun a trim system
run-up area may damage propellers.          which varies the incidence of an all-
damage         tolerance / d md            moving tailplane without moving the
damage tolerance

 tɒlərəns/ noun the ability of a material   cockpit controls In some aircraft, the
or structure to withstand or resist dam-    datum shift is operated automatically.
                                            dB abbreviation decibel

age       The structural efficiency of
bonded and machined structure is not        DC abbreviation direct current

achieved at the expense of damage tol-      DCL abbreviation departure clearance

                                            de- /di / prefix undo, remove or stop

dampen / d mpən/ verb 1. to

                                            deactivate depressurise
decrease or reduce An accumulator is        deactivate /di ktvet/ verb to


fitted to store hydraulic fluid under       turn off a system or a piece of equip-
pressure and dampen pressure fluctua-       ment thus stopping it being ready to
tions. 2. to make slightly wet              operate On some aircraft nose wheel
damper / d mpə/ noun a device to

                                            steering must be deactivated prior to
decrease or reduce something A yaw          retraction.
damper is used for rudder control.          dead reckoning / ded rekənŋ /,
                                            dead reckoning

D & D abbreviation distress and diver-
D & D

                                            ded reckoning noun navigation using
sion cell                                   calculations based on airspeed, course,
danger area / dend ə eəriə/ noun
danger area

                                            heading, wind direction and speed,
airspace of a particular length, width      ground speed, and time In the early
and depth, within which at particular       stages of practical navigation, the stu-
times there may be activities which are     dent pilot navigates by using dead reck-
                                              65                                           deck
oning. Abbreviation DR (NOTE: The                  decimal / desm(ə)l/ noun a decimal

term comes from ‘deduced’ reckoning                fraction í adjective decimal fraction
or ‘ded’ reckoning.)                               a fraction as expressed in the decimal
de-aerate / di eərəet/ verb to                    system 0.50 is a decimal fraction that

remove gas, especially carbon dioxide              is equal to 1/2.       correct to three
or air, from a liquid such as fuel The             places of decimal or to three decimal
pump helps to de-aerate the fuel before            places correct to three figures after the
it enters the engine.                              decimal point 2.754 is correct to three
de-aeration / di eə reʃ(ə)n/ noun

                                                   decimal places, 2.7 is correct to one
the process of removing gas from a liq-            decimal place.
                                                   decimal notation / desm(ə)l nəυ
                                                   decimal notation

uid such as fuel Partial de-aeration of                                                            |

fuel takes place in the pump.                       teʃ(ə)n/ noun the method of writing a
de-aerator / di eə retə/ noun a

                                                   number in the decimal system The
device to remove gas from a liquid                 fraction 3/4 can be written as 0.75 in
                                                   decimal notation. Prices and number
de-aerator tray / di eə retə tre/
de-aerator tray

                                                   are normally written using decimal
noun a device in the lubrication system            notation. He finds it difficult to under-
to remove air bubbles from oil                     stand how the computer works because
deal /di l/ noun a great deal a large

                                                   it uses binary not decimal notation.
amount of, a lot of A great deal of                decimal place / desm(ə)l ples/
                                                   decimal place

damage was done to the aircraft as a               noun the position of a number to the
result of the fire. í verb to handle or            right of the decimal point
manage A computer can deal with the
                                                   decimal point / desm(ə)l pɔnt/
                                                   decimal point

constant inputs required to control an
unstable aircraft.                                 noun the dot (.) used to separate a whole
                                                   number from a decimal fraction
debris / debri / noun scattered broken

pieces Before running up the engine,                      COMMENT: The decimal point is used
check that the aircraft is on firm ground                 in the USA and Britain. In most
                                                          European countries a comma (,) is
and that the area is free of stones and                   used to show the decimal, so 4,75% in
other debris. The aircraft exploded in                    Germany is written 4.75% in Britain.
mid-air, spreading debris over a wide
                                                                              / desm(ə)l
                                                   decimal system

area of the countryside.                           decimal        system
decal /d k l/ noun picture, letters or

                                                    sstəm/ noun system of counting
digits printed on adhesive paper, which            based on the number 10 and using the
is transferred onto a surface and may be           digits 0 – 9
                                                   decision /d s (ə)n/ noun the act of

peeled away A red decal with AVGAS                                     |

100LL in white letters indicates the type          deciding or of making up one’s mind
of fuel to be used.                                to make a decision to choose a course
decelerate /di seləret/ verb to slow

                                                   of action The decision to evacuate the
down Reverse thrust and brakes help                aircraft was made by the captain.
                                                   decision height /d s (ə)n hat/
                                                   decision height

to decelerate the aircraft after landing.                                         |

Opposite accelerate                                noun the altitude at which, during an

deceleration           /di selə reʃ(ə)n/
                                  |       |
                                                   ILS landing approach, a pilot must
noun slowing down Anti-skid braking                decide whether to land or carry out a
systems units are designed to prevent              missed approach      The pilot waited
the brakes locking the wheels during               until she was at decision height before
landing, thus reducing the possibility of          initiating the missed approach proce-
wheel skid caused by the sudden decel-             dure. Abbreviation DH
eration of the wheel. Opposite acceler-                   COMMENT: An ILS approach generally
ation                                                     has a decision height of 200 ft (60 m)
                                                          above ground level.
decibel / desbel/ noun a unit for

                                                   deck /dek/ noun the floor of a ship or

measuring the loudness of a sound.
Abbreviation dB                                    aircraft
decode                                         66
decode /di kəυd/ verb to change                     word itself A sphere is, by definition,


coded information into readable form                round.
Incorrectly spaced information pulses               deflate /di flet / verb to allow air to


can result in failure by the ground sta-            escape from something, so that it
tion to decode the aircraft information.            becomes smaller or collapses. Opposite
decoder / di kəυdə / noun a device

                                                    inflate to deflate a tyre to allow the
used to decode signals from the air traf-           air to escape from a tyre
                                                    deflation /di fleʃ(ə)n/ noun the act

fic control radar beacon system The                                               |

aircraft receiver is set to the required            of allowing air to escape from some-
frequency and linked to a selective call            thing, so that it becomes smaller or col-
system decoder which has a 4-letter                 lapses Deflation of a tyre is done by
code.                                               depressing the valve.
decrease noun / di kri s/ a lessening               deflect /d flekt/ verb 1. to cause an


or reduction       A decrease in power              object to move away from a neutral or
results in the aircraft descending. í               central position During an out-of-bal-
verb /d kri s/ to become less, to fall
                                                    ance turn, the ball in the slip indicator
Air density and pressure decrease with              will be deflected to the left or right. 2. to
an increase in altitude. opposite (all              move a moving object, gas or liquid
senses) increase                                    away from its intended path In an
                                                    open-cockpit aircraft, the windshield
deduce /d dju s/ verb to work some-

                                                    deflects the airflow over the pilot’s
thing out in the mind using information             head.
provided Sometimes, it is possible to
                                                    deflection /d flekʃ(ə)n/ noun 1.

estimate the depth of the layer of mist or                                            |

fog from the ground observations and                movement away from a central or neu-
hence to deduce the ground range from               tral position      Full deflection of the
any height.                                         ailerons is sometimes needed on take-
                                                    off to counteract a crosswind. 2. the
defect / di fekt/ noun a fault or error

                                                    movement of a moving object, gas or
  Low oil pressure or excessive temper-             liquid away from its intended path In
ature indicate the development of a pos-            the southern hemisphere the deflection
sible defect.                                       of wind at the equator is to the left.
defective /d fektv/ adjective faulty

                                                    deformation            / di fɔ meʃ(ə)n/


or not operating correctly Loss of sup-             noun a change of the correct shape
ply pressure is caused by either a defec-           caused by stress Deformation of wing
tive booster pump or lack of fuel.                  panels may be an indication of serious
define /d fan/ verb 1. to give an                 structural damage.


exact explanation, as in a dictionary it            deg abbreviation degree

is not easy to define the word it is dif-           degradation / de rə deʃ(ə)n/ noun


ficult to say exactly what the word                 a decrease in quality Degradation of
means 2. to set the limits of something             the radio signal sometimes makes it
  Cloud tops are very difficult to define.          impossible to understand the message.
definite / def(ə)nət/ adjective refer-              degrade /d red/ verb to decrease


ring to something which is not in doubt,            the quality of something Interfering
which is certain Using a time scale on              signals degrade VOR performance.
the track, the pilot should be prepared             degree /d ri / noun 1. a level,


to look for a definite feature at a definite        amount or quantity         the degree of
time. Opposite indefinite                           compression the amount of compres-
definition / def nʃ(ə)n/ noun an

                                 |                  sion a high degree of safety a high
exact explanation of what a word or                 level of safety to a greater degree
expression means The definition of a                more than to a lesser degree less than
year is the time taken for a planet to              2. a unit of temperature             twenty
describe one orbit around the sun. by               degrees Celsius (20°C)               twenty
definition understood by the use of the             degrees Centigrade (20°C)           seventy
                                            67                               density altitude
degrees Fahrenheit (70°F) 3. a unit of           delivery /d lv(ə)ri/ noun the act of


measurement of an angle equal to                 providing or giving On some pumps, a
1/360th of a circle – each degree is             depressurising valve is used to block
divided into 60 minutes and each min-            delivery to the system.
utes into 60 seconds Make a turn to              delivery pressure /d lv(ə)ri
                                                 delivery pressure


the right at a bank angle of 30°. an              preʃə/ noun the pressure normally
angle of 90° a right angle 4. a unit of          expected when fuel is being pumped
direction as measured on a compass
                                                 deluge / delju d / noun ‘ fire deluge

east = 090° west = 270°
degrees true /d ri z tru / noun
degrees true

                                                 demand / d mɑ nd/ noun 1. a need or
                         |                       demand

degrees of direction measured from true                              |

north, not magnetic north. Also called           use caused by necessity high current
true degrees. Symbol °T                          demand on a generator a situation
                                                 requiring the generator to produce a lot
dehydration          / di ha dreʃ(ə)n/

                                                 of electricity 2. a request which is made
noun an unwanted and sometimes dan-              firmly on demand when asked for or
gerous loss of water from the body               ordered A computer will produce, on
Dehydration can be avoided by drink-             demand, a flight plan giving the opti-
ing plenty of water.                             mum route, levels and fuel. í verb 1. to
de-ice / di as/ verb to remove ice

                                                 require as a necessity Higher operat-
The ground crew de-iced the aircraft             ing weights of modern aircraft demand
prior to take-off.                               an increase in the number of wheels fit-
de-icer / di asə/ noun a device or

                                                 ted to the landing gear. 2. to ask firmly
substance used to remove ice De-icer               He demanded an explanation.
spray should be checked to make sure it          demonstrate / demənstret/ verb to

is not harmful to light aircraft wind-           show by clear example or explanation
screens.                                         Torricelli first demonstrated that the
de-icing / di        asŋ/ noun the

                                                 atmosphere has weight.         It will be
removal of ice í adjective referring to          demonstrated in chapter 12 that turbu-
the removal of ice      de-icing fluid           lence is associated with strong winds.
anti-icing, icing                                demonstration / demən streʃ(ə)n/


delay /d le / noun a period after the

                 |                               noun a clear, often visual, description or
expected time that you have to wait              explanation Your instructor will give a
before something happens, the length of          demonstration of the stall-recovery
time by which something is late By               technique.
day, the presence of cloud can cause a           dense /dens/ adjective 1. referring to

delay in clearance of fog. í verb 1. to          a substance which is closely compacted
make late, to cause to be late Take-off            dense fog thick fog 2. referring to the
was delayed because of fog. 2. to put            amount of mass of a substance for a
something off until later He delayed             given unit of volume Air which con-
telling her the news until they had              tains water vapour is less dense than air
landed.                                          which does not.
delayed-action /d led            kʃən/

                                                 density / densti/ noun a quantity of

adjective in which there is an unusual           mass for a given unit of volume air
passing of time between stimulus and             density
response      The door is fitted with a
                                                 density                         / densəti
                                                 density altitude

delayed-action lock which operates one                            altitude
minute after the power has been                     lttju d/ noun the pressure altitude
switched off.                                    corrected for non-ISA temperature
                                                     COMMENT: Density altitude is a very
deliver /d lvə/ verb to provide, to


                                                     important factor in calculating aircraft
give The motor will continue to run                  performance because of its effect on
but will deliver only one-third the rated            engine performance, time to reach
power. The pump can deliver fuel at                  takeoff speed (and therefore length of
the rate of 2,000 gph.                               take-off run) and rate of climb.
density error                                              68
density error / densəti erə/ noun a                             deposit /d pɒzt/ noun a layer of
density error                                                   deposit


correction to airspeed to give true air-                        collected matter on a surface           A
speed                                                           deposit of ice crystals causes the air-

DEP abbreviation departure message                              craft surfaces to change their aerody-
depart /d pɑ t/ verb to leave The

                                                                namic characteristics. Wheel brakes
flight departs at 0200 GMT. Opposite                            should be inspected for snow or ice
                                                                depreciate /d pri ʃiet/ verb to

department /d pɑ tmənt/ noun a

separate part of a complex whole, espe-                         decrease in value The aircraft depre-
cially of an organisation                                       ciated by 100% over the 5 year period.
                                                                Opposite appreciate
departure /d pɑ tʃə/ noun 1. the act

                                                                                       /d pri ʃi eʃ(ə)n/
                               |                                depreciation

of leaving departure time the time                              depreciation                           |           |

when an aircraft becomes airborne 2.                            noun a decrease in value There was a
the distance between two meridians at                           depreciation of 100% in the value of the
any given latitude                                              aircraft over the 5 year period. Oppo-
                                                                site appreciation
departure         lounge /d pɑ tʃə
departure lounge


                                                                depress /d pres / verb to push down

laυnd / noun a room at an airport                                                          |

where passengers wait to board their                                Switches on the control columns
aircraft                                                        instantly disengage the autopilot when
departure point /d pɑ tʃə pɔnt/
departure point

                                                                depression /d preʃ(ə)n/ noun 1. an

noun a place on the map representing                                                           |

the place from which a flight begins                            area of low atmospheric pressure In
departures /d pɑ tʃəz/ noun the

                                                                the northern hemisphere, the wind
part of an airport that deals with passen-                      blows anticlockwise round a depression
gers who are leaving                                            and clockwise round an anticyclone and
                                                                vice versa in the southern hemisphere.
depend /d pend/ verb 1. to be con-

                                                                deep depression area of very low rela-
trolled or affected entirely by some-                           tive atmospheric pressure 2. a lower
thing Whether or not an object can be                           area on a surface, which is often diffi-
seen by aircrew at a given distance will                        cult to see A depression on the wing
depend on factors such as size, shape                           surface must be investigated in case it is
and colour of the object. If an aircraft                        an indication of more serious structural
ditches in the sea, early rescue depends                        damage.
on rapid location of survivors. 2. to rely
                                                                                            /di preʃəra

on Pilots depend on air traffic con-                            depressurisation                               |       |

trollers to help them conduct a safe                             zeʃ(ə)n/, depressurization noun a
flight.                                                         loss, especially sudden, of cabin pres-
                                                                sure Emergency oxygen must be avail-
dependable /d pendəb(ə)l/ adjec-


                                                                able in the event of depressurisation.
tive reliable, trustworthy        Mercury
                                                                                         /di preʃəraz/,

barometers have largely been replaced                           depressurise                               |

by precision aneroid barometers which                           depressurize verb to lose pressure
are smaller, simpler to use, and more                           suddenly, or to cause to lose pressure
dependable.                                                     The aircraft began to depressurise at
dependent /d pendənt/ adjective

                                                                20,000 feet.
                                                                depth /depθ/ noun the distance from

relying on or unable to do without
something The height indicated by an                            the top surface of something to the bot-
altimeter is dependent on the pressure                          tom The troposphere’s depth is varia-
which is set on the sub-scale.                                  ble in temperate latitudes.
deploy /d plɔ/ verb to come into                              derive /d rav/ verb to get or to obtain
deploy                                                          derive

                       |                                                           |

action, to become ready to be used                                  Performance data is derived from
Slide rafts are door-mounted and auto-                          flight tests. Kepler derived the laws
matically deploy and inflate when the                           which relate to the motion of planets in
door is opened in the armed position.                           their orbits.
                                              69                            detachable wheel spats
descend /d send/ verb to lose alti-               designer /d zanə/ noun a person
descend                                            designer

                      |                                                                 |

tude, usually in a planned manoeuvre               who has the idea for, and makes plans to
the aircraft descended to 10,000 feet              produce, something         Rutan is a
the pilot reduced altitude until the air-          designer of unusual-looking aircraft.
craft was at 10,000 feet. Opposite                  ‘…test-pilot’s tip for a safe first flight –
climb, ascend                                       take the designer with you’ [Flight
descent /d sent/ noun a planned loss

                                                    International 9–15 Oct. 1996]
                                                   desirable /d zaərəb(ə)l/ adjective

of altitude The descent from cruise                                                         |

altitude took 40 minutes.        in the            preferred or wanted Equalisation of
descent during planned loss of altitude,           the air pressure across the eardrum is
usually in preparation for landing                 more difficult to achieve during
    ‘…a search of radar recordings showed
                                                   descents than ascents, and a minimum
    that a DC-10 had tracked within a few          rate of pressure change is desirable.
                                                   despite /d spat/ preposition in spite

    hundred metres of the house while                                           |

    passing 9,500 feet in the descent to           of Many beacons and aids which are
    Gatwick’ [Pilot]                               provided for low operations are left out
describe /d skrab/ verb 1. to give

                                                   to keep the chart clear – despite this, the
the particular features of something to            charts still look very difficult to under-
describe what happened put into                    stand. despite the weather, we took
words exactly what happened 2. to draw             off although the weather was bad, we
a geometric figure or to move in a line            took off
                                                   DEST abbreviation destination

that forms a geometric figure The def-
                                                   destination / dest neʃ(ə)n/ noun

inition of a year is the time taken for a                                                               |

planet to describe one orbit around the            the place to which somebody or some-
sun. to describe an arc to draw or                 thing is going Aerodrome forecasts
move in an arc                                     are normally given in code form for
                                                   destination and alternates.
description /d skrpʃən/ noun 1.

                                                   destroy /d strɔ/ verb to damage so
                              |                    destroy

the act of giving the particular features                                           |

of something a detailed description of             much as to make useless The aircraft
world climate 2. the drawing or making             was destroyed in the accident.
                                                   destruction /d str kʃən/ noun an

of a geometric figure the description                                                               |

of a triangle the drawing of a triangle            act or instance of making completely
                                                   useless by breaking           By testing
desert / dezət/ noun a large area of

                                                   selected parts to destruction, a safe life
dry often sandy country Over desert                can be assessed for all structures and
areas the lack of water vapour produces            components.
cold nights.
                                                   destructive /d str ktv/ adjective

design /d zan/ noun a plan or draw-

                                                   referring to something which destroys
ing of something before it is made The             the winds of a tornado are extremely
design and testing of aircraft are impor-          destructive tornadoes cause a lot of
tant stages in the development pro-                serious damage
gramme. í verb to draw plans using                 detach /d t tʃ/ verb to remove a part


accurate information in preparation for            from something, or to be removed A
constructing something to design an                fuselage panel became detached and
aircraft to have the idea, make draw-              had to be replaced. The parachute
ings, calculate data, etc., with the inten-        flare is a device which is fired to a
tion of producing an aircraft                      height of 1,200 ft where a red flare and
designate / dez net/ verb to

                                                   parachute detach.
choose for a special purpose           This        detachable /d t tʃəb(ə)l/ adjective


region is designated as a fire zone.               referring to something which can be
designator / dez netə/ noun a                    unfixed and removed

                                                   detachable wheel spats /d
                                                   detachable wheel spats

group of letters and/or numbers that                                                                        |

identify something                                  t tʃəb(ə)l wi l sp ts/ plural noun
detail                                              70
streamlined coverings for the wheels of                  the safety of hundreds of passengers is
light aircraft which can be taken off to                 involved, and regulations determine the
allow inspection and repairs of tyres                    minimum crew that must be carried.
detail / di tel/ noun the important and                 detonation / detə neʃ(ə)n/ noun a
detail                                                   detonation


less important facts about something                     sudden, explosive burning of the
The amount of detail which appears on                    air/fuel mixture Prior to the accident,
a topographical chart depends upon the                   engine detonation could be heard by
scale.                                                   people on the ground.
detect /d tekt / verb to discover the

                                                             COMMENT:        Detonation imposes
presence of something         Apart from                     excessive loads on the pistons and
sensing the abnormal rate of descent of                      other engine components, possibly
a false glide slope, the pilot can detect                    causing engine damage and resulting
an error by comparing height with dis-                       in engine failure.
tance to go.                                             develop /d veləp/ verb 1. to come


detection /d tekʃən/ noun the dis-

                        |                                into being      Carburettor icing may
covery of the presence of something                      develop in any type of carburettor in
detector /d tektə/ noun a device for

                                                         relatively warm air temperatures.
discovering the existence of something                   Vertical motion and therefore turbu-
  ice detector a device for detecting the                lence suggest that thunderstorms may
presence of ice on the airframe When                     develop. 2. to get bigger, to grow and
ice forms on the vibrating rod ice detec-                change During the day, light breezes
tor head, the probe frequency                            may develop into strong winds.
                                                         development /d veləpmənt/ noun

decreases.                                                                         |

deteriorate /d təriəret/ verb to                      1. something new, made as an improve-


become or make bad or worse The                          ment on something older          Satellite
electrolyte in the cells of a nickel-cad-                navigation aids for light aircraft are a
mium battery does not chemically react                   recent development. 2. growth and
with the plates and so the plates do not                 change       To study weather and its
deteriorate.     deteriorating weather                   development, the meteorologist has to
worsening weather                                        be aware of the horizontal changes in

                      /d təriə reʃ(ə)n/
                                        |       |
                                                         atmospheric pressure both in space and
noun worsening a deterioration in
                                                         deviate / di viet / verb to move away

the situation a worsening of the situa-
tion                                                     from the normal position or path If the
determination /d t m neʃ(ə)n/

                                    |       |
                                                         aircraft deviates beyond the normal ILS
noun 1. the act of finding out by calcu-                 glide slope, the flight crew are alerted.
                                                         deviation / di vi eʃ(ə)n/ noun 1. the

lation     Structure design for a given                                        |

safe life has led to the determination of                process of moving away from the nor-
the minimum number of flying hours                       mal position or path           On final
which should pass before major failure                   approach, any deviation from the
occurs. 2. the strength of mind to do                    extended centreline of the runway
what is required Determination was a                     should be corrected immediately. 2. a
major factor in the trainee passing his                  magnetic compass error in a particular
exams.                                                   aircraft caused by magnetic influences
determine /d t mn/ verb 1. to find

                                                         in the structure and equipment of the
out by calculation To determine the                      aircraft itself Deviation is not a con-
average age, divide the total number of                  stant value but varies from one aircraft
years by the number of people. When                      to another.
                                                         device /d vas/ noun an object, espe-

we wish to fly from one place to another,                              |

it is first necessary to determine the                   cially mechanical or electrical, which
direction of the destination from the                    has been made for a particular purpose
departure point. 2. to set or to fix pre-                  A capacitor is a device with the ability
cisely On a large transport aircraft,                    to temporarily store an electric charge.
                                               71                                                               diffusion
dew /dju / noun drops of condensed                  diaphragm / daəfr m/ noun a thin
dew                                                 diaphragm

moisture left on the ground overnight in            sheet of material used to separate parts
cool places                                         or chambers Some switches are oper-
dew point / dju pɔnt/ noun the                     ated by a diaphragm which flexes under
dew point

temperature at which air is saturated               fluid or air pressure.
with water vapour and condensation                  differ / dfə/ verb to be unlike Track

begins                                              and heading differ by the amount of
       COMMENT: Weather reports usually             drift. Because the chart time and the
       include the air temperature and dew          departure/arrival times differ, it is nec-
       point     temperature.   When     the        essary to consider the movement of any
       difference between temperature and           weather system which might affect the
       dew point is small, there is a strong        route.
       possibility    of  fog,  clouds,   or
                                                    differential / dfə renʃəl/ adjective

       precipitation.                                                                                   |

                                                    referring to things which react differ-
DF abbreviation direction finding

                                                    ently when measured against a norm or
DFDR abbreviation digital flight data

                                                    standard differential heating of the
recorder                                            atmosphere the heating of the atmos-
DFR abbreviation departure flow regu-

                                                    phere to varying temperatures depend-
lation                                              ing on the relative warmth of the land at
DFTI abbreviation Distance from

                                                    the equator and the poles
touchdown indicator                                 differential expansion switch
                                                    differential expansion switch

DH abbreviation decision height                     / dfərenʃəl k sp nʃ(ə)n    swtʃ/


DI abbreviation direction indicator
                                                    noun a switch which operates on the
diagonal / da ən(ə)l/ adjective 1.

                                                    principle that the coefficients of expan-
joining two opposite corners of a rec-              sion of dissimilar metals are different
                                                    differentiate / dfə renʃiet/ verb to

tangle 2. sloping halfway between the                                                                       |

vertical and horizontal Early aircraft              recognise the difference between two
were of the wire braced type of con-                things; to show two things to be differ-
struction, the wire being superseded by             ent Some types of colour blindness
tubular diagonal struts. í noun a line              make the sufferer unable to differentiate
joining two opposite corners of a rec-              between blue and red.
                                                    diffraction /d fr kʃ(ə)n/ noun the

tangle                                                                                          |

diagram / daə r m/ noun an often                   breaking down of a beam of radiation

simplified drawing showing the struc-               Diffraction produces a surface wave
ture or workings of something The                   which follows the curvature of the
diagram shows a simple open-circuit                 earth.
system.                                             diffuse / d fju s/ adjective spread out


diagrammatic          / daə rə m tk/              in every direction Glare caused by dif-


adjective referring to something which              fuse reflection of sunlight from the top
is shown as a drawing of a system or                of a layer of fog or haze can seriously
structure     diagrammatic format in                reduce air-to-ground visibility. í verb to
the form of a diagram                               spread out in every direction Light dif-
dial / daəl/ noun the face of an instru-
                                                    fuses as it passes through fog.
                                                    diffuser /d fju zə/ noun a device in a

ment showing a scale A cup anemom-                                                      |

eter is connected to an instrument with             jet engine that alters the direction of
a dial showing wind speed in knots.                 flow of the air entering the engine as
diameter /da mtə/ noun the dis-                   part of the process of compressing it


tance from one side of a circle to the              before it reaches the combustion cham-
other, passing through the centre                   ber
                                                    diffusion /d fju (ə)n/ noun the

equatorial diameter the distance from                                                       |

the equator, through the centre of the              process of spreading out Gas from the
Earth to the equator on the opposite side           turbine enters the exhaust system at
of the globe                                        high velocities but, because of high fric-
digit                                       72
tion losses, the speed of flow is                direct current /da rekt k rənt/
                                                 direct current


decreased by diffusion.                          noun an electric current flowing in one
digit / dd t/ noun any number from             direction only An electric starter is

0 to 9 Information is provided in a              usually a direct current electric motor
four-digit group.                                coupled to the engine, which automati-
                                                 cally disengages after the engine starts.
digital / dd t(ə)l/ adjective referring

                                                 Abbreviation DC
to a system or device which uses signals
                                                 direction /da rekʃən/ noun the

or information in the form of numbers                                             |

                                                 course taken by somebody or some-
dihedral / da hedr(ə)l/ noun the

                                                 thing The Earth rotates about its own
angle between an upward sloping air-             axis in an anticlockwise direction.
craft wing and a horizontal line                 directional /da rekʃən(ə)l/ adjec-


diluted /da lu td/ adjective made

                                                 tive referring to the course taken by
weaker by adding water or some other             somebody or something
fluid Spillage from a lead acid battery          directional gyro / da rekʃ(ə)n(ə)l
                                                 directional gyro


may be neutralised by washing with a              d arəυ/ noun a gyroscopic instrument
diluted solution of sodium bicarbonate.          which indicates direction but does not
diluter / da lu tə/ noun a device for

                  |                              have a north-seeking magnet          The
decreasing the strength or concentration         directional gyro should be set to corre-
of a liquid or gas Most flight decks use         spond with the magnetic compass.
the diluter demand system in which the           heading indicator
oxygen is diluted with cabin air.                directional       radar beam /da
                                                 directional radar beam


dimension /da menʃən/ noun a                     rekʃ(ə)n(ə)l redɑ bi m/ noun a sig-


measurable distance such as height,              nal from a directional beacon enabling
length, etc., or a measurement of height,        the pilot to determine a bearing from the
length, etc. Variations of atmospheric           beacon with a communications receiver
pressure produce changes in the dimen-           direction indicator /da rekʃən
                                                 direction indicator


sion of the capsule chamber.                      ndketə/ noun an instrument which
diminish /d mnʃ/ verb to decrease

                                                 gives direction information. Abbrevia-
or to reduce in size or importance               tion DI
                                                 directive /da rektv / adjective refer-

Friction is greatest near the ground and                                      |

diminishes with height. At higher alti-          ring to the ability of a device to send or
tudes, ground objects are less easily            receive signals in straight lines The
seen because of diminished size.                 antenna is highly directive in transmis-
diode / daəυd/ noun an electronic
                                                 sion and reception. í noun general or
component that allows an electrical cur-         detailed instructions from management
rent to pass in one direction and not the        to staff to guide them in their work
other                                            According to the management directive,
                                                 all late arrivals should be logged.
dioxide /da ɒksad/ noun an oxide

                                                 director /da rektə/ noun 1. a device
                      |                          director


containing two atoms of oxygen. car-             with a central controlling function
bon dioxide
                                                 EFIS is a highly sophisticated type of
dip to move e.g. the wing or nose of an          flight director system. 2. a person who
aircraft so that it points downwards             is a member of the board that controls
direct /da rekt/ adjective 1. in a              the activities of a company managing


straight line; by the shortest route a           director
                                                 disadvantage            / dsəd vɑ ntd /

direct flight 2. complete the direct                                                              |

opposite í verb to guide or control the          noun an unwanted situation or condi-
movement of something          Clamshell         tion, or a factor which makes somebody
doors are hydraulically or pneumati-             or something less likely to succeed
cally opened, and direct the exhaust             The disadvantage of a booster pump is
gases forwards to produce reverse                that the output is constant so that when
thrust.                                          engine demand is high, fuel pressure
                                                      73                                                dispense
tends to be low and vice versa. Opposite                   discuss /d sk s/ verb to write about


advantage                                                  or talk about a subject This chapter
disadvantaged / dsəd vɑ ntd d/

                                                           will discuss HF and VHF voice commu-
adjective  physically disadvantaged                        nications.
                                                           disembark / dsm bɑ k/ verb to

(person) a person who has a physical                                                        |

disability                                                 leave the aircraft after landing The
                                                           passengers finally disembarked at
       COMMENT: The word ‘disadvantaged’
       may be regarded by some people as a                 20.00 hours.
                                                           disembarkation                / dsmbɑ

       politically correct term for ‘disabled’.                                                                     |

       With the help of specially-adapted                   keʃ(ə)n/ noun the act of leaving the
       controls, more and more disabled                    aircraft after landing    The exits are
       people are learning to fly.                         used as conventional doors for disem-
disappear / dsə pə/ verb 1. to van-

                                                           disengage / dsn ed / verb to

ish If air blew at right angles to iso-                                                 |

bars, the horizontal pressure differ-                      switch off a system or device Switches
ences would eventually disappear. 2. to                    on the control columns instantly disen-
pass out of sight The aircraft took off,                   gage the autopilot when depressed.
                                                           dish /dʃ/ noun a shallow container for

climbed out and soon disappeared from
view.                                                      food
disarm /ds ɑ m/ verb 1. to switch off                     dish antenna / dʃ n tenə/ noun a
disarm                                                     dish antenna


an active or live system On the ground                     circular antenna with a shape like a
approaching the terminal, the flight                       shallow bowl
                                                           disintegration /ds nt reʃ(ə)n/

deck will instruct the cabin crew to dis-                                                       |       |

arm the escape devices. 2. to forcibly                     noun the falling apart or destruction of
remove a weapon from somebody The                          something        Electromagnetic radia-
hijacker was disarmed by security                          tions resulting from the disintegration
forces.                                                    of radioactive materials are known as
disc /dsk/ noun a circular flat plate
                                                           gamma rays.
                                                           dismantle /ds m nt(ə)l/ verb to

A turbine consists of a disc on which is                                            |

mounted a number of blades.                                take apart into single components One
                                                           type of inspection is able to reveal
discharge / ds tʃɑ d / noun a

                                                           fatigue cracks, corrosion, internal dam-
release of power from a source such as                     age, the presence of loose articles and
a battery A lightning flash is a large-                    mercury spillage without the need to
scale example of an electrical spark, or                   dismantle the aircraft. Opposite
discharge. battery discharge the loss                      assemble (NOTE: The verb ‘mantle’ is
or release of electrical supply from a                     not used.)
battery í verb to release electrical sup-                  disorientation / dsɔ riən teʃ(ə)n/


ply from a source such as a battery                        noun a state of confusion in which there
The battery discharged overnight.                          is loss of understanding of where one is
disconnect / dskə nekt/ verb to

                                  |                        or which direction one is facing, etc.
separate two things attached to one                        When the cabin is rapidly and com-
another The electrical supply can be                       pletely filled by smoke and fumes pas-
disconnected by pulling out the plug.                      sengers will suffer from disorientation.
                              /d skrm                   dispensation          / dspen seʃ(ə)n/
discrimination                                             dispensation

discrimination                            |       |

 neʃ(ə)n/ noun the ability to know or                     noun permission not to have to do
see the difference between two similar                     something At very high altitudes the
things Targets on the same bearing                         flying pilot must be on oxygen at all
which are separated radially by less                       times, unless an aircraft dispensation
than half a pulse length distance will                     has been obtained.
                                                           dispense /d spens/, dispense with

appear at the receiver as one echo, so                                          |

good target discrimination requires                        verb not to include or not to use some-
short pulses.                                              thing In some cases the rivets are dis-
dispersal                                   74
pensed with and the skin is fixed to the         ential expansion switches operate on
internal members by the redux process.           the principle that the coefficients of
dispersal /d sp s(ə)l/ noun 1. the

                                                 expansion of dissimilar metals are dif-
act of leaving an area and going in dif-         ferent.
                                                 dissipate / dspet/ verb to spread

ferent directions the dispersal of a
crowd the disappearance of a crowd 2.            out and lose power or strength, or to
the clearing away of something such as           cause something to do this Tropical
mist, e.g. by the wind the dispersal of          storms often dissipate as they pass from
hill fog Dispersal of cloud takes place          sea to land.
when surface heating lifts the cloud
                                                 dissipation / ds peʃ(ə)n/ noun the

base or drier air is advected.

                                                 process of spreading out and losing
disperse /d sp s/ verb 1. to leave an

                                                 power or strength The rubber used on
area going in different directions the           nose or tail wheels is usually con-
crowd dispersed the people in the                structed to form a good electrical con-
crowd left the area, going in different          ductor for the safe dissipation of static
directions, so that eventually the crowd         electricity.
disappeared 2. to clear away The fluo-
                                                 dissolve /d zɒlv/ verb to become or

rescent green dye will disperse slowly in                                       |

a calm sea but quickly in a moderate to          to cause to become part of a liquid and
rough sea.                                       form a solution Sugar dissolves in
                                                 water. There is a possibility that in
displace /ds ples/ verb to move

                                                 some types of accumulator, gas may be
something out of its normal position             dissolved into the fluid and thus intro-
The atmosphere is said to be stable if,          duced into the system.
when a parcel of air is displaced verti-
                                                 dissolved /d zɒlvd/ adjective that

cally, it tends to return to its original                                           |

level.                                           has melted and become of a liquid
                                                 dissolved water water in solution in
displacement /ds plesmənt/ noun


movement away from the normal posi-
                                                 distance / dstəns/ noun a space

tion The ILS is a cross-pointer indica-
tor which shows the aircraft horizontal          between two places or points, or the
displacement from the localiser and              measurement of such a space The dis-
vertical displacement from the glide             tance from point A to point B is 100 nm.
path.                                              The distance from point A to point B
display /d sple/ noun 1. the appear-

                                                 on the diagram is 2 cm. The height of
ance of information on a monitor screen          the aircraft is the vertical distance,
or on the panel of an instrument or of an        measured in feet, of the aircraft above
indicator      There are three different         the surface of the Earth.
                                                 distance measuring equipment

types of electronic display systems:             distance measuring equipment
EFIS, EICAS and ECAM. digital dis-               / dstəns me (ə)rŋ  kwpmənt/            |

play information shown as numbers                noun an airborne secondary radar
The clock uses a digital display to show         whose signal is converted into distance
the time of 12:33. 2. a show or demon-             It is quite common to find a VOR
stration í verb to show, e.g. on a panel         located together with DME (Distance
or a screen        Alerting and warning          Measuring Equipment) to give simulta-
information is displayed.                        neous range and bearing from the same
disseminate /d semnet/ verb to

                                                 point on the ground. Abbreviation DME
send out or spread         Meteorological            COMMENT: DME equipment is usually
stations make routine weather observa-               located in a VOR station. Other
tions at fixed intervals and disseminate             equipment in the aircraft transmits a
this information locally.                            signal to the VOR station, which
                                                     replies. The equipment in the aircraft
dissimilar /d smlə/ adjective refer-

                                                     converts the signal into distance and
ring to something which is not the same              also calculates ground speed and the
as, or is unlike, something else Differ-             time needed to reach the station.
                                                                      75                                                 diurnal
distillation / dst leʃ(ə)n/ noun the                                    provides immediate assistance to air-


process by which a liquid is heated and                                    craft in difficulty
the resulting vapour is then condensed                                     distress signal /d stres s n(ə)l/
                                                                           distress signal


and collected         With kerosene-type                                   noun a signal transmitted by an aircraft
fuels, the volatility is controlled by dis-                                in danger
tillation.                                                                 distribute /d strbju t/ verb 1. to


distinct /d stŋkt/ adjective clear

                                                                           give or send out There are two basic
and easily seen or understood When a                                       configurations which are used to dis-
lead-acid battery is fully charged, each                                   tribute electrical power, the parallel
cell displays three distinct indications.                                  system and the split bus system. 2. to
distinction /d stŋkʃən/ noun                                             spread over a wide area          Multiple


something which makes one thing dif-                                       wheel undercarriage units distribute
ferent from another A clear distinc-                                       the weight of the aircraft.
tion is made between showers and gen-                                      distribution / dstr bju ʃ(ə)n/ noun


eral precipitation.                                                        1. the act of giving or sending out Par-
distinctive /d stŋktv/ adjective                                        allel AC and DC power distribution sys-


easily recognised because of particular                                    tems are found on commercial aircraft
features or characteristics Concorde is                                    containing three or more engines. 2. the
a very distinctive-looking aeroplane.                                      fact of being spread over an area
distinguish /d stŋ wʃ/ verb to

                                                                           There is a high distribution of used and
know or to see the difference between                                      disused airfields in the south of Eng-
things A receiver antenna would be                                         land.
                                                                           distributor /d strbjυtə/ noun a

unable to distinguish between signals                                                                    |

unless they had some differing charac-                                     device which sends an electrical charge
teristics.                                                                 to each spark plug in turn The distrib-

distinguishable                         /d                       |
                                                                           utor directs the high voltage impulses to
 stŋ wʃəb(ə)l/ adjective easily rec-                                     the cylinders in turn as they reach their
ognised as different from           Useful                                 ignition point.
                                                                           disturb /d st b/ verb to upset the

ground features must be easily distin-                                                       |

guishable from their surroundings.                                         normal condition of something Small
distort /d stɔ t/ verb 1. to put out of

                                                                           hills can disturb the flow of air.
                                                                           disturbance /d st bəns/ noun

shape Stress could cause the body of                                                                         |

the aircraft to distort or change its                                      something that upsets the normal condi-
shape. 2. to produce a bad radio signal                                    tion of something         In general, the
   The sound of the transmission is dis-                                   higher the mountain and the faster the
torted if the volume is set too high.                                      air flow the greater is the resulting dis-
distortion /d stɔ ʃ(ə)n/ noun 1. the

                                                                           ditch /dtʃ/ verb to land a plane in the

bending or twisting of something so
that it is out of shape Difficulty in                                      sea, in an emergency Even though air-
closing a door may be caused by distor-                                    craft have ditched successfully, lives
tion of the airframe. 2. alteration of the                                 have been lost because life rafts were
electrical signal that makes a transmis-                                   not launched in time.
sion unclear Distortion of the signal                                      ditching / dtʃŋ/ noun the act of

made it difficult for the controller to                                    landing a plane in the sea, in an emer-
understand what the pilot said.                                            gency After all four engines stopped,
distress /d stres/ noun 1. serious

                                      |                                    the captain had to seriously consider
danger or difficulty 2. a personal worry                                   the possibility of a ditching in the
or anxiety Some passengers were in                                         Indian Ocean.
distress after the incident.                                               diurnal /da n(ə)l/ adjective refer-


distress and diversion cell /d
distress and diversion cell

                                                                  |        ring to the 24-hour cycle of day and
 stres ənd da v (ə)n sel/ noun a         |                                night Diurnal changes in surface tem-
unit at an air traffic control centre that                                 perature over the sea are small.
dive                                             76
dive /dav/ noun a steep nose-down                    the calculation of how may times a

attitude of an aircraft to pull out of or             number is contained in another number
from a dive to return the aircraft to                   The division sign is ÷.
level flight after a nose-down flight path            DME

                                                      DME abbreviation distance measuring
   During manoeuvring of an aircraft,                 equipment
when banking, turning and pulling out                 document / dɒkjυmənt/ noun a

from a dive, stresses on the airframe are             piece of writing, e.g. a memo, letter or
increased. í verb to put the aircraft into            report The flight crew route flight plan
a steep nose-down attitude The air-                   is a composite document which also
craft dived to avoid the other aircraft.              serves as a navigation log.
(NOTE: diving – dived)
                                                      documentation                 / dɒkjυmen

diverge /da v d / verb to move fur-
diverge                                                                                         |

                                                       teʃ(ə)n/ noun a collection of letters,

ther apart from something else Air
diverges at low levels and converges at               memos, reports, etc. Flight crews are
high levels, causing a sinking or subsid-             provided with a full meteorological
ing effect in the atmosphere. Opposite                briefing, backed by documentation, a
                                                      short time before ETD.
                                                      domestic /də mestk/ adjective

divergence /da v d əns/ noun the

act of moving apart Divergence of air                 referring or belonging to inside a coun-
at high levels leads to rising air at low             try     Domestic flights usually leave
levels with a consequent pressure fall.               from Terminal 1.
                                                      dominant / dɒmnənt/ adjective

Opposite convergence
divergent /da v d ənt/ adjective

                                                      main or most influential Both pres-
referring to something which moves                    sure and temperature decrease with
further apart from something else                     height but the pressure change is the
                                                      dominant one and so, as pressure
divergent duct /da v d ənt d kt/
divergent duct


                                                      decreases with height, so does density.
noun a duct which has an inlet area
                                                      dominate / dɒmnet/ verb to have

which is smaller than the outlet area
diversion /da v ʃ(ə)n/ noun a

                                                      the most effect or influence on
change in route or destination caused by              Because the chart time and the depar-
bad weather, technical problem, etc.                  ture/arrival times differ, it is necessary
                                                      to consider the movement of any
The aircraft had to make a diversion to
                                                      weather system which will dominate the
another airport due to fog.
divert /da v t/ verb to turn away

                                                      Doppler radar / dɒplə redɑ / noun
                     |                                Doppler radar

from a course or a destination         An
automatic cut-out valve is fitted to                  radar which can distinguish between
divert pump output to the reservoir                   fixed and moving targets or provide
when pressure has built up to normal                  ground speed and track information
operating pressure. The aircraft was                  from an airborne installation
                                                      Doppler VOR / dɒplə vi əυ ɑ /
                                                      Doppler VOR

diverted to Manchester airport because
of fog.                                               noun an adaptation of VOR to reduce
divide /d vad/ verb 1. to separate

                                                      errors caused by location
                                                      dot /dɒt/ noun a small circular mark on

into parts Air masses are divided into
two types according to source region                  paper The highest point in a locality is
and these are known as polar and trop-                marked by a dot with the elevation
ical air masses. 2. to calculate how                  marked alongside.
many times a number is contained in                   downdraught / daυndrɑ ft/ noun 1.

another number Eight divided by four                  cool air which flows downwards as a
equals two (8 ÷ 4 = 2).                               rainstorm      approaches.         Opposite
division /d v (ə)n/ noun 1. separa-

                         |                            updraught 2. air which flows rapidly
tion into parts the division of the                   down the lee side of a building, moun-
lower atmosphere the separation of the                tain, etc. (NOTE: It is also written down-
atmosphere into its component layers 2.               draft in US English.)
                                                  77                                        drive
downstream / daυn stri m/ adverb                       in the lower skin of the cabin are open


in the direction of flow, or further along             when the cabin is unpressurised, allow-
the line of flow       Internally driven               ing moisture to drain.
superchargers are generally used on                    drainage / drend / noun 1. the act

medium and high powered engines and                    of allowing a fluid to escape from its
are fitted downstream of the throttle                  container Drainage of water from the
valve.                                                 fuel system should be carried out before
downward / daυnwəd/ adjective

                                                       the first flight of the day. 2. a system of
moving to a lower level When flying in                 outlets for fluid such as water or fuel to
turbulent air conditions, an aircraft is               pass out of a closed area
subjected to upward and downward
                                                       draught /drɑ ft/ noun a local current

gust loads.
                                                       of air a down draught or an updraught
downwards / daυnwədz/ adverb to

                                                       (NOTE: This word is written draft in US
a lower level, towards the bottom Pull                 English.)
the toggles downwards to inflate the life
                                                       draw /drɔ / verb 1. to make a picture as

jacket. Opposite upwards (NOTE: In US
English, downward is used as an                        with a pencil, on paper, etc. Because
adverb and as an adjective.)                           there is a temperature gradient across
                                                       each front it is possible to draw iso-
downwind /daυn wnd/ adjective,


adverb in the same direction as the wind
                                                       therms which reduce in value from
is blowing turn downwind turn the                      warm to cold air. 2. to pull or to take
aircraft so that it is flying in the same              Fluid is drawn into the pump body. 3. to
direction as the wind is blowing. Oppo-                pull towards oneself (NOTE: drawing –
site upwind                                            drew – drawn)
                                                       drift /drft/ noun movement away

downwind leg / daυnwnd le /
downwind leg

noun part of the airfield traffic circuit              from the desired course, created by
which runs parallel to, but in the oppo-               wind blowing at an angle to the
site direction to, the approach to land                intended direction of flight If the wind
which is made into wind                                direction is not the same as the aircraft

DR abbreviation dead reckoning                         track or its reciprocal, then the aircraft
                                                       will experience drift. í verb to move
draft /drɑ ft/ noun US same as

                                                       away from the desired course When
draught a down draft or an updraft                     landing, a cross-wind from the right
drag /dr / noun the resistance of the

                                                       will cause the aircraft to drift to the left.
air created by moving the aircraft
                                                       drill /drl/ noun 1. a short series of

through the air To reduce the effect of
drag on an aircraft by the fixed under-                actions carried out in a particular
carriage a retractable type was intro-                 sequence       The starting drill varies
duced. If an engine failure occurs, the                between different aircraft types and a
windmilling propeller may cause con-                   starting check procedure is normally
siderable drag.                                        used. 2. a tool, often electrically pow-
                                                       ered, for making holes in metal, wood,
       COMMENT: There are two basic types              etc.
       of drag called parasite drag and
                                                       drive /drav/ noun a series of con-

       induced drag. Parasite drag is caused
       by friction between the air and the             nected devices that transmit power to
       aircraft surface, aerials, landing gear,        the wheels, propellers, etc. Rotation
       etc. Induced drag is produced by lift.          of the engine for starting is done by an
drain /dren/ noun a device to allow                   electric starter motor connected to a

fluid to escape from its container                     drive shaft in the accessories gearbox. í
When the cabin is pressurised the                      verb 1. to make something move or turn
drains close, preventing loss of pres-                   shaft-driven using a rotating shaft as
sure. í verb to allow fluid to escape by               a means of transmitting power from one
providing a hole or tube, etc., through                part to another, e.g. from a turbine
which it can pass The moisture drains                  engine to a helicopter rotor 2. to control
driven                                            78
and guide            He’s learning to drive.           wind speed increases. í adverb exactly
(NOTE: driving – drove – driven)                       and directly       The aircraft flew due
driven / drv(ə)n/ ‘ drive                             east.

drizzle / drz(ə)l/ noun precipitation,                dump /d mp/ verb to offload quickly

often persistent, in the form of very                     Normal operating cabin pressure can
small drops of water Drizzle is the                    be reduced rapidly in the event of emer-
lightest form of precipitation consisting              gency landings, by dumping air. The
of fine water droplets.                                aircraft flew out to sea in order to dump
       COMMENT : In weather reports and
                                                       fuel before landing.
                                                       duplication / dju pl keʃ(ə)n/ noun

       forecasts, drizzle is abbreviated to DZ.                                      |

drogue parachute

                     parachute          / drəυ         the act of copying or doubling Control
 p rəʃu t/ noun a small parachute used                 surfaces are divided into sections oper-
in releasing a larger parachute from its               ated by a separate control unit, thus
pack                                                   providing duplication to guard against
                                                       failure of a unit.
drone /drəυn/ noun an aircraft whose

                                                       durability / djυərə blti/ noun the

flight is controlled from the ground                                             |

drop /drɒp/ noun 1. a small amount of
                                                       ability of a substance or device to last a
liquid that falls a drop of water a few                long time High quality components
drops of rain 2. a sudden lowering The                 have good durability.
                                                       duration /djυ reʃ(ə)n/ noun the

passage of a cold front is usually fol-                                  |

lowed by a drop in temperature. A                      length of time for which something
sudden drop in oil pressure is normally                continues The duration of the exami-
an indication of serious engine trouble.               nation is two hours. The duration of
í verb to become lower or to decrease                  the flight was three hours.
suddenly The temperature dropped by                    dust /d st/ noun a fine powdery sub-

several degrees.                                       stance blown by the wind and found on
droplet / drɒplət/ noun a small drop                   surfaces      Solid particles in the air

of liquid        Experiments show that                 include dust, sand, volcanic ash and
smaller droplets of rain can remain                    atmospheric pollution.
super cooled to much lower tempera-                    duty / dju ti/ noun 1. a period of work

tures than large droplets.                                on duty at work off duty not at
drove /drəυv/ ‘ drive

                                                       work 2. same as import duty the duty
drum /dr m / noun a cylindrical                        payable on a carton of cigarettes

device, often with closed ends                         dye /da/ noun a material used to

dry /dra/ adjective containing no                     change the colour of something

water or no moisture dry air lapse                     Minute surface cracks which are diffi-
rate                                                   cult to detect by visual means may be
dry ice / dra as/ noun solidified car-
dry ice
                                                       highlighted by using penetrant dyes.
                                                       dynamic /da n mk/ adjective

bon dioxide                                                                  |

dual / dju əl/ adjective double, in pair               referring to something in motion

   Most light aircraft with side-by-side               dynamic pressure pressure created by
seating have dual controls.                            the forward movement of the aircraft
duct /d kt / noun a channel or tube
                                                       If the dynamic pressure increases due to
through which fluids or cables can pass                an increase in forward speed, the force
   The modern jet engine is basically a                required to move the control column
duct into which the necessary parts are                will increase. Opposite static pressure
                                                       dynamic seal /da n mk si l/
                                                       dynamic seal

fitted.                                                                                  |

due /dju / adjective 1. expected to
                                                       noun a seal which is part of a moving
arrive the flight is due at 10 o’clock                 component, e.g. in a hydraulic system
the flight should arrive at 10 o’clock 2.              dynamic seals require lubrication to
   due to because of Due to daytime                    remain effective
                                                       DZ / di zed/ abbreviation drizzle

heating, the stability decreases and the
E abbreviation east                           easterly direction to move towards the

ear /ə/ noun the hearing organ
                                              east í noun a wind which blows from
ear defenders / ə d fendəz/ plural
ear defenders

                                              the east
                                              eastern / i st(ə)n/ adjective situated

noun same as acoustic ear muffs
eardrum / ədr m/ noun a membrane             in the east one of the eastern prov-

inside the ear which vibrates with sound      inces of Canada
                                              Eastern Standard Time / i stən
                                              Eastern Standard Time

and passes the vibrations to the inner
ear Equalisation of the air pressure           st ndəd tam/ noun the time zone of
across the eardrum is more difficult to       the eastern USA and Canada, 5 hours
achieve during descents than ascents.         behind GMT. Abbreviation EST
ear muffs / ə m fs/ plural noun ‘            eastward / i stwəd/ adjective going
ear muffs

acoustic ear muffs                            towards the east í adverb US same as
ear protectors / ə prə tektəz/ plu-
ear protectors

                              |               eastwards
ral noun same as acoustic ear muffs           eastwards

                                              eastwards         / i stwədz/ adverb
earth / θ/ noun 1.

                           (the planet)       towards the east Flying eastwards or
Earth the planet where we live 2.             westwards for long periods of time
ground or soil í verb to connect an elec-     affects sleep patterns.
trical appliance to a position of zero
                                              east wind /i st wnd/ noun a wind
                                              east wind

potential When refuelling a light air-
craft, ensure that the aircraft is properly   blowing from or coming from the east
earthed. (NOTE: The US expression is          (NOTE: A wind is named after the direc-
                                              tion it comes from.)
to ground.)                                   EAT

east /i st / noun 1. a compass point on
                                              EAT abbreviation expected approach
the mariner’s compass 90° clockwise           time

from due north and directly opposite          EATMP abbreviation European air
west London is east of New York. 2.           traffic management programme
the direction in which the Earth rotates,     ECAC

                                              ECAC abbreviation European civil
the direction of the rising sun í adjec-      aviation conference
tive 1. referring to areas or regions lying   ECAM

in the east the east coast of Canada 2.       ECAM abbreviation electronic central-
the eastern part of a region East Africa      ised aircraft monitor
                                              echo / ekəυ/ noun 1. the repetition of

í adverb towards the east      The aircraft
was flying east.                              a sound by reflection of sound waves
eastbound / i stbaυnd/ adjective              from a surface 2. the return of a signal

travelling towards the east an east-          back to the source from which it was
bound flight                                  transmitted The strength of the return-
easterly / i stəli/ adjective 1. situated
                                              ing echo from a radar transmission
towards the east 2. easterly compo-           depends on a number of factors.
                                              economic / i kə nɒmk/ adjective

nent one part of the wind direction                                   |

coming from the east 3. to move in an         financially rewarding It was no longer
economical                                  80
economic to keep the maintenance                 efficiency / fʃ(ə)nsi/ noun 1. the


operation going.                                 fact of being able to act or produce
economical / i kə nɒmk(ə)l/ adjec-              something with a minimum of waste,


tive referring to a substance or device          expense, or unnecessary effort Effi-
for which input is minimised and output          ciency is a key component of a success-
maximised (thereby saving costs)                 ful business. 2. the ratio of the energy
economical engine an engine which                delivered by a machine to the energy
uses less fuel to produce the same               supplied for its operation mechanical
power as comparable engines           Jet        efficiency propeller efficiency ther-
engines are more efficient and econom-           mal efficiency the efficiency of conver-
ical when operated at high altitudes.            sion of fuel energy to kinetic energy
                                                 efficient / fʃ(ə)nt/ adjective able to

ECS abbreviation environmental con-


trol system                                      act or produce something with a mini-
EDDUS abbreviation electronic data
                                                 mum of waste, expense, or unnecessary
display and update system                        effort At some speeds and altitudes
eddy / edi/ noun a current of air mov-
eddy                                             the pure jet engine is less efficient than
ing in the opposite direction to the main        a piston engine. efficient combustion
current, especially in a circular motion         combustion in which fuel energy is used
   When wind flows over an obstruction           to its maximum capability
                                                 effort / efət/ noun 1. the use of physi-

such as a building, an eddy is formed on
the lee, or downwind side.                       cal or mental energy to do something
edge /ed / noun a line of intersection
                                                 In order to qualify for a licence, it is
or joining of two surfaces                       necessary to put some effort into the
                                                 training course. Flying a high per-
EET abbreviation estimated elapsed

                                                 formance aerobatic light aircraft to its
time                                             limits requires a lot of physical effort on
effect / fekt/ noun 1. something

                                                 the part of the pilot. 2. force applied
which results from a cause Ultra-vio-            against inertia Actuators are capable
let radiation has the effect of warming          of exerting low-speed turning effort.
the atmosphere.        Pressure patterns         EFIS abbreviation electronic flight

have an effect on weather. 2. the condi-         instrument system
tion of being in full force in effect in
                                                 eggbeater / e bi tə/ noun a rotary-

operation to take effect, to come into
effect to start to operate A new regula-         wing aircraft (informal)
                                                 EGNOS noun a European system that

tion comes into effect tomorrow. with
effect from starting from í verb to              improves the quality of data from exist-
cause or carry out to effect a change            ing satellite navigation systems to make
to make a change modifications were              the data suitable for use by aircraft. Full
effected modifications were carried              form European Geostationary Navi-
out. Compare affect                              gation Overlay Service (NOTE: The
effective / fektv/ adjective 1. hav-

                                                 US equivalent is WAAS.)
                                                 EICAS noun a cockpit display for

ing an expected and satisfactory result
the new cleaning fluid was very effec-           monitoring the engines and warning of
tive it cleaned well 2. operative, in            malfunction. Full form engine indicat-
effect      The regulation is effective          ing and crew alerting system
                                                 eject / d ekt/ verb to throw out force-

immediately.                                                     |

effectiveness / fektvnəs/ noun                 fully On depressurisation the oxygen


how well something works Ice cover-              mask is ejected automatically from the
ing reduces the effectiveness of an aer-         service panel.
                                                 ejection / d ekʃən / noun an act of

ial.                                                                         |

effective pitch / fektv ptʃ/ noun             throwing out forcefully ejection seat
effective pitch


                                                 ejection seat / d ekʃən si t/, ejec-
                                                 ejection seat

the distance the aircraft moves forward                                              |

in flight for one 360° rotation of the           tor seat / d ektə si t/ noun an emer-

propeller                                        gency escape seat in military aircraft
                                                                       81                                                               electronic
which is fired out of the aircraft while                                    ductive when dissolved or molten The
the crew-member is still in it                                              electrolyte in a lead-acid battery con-
ejector / d ektə/ noun 1. a device to                                      sists of sulphuric acid diluted with dis-


throw something out forcefully 2. a                                         tilled water.
                                                                            electrolytic / lektrə ltk / adjective

device using a jet of water, air, or steam                                                                                |        |

to withdraw a fluid or gas from a space                                        electrolytic cell a cell consisting of
   A jet transfer pump or fuel ejector is                                   electrodes in an electrolyte solution
used to transfer fuel.                                                      electro-magnet

                                                                            electro-magnet                 / lektrəυ                     |

elapse / l ps/ verb to pass The                                             m nt/ noun a magnet consisting of


radio altimeter works on the principle                                      a coil of insulated wire wrapped around
that, if the path followed by the radio                                     a soft iron core that is magnetised only
wave is straight down and up, then the                                      when current flows through the wire
elapsed time between the outgoing and                                       electro-magnetism

                                                                            electro-magnetism              / lektrəυ                     |

incoming signal is a function of the air-                                    m nə tz(ə)m/ noun a force exerted

craft’s height.                                                             by a magnetic field found around any
elastic / l stk / adjective flexible,

                           |                                                conductor carrying current, the strength
easily returning to its original shape                                      of which will depend on the amount of
after being stretched or expanded At                                        current flow
low values of stress, if the plot of stress                                 electromotive force

                                                                            electromotive              force        /                           |

and strain is a straight line, this indi-                                    lektrəυməυtv fɔ s/ noun a source of
cates that the material is elastic within                                   electrical energy required to produce an
this range.                                                                 electric current, produced by devices
elasticity / l ststi/ noun the prop-

                                                   |                        such as batteries or generators and
erty of returning to an original form or                                    measured in volts. Abbreviation emf
state following deformation Titanium                                        electron / lektrɒn/ noun a sub-


falls between aluminium and stainless                                       atomic particle that has a negative elec-
steel in terms of elasticity, density and                                   trical charge Electrons in the outer
elevated temperature strength.                                              orbits of an atom may not be strongly
electric / lektrk/ adjective powered

                               |                                            attracted to the nucleus and may be lost.
or worked by electricity                                                    electronic / elek trɒnk/ adjective


electrical / lektrk(ə)l/ adjective 1.

                                       |                                    referring to, based on, operated by, or
referring to electricity an electrical                                      involving the controlled conduction of
fault 2. powered or worked by electric-                                     electrons especially in a vacuum, gas, or
ity Activation may be mechanical or                                         semi-conducting material Lightning
electrical.                                                                 does not often seriously damage air-
electric current / lektrk k rənt/                                         craft but it may affect sensitive elec-
electric current


noun the mass movement of electric                                          tronic equipment.
charge in a conductor                                                       electronic centralised aircraft monitor

                                                                            electronic centralised aircraft
electricity / lek trsti/ noun an

                                               |           |
                                                                            monitor / elektrɒnk sentrəlazd
electric current used to provide light,                                      eəkrɑ ft mɒntə/ noun a display on
heat, power                                                                 two cathode ray tubes giving pilots
electric power / lektrk paυə/
electric power

                                                                            engine and systems information.
noun electricity used to drive machines                                     Abbreviation ECAM
                                                                            electronic                                    flight       instrument

or devices
electro- / lektrəυ/ prefix electricity
                                                                            system       / elektrɒnk    flat
                                                                              nstrυmənt sstəm/ noun primary

electrode / lektrəυd/ noun a solid

                                                                            flight and navigation information on a
electrical conductor through which an                                       cathode ray tube. Abbreviation EFIS
electric current enters or leaves an elec-
trolytic cell A battery has a positive                                          COMMENT:     The electronic flight
and a negative electrode.                                                       instrument system can show basic
                                                                                flight  information   and   engine
electrolyte / lektrəlat/ noun a

                                                                                performance information, as well as
chemical compound that becomes con-                                             moving maps and checklists.
element                                         82
element / elmənt / noun 1. a sub-                   elliptical /  lptk(ə)l/ adjective hav-
element                                              elliptical


stance composed of atoms with an iden-               ing an oval shape the elliptical path of
tical number of protons in each nucleus              the Earth around the sun
   Elements cannot be reduced to sim-                ELR abbreviation 1. environmental

pler substances by normal chemical                   lapse rate 2. extra long range (ICAO)
methods. 2. the resistance coil in an                embarkation

                                                                            / embɑ keʃ(ə)n/          |

electrical device such as a heater 3. a              noun the act of going onto an aircraft
removable component or removable                     Embarkation will start in ten minutes.
part, such as in an air filter or oil filter         (NOTE: Boarding is usually preferred.)
elevate / elvet/ verb to move some-

                                                       embarkation time the time at which
thing to a higher place or position from             passengers will be asked to go onto the
a lower one; to lift In some light air-              aircraft
craft the magnetic compass is elevated               embed /m bed/ verb to fix firmly in a


to a position as far away from the inter-            surrounding mass          A temperature
fering effect of other components as                 probe is embedded into the stator of the
possible.                                            generator. Water outlets have heater
elevated / elə vetd/ adjective ele-

                                                     elements embedded in rubber seals in
vated temperature increased or raised                the outlet pipe.
                                                     emergency / m d ənsi/ noun a

temperature                                                                             |

elevation / elə veʃ(ə)n/ noun the

                                                     serious situation that happens unexpect-
height at which something is above a                 edly and demands immediate action
point of reference such as the ground or             to deal with or to handle an emergency
                                                     emergency descent / m d ənsi
                                                     emergency descent

sea level The highest point in a local-                                                           |

ity is marked by a dot with the elevation            d sent/ noun a planned rapid losing of

marked alongside. aerodrome eleva-                   altitude because of a serious situation
                                                     emergency                              equipment
                                                     emergency equipment

tion distance in feet of the aerodrome                                                                    noun
above sea level Elevation is indicated               devices for use only in serious situa-
on charts by means of contour lines,                 tions
spot heights, etc.                                   emergency           exit / m d ənsi
                                                     emergency exit


elevator / elvetə/ noun 1. a mova-

                                                      e zt/ noun a way out only to be used
ble control surface, usually attached to             in case of an emergency How many
the horizontal stabiliser of an aircraft,            emergency exits are there in the air-
used to produce the nose up/down                     craft?
                                                     emergency             frequency      /
                                                     emergency frequency

motion of an aircraft in level flight                                                                            |

known as pitch Elevators should be                    m d ənsi fri kwənsi/ noun 121.5
checked for full and free movement                   MHz, the frequency on which aeronau-
immediately prior to take-off. 2. US                 tical emergency radio calls are made
same as lift noun 2                                  emergency landing / m d ənsi
                                                     emergency landing


    COMMENT : Some aircraft have an all-              l ndŋ/ noun a landing made as a
    moving tailplane called a ‘stabilator’ (a        result of an in-flight emergency
    combination of the words stabiliser              emergency procedures plural
                                                     emergency procedures

    and elevator).                                   noun a set of actions pre-planned and
eliminate / lmnet/ verb to get rid               followed in the event of a serious situa-


of or remove Air dryers are provided                 tion
                                                     emergency services / m d ənsi
                                                     emergency services

to eliminate the possibility of ice form-                                                         |

ing. To eliminate the need for complex                s vsz/ plural noun the fire, ambu-
mechanical linkage, the selector is                  lance and police services The alarm
operated electrically. to eliminate a                will activate the emergency services.
danger to remove a danger                            emf abbreviation electromotive force

ellipse / lps/ noun an oval-shaped                 emission / mʃ(ə)n/ noun 1. the
ellipse                                              emission

              |                                                                     |

line Each planet moves in an ellipse                 process of sending out e.g. matter,
and the sun is at one of the foci.                   energy or signals light emissions
                                             83                               engine block
radio emission One factor on which                encounter /n kaυntə/ verb to meet


the operational range of a radio emis-            something unexpected or unwanted
sion depends is the transmitted power.            Severe icing can be encountered in
2. a substance discharged into the air, as        wave cloud.
by an internal combustion engine
                                                  endurance /n djυərəns/ noun the

Exhaust emissions contain pollutants.                                     |

                                                  length of time an aircraft can stay in the
emit / mt/ verb to send out e.g. mat-

                                                  air without refuelling The flight time
ter, energy or radiation radiation emit-          to the PNR and back will equal the
ted by the sun An X-ray tube emits                endurance of the aircraft.
radiation. Latent heat is emitted when
                                                  energy / enəd i/ noun 1. the ability of

condensation takes place. (NOTE: emit-
ting – emitted)                                   a physical system to do work 2. power
empennage /em pend / noun the

                                                  from electricity, petrol, heat, etc. The
tail assembly of an aircraft          The         engine converts heat energy into
empennage usually includes the fin,               mechanical energy.        The generator
rudder, horizontal stabiliser (or tail-           converts mechanical energy into elec-
plane), and elevator.                             trical energy.
                                                  engage /n ed / verb 1. to switch

emphasis / emfəss/ noun force of

expression that gives importance to               on and use       The autopilot may be
something It is only in recent years              engaged during climb or descent.
that much emphasis has been placed on             Opposite disengage 2. engaged in
determining the causes of metal fatigue.          working on a particular job or task
                                                  Personnel engaged in ground running
emphasise / emfəsaz/, emphasize

                                                  must ensure that any detachable cloth-
verb to give importance to something
On some maps, different elevations are            ing is securely fastened and they should
emphasised by colouring.                          wear acoustic ear muffs.
                                                  engine / end n/ noun a machine that

employ /m plɔ/ verb 1. to use


There are two methods employed to                 converts energy into mechanical force
cool the cylinders down. In some air-             or motion, different from an electric or
craft, particularly those employing               hydraulic motor because of its use of a
nickel-cadmium batteries, temperature             fuel jet engine piston engine inter-
sensing devices are located within the            nal combustion engine combustion,
batteries to provide a warning of high            jet, piston engine-driven referring to
battery temperatures. 2. to give some-            equipment and devices which take their
body regular paid work                            power from the engine when it is run-
empty weight / empti wet/ the
empty weight
                                                  ning       engine-driven generator
weight of a plane without fuel, people            engine-driven pump engine running
or freight                                        engine operating or working           the
                                                  engine is running the engine is work-
enable /n eb(ə)l/ verb to make

                                                  ing The accident investigation demon-
something possible or easier Isolation            strated that the engine was running at
valves are fitted to enable servicing and         full power when the aircraft hit the
maintenance to be carried out.                    ground.
enclose /n kləυz/ verb to surround

                                                      COMMENT: In British usage, there is a

on all sides The housing encloses the                 clear distinction between the terms
various mechanical parts. Fuses form                  ‘engine’ and ‘motor’, the term ‘motor’
a weak link in a circuit and are usually              only being used for electric power
made of a strip of tinned copper                      units. In American usage, however,
enclosed in a glass tube.                             ‘motor’ is used for all types of power
                                                      unit including the internal-combustion
encode /n kəυd/ verb to put into

code Weather information is encoded
                                                  engine block / end n blɒk/ noun a
                                                  engine block

to allow large amounts of information
to be given in a short space of time.             cylinder block with integral crankcase
engine capacity                                                      84
engine      capacity / end n kə                                           the   crew,   not replace them’
engine capacity

                                                             |   |

 p sti/ noun the swept volume of an                                       [INTER PILOT]
engine                                                                    enhancement /n hɑ nsmənt/ noun


engine compartment / end n                                               the process of making greater, better or
engine compartment

kəm pɑ tmənt / noun a space in the air-
                                                                          clearer enhancement of an image on
frame where the engine is located                                         a screen the improvement of an image
engineer / end  nə/ noun a person

                                                                          on a screen
                                                                          enlarge /n lɑ d / verb to make big-

who is qualified to design, build and                                                           |

repair machines aircraft engineer an                                      ger or larger enlarge the hole make
engineer who specialises in the mainte-                                   the hole bigger
                                                                          enplane /en plen/ verb to board or

nance and repair of aircraft                                                                            |

engineering / end  nərŋ/ noun

                                                                          allow somebody to board an aircraft
                                                                          en route / ɒn ru t/ adverb, adjective
                                                                          en route

the use of scientific and mathematical
principles for practical reasons such as                                  on or along the way en route from
the design, manufacture, and operation                                    New York to London on the way from
of machines and systems, etc. aircraft                                    New York to London en route alter-
engineering the branch of aviation con-                                   nate an airfield where it is possible to
cerned with the maintenance and repair                                    land if there is an in-flight problem en
of aircraft Reinforced plastics or com-                                   route weather conditions a description
posites are being used in aircraft engi-                                  of the weather along the path of flight
neering instead of metals because they                                    ensure /n ʃυə/ verb to make certain,


are much lighter.                                                         to make sure The generator cut-out
engine failure / end n feljə/                                           ensures that the battery cannot dis-
engine failure

noun a situation in which an engine                                       charge. Before the engine is stopped,
stops during running                                                      it should normally be allowed to run for
engine indicating and crew alerting system

engine indicating and crew                                                a short period at idling speed, to ensure
alerting   system    / end n                                             gradual cooling.
 ndketŋ ən kru ə l tŋ sstəm/                                        enter / entə/ verb 1. to come or go into


noun full form of EICAS                                                      Air enters at the front of the cabin and
engine instruments / end n
engine instruments
                                                                          leaves at the rear. 2. to write down e.g.
 nstrυmənts/ plural noun instruments                                     information Enter the rectified air-
which give the pilot information about                                    speed in the log. Enter your name in
engine temperature, speed, etc.                                           the correct place in the form. 3. to put
                                                                          data into a computer, especially by
engine intake / end n ntek/
engine intake

                                                                          using the keyboard to type it in Enter
noun the front part of the engine where                                   the data into the computer.
air enters the engine
                                                                          entire /n taə/ adjective whole, hav-

engine malfunction / end n m l
engine malfunction                                                                      |

                                                                          ing no part excluded or left out the
 f ŋkʃən/ noun a situation in which the                                   entire life of a thunderstorm the com-
engine does not work as it should                                         plete life of a thunderstorm
engine oil / end n ɔl/ noun oil used
engine oil

                                                                          entry / entri/ noun 1. the act or

especially to lubricate engines                                           instance of going in the flow of traffic
engine performance / end n pə
engine performance

                                                                 |        at entry points to the airfield. 2. the
 fɔ məns/ noun a description of how                                       writing in of an item, as in a record or
well the engine works or detailed statis-                                 log An entry should be made in the
tical information about the capabilities                                  technical log.
of the engine                                                             entry point / entri pɔnt/ noun a
                                                                          entry point

enhance /n hɑ ns/ verb to make

                                             |                            position on the ground above which an
greater or better or clearer Chances of                                   aircraft entering a control zone crosses
survival are enhanced if passengers                                       the boundary
know where the emergency exits are.                                       envelop /n veləp/ verb to surround


    ‘…any automation must be designed to                                  and cover The atmosphere envelops
    enhance the decision making abilities of                              the earth.
                                                                  85                 equivalent shaft horsepower
envelope / envələυp / noun 1. the set                                  pressure equalise at normal system

of limitations within which a techno-                                  pressure.
logical system, especially an aircraft,                                equate / kwet/ verb to be the same


can perform safely and effectively                                     as In an electrical circuit, an increase
The boundaries of flight envelopes vary                                in length equates to an increase in
between aircraft categories and per-                                   resistance.
formance groups but in each case, there
                                                                       equation / kwe (ə)n/ noun a state-

is a speed which must not be exceeded                                                                        |

which is called the Vne (never-exceed                                  ment, usually in symbols, that two
speed). 2. a cover The atmosphere is                                   quantities or mathematical expressions
the gaseous envelope surrounding the                                   are equal X2 + Y2 = Z2. The equa-
earth.                                                                 tion Vg = P can be used to find the geos-
                                                                       trophic wind.
environment /n varənmənt/ noun

                                                                       equator / kwetə/ noun the imagi-

1. nearby conditions or circumstances

                                                                       nary great circle around the Earth’s sur-
A body of air warmer than its environ-
                                                                       face, equidistant from the poles and per-
ment will rise. a non-computer envi-
                                                                       pendicular to the Earth’s axis of rotation
ronment a computer-free working situ-
                                                                       which divides the Earth into the north-
ation 2. the natural world in which
                                                                       ern hemisphere and the southern hemi-
people, animals and plants live People
                                                                       sphere Every point on the equator is
are interested in issues to do with the
                                                                       equidistant from the poles.
environment, such as global warming.
                                                                       equatorial / ekwə tɔ riəl/ adjective

                              /n varən


                                           |                  |

                                                                       referring to the equator or to conditions
 ment(ə)l/ adjective referring to the                                  that exist at the Earth’s equator equa-
immediate surroundings environmen-                                     torial heat equatorial climate
tal conditions
                                                                       equilibrium / i kw lbriəm/ noun a

environmental control system

environmental control system

                                                                       state of physical balance When an air-
/n varənment(ə)l            kən trəυl
           |                                       |

                                                                       craft is in unaccelerated straight and
 sstəm/ noun an air-conditioning sys-                                 level flight at a constant speed, the
tem for the aircraft. Abbreviation ECS                                 forces of lift, thrust, weight and drag
environmental lapse rate

environmental                      lapse               rate            are in equilibrium.
/ nvarənment(ə)l l ps ret/ noun
                                                                       equipment / kwpmənt/ noun


the rate at which the temperature of the                               devices, systems, machines, etc., that
air falls as one rises above the earth                                 are needed for a particular purpose
Although there is an average ELR of                                    (NOTE: Equipment has no plural form;
1.98°C per 1,000 feet, in practice the                                 for one item say: a piece of equipment.)
ELR varies considerably with space                                        electrical equipment devices, com-
and time. Abbreviation ELR                                             ponents, systems, etc., which use elec-
epoxy-based primer / pɒksi
epoxy-based primer

                                               |                       tricity
best pramə/ noun a primer contain-                                   equivalent / kwvələnt/ adjective


ing epoxy resin, a substance which,                                    having the same purpose or value as
with the addition of hardeners, becomes                                something else The function of a logic
very strong and hard after a time at nor-                              gate is equivalent to that of a switch.
mal temperatures                                                       A metal part could be as much as 25
equal / i kwəl/ adjective having the

                                                                       times heavier than an equivalent plastic
same quantity, measure, or value as                                    part.
another For every action, there is an                                  equivalent shaft horsepower /
                                                                       equivalent shaft horsepower


equal and opposite reaction. í verb to                                  kwvələnt ʃɑ ft hɔ spaυə/ noun the
be the same in value as Two plus two                                   unit used for stating the total power of a
equals four (2 + 2 = 4).                                               turboprop engine, consisting of the
equalise / i kwəlaz/, equalize verb

                                                                       shaft horsepower of the engine plus
to become the same in quantity, meas-                                  the thrust from the engine. Abbrevia-
ure or value Fluid pressure and gas                                    tion ESHP
error                                        86
error / erə/ noun 1. a mistake or incor-          will take about two hours for us to reach

rect calculation    an error in some-             our destination. Cloud heights may be
body’s work errors caused by location             measured or estimated. 2. to form a
2. the known inaccuracy of an instru-             judgement about        to estimate the
ment or system which has to be cor-               chances of something to weigh the
rected by calculating the true value              possibilities and form an opinion
escape / skep/ noun the act of get-
                                                  estimated take-off time

                                                  estimated                                            take-off                time


ting away from or out of a place after            / estmetd tek ɒf tam/ noun the
being held      escape of fuel or oil             time when an aircraft is expected to take
unwanted loss of fuel or oil escape               off. Abbreviation ETOT
from danger getting to a safe place í             estimated time of arrival

                                                  estimated                                           time           of   arrival
verb to get away from or out of after             / estmetd tam əv ə rav(ə)l/ noun                      |

being held If there is a hole in the              the time when an aircraft is expected to
fuselage of a pressurised aircraft, air           arrive. Abbreviation ETA
escapes from the cabin to the atmos-              estimated time of departure

phere.                                            estimated time of departure
                                                  / estmətd tam əv d pɑ tʃə/ noun
escape hatch / skep h tʃ/ noun a
escape hatch                                                                                                     |

                                                  the time when an aircraft is expected to
small doorway only used in emergen-               take off. Abbreviation ETD
                                                  estimation / est meʃ(ə)n/ noun 1.

escape route / skep ru t/ noun the
escape route                                                                                            |


                                                  an approximate calculation an estima-
passengers’ way out of an aircraft after          tion of ground speed Estimation of
an emergency landing                              visibility is achieved by noting the dis-
escape slide / skep slad/ noun a
escape slide

                                                  tances at which lights of known candle
device which allows passengers to exit            power can be observed and relating
the aircraft safely in an emergency,              these distances to visibility-by-day val-
when no steps are available                       ues. 2. an opinion in my estimation in
ESHP abbreviation equivalent shaft

                                                  my opinion
horsepower                                        ETA

                                                  ETA abbreviation estimated time of
essential / senʃəl/ adjective abso-

lutely necessary Teamwork within the              ETD

                                                  ETD abbreviation estimated time of
crew is essential. A knowledge of the             departure
tropopause is essential. non-essential
                                                  ETOT abbreviation estimated take-off

not necessary
EST abbreviation 1. Eastern Standard
EST                                               time
                                                  Eurocontrol           / jυərəυkən trəυl/

Time 2. estimate (ICAO) 3. estimated                                                                                       |

(ICAO)                                            noun the European organisation for the
establish / st blʃ/ verb 1. to be

                                                  safety of air navigation (NOTE: Eurocon-
confirmed as stable in a particular flight        trol operates the ATC centre at Maas-
condition, such as a flight level or              tricht in the Netherlands and the Cen-
glideslope, etc. Once established on              tral Flow Management Unit in
the downwind leg, the pilot should per-           Brussels.)
                                                  European Geostationary Navigation Overlay Service

form the checks. 2. to work out or to cal-        European Geostationary Navi-
culate establish your position find               gation   Overlay     Service
out where you are 3. to position Low-             / jυərəpiən        d i əυsteʃ(ə)n(ə)ri
power NDBs (Non-Directional Radio                  n v eʃ(ə)n əυvəle s vs/ noun
Beacons) are often established at the             full form of EGNOS
outer or middle marker sites. 4. to               evacuate / v kjuet/ verb 1. to


establish communication to make                   remove all the people from somewhere
contact with to establish control to              in the event of an emergency to evac-
get control                                       uate all passengers from the airport 2.
estimate / estmet/ verb 1. to calcu-

                                                  to empty somewhere of all people in it
late approximately the cost, value or             because of an emergency to evacuate
size of something I estimate that it              the aircraft 3. to create a vacuum
                                           87                                         examination
evacuate a glass jar remove all the air         event / vent/ noun a happening The


from a glass jar                                Paris air show is a major event. in the
evacuation /  v kju eʃ(ə)n/ noun              event of if something should happen

                      |               |

1. the act of removing all people from          Passengers should fasten their seat
somewhere in the event of an emer-              belts in the event of turbulence. in the
gency The evacuation of the passen-             event of main pump failure if there
gers from the airport was not ordered.          should be a failure of the main pump
2. an act of emptying somewhere of all          in the event of fire if there should be a
people in it because of an emergency            fire
                                                eventual / ventʃuəl/ adjective hap-

The evacuation of the aircraft did not                                    |

take long. evacuation command an                pening at an unspecified time in the
evacuation order from the captain               future Water in the fuel may lead to
ditching evacuation an evacuation               eventual engine stoppage.
after the aircraft has force-landed on          eventually / ventʃuəli/ adverb at an


water                                           unspecified time in the future Vapour
evaluate / v ljuet/ verb to examine

              |                                 cools and eventually condenses.
and judge carefully Deposits of ice             evidence / evd(ə)ns/ noun an out-

are detected and continuously evalu-            ward sign         external evidence of
ated to operate a warning system.               cracks something which can be seen on
evaluation /  v lju eʃ(ə)n/ noun

                      |       |                 the surface which suggests that there is
the examination and judgement of                a deeper structural problem Deformed
something      The ice detector system          wing panels may be evidence of an
provides continuous evaluation of con-          over-stressed airframe.
ditions conducive to the formation of           evident / evd(ə)nt/ adjective obvi-

ice.                                            ous, easily seen or understood It is
evaporate / v pəret/ verb to con-

                  |                             evident from the information available
vert or change a liquid into a vapour In        that language problems played a part in
the heat of the day, water evaporates           the cause of the accident. self-evident
from the surface of the earth. Opposite         clear in itself, without further explana-
condense                                        tion
                                                exact / z kt/ adjective completely

evaporation / v pə reʃ(ə)n/ noun

                          |       |

the changing of a liquid into vapour,           accurate or correct The exact fuel flow
vaporisation Carburettor icing can be           and pressure is adjusted. the calcula-
caused by the expansion of gases in the         tion is not exact the calculation is not
carburettor and the evaporation of liq-         100% correct
uid fuel.                                       exactly / z ktli/ adverb 1. accu-


even / i v(ə)n/ adjective 1. flat or            rately, correctly Measure the quantity

smooth, with no bumps or dents 2. the           exactly. 2. absolutely, completely A
same in all parts of an area or over a          fuel injection system performs exactly
whole surface an even distribution of           the same function as a carburettor.
passengers      an even application of                                / z m neʃ(ə)n/

                                                examination                       |      |

paint 3. even numbers exactly divis-            noun 1. a set of questions or exercises
ible by 2, e.g. 4, 6, 20 í adverb 1. yet        testing knowledge or skill The exami-
more It will be even higher than the            nation includes a flight plan. 2. med-
new building. even faster not just as           ical examination medical check-up 3. a
fast as, but more 2. even if whether or         careful observation or inspection the
not Stop at the holding point even if           examination of a faulty component
there are no other aircraft on the                  ‘…the pilot of a Grumman Cheetah
approach. even though in spite of the               refused to be breathalysed, and was taken
fact that He gained his private pilot’s             to a police station for examination by a
licence even though he was 73 years                 police surgeon, who confirmed that he
old.                                                had been drinking’ [Pilot]
examine                                          88
examine / z mn/ verb 1. to find                     the direct current for the motor of the


out how much knowledge or skill some-                 alternating current generator.
body possesses by means of questions                  exciter /k satə/ noun the source of a


or exercises Students will be examined                small current to supply electrical cur-
in four subjects. 2. to test or check the             rent to the windings of larger electrical
condition or health of somebody to                    motors, etc., e.g. a battery Pilot exci-
examine a patient 3. to study or analyse              tation consists of a pilot exciter and a
something to examine charts                           main exciter, to provide the direct cur-
exceed /k si d/ verb to be greater

                     |                                rent for the motor of the alternating
than Vertical velocity of updraughts                  current generator.
can exceed 50 kt.                                     exclude /k sklu d/ verb to keep out,


exception /k sepʃən/ noun some-

                                                      to prevent from entering Joints and
thing or somebody not included an                     interfaces should exclude moisture and
exception to the rule an example                      improve fatigue life.
which does not conform to a general
                                                      exercise / eksəsaz/ noun an activity

rule with the exception of not includ-
ing with the exception of Smith, all                  that requires physical or mental effort or
the students passed their exams                       practice a classroom exercise Swim-
Smith did not pass, but the other stu-                ming is good physical exercise for peo-
dents did                                             ple such as pilots who spend a lot of
                                                      time sitting down. í verb to use or to put
exceptional /k sepʃən(ə)l/ adjec-

                                                      into play or operation Student pilots
tive 1. being an exception, uncommon                  must exercise special care when land-
in exceptional circumstances in unu-                  ing in a strong crosswind.
sual circumstances 2. well above aver-
                                                      exert / z t/ verb to exert a force

age, extraordinary       an exceptional                                |

pilot a very good pilot                               to put a force on something Pressure
                                                      is the force per unit area exerted by the
excess /k ses/ noun an amount or


                                                      atmosphere on a given surface area.
quantity beyond what is normal or suf-                to exert an influence to have an influ-
ficient excess power the difference                   ence to exert pressure to put pressure
between horsepower available and                      onto something
horsepower required        in excess of
                                                      exhaust / zɔ st/ noun 1. the escape

more than        a height in excess of                                         |

50,000 feet a height greater than 50,000              or release of vaporous waste material
feet                                                  from an engine 2. a pipe through which
excess baggage / ekses b d /
excess baggage
                                                      waste gases pass out of the engine The
noun an amount, usually expressed as                  exhaust valve opens to allow for the exit
weight, of baggage which exceeds the                  of exhaust gases. í verb to consume or
airline’s limit per passenger                         use up all of something Supplies of
                                                      fuel are exhausted. (NOTE: To run out is
excessive /k sesv/ adjective more

                                                      less formal.)
than the normal, usual, reasonable, or
                                                      exhaust gas / zɔ st         s/ noun gas
                                                      exhaust gas

proper limit Excessive use of power                                                |

when taxiing will require excessive use               which is the product of the combustion
of brakes.                                            process and which is passed out through
                                                      the exhaust system       Exhaust gases
exchange /ks tʃend / verb to give

                                                      contain carbon monoxide.

in return for something received
                                                      exhaust system / zɔ st sstəm/
                                                      exhaust system

Meteorological stations exchange                                                           |

information with other meteorological                 noun a system of pipes, silencers, etc.,
stations.                                             which carry exhaust gases from the
excitation / eks teʃ(ə)n/ noun the

                                                      engine to a point where they are
act of supplying a small current to the               released into the atmosphere
                                                      exhaust valve / zɔ st v lv/ noun
                                                      exhaust valve

windings of larger electrical motors,                                                  |

etc. Pilot excitation consists of a pilot             a valve in a piston engine which allows
exciter and a main exciter, to provide                exhaust gases to leave the cylinder
                                                    89                                                  experimental
exhibit / zbt / verb to have or to                    place                    the expected number of passen-


display Composites, due to their con-                    gers
struction, exhibit good fatigue behav-                                    approach time /k
                                                         expected approach time

                                                         expected                                                  |

iour. Altocumulus are (usually) white                     spektd ə prəυtʃ tam/ the time at

layers or patches of cloud frequently                    which air traffic control expects an
exhibiting a waved appearance.                           arriving aircraft to complete its
exist / zst/ verb to be present under

                    |                                    approach for landing, following a delay.
particular circumstances or in a speci-                  Abbreviation EAT
fied place      Water can exist in the                   expedite / ekspdat/ verb to speed

atmosphere in three forms. A fire risk                   up the progress of to expedite the
may exist following failure or leakage of                evacuation to speed up the evacuation
any component.                                           to expedite the disembarkation to get
existence / zstəns/ noun the fact

                                                         the passengers off the aircraft quickly
or state of being Warning systems are
                                                         expel /k spel/ verb to force out, to

provided to give an indication of a pos-                                            |

sible failure or the existence of a dan-                 drive out Exhaust gases are expelled
gerous condition.                                        from the cylinder by the upward move-
                                                         ment of the piston. The piston draws
exit / e zt/ noun 1. the act of going

                                                         fluid into the cylinders on the outward
out of a place The exhaust valve opens                   stroke and expels fluid into the system
to allow for the exit of exhaust gases.                  on the inward stroke.
exit velocity the velocity of exhaust
                                                         experience /k spəriəns/ noun 1.

gases from a jet engine 2. a way out                                                        |

                                                         the building up of knowledge or skill
exit nozzle / ekst nɒz(ə)l/ noun a
exit nozzle

                                                         over a period of time by an active partic-
pipe or opening through which exhaust                    ipation in events or activities a pilot
gases leave a jet engine                                 with 20 years’ experience 2. an event or
exit point / ekst pɔnt/ noun a posi-
exit point

                                                         incident The first solo is an experi-
tion on the ground above which an air-                   ence most pilots never forget. í verb to
craft leaving a control zone crosses the                 undergo, participate in or find oneself in
boundary                                                 a particular situation It is not unusual
expand /k sp nd/ verb to increase in

                                                         to experience traffic delays on the
size, volume or quantity, to enlarge                     ground prior to departure. Turbulence
Air expands when heated and contracts                    can be experienced when flying through
when cooled.                                             a trough.
expansion /k sp nʃən/ noun an

                                                         experiment noun /k spermənt/ a

increase in size, volume or quantity                     scientific test, carried out under control-
There is an expansion of the gas when it                 led conditions, that is made to demon-
is heated.                                               strate or discover something Experi-
expansion chamber /k sp nʃən
expansion chamber

                                                |        ments have shown that left-handed
 tʃembə/ noun a container which                         people often have better hand/eye coor-
allows for expansion of a fluid caused                   dination than right handed people. to
by increase in temperature, etc.                         conduct an experiment to perform an
expect /k spekt/ verb to hope or to                     experiment í verb /k sperment/ to

                        |                                                                       |

assume that something is going to hap-                   experiment (with) to carry out a scien-
pen the weather to be expected along                     tific test under controlled conditions in
a route We expect flight AC 309 within                   order to demonstrate or discover some-
ten minutes. as might be expected as                     thing
people think would happen                                experimental /k sper ment(ə)l/

                                                                                                    |       |

 ‘…by 1959 there were some 40 pilots                     adjective referring to something still at
 past age 60 flying the line with the                    an early stage of development, not tried
 number expected to rise to 250 within the               and tested the experimental and test-
 next few years’ [INTER PILOT]                           ing stages of a new type of aircraft. an
expected /k spektd/ adjective

                                        |                experimental aircraft an aircraft
being thought or hoped to be taking                      designed to be used for experimental
explanatory                                  90
purposes      The experimental aircraft           Mexico can extend into Canada.
were used to investigate high-speed               Cumulonimbus clouds may extend to
flight.                                           over 50,000 ft. to extend the dura-
explanatory /k spl nət(ə)ri/ adjec-

                                                  tion of something to prolong the time
tive referring to something which                 The visit was extended to allow time for
explains explanatory paragraph a                  more discussions.
                                                  extensive /k stensv/ adjective

paragraph of text which explains some-                                                        |

thing      self-explanatory something             large in range or amount an extensive
which does not need any further expla-            area a large area extensive cloud a lot
nation                                            of cloud extensive use is made of
explosion /k spləυ (ə)n/ noun 1. a

                                                  much use is made of
                                                  extent /k stent/ noun a range or

release of energy in a sudden and often                                       |

violent way an explosion caused by a              amount of something The horizontal
bomb 2. an act of bursting as a result of         extent of the cloud averages about 50
internal pressure tyre explosion due to           km. Clouds of great vertical extent are
overheating 3. the loud sound made as             not uncommon. to a certain extent, to
a result of an explosion The passen-              some extent partly The accident was
gers heard an explosion.                          caused, to a certain extent, by the poor
explosive /k spləυsv/ adjective

                                                  weather.       to a lesser extent not as
referring to something having the                 much as something previously stated
nature of an explosion an explosive               The cloud types which are most likely to
effect having the effect of an explosion          affect flying conditions in terms of
í noun a substance, especially a pre-             icing, precipitation and turbulence are
pared chemical, that explodes or causes           cumulus, cumulonimbus and, to a lesser
explosions, e.g. Semtex                           extent, nimbostratus.
                                                  external /k st n(ə)l/ adjective refer-

expose /k spəυz/ verb to uncover

something or leave something uncov-               ring to, existing on, or connected with
ered so that it is not protected from             the outside or an outer part The only
something such as rain or sunlight                external force acting on air is gravity.
When the slope of a hill is exposed to            Opposite internal external appear-
solar radiation, wind currents are set            ance the appearance of something from
up. exposed to the sun in sunlight                the outside
                                                  external ambient pressure /k
                                                  external ambient pressure

without covering exposed surface a                                                                    |

surface without paint or covering of any           st n(ə)l mbiənt preʃə/ noun pres-
sort                                              sure outside the aircraft
exposure /k spəυ ə/ noun 1. the                  extinguish /k stŋ wʃ/ verb to put
exposure                                          extinguish

                              |                                                           |

fact of being exposed, especially to              out The fire services extinguished the
severe weather or other forces of nature          fire.
   After 24 hours in the sea, she was suf-        extinguisher /k stŋ wʃə/ noun a


fering from the effects of exposure and           portable mechanical device for spray-
was taken to hospital. 2. the fact of             ing and putting out a fire with chemicals
being subjected to something Expo-                   Hand-operated fire extinguishers are
sure to radio-active substances may               provided to combat any outbreaks of
cause cancer.                                     fire in the flight crew compartment and
express /k spres/ verb to put into

                      |                           passengers’ cabins.
words, symbols or signs          Bearings         extract noun / ekstr kt/ a part taken

may be expressed as true or relative.             from a longer text The following par-
An angle may be expressed in degrees,             agraph is an extract from a flight man-
minutes and seconds. Pressure alti-               ual. í verb /k str kt/ 1. to obtain from

tudes are expressed in hundreds of feet.          a substance by chemical or mechanical
extend / k stend/ verb to stretch or

              |                                   action A dehumidifier extracts mois-
spread from one point to another in               ture from the atmosphere. 2. to take out
space or time Air from the Gulf of                or to obtain information from some-
                                          91                                         eye
thing Extract the important informa-           degree, very great extreme care must
tion from a text.                              be taken the greatest care must be taken
extrapolate /k str pəlet/ verb to               extreme difficulty great difficulty í


estimate by using known facts Infor-           noun either of the two things, values,
mation given on a synoptic chart can be        situations, etc., situated at opposite ends
extrapolated, by the use of some simple        of a range the extremes of boiling and
guidelines.                                    freezing       The region experiences
extreme /k stri m / adjective 1. most

                                               extremes of temperature.
                                               eye /a/ noun an organ in the head

distant in any direction, the outermost
or farthest the most extreme point on          which lets you see. coordination,
the map 2. to the greatest or highest          vision
F symbol 1. Fahrenheit 2. farad

                                             thing a facility in learning to fly a

FAA abbreviation US Federal Aviation         good natural ability for flying 2. an
Administration                               installation or building which provides
                                             specific operating assistance        DME
fabric / f brk / noun material or cloth

                                             (Distance Measuring Equipment)
produced especially by knitting or           ground facility 3. a mode of operation
weaving A breathing mask has a fab-          which allows the user of equipment to
ric carrying bag.                            do something The printer has a self-
fabricate / f brket/ verb to make

                                             test facility. 4. facilities things, espe-
or manufacture Selected wing panels          cially buildings or equipment, that peo-
are fabricated entirely from magnesium       ple can use a clubhouse with good
alloys. The ease with which alumin-          facilities a clubhouse with a number of
ium can be fabricated into any form is       features which can be used by members
one of its most important qualities.         and guests, e.g. restaurant, bar, reading
face /fes / noun 1. the surface of an

                                             room, swimming pool medical facili-
object the face of the earth The             ties hospitals, clinics, etc.
exhaust cone prevents the hot gases          facsimile / f k smli/ noun same as


from flowing across the rear face of the     fax
turbine disc. the north face of the
                                             fact /f kt/ noun information pre-

mountain the vertical or near-vertical
side facing north 2. the front part with     sented as real Temperature changes
dial, indicators, etc. the face of an        are an important fact in meteorology.
instrument the face of a clock the           in (point of) fact in reality, in truth
front part of the clock with numbers 3.      factor / f ktə/ noun 1. an important

the front of the head, including the eyes,   part of a result, a process, etc. Visibil-
nose, mouth full face smoke mask a           ity remains a very important factor in
protective mask for fighting fires which     aviation.     critical factor extremely
covers the whole face í verb to be           important factor        dominant factor
turned towards a particular direction        most important factor safety factor
Hills and mountains which face the sun       something which plays an important
receive more intense radiation. the          part in safety 2. by a factor of quan-
building faces north the building has        tity by which a stated quantity is multi-
its front towards the north                  plied or divided, so as to indicate an
facilitate /fə sltet/ verb to enable

                                             increase or decrease in a measurement
something to happen more easily or           by a factor of ten ten times The rate
quickly A ramp is used to facilitate         is increased by a factor of 10. conver-
access to the wing. Clearly marked           sion factor a formula or figure used for
exits facilitate rapid evacuation of pas-    conversion of temperatures, distances,
sengers.                                     etc., from one system to another The
facility /fə slti/ noun 1. ability or

             |                               conversion factor for converting UK
ease in moving, acting, or doing some-       gallons to litres is: x 4.546.
                                             93                                       false
fade /fed/ noun 1. a periodic reduc-             emergency situation worse. 3. the fact

tion in the received strength of a radio          of not passing a course, a test, or an
transmission Surface wave at night                examination His failure in the GFT
causes fade of the signal. 2. a periodic          (General Flying Test) meant that he
reduction in braking power         Hard           didn’t finish the course.
braking can cause fade and tyre burst             fair /feə/ adjective 1. free of clouds or

through overheating. í verb to lose               storms, clear and sunny fair weather
strength, brightness, loudness, or bril-          good weather 2. just, reasonable, free of
liance gradually the lights faded the             favouritism or bias a fair exam an
lights became less and less bright, the           exam which tested students on what
lights dimmed the radio signal faded              they had been taught, was of reasonable
the radio signal became weaker and                difficulty and duration and which did
weaker                                            not trick the candidates it is fair to
Fahrenheit / f rənhat/ noun a scale

                                                  say that he should have done better it
of temperatures where the freezing and            is reasonable to say that he should have
boiling points of water are 32° and 212°          done better í verb to join pieces so as to
respectively. Compare Celsius, centi-             be smooth, even, or regular The air-
grade (NOTE: Used in the USA but now              craft’s wing is faired into the fuselage.
less common in the UK; usually written
                                                  fairing / feərŋ/ noun a device to

as an F after the degree sign: 32° F.)
                                                  improve the flow of air over a surface
fail /fel/ verb 1. to stop working prop-

                                                  There is a dorsal fairing at the base of
erly the brakes failed the brakes did             the fin or vertical stabiliser. Wheel
not work the wing failed during a                 fairings, called spats, are fitted to light
high-speed turn the wing broke during             aircraft to reduce drag. spat, nacelle
a high-speed turn 2. to receive an aca-
                                                  fairly / feəli/ adverb moderately,

demic grade below the acceptable min-
imum in an examination or a course of             rather, quite fairly high levels moder-
study the trainee failed his naviga-              ately high levels fairly simple moder-
tion examination the trainee did not              ately simple
pass her navigation exam without fail             fall /fɔ l/ noun 1. a drop or lessening in

certainly, definitely      Be here at 8           amount fall in pressure a drop in
o’clock without fail.                             pressure 2. the amount of rain or snow
fail safe / fel sef/ noun the principle
fail safe

                                                  which comes down at any one time an
of designing a structure so that the fail-        overnight fall of snow 3. US autumn í
ure of one part does not affect the safety        verb 1. to become less in amount
of the whole                                      atmospheric pressure is falling atmos-
fail safe system / fel sef sstəm/
fail safe system
                                                  pheric pressure is decreasing 2. to be
noun a system or device which has in-             included within the range of something
built safeguards against total failure              Aircraft fall into a number of type cat-
The term fail safe means that the struc-          egories. Design methods fall into four
ture, though damaged, is capable of               groups.      Long-range high-frequency
supporting a reasonable percentage of             communications fall in the frequency
its design load.                                  bracket 2–25 MHz. 3. to drop or come
                                                  down freely because of gravity Light
failure / feljə/ noun 1. a stoppage or

                                                  rain may fall occasionally. 4. to occur at
a breakdown bearing failure Engine
                                                  a particular time New Year’s Day falls
failure is sometimes accompanied by
fire.    power failure loss of engine             on a Thursday this year. (NOTE: falling
                                                  – fell – fallen)
power, or loss of electrical power sup-
                                                  false /fɔ ls/ adjective not true, incor-

ply 2. the fact of not achieving the
desired goal or result the failure of an          rect Lightning may cause false read-
experiment failure to do something                ings from sensitive instruments. false
not doing something The steward’s                 glide path information incorrect glide
failure to remain at his station made the         path information
familiar                                      94
familiar /fə mliə/ adjective 1. often             and received by a fax machine con-


seen, common Clouds are the most                   nected to a telephone link 2. an elec-
familiar visible meteorological feature.           tronic apparatus linked to a telephone
2. known Symbols and abbreviations                 used to send and receive a fax Charts
which are strange at present become                are transmitted by fax to meteorological
familiar after a time. to be familiar              offices. CAMFAX í verb to send a fax
with to have some knowledge of some-                  Charts are faxed to meteorological
thing He is familiar with the proce-               offices.
dure.                                              FDPS abbreviation flight data process-

familiarise /fə mliəraz/, familiar-              ing system


                                                   FDR abbreviation flight data recorder

ize verb to familiarise yourself with
to get to know something well                      FDS abbreviation flight director sys-

fan /f n/ noun a circular device with

rotating blades, powered by an engine              feather / feðə / verb to feather a

or motor, for moving a gas such as air             propeller to turn the blades of a
The compressor has large rotating fan              stopped propeller edge on to the airflow
blades and stator blades.                          in order to reduce drag or wind resist-
fanjet / t bəυf n/ noun US same as                 ance The feathered position not only

turbofan                                           reduces drag, but also minimises engine

FANS abbreviation future air naviga-               rotation, thus preventing any additional
tion systems                                       damage to the engine.
                                                   feathering / feðərŋ/ noun the act of

FAR abbreviation US Federal Aviation

Regulation                                         turning the blades of a stopped propel-
                                                   ler edge on to the airflow in order to
farad / f r d/ noun the SI unit of

                                                   reduce drag       Feathering is accom-
capacitance. Symbol F                              plished by moving the pilot’s control
fasten / fɑ s(ə)n/ verb to secure or to

close, as by fixing firmly in place fas-           feathering gate / feðərŋ et/
                                                   feathering gate

ten your seat belt put on and attach               noun a device on the propeller pitch
your seat belt If in-flight conditions             control to prevent unwanted selection
require the captain to activate the fas-           of the feathering position
ten seat belt sign, all cabin service              feathering position / feðərŋ pə
                                                   feathering position


ceases and cabin crew take up their                 zʃ(ə)n/ noun a position of the propel-
assigned seats and strap in.                       ler pitch control in which the blades are
fatigue /fə ti / noun 1. physical or

mental tiredness resulting from exertion           feature / fi tʃə/ noun 1. an important,

  Pilot fatigue was a contributing factor          noticeable or distinctive aspect, quality,
in the accident. 2. the weakening or fail-         or characteristic Sea breeze is a regu-
ure of a material such as metal, result-           lar feature of coastal climates. 2.
ing from stress Fan blades must be                 ground features noticeable, important
resistant to fatigue and thermal shock.            objects in the landscape which are use-
Titanium has good fatigue resistance.              ful aids to navigation, e.g. bridges, riv-
fatigue crack crack due to material                ers, railway lines, etc. í verb to have as
fatigue                                            a particular characteristic Many Rutan
fault /fɔ lt/ noun a defect in a circuit or

                                                   designs feature a canard wing.
wiring caused by bad connections, etc.             Federal Aviation Administra-
                                                   Federal Aviation Administration

  A fault in the automatic boost control           tion   / fed(ə)rəl evi eʃ(ə)n                   |

unit was repaired.                                    dmnstreʃ(ə)n/ noun the body
faulty / fɔ lti/ adjective containing a

                                                   responsible for the regulation of avia-
fault or defect, imperfect The faulty              tion in the United States The FAA
component was replaced.                            issues licenses. Abbreviation FAA
fax /f ks / noun 1. an exact copy of a

                                                   Federal                           Aviation   Regulation
                                                   Federal Aviation Regulation

document, drawing, etc., transmitted               / fed(ə)rəl                         evieʃ(ə)n       re jυ   |
                                            95                                         fine
 leʃ(ə)n/ noun a regulation governing           unwanted substances fuel filter oil
aviation in the United States. Abbrevia-         filter 2. an electric, electronic, acoustic,
tion FAR                                         or optical device used to reject signals,
feed /fi d / noun a supply of fuel,              vibrations, or radiations of particular

energy, etc. provided for use                    frequencies while passing others The
feedback / fi db k / noun 1. the
                                                 tuner is a band pass filter which con-
return of part of the output of a process        fines the bandwidth passed to the
or system to the input, especially when          receiver to that required. í verb to pass
used to maintain performance or to con-          a liquid or gas through a filter in order
trol a system The LC ensures that a              to remove unwanted substances Fuel
feedback signal of the monitored output          is filtered before entering the carburet-
frequency is sent back to the CSDU. 2. a         tor.
                                                 filter cartridge / fltə kɑ trd /
                                                 filter cartridge

feedback mechanism
ferry / feri/ verb to make a delivery of         noun same as filter element

an aircraft by flying it to its operator         filter element / fltə elmənt/ noun
                                                 filter element

fibre / fabə/ noun a natural or syn-            a removable paper or metal component

thetic filament like cotton or nylon             in a filter housing which must be
(NOTE: The US English is fiber.)                 replaced periodically        From time to
FIC abbreviation flight information
                                                 time the filter element must be removed
centre                                           and cleaned or replaced. Also called fil-
field /fi ld/ noun 1. an area of grass on
                                                 ter cartridge
                                                 fin /fn/ noun a fixed vertical aerofoil at

farmland, in the countryside In the
event of a power failure, it is important        the rear of a plane, the vertical stabiliser
to select the most suitable field for a            The fin provides directional stability
forced landing. 2. an imaginary area             about the vertical axis. Also called ver-
field of vision / fi ld əv v (ə)n/              tical stabiliser
field of vision

                                                 final / fan(ə)l/ noun the end part of a

noun the area in which something can
be seen without moving the head or the           series or process í adjective coming at
eyes                                             the end final assembly the last in a
fighter / fatə/ noun small, single-seat         series of stages of construction of an

or two-seat aircraft for use in military         aircraft when all the pre-assembled
conflict The F16 is an American-built            parts are put together
fighter.                                         final approach / fan(ə)l ə prəυtʃ/
                                                 final approach


figure / f ə/ noun 1. a diagram or

                                                 noun 1. a flight path in a direction along
drawing Figure 1 shows a cross-sec-              the extended centre line of the runway
tion of an internal combustion engine.           on which a plane is about to land The
2. a number, especially in mathematical          aspect of the runway on final approach
calculations a head for figures good             helps the pilot to judge height and
at figures, arithmetic, accounting, etc.         progress. 2. the last stage of an aircraft’s
a two-figure code a code with two                descent before landing, from when it
numbers between 0 and 9 3. a form con-           turns into line with the runway to the
sisting of any combination of points or          procedures immediately before it lands
lines, e.g. a triangle                           fine /fan/ adjective 1. of superior

film /flm/ noun 1. a thin skin or layer

                                                 quality, skill, or appearance a fine day
   An electrical element made of gold            a day when the weather is good fine
film is sandwiched between the layers of         weather good weather 2. very small in
glass. 2. a thin covering or coating             size, thickness or weight Cirrus cloud
There is a film of oil between the piston        has a fine, hair-like appearance. fine
and cylinder wall.                               powder powder consisting of very
filter / fltə/ noun 1. a material or

                                                 small particles fine spray a spray con-
device through which a liquid or a gas is        sisting of very small drops of liquid 3.
passed in order to separate the fluid            fine wire very thin wire 4. referring to
from solid matter or to remove                   the pitch or blade angle setting of the
FIR                                           96
propeller       Fine pitch enables full            exercise. í noun the exactness with
engine speed to be used on take-off and            which surfaces are adjusted to each
coarse pitch allows an economical                  other in a machine There should be a
engine speed to be used for cruising.              loose fit between the cylinder and the
FIR abbreviation flight information
                                                   piston, the difference being taken up by
region                                             the piston rings. í verb 1. to be the cor-
fire /faə / noun an area of burning To
                                                   rect size and shape for Oxygen masks
guard against the risk of fire, passen-            should fit the wearer properly. 2. to put
gers are requested not to smoke in the             on or attach Wheel fairings, called
toilets. an engine fire a fire in an               spats, are fitted to some light aircraft to
engine í verb to shoot a gun, or to                reduce drag. (NOTE: fitting – fitted)
                                                   fitment / ftmənt/ noun an act of

launch something such as a flare or a
rocket                                             attaching or fixing Attachment points
fire deluge system / faə delju d
fire deluge system
                                                   are supplied for the fitment of heavy
 sstəm/ noun a system which extin-                equipment.
                                                   fitness / ftnəs/ noun the state or con-

guishes fire by spraying large quantities
of water on it A lever actuates the fire           dition of being physically fit, especially
deluge system.                                     as the result of exercise and proper eat-
fire detection system / faə d
fire detection system

                                                   ing habits The age and physical fit-
 tekʃən sstəm / noun a system to                  ness of some passengers can be a limit-
detect the presence of fire in an aircraft         ing factor in an evacuation. fitness to
                                                   fly description of the physical or mental
fire      extinguisher / faər k
fire extinguisher

                                                   capabilities a person needs to fly an air-
 stŋ wʃə/ noun a portable device full            craft
of foam, water, powder, etc., for putting
                                                   fixed-wing / fkst wŋ/ adjective

out fires
                                                   referring to an aircraft that has wings
                 / faəpru f/

fireproof                         adjective        that do not move, rather than rotor
designed to resist the effect of fire A            blades
fireproof bulkhead is provided to sepa-
                                                   FL abbreviation flight level

rate the cool area of the engine from the
                                                   flag /fl / noun 1. a usually square or

hot area.
                                                   rectangular piece of cloth with a sym-
fire triangle / faə tra ŋ əl/ noun
fire triangle

                                                   bolic design or colour Flags are flown
the illustration of the chemistry of fire          from the signal mast. 2. a small visual
as the three sides of a triangle represent-        warning or indicating device on the face
ing fuel, oxygen and heat If fuel, oxy-
                                                   of an instrument There is a warning
gen or heat is removed from the fire tri-
                                                   flag on the instrument if there is a prob-
angle, combustion will cease.
first aid kit / f st ed kt/ noun a
first aid kit

                                                   flame /flem/ noun the usually yellow

small pack containing plasters, band-              area of burning gases seen when some-
ages, antiseptic cream, etc., to be used           thing is burning Flames were seen
in case of an emergency
                                                   coming from number 2 engine.
first officer / f st ɒfsə/ noun the
first officer

                                                   flame arrester / flem ə restə/ noun
                                                   flame arrester


officer who is second-in-command to                a device to prevent flame from an exter-
the captain of an aircraft                         nal source from entering a fuel tank
FIS abbreviation flight information

                                                   flame out / flem aυt/ verb to cease
                                                   flame out

service                                            from some cause other than the shutting
fishtail / fʃtel/ verb to move the tail

                                                   off of fuel Air in the fuel line can
of an aircraft from side to side as a way          cause an engine to flame out or stop.
of reducing speed                                  flame-out / flem aυt/ noun the ceas-

FISO abbreviation flight information

                                                   ing of combustion in a gas turbine
service operator                                   engine from some cause other than the
fit /ft/ adjective in good physical con-

                                                   shutting off of fuel (NOTE: The word is
dition, healthy Keep fit with diet and             also written flameout.)
                                                97                             flight attendant
flammable / fl məb(ə)l/ adjective                    trical charge left in it       The engine

easily ignited and capable of burning                wouldn’t start because the battery was
fiercely and rapidly, and therefore haz-             flat.
ardous Aviation gasoline is a flamma-                flat spin / fl t spn/ noun a descent
                                                     flat spin

ble liquid. (NOTE: Flammable and                     in small circles by an aircraft flying in a
inflammable mean the same thing.)                    nearly horizontal position
flange /fl nd / noun the outside edge                flatten / fl t(ə)n/, flatten out verb to
flange                                               flatten

or rim of a part such as a beam or wheel             make flat As altitude increases, the
  The web connects the upper and lower               countryside appears to flatten out.
flanges of a beam.                                   The Earth is spherical in shape but it is
flap /fl p/ noun a movable control sur-
                                                     flattened at the poles.
                                                     flaw /flɔ / noun an imperfection in a

face on the trailing edge of an aircraft
wing, used primarily to increase lift and            material, often hidden, that may be an
drag during final approach and landing               indication of future structural failure
   Flaps should be retracted immedi-                 flaw detection a process or system by
ately after landing to decrease lift and             which small weaknesses in metal struc-
therefore increase brake effectiveness.              tures are found
cowl                                                 flew /flu / ‘ fly

                                                     flexibility / fleks blti/ noun 1. the

       COMMENT: Flaps are not usually used                                 |

       for take-offs in light aircraft except        amount or extent to which something
       when a short take-off run is required.        can be bent or flexed Wing structures
       Flaps are not primary control surfaces        must have flexibility in order to absorb
       of an aircraft.
                                                     sudden changes in loading. 2. the extent
flare /fleə/ noun 1. a stage of the flight

                                                     to which a system or device can change
immediately before touchdown when                    or respond to a variety of conditions or
the nose of the aircraft is raised into the          situations The more reliable and quick
landing attitude The approach, flare                 fly-by-wire system allows a much
and landing can be carried out by auto-              greater degree of flexibility with aircraft
matic systems. 2. a small rocket-like                stability. Opposite rigidity
device with a bright light, for attracting           flexible / fleksb(ə)l/ adjective 1. not

attention                                            rigid, not stiff flexible pipes pipes
flash /fl ʃ/ noun giving off light in

                                                     made of soft material such as rubber or
sudden or periodic bursts Lightning is               plastic 2. capable of responding to a
accompanied by a brilliant flash. Loss               variety of conditions or situations;
of vision may occur due to lightning                 adaptable        AC electrical energy is
flashes especially at night. í verb 1. to            more flexible and more efficient than
give off light in regular bursts warn-               DC. Opposite rigid
ing lights flash warning lights go on                flier / flaə / noun 1. the pilot of an air-

and off rapidly 2. to appear or to happen            craft 2. a passenger on an aircraft
suddenly The image flashed onto the                  flight / flat/ noun 1. the motion of an

screen.                                              object in or through the Earth’s atmos-
flash point /fl ʃ pɔnt/ noun tem-
flash point

                                                     phere or through space 2. the distance
perature at which fuel vapour or oil                 covered by a body, e.g. an aircraft, as it
vapour will burst into flame                         flies through the atmosphere            The
flat /fl t/ adjective 1. having a hori-              flight from London to Paris took 55 min-

zontal surface without a slope, tilt or              utes. 3. a scheduled airline journey
curvature It has been shown that the                 Passengers for flight GF 008 to Amman
flat chart misrepresents the globe-                  should proceed to gate number 4.
                                                     flight attendant / flat ə tendənt/
                                                     flight attendant

shaped earth. flat country country                                                    |

with no hills or mountains 2. having no              noun a member of the flight crew who
air inside     The flat tyre had to be               looks after passengers, serves food, etc.
changed because it had a puncture. 3.                   If you need something, press the call
electrically discharged or with no elec-             button and a cabin attendant will
flight bag                                     98
respond within a few minutes. Also                  flight          operations          / flat
                                                    flight operations

called cabin attendant                               ɒpəreʃ(ə)nz/ plural noun the use of
flight bag / flat b / noun a bag                   aircraft
flight bag

used by flight crew to carry manuals,               flight path / flat pɑ θ/ noun a line,
                                                    flight path

documents, headset, etc.                            course or track along which an aircraft
flight-briefing room / flat bri fŋ                flies
flight-briefing room

ru m/ noun a room where instructors                 flight plan / flat plan / noun a writ-
                                                    flight plan

talk to trainees immediately before a               ten statement that gives details of the
training flight or where a pilot talks to           flight that a pilot intends to make
his or her crew immediately before                  flight progress strip / flat
                                                    flight progress strip

boarding the aircraft                                prəυ res strp/ a thin cardboard strip
flight crew / flat kru / noun airline
flight crew

                                                    with information on it about a flight,
staff responsible for flying the aircraft           which is updated by air traffic control-
flight data recorder / flat detə r
flight data recorder

                                                    lers as the flight progresses
 kɔ də/ noun an electronic device                   flight simulator / flat smjυletə/
                                                    flight simulator

located in the tail section of an aircraft          noun a device or computer program
that picks up and stores data about a               which allows a user to pilot an aircraft,
flight. Abbreviation FDR. Also called               showing a realistic control panel and
black box (NOTE: It is often called the             moving scenes, used as training pro-
black box, although it is not black.)               gramme
flight deck / flat dek/ noun a place               flight-test / flat test/ verb to test the
flight deck

where the flight crew of an airliner sit            performance of an aircraft or compo-
while flying the aircraft                           nent in flight
                                                    float /fləυt/ noun 1. a floating ball

flight deck instruments plural
flight deck instruments

noun instruments used by the flight                 attached to a lever to regulate the level
crew when flying an aircraft                        of a liquid in a tank, etc. float-oper-
flight engineer / flat end nə/
flight engineer
                                                    ated switch a shut-off valve operated
noun the member of the crew of a plane              by a float 2. a hollow structure fixed
who is responsible for checking that its            below an aircraft that allows it to float
systems, including the engines, perform             on water. Also called pontoon í verb to
properly                                            remain on the surface of a fluid without
                                                    sinking       Because of the air-tight
flight envelope / flat envələυp/
flight envelope

                                                    nature of the fuselage, most large air-
noun same as envelope                               craft will float for some time before
flight information region / flat
flight information region

 nfə meʃ(ə)n ri ən/ noun airspace
                                                    float chamber / fləυt tʃembə/
                                                    float chamber

with defined limits which has an air                noun the part of a carburettor which
traffic control information and alerting            houses the float
service. Abbreviation FIR
                                                    floatplane / fləυtplen/ noun a sea-

flight level / flat lev(ə)l/ noun 1.
flight level

                                                    plane that has hollow structures
the level of constant atmospheric pres-             attached underneath its wings and
sure related to a reference datum of                sometimes its fuselage on which it
1013.25 mb        FL 250 = 25,000 ft.               floats so that the main body of the plane
Abbreviation FL 2. the height at which              is not in contact with the water. Com-
a particular aircraft is allowed to fly at a        pare flying boat
particular time                                     flow /fləυ/ verb 1. to move or run

flight line / flat lan/ noun the area
flight line

                                                    smoothly with continuity, as a fluid
of an airfield, especially a military air-          Air flows over the wing surfaces and lift
field, where aircraft are parked, serv-             is produced. 2. to circulate       Liquid
iced, and loaded or unloaded                        coolant flows around the engine. í noun
Flight Manual / flat m njυəl/
Flight Manual

                                                    continuous movement in a particular
noun same as Pilot’s Operating Hand-                direction The flow of fuel from the fuel
book                                                tanks to the engines.
                                              99                                        fog
flowmeter / fləυmi tə/ noun a device               flying     conditions / flaŋ kən
flowmeter                                          flying conditions


for measuring the flow of a liquid or gas           dʃ(ə)nz/ plural noun the weather and
   The oxygen flowmeter should blink               its suitability for flying
once for each breath.                              flying controls / flaŋ kən trəυlz/
                                                   flying controls


fluctuate / fl ktʃuet/ verb to vary or
                                                   plural noun the yoke or control column,
change irregularly The magnetic field              rudder pedals and other devices used by
will fluctuate at the supply frequency.            the pilot in order to manoeuvre the air-
fluid / flu d/ noun a substance which

                                                   flying field / flaŋ fi ld/ noun a
                                                   flying field

is not solid, whose molecules move                 small airfield from which light aircraft
freely past one another and that takes             can operate
the shape of its container de-icing
                                                   flying instructor / flaŋ n
                                                   flying instructor

fluid a liquid for removing ice                                                             |

                                                    str ktə/ noun a trained person, a pilot,
fluorescent /flυə res(ə)nt / adjective

                                                   who teaches people how to fly an air-
referring to the emission of electromag-           craft
netic radiation of visible light The flu-          fly-past / fla pɑ st/ noun the flight of

orescent penetrant process of flaw                 an aircraft or group of aircraft over a
detection uses a penetrant containing a            place as a spectacle for people on the
fluorescent dye which fluoresces in                ground
ultra-violet light.                                FMS / ef em es/ abbreviation flight

fly /fla/ verb to move through the air or

                                                   management system
to cause an aircraft to move through the           foam /fəυm/ noun 1. a mass of bub-

air in a controlled manner An aero-                bles of air or gas in a liquid film foam
plane may not fly over a city below such           fire extinguishers Airport fire crews
a height as would allow it to alight in            covered the fuselage with foam to con-
the event of an engine failure. He’s               trol the fire. 2. any of various light,
learning to fly. (NOTE: flying – flew –            porous, semi-rigid or spongy materials
flown) to fly in formation to fly as a             used for thermal insulation or shock
group which maintains a particular pat-            absorption Polyurethane foam is used
tern or arrangement in the air                     in packaging.
fly-by-wire / fla ba waə/ noun                  focal point / fəυk(ə)l pɔnt/ noun
fly-by-wire                                        focal point

technology which interprets move-                  same as focus
ments of the pilot’s controls and, with            focus / fəυkəs/ noun the point at

the aid of computerised electronics,               which rays of light or other radiation
moves the control surfaces accordingly             converge The focus of a lens is also
    Using fly-by-wire technology, the              called the focal point. (NOTE: The plural
stalling angle cannot be exceeded                  form is foci. / fəυsa/) to come into
regardless of stick input. The more                focus to become clearer as through the
reliable and quick fly-by-wire system              viewfinder of a camera í verb 1. to
allows a much greater degree of flexi-             make things such as light rays converge
bility with aircraft stability.                    on a central point A parabolic reflec-
      COMMENT: Fighters like the General
                                                   tor focuses the transmission into a nar-
      Dynamics F16 and large transport             row beam. 2. to give an object or image
      aircraft such as the Boeing 777 and          a clear outline or detail by adjustment of
      Airbus A320 have fly-by-wire systems.        an optical device Focus the micro-
                                                   scope in order to make the image easier
flying / flaŋ/ noun the act of making

                                                   to see. 3. to direct toward a particular
an aircraft move through the air in a              point or purpose The crew focused all
controlled manner                                  their attention on finding a solution to
flying boat / flaŋ bəυt/ noun a sea-             the problem.
flying boat

plane with a body that acts like a boat’s          fog /fɒ / noun condensed water

hull and allows the plane to float on              vapour in cloud-like masses lying close
water. Compare floatplane                          to the ground and limiting visibility
föhn                                      100
When visibility is less than 1,000 m          force-land / fɔ s l nd / verb to land

owing to suspended water droplets in          an aircraft before it gets to its destina-
the atmosphere, the condition is known        tion because of an emergency situation,
as fog. evaporation fog steam fog             or land in these circumstances
Evaporation fog is usually confined to
                                              forces of flight / fɔ sz əv flat/
                                              forces of flight

water surfaces and adjacent areas of
land.                                         plural noun the aerodynamic forces, lift,
                                              drag, weight and thrust, which act on an
föhn /f n/ noun a warm dry wind that

                                              object that is travelling though the air
blows down the lee side of a mountain,
                                              fore /fɔ / adjective located at or

particularly in the Alps (NOTE: The
word is also written foehn.)                  towards the front the fore and aft axis
                                              of the aircraft the longitudinal axis of
foil /fɔl/ noun same as aerofoil

                                              the aircraft to come to the fore to
foot /fυt/ noun a unit of length in the

                                              become important or to start to play a
US and British Imperial Systems equal         leading role The jet engine came to
to 12 inches or 30.48 centimetres. Sym-       the fore in the late forties. aft
bol ft (NOTE: The plural form is feet; foot   forecast / fɔ kɑ st/ noun a statement

is usually written ft or ’ after figures:     of what is likely to happen in the future
10ft or 10’.)                                 or describing expected events or condi-
foot-pound / fυt paυnd/ noun the

                                              tions      weather forecast       forecast
ability to lift a one pound weight a dis-     weather charts charts with information
tance of one foot. Abbreviation ft-lb         about the weather coming to a particu-
force /fɔ s/ noun 1. the capacity to do
                                              lar area í verb to estimate or calculate
work or cause physical change the             weather conditions by studying meteor-
force of an explosion 2. power used           ological information Rain is forecast
against a resistance In small aerobatic       for this afternoon. (NOTE: forecasting –
aircraft, considerable force is needed        forecast or forecasted)
                                              forecast chart / fɔ kɑ st tʃɑ t/
                                              forecast chart

on the control column when performing
high-speed manoeuvres. 3. a vector            noun same as prognostic chart
quantity that produces an acceleration        Prognostic or forecast charts are pre-
of a body in the direction of its applica-    pared, by the central meteorological
tion (NOTE: We say centrifugal force,         office of each region, normally for peri-
but the force of gravity.) the force of       ods up to 24 hours ahead.
gravity the natural force of attraction
                                              form /fɔ m/ noun 1. a document with

which pulls bodies towards each other
and which pulls objects on Earth              blanks for the insertion of details or
towards its centre í verb 1. to use power     information insurance form appli-
against resistance Because of distor-         cation form 2. a kind or type        The
tion to the airframe, the pilot had to        ground automatic relief valve is a form
force the door open in order to exit the      of discharge valve.       Drizzle is the
aircraft. 2. to force someone to do           lightest form of precipitation. 3. the
something to use physical or psycho-          shape of an object Fluids take on the
logical power to make somebody do             form of the container in which they are
something they otherwise would not do         found. in the form of a triangle in the
  The hijackers forced the crew to fly to     shape of a triangle 4. the way in which
Athens.                                       a thing exists, acts, or shows itself
                                              water in the form of ice fuel in the
forced landing / fɔ st l ndŋ/
forced landing

                                              form of a spray í verb 1. to come into
noun an unexpected landing that a pilot       being In some conditions, ice forms
of an aircraft has to make because of an      on the leading edge of the wing.
emergency situation                           Cumulus clouds only form in an unsta-
force down / fɔ s daυn/ verb to
force down

                                              ble atmosphere. 2. to make a shape
force an aircraft to land, usually            Three points on the chart form a trian-
because of an emergency situation             gle. 3. to make up or constitute The
                                               101                                          front
classroom and accommodation build-                 FPPS

                                                   FPPS abbreviation flight plan process-
ing form the main part of the college.             ing system
formation /fɔ meʃ(ə)n/ noun 1. the                frame /frem/ noun 1. a structure that


process of coming into being or form-              gives shape or support Early aircraft
ing cloud formation the natural pro-               fuselages were made of a frame covered
duction and development of clouds                  by a fabric. 2. an open structure for
ice formation the natural production               holding, or bordering a door or win-
and development of ice 2. to fly in                dow frame
formation to fly in a group which                  FREDA

                                                   FREDA ‘ mnemonic
maintains a particular pattern or
                                                   freeze /fri z/ verb to pass from the liq-

arrangement in the air
                                                   uid to the solid state by loss of heat In
former / fɔ mə/ adjective having been

                                                   some conditions, rain droplets freeze
in the past a former military pilot a              rapidly on striking the aircraft. (NOTE:
pilot who used to be a military pilot í            freezing – froze – frozen)
noun 1. the first of two things men-
                                                   freight /fret/ noun anything other

tioned 2. a light secondary structure of
the airframe which gives improved                  than people transported by a vessel or
shape                                              vehicle, especially by a commercial car-
                                                   rier Freight holds are usually located
      ‘…much has changed in the former             beneath the passenger cabins.
      Eastern European States, especially in
                                                   freighter / fretə/ noun an aircraft

      terms of aviation operations and training’
      [Civil Aviation Training]                    designed to carry freight
                                                   frequency / fri kwənsi/ noun 1. the

formula / fɔ mjυlə/ noun a mathe-

matical rule expressed in symbols The              number of times or the rate at which
formula for calculating speed is D ÷ T             something happens in a given period of
= S (where D = distance, T = time and              time The frequency of flights to holi-
S = speed). (NOTE: The plural form is              day destinations increases during the
formulas or formulae.)                             summer time. 2. the number of repeti-
                                                   tions per unit time of a complete wave-
forward / fɔ wəd/ adjective at, near,

                                                   form, as of an electric current frequency
or belonging to the front the forward
section of the aircraft forward and aft                   ‘…a Baltimore man adjusted a baby
exits                                                     alarm to improve its performance and
                                                          found his youngster’s squawks were
forwards / fɔ wədz/ adverb towards

                                                          being picked up by incoming aircraft
a position in front The throttles are                     tuned to the local NDB frequency’ [Pilot]
moved forwards for take-off. (NOTE: The            frequency bracket

                                                   frequency        bracket / fri kwənsi
US English is forward.)                             br kt/ noun a range of frequencies
fouling / faυlŋ/ noun contamination

                                                   VHF communications are allocated the
of the spark plugs with oil or petrol so           frequency bracket 118–137 MHz.
that they do not fire correctly      The           frequent / fri kwənt/ adjective hap-

engine should be run at a positive idling          pening or appearing often         frequent
speed to prevent spark plug fouling.               inspection
four-digit group / fɔ             dd t
four-digit group

                                                   friction / frkʃ(ə)n/ noun a force that

  ru p/ noun four single numbers found             resists the relative motion or tendency
together                                           to such motion of two bodies in contact
four-stroke combustion engine

four-stroke combustion engine                         Energy is converted to heat through
/ fɔ strəυk kəm b stʃ(ə)n end n/   |              friction.
noun an engine which operates in                   front /fr nt/ noun 1. the forward part

accordance with the four-stroke cycle              or surface The entrance is at the front.
Induction, compression, power and                  2. the area, location, or position directly
exhaust are the four phases of the four-           before or ahead in front in a forward
stroke combustion engine.                          position relative to something else

fpm abbreviation feet per minute                   Row 23 is in front of row 24. 3. the
frontal                                         102
mixed area between air masses of dif-               fuel injector / fju əl n d ektə/
                                                    fuel injector


ferent temperatures or densities                    noun an injector that sprays fuel into the
frontal / fr nt(ə)l/ adjective 1. refer-
                                                    combustion chamber of an engine
                                                    fuel pump / fju əl p mp/ noun a
                                                    fuel pump

ring to the forward part or surface area
of something the frontal area fron-                 device which moves fuel along pipes
tal surface the boundary between two                from the tanks to the engine
air masses 2. of or relating to a meteor-           fumes /fju mz/ plural noun smoke,

ological weather front a frontal storm              gas or vapour given off by a substance,
frontal depression / fr nt(ə)l d
frontal depression

                                                    often unpleasant or harmful When the
 preʃ(ə)n/ noun an area of low pressure             cabin is rapidly and completely filled by
found together with a weather front                 smoke and fumes, passengers will suffer
                                                    from disorientation.
frontal system / fr nt(ə)l sstəm/
frontal system

                                                    function / f ŋkʃən / noun 1. a spe-

noun a series of rain-bearing changes in
the weather                                         cific occupation or role Rota planning
                                                    is one of the functions of the chief
frost /frɒst/ noun a deposit of very

                                                    instructor. 2. purpose Seals perform a
small ice crystals formed when water                very important function in a hydraulic
vapour condenses at a temperature                   system. The function of the flaps is to
below freezing Frost had to be cleared              increase lift and drag. í verb 1. to act
from training aircraft which had been               as, or to serve the purpose of The
parked outside overnight. hoar                      escape slide also functions as a life raft.
ft /fυt/ abbreviation foot                          2. to operate or to work The system

                                                    functions well.
fuel / fju əl/ noun a substance such as

                                                    fundamental            / f ndə ment(ə)l/

gas, oil, petrol, etc., which is burnt to                                          |

produce heat or power Each wing tank                adjective 1. of or relating to the founda-
holds 20 gallons of fuel. A fuel system             tion or base the fundamental laws of
includes tanks, fuel lines, fuel pumps,             aerodynamics 2. central, forming or
fuel filters and a carburettor or fuel              serving as an essential component of a
injection system.                                   system or structure Electricity is one
                                                    of the fundamental types of energy that
              mixture / fju əl eə
fuel/air mixture

fuel/air                                            exist in nature.
 mkstʃə/ noun a combination of fuel                fungal growth / f n əl
                                                    fungal growth

and air which is ignited in a piston                noun a type of organism which lives
engine to provide power                             and multiplies in particular fuels Fuel
       COMMENT : Aircraft engines operate at        contains chemicals for the inhibition of
       different altitudes and the pilot must       fungal growth.
       adjust the mixture to produce the most
                                                    fuse /fju z / noun a safety device that

       efficient fuel/air mixture for the
       atmospheric density.                         protects an electric circuit from an
                                                    excessive current        Circuit breakers
fuel gauge / fju əl ed / noun an
fuel gauge

                                                    perform the same function as a fuse.
instrument indicating fuel contents                 fuselage / fju zəlɑ / noun the cen-

fuel injection / fju əl n d ekʃ(ə)n/,
fuel injection

                                 |                  tral body of a plane, to which the wings
fuel injection system noun system in                and tail assembly are attached and
which fuel is sprayed under pressure                which accommodates the crew, passen-
into the combustion chamber of an                   gers, and cargo The fire started in the
engine                                              wing but soon spread to the fuselage.
g /d i / symbol the acceleration due to         The pilot could see the airfield

Earth’s gravity í abbreviation gram         through a gap in the clouds.
                                            gas / s/ noun a state of matter other

G /d i / abbreviation giga-

GA                                          than solid and liquid       Oxygen and
GA abbreviation general aviation            nitrogen are gases.         gas turbine
gain / en/ noun 1. an increase

                                            engine an engine with a turbine which
There is a gain of heat by the Earth due    is rotated by expanding hot gases
to solar radiation. a gain in altitude      gaseous

                                            gaseous /         siəs/ adjective relating
an increase in altitude 2. an increase in   to, or existing as a gas The atmosphere
signal power, voltage, or current The       is the gaseous envelope surrounding the
amplifier boosts the gain of the incom-     earth.
ing signal. 3. a benefit or advantage í
                                            gasket / skt/ noun any of a wide

verb 1. to increase He failed the test
because the aircraft gained 100 ft in the   variety of seals or packings used
360° level turn. 2. to get or obtain She    between matched machine parts or
gained a pass in her meteorology exam.      around pipe joints to prevent the escape
                                            of a gas or fluid Seals, gaskets and
gale / el/ noun a very strong wind

                                            packing make a seal by being squeezed
usually blowing from a single direction     between two surfaces.
  Gales are forecast for the area.
                                            gasoline / səli n/ noun US a liq-

gallon / lən/ noun 1. imperial

                                            uid made from petroleum, used as a fuel
gallon unit of volume in the British        in an internal combustion engine
Imperial System, used in liquid meas-       GAT abbreviation general air traffic

ure and sometimes in dry measure,
                                            gate / et/ noun 1. a device for con-

equal to 4.546 litres The system deliv-
ers fuel at the rate of 100 to 2,000 gal-   trolling the passage of water or gas
lons per hour. Abbreviation gal 2. a unit   through a pipe The waste gate may be
of volume in the US Customary Sys-          controlled manually by the pilot. Dur-
tem, used in liquid measure, equal to       ing a descent from altitude, with low
3.785 litres                                power set, the turbocharger waste gate
GAMA                                        is fully closed. 2. a circuit with many
GAMA abbreviation General Aviation          inputs and one output that works only
Manufacturers Association                   when a particular input is received A
                        mə rez/ plural
gamma rays

gamma rays /                                logic gate is almost the same as a
noun electromagnetic radiation given        switch. 3. a device to prevent a lever
off by some radioactive substances          from being moved to an incorrect set-
Gamma rays are given off when radio-        ting It is necessary to move the rpm
active material breaks down.                control lever through a feathering gate
gap / p/ noun 1. a space between            to the feathering position.

                                            gauge / ed / noun 1. an instrument

objects or points 2. the difference
Micro switches have a very small gap        for measuring or testing temperature
between make and break. 3. an opening       gauge      pressure gauge 2. a unit of
GCA                                      104
diameter or width heavy gauge wire           such as heat or electricity as a result of
thick wire í verb calculate approxi-         a chemical or physical process The
mately by using the senses In fog, it is     passage of air around the wing gener-
difficult to gauge horizontal distances.     ates lift.
(NOTE: gauging – gauged)                     generation / d enə reʃ(ə)n/ noun


GCA abbreviation ground-control

                                             1. the act or process of creating or mak-
approach                                     ing generation of ideas the process of
gear / ə/ noun 1. a toothed wheel that      producing or getting ideas generation

turns with another toothed part to trans-    of electricity the production of electric-
mit motion or change speed or direction      ity 2. a class of objects derived from an
2.    valve gear the mechanism for           earlier class     a new generation of
opening and closing valves 3. equip-         computers computers which share a
ment and/or clothing                         recent development in computer tech-
 ‘…as pilots, we understand the need for a   nology which separates them as a class
 convenient way to transport flight gear.    from earlier computers
                                             generator / d enəretə/ noun a

 That’s why we custom-designed this line
 of soft-sided flight bags in a variety of   power-operated device for making elec-
 styles’ [Advertisement in Pilot]            tricity Starter generators are a combi-
gearbox / əbɒks/ noun a device to           nation of a generator and a starter

allow changes in the ratio of engine         housed in one unit.
speed to final drive speed The auxil-        genus / d i nəs/ noun a class, group,

iary power unit (APU) is a small gas         or family Various types of cloud are
turbine engine which is connected to a       grouped into ten basic cloud genera.
gearbox.                                     (NOTE: The plural form is genera.)
GEM abbreviation ground-effect               geographic /d i ə r fk/, geo-
GEM                                          geographic


machine                                      graphical / d i ə r fk(ə)l/ adjective

genera / d enərə/ plural of genus            referring to geography a specific geo-

general / d en(ə)rəl/ adjective con-
                                             graphical area the north geographic
cerned with or applicable to a whole         pole
                                             geography /d i ɒ rəfi/ noun

group of people or things         general                              |

description not a detailed description       physical geography the study of the
general principles main ideas gen-           Earth’s surface and its features
eral purpose switches all-purpose            geometric / d i ə metrk/ adjective


switches general weather situation           referring to geometry A triangle is a
the overall weather picture without the      geometric figure.        Geometric pitch
detail as a general rule usually in          (US) is the distance which a propeller
general use used a lot                       should move forward in one revolution.
general aviation / d en(ə)rəl evi           geometry /d i ɒmətri/ noun 1. the
general aviation


 eʃ(ə)n/ noun all aviation other than       study of the properties, measurement,
commercial airlines or the military          and relationships of points, lines,
The number of GA aircraft stolen is          angles, surfaces, and solids An under-
down sharply since the general aviation      standing of geometry is essential to the
community has taken steps to enhance         student of navigation. 2. a configuration
security. Abbreviation GA                    or arrangement the geometry of the
general flying test / d en(ə)rəl
general flying test

                                             engine nacelle
 flaŋ test/ noun a test of aircraft-han-   geostationary

                                                                               / d i əυ|

dling skills for student pilots. Abbrevia-    steʃ(ə)n(ə)ri/ adjective referring to an
tion GFT                                     object, such as a satellite in space,
generate / d enəret/ verb 1. to

                                             which rotates round the Earth at the
bring into being In an emergency, it         same speed as the Earth and is therefore
may be necessary for crew to generate a      stationary with reference to a point on
little panic in passengers to motivate       the Earth There are two main types of
them to move. 2. to produce something        satellite that are used for collection and
                                         105                                           governor
transmission of meteorological data,         gliding / ladŋ/ noun 1. flying in a

polar and geostationary.                     glider    gliding club association of
geostrophic wind / d i əυstrɒfk             members who fly gliders as a pastime 2.
geostrophic wind

 wnd/ noun a wind which blows hori-         flying in a powered aircraft with the
zontally along the isobars, across the       engine either switched off or idling
surface of the earth                         The best gliding speed for the aircraft is

GFT abbreviation general flying test         75 knots.

GHz abbreviation gigahertz                          COMMENT: On June 24th 1982, a
                                                    British Airways 747 flying from Kuala
giga- /  ə/ prefix one thousand mil-

                                                    Lumpur to Perth lost all power from all
lion. Symbol G                                      four engines for 13 minutes, yet
gigahertz /  əh ts/ noun a fre-                    landed safely in Jakarta: proof that

quency of 109 Hertz. Abbreviation GHz               even a large aircraft is capable of
given / v(ə)n/ adjective 1. particu-

                                             global / ləυb(ə)l/ adjective world-

lar, specified, fixed At high altitudes,
less fuel is consumed for a given air-       wide, referring to something related to
speed than for the same airspeed at a        the whole Earth global pressure pat-
lower altitude. 2. given (that) taking       terns the pressure patterns of the whole
into account, considering Given the          planet
                                             global                      positioning    system
                                             global positioning system

condition of the engine, it is surprising
that it starts.                              / ləυb(ə)l pə zʃ(ə)nŋ sstəm/ noun

glare / leə/ noun a strong blinding
                                             a satellite-based navigation system.
light Glare can be caused by diffuse         Abbreviation GPS
                                             globe / ləυb / noun an object shaped

reflection of sunlight from the top of a
layer of fog.                                like a ball If the Earth were a uniform
glass fibre reinforced plastic
glass fibre reinforced plastic
                                             globe, the average temperature would
noun a composite material made of            vary only with latitude.
                                             GLONASS noun a system of satellite

plastic which is strengthened by glass
fibres, used in the manufacture of air-      navigation operated by Russia. Full
frames and other aircraft components.        form Global Orbiting Navigation Sat-
Abbreviation GRP                             ellite System
glide / lad/ verb to fly without power      GMT abbreviation Greenwich Mean

  In the event of an engine failure, it is   Time
                                             GNSS abbreviation global navigation

important to have enough altitude to be
able to glide clear of houses, people,       satellite system
etc.                                         go-around / əυ ə raυnd/ noun a


glidepath / ladpɑ θ/, glide path

                                             climb into the circuit and manoeuvring
noun a path followed by the aircraft         into position for a new approach and
down the glide slope glidepath cov-          landing Because the plane was too
erage the vertical and horizontal            high on the approach, the pilot executed
dimensions of the glide slope radio          a go-around.
beam                                         govern / v(ə)n/ verb to control or

glider / ladə/ noun a fixed wing aer-

                                             limit the speed, size or amount of some-
oplane, normally with no power plant         thing The size and number of valves
propulsion       Nowadays, gliders are       required for a particular type of aircraft
often made of composite materials.           is governed by the amount of air neces-
glideslope / ladsləυp/, glide               sary for pressurisation and air condi-

slope noun the part of the ILS which         tioning. The type of undercarriage fit-
provides a radio beam at an angle of         ted to an aircraft is governed by the
approximately 3° to the point of touch-      operating weight.
                                             governor / v(ə)nə / noun a device

down from the outer marker thus giving
the pilot information about the height of    for controlling or limiting the speed size
the aircraft on final approach               or amount of something Overspeed-
gph                                      106
ing of the engine is prevented by a gov-     graphic / r fk/ adjective 1.

ernor in the fuel system. valve              graphic solution a technique of using
gph / d i pi etʃ/ abbreviation gal-         geometric constructions to solve prob-

lons per hour                                lems One side of the calculator has a
GPS abbreviation global positioning
                                             moveable slide which is used for the
system                                       graphic solution of triangle of velocities
GPWS abbreviation ground proximity
                                             problems. 2. described in vivid detail
warning system                               The eye witness provided a graphic
                                             description of the events leading to the
GR abbreviation hail

                                             accident. í noun a picture used in a
grade / red/ noun 1. a position in a

                                             computer application The instructor’s
scale of size or quality Kevlar 49 is the    worksheets were greatly improved by
grade used in aircraft composites. 2. a      the incorporation of graphics to aid
mark indicating a student’s level of         comprehension of the subject matter.
accomplishment Students who scored           grasshopper / rɑ shɒpə/ noun a

below a particular grade in the exami-       light, unarmed military aeroplane used
nations were not allowed to continue         for reconnaissance
the course.
                                             graticule / r tkju l/ noun 1. a

gradient / rediənt/ noun the rate at

which a quantity such as temperature or      series of fine lines in an optical instru-
pressure changes relative to change in a     ment such as a telescope, used for
given variable, especially distance          measuring 2. the network of lines
Because there is a temperature gradient      formed by the meridians and parallels
across each front it is possible to draw     of longitude and latitude of the Earth on
isotherms which reduce in value from         a flat sheet of paper A graticule of
warm to cold air. A pressure gradient        lines of latitude and longitude is imag-
occurs aloft from land to sea.               ined to cover the Earth.
                                             gravity / r vti/ noun 1. a natural

gradual / r d uəl/ adjective hap-

pening slowly but continuously Loss          force of attraction which pulls bodies
of cabin pressure may be gradual rather      towards each other and which pulls
than sudden.         gradual change a        objects on Earth towards its centre In
change which takes place over a period       order for an aeroplane to fly, lift must
of time                                      overcome the force of gravity. 2. seri-
                                             ousness Throughout the crisis caused
graduate / r d u et/ verb 1. to be


                                             by the engine failure, the passengers
granted an academic degree or diploma        were unaware of the gravity of the situ-
   She graduated from Oxford Univer-         ation.
sity with a first class honours degree. 2.
                                             gravity feed / r vəti fi d / noun a
                                             gravity feed

to advance to a new level of skill,
achievement, or activity         After 50    feed which uses the force of gravity to
hours of flying the single engine trainer,   move the fuel from the tank to the car-
the student pilots graduate to flying the    burettor
                                             great / ret / adjective 1. large in size,

twin engine aircraft. 3. to divide into
marked intervals, especially for use in      quantity, number, etc. great distances
measurement A thermometer has a              long distances a great deal of money
scale graduated in degrees Celsius.          a large sum of money great impor-
gram / r m/ noun a unit of measure-          tance enormous importance 2. very

ment of weight, equal to one thousandth      good, enjoyable or exciting
of a kilogram. Symbol g                      Greenwich Mean Time / rentʃ
                                             Greenwich Mean Time

graph / rɑ f/ noun a diagram that             mi n tam/ noun local time on the

shows a relationship between two sets        Greenwich Meridian. Abbreviation
of numbers as a series of points often       GMT
joined by a line The graph shows the             COMMENT:      GMT is now called
relationship between lift and drag at            Coordinated Universal Time (UTC)
various airspeeds.                               and is also known as Zulu time. UTC is
                                          107                                               guard
       expressed in 24-hour format; for        on the ground, or any movement on an
       example, 7:00 P.M. is 1900 hours        airfield by people or surface vehicles
       (say: nineteen hundred hours).
                                               ground position / raυnd pə
                                               ground position


grid / rd/ noun 1. a pattern of equally        zʃ(ə)n/ noun the point on the surface

spaced vertical and horizontal lines,          of the Earth immediately beneath the
sometimes used on a map Grid lines             aircraft
facilitate the quick location of a point of    ground proximity warning system

                                               ground proximity warning sys-
reference. 2. a metal cylinder in a cath-      tem / raυnd prɒk smti wɔ nŋ        |

ode ray tube 3. a pattern of equally            sstəm/ noun a system in aircraft
spaced vertical and horizontal metal           which warns pilot, by means of an audi-
rods or bars Lead-antimony alloy grid          ble signal, that the aircraft is below a
plates are components in a lead-acid           preset height. Abbreviation GPWS
battery.                                       ground-running operation

                                               ground-running                            operation
ground / raυnd/ noun the solid sur-

                                               / raυnd r nŋ ɒpə reʃ(ə)n/ noun a|

face of the earth        Hail being much       procedure of running the engine while
denser and heavier than snow, falls at a       the aircraft is stationary on the ground
much faster rate and can reach the             to check engine performance
ground even with the 0° isotherm at
                                               ground signal / raυnd s n(ə)l/
                                               ground signal

10,000 ft. í verb 1. to prohibit an air-
craft or member of an aircrew from fly-        noun a visual signal displayed on an air-
ing The pilot was grounded after fail-         field to give information about local
ing a medical examination. 2. US to            traffic rules to aircraft in the air
                                               ground speed / raυnd spi d/ noun
                                               ground speed

connect an electrical circuit to a posi-
tion of zero potential While refuelling        the speed of the aircraft in relation to
a light aircraft it is important to ground     the ground over which it is flying.
the airframe to prevent sparking caused        Abbreviation GS, G/S
by static electricity. (NOTE: To earth is      ground temperature / raυnd
                                               ground temperature

preferred in British English.)                  temprtʃə/ noun the temperature
ground crew / raυnd kru / noun a               recorded by a thermometer placed at
ground crew

team of employees who service and              ground level
maintain the aircraft while it is on the       ground                             / raυnd
                                               ground visibility

ground                                          vzblti/ noun horizontal visibility
ground-effect machine / raυnd                 near the surface of the earth
ground-effect machine


 fekt mə ʃi n/ noun a hovercraft.
                                               group / ru p/ noun 1. a number of

Abbreviation GEM                               individual items or people brought
ground          elevation        / raυnd       together because of similarities 2. a col-
ground elevation

 eləveʃ(ə)n/ noun the vertical dis-           lection of letters, numbers or symbols
tance, in feet, of the ground above sea        used in weather forecasting, etc.
level                                          growth / rəυθ/ noun an increase in

ground instructor / raυnd n                   size, number, amount, etc. the growth
ground instructor


 str ktə/ noun a trained person who            of ice crystals the growth of air travel
teaches support subjects such as mete-         GRP abbreviation glass fibre rein-

orology in a classroom                         forced plastic
groundling / raυndlŋ/ noun a

                                               GS, G/S abbreviation ground speed

member of the ground crew at an airport        guard / ɑ d/ noun 1. a device to pre-

or air force base                              vent injury or loss, etc. The thermo-
ground loop / raυnd lu p/ noun a
ground loop

                                               couple probes consist of two wires of
sharp unplanned turn made by an air-           dissimilar metal that are joined
craft that is taxiing, taking off, or land-    together inside a metal guard tube. 2. a
ing, caused by unbalanced drag                 person who protects or keeps watch a
ground          movement / raυnd
ground movement

                                               security guard í verb to protect from
 mu vmənt/ noun a manoeuvre such as            harm by watching over             to guard
taxiing carried out by an aircraft while       against to take steps to ensure that
guidance                                   108
something does not happen To guard             magnetic compass and reset if neces-
against the risk of fire, passengers are       sary.
requested not to smoke in the toilets.         gyroplane / d arəυplen/ noun an

guidance / ad(ə)ns/ noun 1. help-

                                               aircraft fitted with an unpowered rotor
ful advice Guidance is provided to             for producing lift
assist people in filling in the form. The      gyroscope / d arəskəυp/ noun a

booklet contains guidance on the advis-        device consisting of a spinning wheel,
ability of flying with a cold. 2. the action   mounted on a base so that its axis can
of giving directions to an aircraft            turn freely in one or more directions and
guidance system / ad(ə)ns
guidance system

                                               thereby maintain its own direction even
 sstəm/ noun a system which provides          when the base is moved The tradi-
signals to the flight control system for       tional attitude indicator, heading indi-
steering the aircraft                          cator and turn-coordinator contain
guide / ad/ noun something that

                                               gyroscopes. directional (NOTE: The
directs or indicates rough guide a             word is often shortened to gyro.)
simple explanation to help a person to             COMMENT: A spinning gyro maintains
find his or her own way through more               its position even when an aircraft
complex information í verb to direct or            banks, climbs, or dives. Gyros drive
to indicate If there is smoke in the               the attitude indicator, direction
cabin, clear commands from the crew                indicator and turn coordinator to help
will help to guide passengers to the               pilots control an aircraft while flying in
emergency exits.                                   cloud or in poor visibility.
gust / st/ noun a strong, sudden rush          gyroscopic / d arə skɒpk/ adjec-
gust                                           gyroscopic


of wind a gust of 30 feet per second           tive referring to a gyroscope or using the
On final approach, the pilot must be           properties of a gyroscope
prepared to counteract the effect of           gyroscopic compass

                                               gyroscopic                        compass
gusts in order to maintain a smooth            / d arəskɒpk k mpəs/ noun a com-
descent along the extended centreline of       pass which uses gyroscopic directional
the runway. gust load an increased             stability rather than magnetism to indi-
load to the airframe caused by a sudden        cate directions. Also called gyrocom-
increase in wind strength í verb to            pass
increase in strength suddenly Wind is          gyroscopic precession

                                               gyroscopic                       precession
at 10 knots gusting to 20 knots.               / d arəskɒpk pri seʃ(ə)n/ noun a
gyro / d arəυ/ noun same as gyro-

                                               characteristic of a gyroscope, that the
scope                                          force applied to a spinning gyroscope
gyro- / d arəυ/ prefix gyroscopic

                                               will act at a point 90° in the direction of
gyrocompass / d arəυ k mpəs/

                                |              rotation, not at the point where the force
noun a compass which uses gyroscopic           is applied Forces of gyroscopic pre-
directional stability rather than magnet-      cession act on the direction indicator to
ism to indicate direction The gyro-            keep it aligned vertically and horizon-
compass should be checked against the          tally.
hail /hel/ noun precipitation as small      handling / h ndlŋ/ noun 1. the act
hail                                         handling

pellets of ice Precipitation is the fall-    of touching with the hands 2. the use of
ing of water, as rain, sleet, snow or hail   the hands to move or operate something
onto the surface of the earth.                 aircraft handling the act of manoeu-
Although hail, and in particular, heavy      vring the aircraft in the desired manner
hail is rare and of short duration, dam-     3. the act of dealing with or managing
age to an aircraft may be severe.            something Her handling of a difficult
       COMMENT: In weather reports and       situation won the admiration of the
       forecasts, hail is indicated by the   whole crew.
       abbreviation ‘GR’.                    hand luggage / h nd l d / noun
                                             hand luggage

hailstone / helstəυn/ noun a small          small bags that passengers can take

pellet of ice which falls from clouds A      with them into the cabin of an aircraft
hailstone starts as a small ice particle     The amount of hand luggage is limited
in the upper portion of a cumulonimbus       to one bag.
cloud.                                       hand signals / h nd s n(ə)lz/ plu-
                                             hand signals

hailstorm / helstɔ m/ noun a storm,         ral noun same as marshalling signals

where the precipitation is hail instead of   hands off / h ndz ɒf/ adjective,
                                             hands off

rain or snow Flying through the hail-        adverb where the operator does not
storm damaged the leading edges.             control the operation, which is auto-
hand flying / h nd flaŋ/ noun fly-
hand flying

                                             matic Automatic flight control system
ing an aircraft by moving the flight con-    capable of landing an aircraft hands
trols with the hands rather than by using    off.
the autopilot                                hangar / h ŋə/ noun a large shelter

hand-held / h nd held/ adjective

                                             for housing and maintaining aircraft
possible to hold in the hand Nowa-           Light aircraft should be left with park-
days, headsets are usually used in pref-     ing brakes off so that they can be moved
erence to hand-held microphones.             quickly in the event of a fire in the
hold                                         hangar.
handle / h nd(ə)l/ noun a device for         hard landing / hɑ d l ndŋ/ noun
handle                                       hard landing

holding, or being operated, by the hand      an uncontrolled landing by an aircraft
  a door handle a fire control handle        that results in its being damaged or
í verb 1. to touch with the hands            destroyed
Cabin staff should not handle                HASELL

                                             HASELL ‘ mnemonic
unwrapped food which is to be served to
                                             haul /hɔ l/ noun ‘ long-haul, short-

passengers. 2. to move or operate by
hand The student pilot handled the           haul
                                             hazard / h zəd/ noun a possible dan-

aircraft well in the turbulent conditions.
3. to deal with, or to manage Flight         ger     Thunderclouds are of special
crew must be able to handle any emer-        interest to aircrew because of the haz-
gency when it occurs.                        ards they may pose to aircraft in flight.
hazardous                                             110
hazardous / h zədəs/ adjective pos-                                          / hedfəυnz/ noun
hazardous                                                 headphones

sibly risky or dangerous Flying over                      small speakers with padding, worn over
mountainous terrain can be hazardous.                     a person’s ears, used for private listen-
   Structural icing is a hazardous phe-                   ing Headphones are used to monitor
nomenon for rotary wing as well as                        the signal.
fixed wing aircraft.                                      headset / hedset/ noun headphones

haze /hez/ noun dust or smoke in the

                                                          with a microphone attached, used for
atmosphere        Haze can seriously                      RT communications         Headsets are
reduce air-to-ground visibility.                          usually used in preference to hand-held
head /hed/ noun 1. the top part of the                    microphones.

body above the shoulders 2. a person                      head-up display noun a cockpit sys-
                                                          head-up display

head count an easy way of counting                        tem where data from flight instruments
large numbers of people 3. a main end                     is projected onto a screen or the wind-
part or top of something 4. a leader,                     screen so that the pilot can see it with-
chief or director head of department                      out having to look down. Abbreviation
the most senior person in the depart-                     HUD
ment í verb to fly in a particular direc-                 headwind / hedwnd/ noun a wind

tion head north to fly towards the                        which is blowing in the opposite direc-
north                                                     tion to the direction of movement or
heading / hedŋ/ noun the direction

                                                          flight. Compare tailwind (NOTE: The
in which the longitudinal axis of the air-                word is also written head wind.)
craft is pointing, expressed in degrees                   headwind component / hedwnd
                                                          headwind component

from north                                                kəm pəυnənt/ noun one of the three

       COMMENT : Wind affects an aircraft in              possible components of a wind, the
       flight, therefore heading does not                 other two being crosswind and tailwind
       always coincide with the aircraft’s
                                                          heap /hi p/ noun a group of things

       track. The pilot must head the aircraft
       slightly into the wind to correct for drift.       piled or thrown one on top of another
                                                          heap cloud / hi p klaυd/ noun same
                                                          heap cloud

heading bug / hedŋ b
heading bug

                                         / noun a
movable plastic marker on the horizon-                    as cumulus cloud
                                                          heat /hi t/ noun warmth, being hot

tal situation indicator
heading correction / hedŋ kə                             The heat generated by combustion is
heading correction


 rekʃ(ə)n/ noun a change of heading in                    considerable. í verb to make warm or
order to deal with a new situation. Also                  warmer The air leaving the turbo-
called course correction                                  charger is very warm and can be used to
heading indicator

                 indicator       / hedŋ                  heat the cabin.
 ndketə/ noun an instrument which                      heater / hi tə/ noun a device for heat-

gives course or direction information                     ing Pitot heads contain heater ele-
e.g. a horizontal situation indicator                     ments to prevent icing.
(HSI) or direction indicator (DI)                         heating / hi tŋ/ noun the process of

       COMMENT : The heading indicator is                 making something warmer the heat-
       driven by a gyro and provides steady,              ing action of the sun kinetic
       exact indications of heading.                      heavier-than-air / heviə θən eə/

heading to steer / hedŋ tə stə /                        adjective weighing more than the air it
heading to steer

noun a gyro-compass point in which to                     displaces, and so needing power to fly
direct the aircraft                                       heavy / hevi/ adjective having a lot of

head-on / hed ɒn/ adjective, adverb                       weight a heavy load a load of great

   to approach head-on to approach                        weight heavy rain rain which is dense
from opposite directions                                  and distributes a lot of water over the
head-on collision / hed ɒn kə                             surface of the Earth in a relatively short
head-on collision


 l (ə)n/ noun a collision between two                    time
                                                          heavy-duty / hevi dju ti/ adjective

things or vehicles coming from oppo-
site directions                                           referring to something designed for
                                        111                                       hill
hard wear or use a heavy-duty battery       hemisphere / hemsfə/ noun half a

   Longerons are heavy-duty steel mem-      sphere
bers.                                       Hertz /h ts/ noun the SI unit of fre-

heavy landing / hevi l ndŋ/ noun
heavy landing

                                            quency, defined as the number of cycles
a routine landing in which the aircraft     per second of time. Abbreviation Hz
makes contact with the surface with         HF abbreviation high frequency

more force than usual, thereby possibly     high /ha/ adjective 1. having great

causing damage to the undercarriage         vertical distance a high mountain 2.
The pilot reported a heavy landing.         great, large, a lot high engine rpm
hedgehop / hed hɒp/ verb to fly at

                                            fast engine speed high pressure a lot
very low height above the ground            of pressure high reliability good reli-
height /hat/ noun the vertical dis-

                                            ability high speed a fast speed high
tance of a point, level or object meas-     temperature a hot temperature í noun
ured from a particular point, e.g. sea      an area of high atmospheric pressure
level Pressure decreases with increas-      There is a high over the British Isles.
ing height. height of the aircraft the      high frequency / ha fri kwənsi/,
                                            high frequency

vertical distance, measured in feet, of     high      frequency         band      / ha
the aircraft above the surface of the        fri kwənsi b nd/ noun a radio com-
earth                                       munications range of frequencies
held /held/ ‘ hold

                                            between 3–30 MHz. Abbreviation HF
heli / heli/ noun a rotary-wing aircraft    high-performance               / ha     pə
heli                                        high-performance


heliborne / helibɔ n/ adjective trans-
                                             fɔ məns/ adjective a system which
ported by helicopter                        provides better-than-usual output an
helicopter / helkɒptə / noun an air-
                                            engine with a high performance Some
craft with one or more rotors rotating      high-performance engines have coolant
around vertical axes which provide lift     and oil system thermostats which aid
and control Helicopter operations are       warming-up.
                                            high performance aircraft / ha
                                            high performance aircraft

carried out at the airport.
                                            pə fɔ məns eəkrɑ ft/ noun an aircraft
helicopter rotor / helkɒptə rəυtə/
helicopter rotor                                     |

noun two or more rotating blades,
                                            capable of flying faster, higher or with
known as the main rotor, which provide      more manoeuvrability than normal air-
lift and thrust for a helicopter;           craft
                                            hijack / had k/ verb to take over

helideck / helidek/ noun a deck on

                                            control of an aircraft by one or several
something such as a ship or offshore oil
                                            unauthorised person or persons with the
platform that is used as a landing area
                                            intention of forcing the crew to fly it to
for helicopters                             a different destination       The airliner
heliograph / hi lə rɑ f/ noun an

                                            was hijacked on its way to Paris.
instrument with a mirror to send mes-       hijacker / had kə/ noun a person

sages by reflecting the sun        Helio-   who hijacks an aircraft or other vehicle
graphs enable reflected sunlight to be
                                            hijacking / had kŋ/ noun the act

directed to a ship or aircraft in periods
of direct sunlight.                         of taking over control of an aircraft by
                                            one or several unauthorised person or
helipad / helip d/ noun an area

                                            persons with the intention of forcing the
where helicopters take off and land         crew to fly it to a different destination
heliport / helipɔ t/ noun an airport

                                            The crew must be alert at all times to the
designed for helicopters                    possibility of hijacking, bombs and
helistop / helistɒp/ noun a place

where helicopters can take off and land,    hill /hl/ noun an easily-seen, natural

but usually one that does not have the      elevation, smaller than a mountain
support facilities found at a heliport      Slopes on the side of a hill or mountain
helo / hi ləυ/ noun 1. a rotary-winged

                                            facing away from the sun receive less
aircraft 2. same as heliport                intense radiation. Hill shading is pro-
hinder                                  112
duced by assuming that bright light is      holds an IMC rating he has an IMC
shining across the chart sheet so that      rating
shadows are cast by the high ground.        holder / həυldə/ noun 1. a device for

hinder / hndə/ verb to make it diffi-      holding something a holder for a fire

cult for something to happen         Free   extinguisher 2. a person who has a par-
flow of fuel may be hindered by a block-    ticular title or qualification a holder of
age in the fuel line. Her illness hin-      two awards for distinguished service
                                            holding fuel / həυldŋ fju əl/ noun
                                            holding fuel

dered his progress on the course.
hinge /hnd / noun a device which
                                            extra fuel carried by an aircraft to allow
allows a door, flap or lid to open and      for time spent in the hold waiting for air
close on a stationary frame Flying          traffic control clearance
                                            holding pattern noun a racetrack-
                                            holding pattern

control hinges should be inspected
before flight. í verb to move against a     shaped flight pattern with two parallel
stationary frame Access to the engine       sides and two turns, flown usually while
compartment is normally via hinged          an aircraft is waiting for clearance to
cowling panels.                             land
                                            holding point / həυldŋ pɔnt/ noun
                                            holding point


HIRF abbreviation high-intensity radi-      1. a particular location, in the air or on
ated fields                                 the ground where aircraft spend time,

HMR abbreviation helicopter main            waiting for further clearance from air
route                                       traffic control 2. a place, often desig-
hoar / hɔ /, hoar frost noun a frozen
                                            nated Alpha, Bravo, Charlie, etc., where
dew which forms on outside surfaces         aircraft wait before entering the runway,
when the temperature falls below freez-     as instructed by air traffic control
                                            holding stack / həυldŋ st k/ an
                                            holding stack

ing point      Rapid descent from cold
altitudes into warm moist air may pro-      area of airspace where planes are
duce hoar frost on the aircraft.            instructed to wait before landing if there
                                            are delays (NOTE: Aircraft circle and
hold /həυld/ noun an area or compart-

                                            descend according to the controller’s
ment within the aircraft for carrying       instructions until they are released from
freight Carry-on baggage is limited         the lowest height in the stack for their
by regulations as to size and weight and    final approach to the airport.)
items in excess of this should be stowed
                                            hollow / hɒləυ/ adjective having a

in the luggage hold. í verb 1. to keep
                                            space within, not solid a hollow drive
and prevent from moving The func-           shaft Opposite solid
tion of the autopilot system is to hold
                                            home /həυm/ noun the home airfield

the aircraft on a desired flight path by
means of gyroscopes and/or accelerom-       home airfield the airfield which one
eters. If the operating pressure falls or   returns to after a two-leg flight
                                            homeward / həυmwəd/ adjective

fails, a mechanical lock holds the
reverser in the forward thrust position.    going towards home homeward jour-
2. to keep an aircraft in a particular      ney í adverb         homeward bound
position on the ground or in the air        heading towards home
                                            homewards / həυmwədz/ adverb

while waiting for further clearance from
air traffic control It is normal practice   towards home         They were heading
for ATC to hold taxiing aircraft well       homewards when the accident hap-
clear of the glide path and localiser       pened.
antenna when visibility is poor. 3. to      homing / həυmŋ/ noun a flight

have and keep in the hand Hold the          towards or away from a radio station
microphone in your right hand. hand-        while using direction finding equip-
held possible to hold in the hand           ment Where an RBI is fitted, homing
Nowadays, headsets are usually used in      to an NDB can be made by initially
preference to hand-held microphones.        turning the aircraft until the relative
4. to have (NOTE: holding – held) he        bearing is zero.
                                                  113                                       hub
homogeneous / həυməυ d i niəs/                        33,000 foot-pounds of work done in one


adjective of the same kind        If the air          minute. Abbreviation h.p., HP
over a large region were homogeneous,                 hose /həυz/ noun a long, flexible pipe

there would be no horizontal differ-                  usually made of fabric, plastic or rubber
ences in surface temperature.           The           for pumping gases or liquids refuel-
atmosphere is not homogeneous – pres-                 ling hose a flexible pipe used to pump
sure, temperature and humidity can all                fuel from the bowser to the aircraft
change with height.                                   hot /hɒt/ adjective very warm, having

hop /hɒp/ noun a flight or section of a

                                                      a high temperature hot weather hot
flight in an aircraft (informal )                     air air introduced to melt ice forming in
horizon /hə raz(ə)n/ noun the line

                                 |                    the carburettor in a piston engine air-
where the sky and the ground appear to                craft
join visual horizon a horizon which                   hour /aυə/ noun 1. a period of time

can be seen                                           which lasts sixty minutes It’s a three-
horizontal / hɒr zɒnt(ə)l/ adjective

                                                      hour flight to Greece from London. 2. a
parallel to the horizon, or at right angles           method of indicating time Flight BA
to the vertical The horizontal motion                 321 landed at Heathrow at 10.30 hours.
of air is known as wind.                              house /haυz/ verb to contain or

horizontal axis / hɒrzɒnt(ə)l
horizontal axis

                                                      accommodate The areas between the
   kss/ noun a horizontal reference line             ribs in the wings are utilised to house
of a graph The plot shows the effect of               fuel tanks. The wing tips house the
airspeed on lift with airspeed shown on               navigation lights.
the horizontal axis and lift on the verti-            housing / haυzŋ/ noun a compart-

cal axis.                                             ment or container The crankcase is
horizontal situation indicator
horizontal situation indicator

                                                      the housing that encloses the various
/ hɒrzɒnt(ə)l          stʃu eʃ(ə)n         |
                                                      mechanical parts surrounding the
 ndketə/ noun a cockpit instrument                 crankshaft.      engine housing engine
which gives the pilot information about               compartment
the direction of the aircraft’s flight path
                                                      hover / hɒvə/ verb to remain station-

   On the aircraft, the horizontal situa-
tion indicator is located on the instru-              ary, relative to the earth, while in the air
                                                      í noun a period of stationary flight
ment panel below the attitude indicator.
Abbreviation HSI                                      During a hover, helicopter pilots must
                                                      be able to coordinate movements of
       COMMENT: The horizontal situation              both hands and feet.
       indicator combines the function of the
                                                      hovercraft / hɒvəkrɑ ft/ noun a

       heading indicator and a VOR/ILS
       display.                                       vehicle that can travel over land and
horizontal stabiliser

                                         stabiliser   water supported on a cushion of air that
/ hɒrzɒnt(ə)l    stebəlazə/ noun a                 is produced by a powerful engine that
tailplane     The horizontal stabiliser               blows air downwards. Also called air
                                                      cushion      vehicle,    ground      effect
provides stability about the lateral axis
of the aircraft.
                                                      however /haυ evə/ adverb but

horn /hɔ n/ noun a device for project-
                                                                       |                The
ing sound        warning horn device                  wind was gusty, however the landing
which emits a loud warning noise                      was good. The incident was serious,
                                                      however she escaped with only a warn-
horn balance / hɔ n b l(ə)ns/
horn balance

noun part of a control surface forward                hrs

of the hinge line which reduces the                   hrs abbreviation hours

force needed by the pilot to move the                 HSI abbreviation horizontal situation
surface                                               indicator
horsepower / hɔ spaυə/ noun the                       hub /h b/ noun a major airport where
horsepower                                            hub

accepted unit for measuring the rate of               international or long-distance flights
doing work Horsepower is defined as                   take off and land
hub airport                             114
hub airport / h b eəpɔ t/ noun              hydraulic pressure /ha drɔ lk
hub airport                                 hydraulic pressure


same as hub                                  preʃə/ noun the pressure exerted by
HUD abbreviation head-up display

                                            hydraulic fluid
human factors / hju mən f ktəz/
human factors

                                                             tubing /ha drɔ lk
                                            hydraulic tubing

                                            hydraulic                             |

noun the study of the way in which           tju bŋ/ noun system of tubes or thin
humans handle, and react to, things in
their environment. It is used in aviation   pipes connecting the main components
to develop safer systems and proce-         of a hydraulic system
                                            hydro- /hadrəυ/ prefix water

dures. (NOTE: Human factors is followed                                            a
by a verb in the singular.)                 hydro-mechanical governor
humid / hju md/ adjective contain-

                                            hygrometer /ha rɒmtə/ noun an


ing a lot of water vapour        humid      instrument used for the measurement of
weather weather which, although
warm, feels damp and uncomfortable          humidity The most common type of
humidity /hju mdti/ noun a meas-

                                            hygrometer is the wet and dry bulb ther-
urement of how much water vapour is         mometer arrangement.
                                            hypoxia /ha pɒksiə/ noun a medical

contained in the air the humidity is                             |

high there is a lot of moisture or water    condition in which not enough oxygen
vapour in the air                           is supplied to the body The symptoms
hydraulic /ha drɔ lk/ adjective

                                            of hypoxia are sometimes difficult to
referring to any system or device which     detect.
uses fluids such as oil to transmit a
force from one place to another using            COMMENT: Cabin pressurisation or
pipes a hydraulic pump                           oxygen equipment is usually required
                                                 for flying at altitudes at or above about
hydraulic fluid /ha drɒlk flu d/
hydraulic fluid

                                                 10,000 ft (3,048 m).
noun thin oil used in hydraulic braking     Hz

systems, etc.                               Hz abbreviation Hertz
IAS / a e es/ abbreviation indicated            such as railway lines or bridges, are

airspeed                                          matched with the real feature on the

IATA abbreviation International Air               ground
                                                  identification beacon /a dentf
                                                  identification beacon

Transport Association                                                                 |     |

I-beam / a bi m/ a large bar of metal
                                                   keʃ(ə)n bi kən/ noun an aeronautical
or some other strong substance with a             beacon which gives out a Morse signal
cross-section shaped like the letter ‘I’          which enables a pilot to establish their
                                                  location in relation to the beacon Civil
ICAO /a keəυ/ abbreviation Interna-

                                                  and military aerodrome identification
tional Civil Aviation Organization                beacons can be distinguished by colour.
ice /as/ noun frozen water

                                                  identifier /a dentfaə/ noun a


ice crystal / as krst(ə)l/ noun a
ice crystal

                                                  grouped number/letter code by which a
type of precipitation composed of crys-           weather station or beacon can be recog-
tals in the form of needles, plates or col-       nised When a TAF requires amend-
umns                                              ment, the amended forecast is indicated
icing / asŋ/ noun a process by which            by inserting AMD (amended) after TAF

part of the aircraft becomes covered in           in the identifier and this new forecast
ice while in flight Engine icing can be           covers the remaining validity period of
extremely hazardous to flight.         Air-       the original TAF.
frame icing can be encountered in wave            identify /a dentfa/ verb to recog-


cloud. anti-icing, de-icing                       nise Crew members can be identified
ideal /a dəl/ adjective perfect, as             by their uniforms. In conditions of


good as can be expected or the best pos-          poor visibility, it is sometimes difficult
sible an ideal situation a very good              to identify ground features.
situation ideal flying conditions very            identity / a dentti/ noun the name


good flying conditions                            and details of a person, aircraft, etc.
ident / adent/ noun a function on the

                                                  The air traffic controllers are trying to
transponder panel which helps a con-              establish the identity of the aircraft.
troller to identify the aircraft The ident        ident
is suppressed until the standby VOR is            idle / ad(ə)l/ noun the state of an

fully run-up and has passed its monitor           engine when it is running but not deliv-
checks. Full form identity                        ering power to move the vehicle or air-
identical /a dentk(ə)l/ adjective

                         |                        craft í verb to turn over slowly without
exactly the same identical computers              providing enough power to move the
computers which are exactly the same              vehicle or aircraft After starting a pis-
identification /a dentf keʃ(ə)n/

                             |   |
                                                  ton engine from cold, it is good practice
noun the process by which a person, air-          to allow it to idle for a short time before
craft, etc., is recognised identifica-            opening the throttle wide.
                                                  idle cut-off / ad(ə)l k t ɒf/ noun a
                                                  idle cut-off

tion of ground features means by
which particular features on a chart,             position on the mixture control of a
idle rpm                                 116
light aircraft which allows the engine to    ignition circuit of an aircraft or a vehi-
be shut down without leaving a com-          cle
bustible fuel/air mixture in the engine      illuminate / lu mnet/ verb 1. to


idle rpm / ad(ə)l ɑ pi em/ noun
idle rpm

                                             give light to an otherwise dark area A
the speed at which a piston engine turns     flare illuminates the ground below it. 2.
when it is not running fast enough to        to show a light or become bright When
move the vehicle or aircraft, i.e. on a      the aircraft is 5 knots above stalling
light aircraft when the throttle is almost   speed, a warning lamp illuminates.
closed                                       illumination / lu m neʃ(ə)n/ noun

                                                                      |       |

idling / ad(ə)lŋ/ noun a state in

                                             light Batteries provide about 20 min-
which the engine is turning over slowly      utes illumination for the lamp. day-
without providing enough power to            light illumination the amount of light
move the vehicle or aircraft                 in normal daytime conditions
idling speed / ad(ə)lŋ spi d/ noun         illustrate / ləstret/ verb 1. to dem-
idling speed

the rpm of the engine when it is idling      onstrate or explain clearly, often by
After start-up, the engine accelerates       using pictures Contour charts illus-
up to idling speed. Before the engine        trate the horizontal distribution of
is stopped, it should normally be            height above mean sea level. 2. to show
allowed to run for a short period at         as an example A number of aviation
idling speed to ensure gradual cooling.      disasters have illustrated the impor-

IF abbreviation 1. instrument flying 2.      tance of clear, correct use of language
intermediate frequency                       in R/T (Radiotelephony) communica-

IFR abbreviation instrument flight           tions.
                                             illustration / lə streʃ(ə)n/ noun 1.

rules                                                                     |

ignite / nat/ verb to burn or cause

                                             a picture which explains something
to burn The spark plug ignites the           The illustration on page 23 shows a
fuel/air mixture. The air/fuel mixture       cross section of a typical gas-turbine
ignites.                                     engine. 2. an example The mechanics
                                             of the föhn wind provide a good illustra-
igniter /  natə/ noun a device for

                                             tion of the adiabatic process in action.
starting gas turbine engines An elec-        ILS

tric spark from the igniter plug starts      ILS abbreviation instrument landing
combustion.                                  system
                                                       glideslope / a el es
                                             ILS glideslope

ignition / nʃ(ə)n/ noun 1. the start-
                                                ladsləυp/ noun a radio beam in an

ing of burning of a substance Satisfac-
tory ignition depends on the quality of      ILS which gives vertical guidance The
the fuel. 2. the moment, in an internal      angle of the glide slope is usually about
combustion engine, when a spark from         three degrees to the horizontal.
the spark plug causes the fuel/air mix-      glideslope
                                             ILS locator beacon / a el es ləυ
                                             ILS locator beacon

ture to burn Ignition should occur just                                                   |

before top-dead-centre. 3. an electrical      ketə bi k(ə)n/ noun a non-direc-
system, usually powered by a battery or      tional beacon used for final approach
magneto, that provides the spark to          Power output can be as little as 15 watts
ignite the fuel mixture in an internal-      for an ILS locator beacon.
combustion engine Ignition problems          IM

                                             IM abbreviation inner marker
are a source of many engine failures. 4.
                                             image / md / noun a reproduction of

a switch that activates the ignition sys-
tem the key is in the ignition the key       the form of an object or person
is in its position in the ignition lock      Although difficult to see, the photo-
                                             graph shows the image of the aircraft
ignition key / nʃ(ə)n ki / noun a
ignition key

                                             with part of the fin missing. (NOTE: It
key used to switch on the ignition           suggests that the image has no detail
ignition lock / nʃ(ə)n lɒk/ noun a
ignition lock

                                |            and that it is the shape which is impor-
key-operated switch for activating the       tant.)
                                                117                                                   inactive
imaginary / m d n(ə)ri/ adjective                 ance will vary with changes in fre-


not real The equator is an imaginary                quency.
line around the earth.                              impede /m pi d/ verb to hinder or



IMC abbreviation instrument meteoro-                obstruct progress Hills and mountains
logical conditions                                  impede the horizontal flow of air.
immediate / mi diət/ adjective 1.                  impeller /m pelə/ noun a rotor used


happening at once or instantly Fire                 to force a fluid in a particular direction
extinguishers should be ready for imme-             importance /m pɔ t(ə)ns/ noun sig-


diate use in the event of an emergency.             nificance, strong effect or influence
  in the immediate future in the very               Upper winds are of great importance in
near future 2. nearby, close at hand                meteorology. (NOTE: The expressions
The immediate area surrounding the                  of fundamental importance, of great
Earth is known as the atmosphere.                   importance, of prime importance, of
immerse / m s/ verb to cover com-                  utmost importance, of vital impor-


pletely in liquid, to submerge Fuel is              tance all mean very important.)
pumped from the main tanks via fully                import duty / mpɔ t dju ti/ noun
                                                    import duty

immersed booster pumps mounted on                   payment made to a government on par-
the base of the fuel tank.                          ticular goods imported or exported the
imminent / mnənt/ adjective due to                duty payable on a carton of cigarettes

happen in a very short time The trans-              Also called customs duty, duty
                                                    impose /m pəυz/ verb 1. to force

mission made it clear that the aircraft                                   |

was in imminent danger. A message                   something upon a person or thing The
from the flight deck informs cabin staff            trimmer is used to ease the loads
that take-off is imminent.                          imposed on the flying controls during
impact / mp kt/ noun the striking of               flight. 2. to impose a fine to require

one body against another, a collision               somebody to pay a sum of money as
on impact as soon as it hit something               punishment to impose restrictions to
One of the tyres burst on impact (with              place limitations on somebody’s actions
the ground).        Super-cooled water              improve /m pru v/ verb to make or


droplets start to freeze on impact with             become better Turbochargers improve
an aircraft surface.                                aircraft performance. The trainee’s
impact resistance / mp kt r                       flying skills improved a lot in a short
impact resistance


 zstəns/ noun the ability of a material            period of time.
                                                    improvement /m pru vmənt/ noun

to withstand an impact                                                                            |

impair /m peə/ verb to cause to                    the process of becoming better, or


become less effective Constant expo-                something that makes a thing better
sure to very loud noise impairs the                 An improvement in weather conditions
hearing.      The pilot’s vision may be             enabled the flight to depart.
                                                    impulse / mp ls/ noun a force of

temporarily impaired by lightning
flashes.     An incorrect grade of fuel             short duration A magneto is designed
impairs engine performance.                         to produce electrical impulses one after
impairment /m peəmənt/ noun a                      another at precise intervals, so that


lessening of effectiveness      De-icing            each separate impulse can be used to
equipment is used to prevent impair-                provide a spark at a spark plug.
                                                    impulse magneto / mp ls m
                                                    impulse magneto

ment of the lifting surfaces through ice                                                                     |

formation.                                           ni təυ/ noun a magneto with a mecha-
impart /m pɑ t/ verb to give, to pass

                                                    nism to give a sudden rotation and thus
on A rotating propeller imparts rear-               produce a strong spark
                                                    inability / nə blti/ noun the fact of

ward motion to a mass of air.                                                             |

impedance /m pi d(ə)ns/ noun total

                                                    being unable to do something
                                                    inactive /n ktv/ adjective not

electrical resistance to current flow in                                              |

an alternating current circuit Imped-               switched on, in a passive state At the
inadvertent                                        118
time of the accident the autopilot was                 incline /n klan/ verb to slope or slant


inactive.                                              from the horizontal or vertical, to tilt
inadvertent / nəd v t(ə)nt/ adjec-                    The runway inclines slightly upwards. í

                                                       noun / nklan/ a slope or slant There

tive not intended, not meant, accidental
   A safety mechanism prevents inad-                   is a steep incline at the end of the run-
vertent retraction of the undercarriage                way.
                                                       inclinometer / nkl nɒmtə/ noun

while the aircraft is on the ground.                                                      |

inboard / nbɔ d/ adverb closer to the
                                                       the lower part of a turn coordinator, in
centre of an aircraft rather than the sides            which a ball in a sealed curved tube
or edges                                               indicates if a turn is coordinated. Also
                                                       called rudder ball. ball
inbound / nbaυnd/ adverb, adjective

                                                       include /n klu d/ verb to take in as a

towards a destination The aircraft flies                                  |

outbound from the beacon along the                     part, to count along with others Solid
airway and inbound to the facility at the              particles in the atmosphere include
other end of the leg. inbound traffic                  dust, sand, volcanic ash and atmos-
                                                       pheric pollution.        A fuel system
aircraft flying towards an airfield
                                                       includes tanks, fuel lines, fuel pumps,
incapacity / nkə p sti/ noun the

                                                       fuel filters and a carburettor or fuel
inability to do what is needed, not hav-               injection system. Opposite exclude
ing the necessary power to do some-                    inclusive /n klu sv/ adjective tak-


thing crew incapacity an injury to a                   ing in the extremes in addition to the
crew member which prevents him or                      part in between       bearings 180° to
her from performing his or her normal                  270° inclusive bearings 180° and 270°
duties Accident research has shown                     are part of the range of bearings men-
that crew incapacity greatly increases                 tioned
the risk to passengers’ safety.
                                                       incoming / nk mŋ/ adjective

inch / nʃ/ noun a British Imperial Sys-

                                                       something which is being received, e.g.
tem unit of length, also used in the US,               radio waves or solar radiation incom-
equal to 25.4 millimetres or 2.54 centi-               ing transmissions incoming signal
metres or 1/12 of a foot. Abbreviation                 There is a fall of temperature until
in (NOTE: The plural form is inches,                   about one hour after dawn when incom-
usually written in or " with numbers, 5ft              ing solar radiation balances outgoing
6in or 5’ 6". Say five foot six inches.)               terrestrial radiation. Opposite outgo-
incidence / nsd(ə)ns / noun the fre-

quency of occurrence The incidence                     incorporate /n kɔ pəret/ verb to


of structural failure has decreased with               include as part of something which
the introduction of modern construction                already exists Some types of outflow
materials and techniques.                              valve incorporate safety valves.
incident / nsd(ə)nt/ noun an event                   Warning lamps often incorporate a

or happening which interrupts normal                   press-to-test facility.
procedure A violent passenger had to                     ‘…the instrument panel on the Mooney
be removed from the aircraft before                      Encore has been re-engineered to
departure, and details of the incident                   incorporate    improvements’   [Civil
were reported in the local newspapers.                   Aviation Training]
                                                       incorrect / nkə rekt/ adjective not

       ‘…in 1995, a pilot flying above Las                                        |

       Vegas was struck by a laser beam and            correct, not right If the trim position is
       incapacitated for more than two hours. It       incorrect, a warning horn will sound
       was one of over fifty incidents involving       when number three thrust lever is
       lasers and aircraft reported in the area that   advanced.
       year’ [Pilot]
                                                       increase noun / nkri s/ a rise to a

inclination / nkl neʃ(ə)n/ noun a

                                 |                     greater number or degree Decreasing
slope or slant from the horizontal or                  engine rpm results in an increase in the
vertical                                               rate of descent. Opposite reduction í
                                         119                                          inductance
verb /n kri s/ to become greater or         indicated airspeed / ndketd
                                             indicated airspeed


more, to rise As you increase height,         eəspi d/ noun the airspeed shown by
the countryside below you appears to         the cockpit or flight-deck instrument
flatten out. Opposite reduce opposite        The aircraft stalls at an indicated air-
(all senses) decrease                        speed of 50 knots. Abbreviation IAS
increment / ŋkrmənt/ noun some-

                                             indication / nd keʃ(ə)n/ noun 1.


thing added The minimum detection            pointing out Indication of altitude is
range of a pulse radar system is equal       given on the altimeter. 2. a sign or
to half the pulse length plus a small        symptom A drop in engine rpm is an
increment.                                   indication of ice forming in the carbu-
incur /n k / verb to acquire or to

                                             rettor.    audible indication a sound
receive something, often something           which serves as a warning, e.g. a bleep
unwanted        Fuel penalties can be
                                             indicator / ndketə/ noun some-

incurred if fuel surplus to requirements
is carried. In some aircraft, the datum      thing which shows information
                                             individual / nd vd uəl/ adjective

shift is operated automatically to cater                                  |

for any large trim changes incurred by       existing as a separate thing          The
operating undercarriage, flaps, etc.         hydraulic braking system consists of a
(NOTE: incurring – incurred)            to   master cylinder with individual brake
incur a financial loss to lose money, in     cylinders at each wheel. There is a
a business or commercial sense               maintenance manual for each individ-
indefinite /n def(ə)nət/ adjective

                                             ual engine. í noun a separate human
without limits an indefinite period of       being considered as one rather than as a
time a period of time which, in reality,     member of a larger group The instruc-
may have no end                              tor regards her trainees as a number of
                                             individuals rather than a group.
independent / nd pendənt/ adjec-


                                             induce /n dju s/ verb to bring about,

tive free from the influence or effects of                        |

other people or things       Airspeed is     to cause to happen If a coil carrying a
independent of wind and is the same          changing current is placed near
regardless whether the aircraft is flying    another coil, the changing magnetic
upwind, downwind or at any angle to          field cuts the other coil and induces a
the wind. independent system a sys-          voltage in it.    Unequal deposits on
tem which can operate by itself              moving parts can induce severe vibra-
index / ndeks/ noun an alphabetical
                                             tion especially on propellers and heli-
list of references to page numbers found     copter rotors.
                                             induced drag /n dju st dr /
                                             induced drag

at the end of a book or long document                                             |

(NOTE: The plural form is indexes or         noun part of total drag, created by lift
indices / ndsi z/ .)                       There are two basic types of drag,
index letter / ndeks letə/, index           induced drag and parasite drag.
index letter

number / ndeks n mbə/ noun a let-               COMMENT: Induced drag is created
ter or number which makes it easier to           when high-pressure air below a wing
reference or look up information Each            rotates around the tip to the low-
observing meteorological station is              pressure area above and increases as
shown on the chart as a small circle,            airspeed decreases and angle of
identified by its own index number.              attack increases.
indicate / ndket/ verb 1. to show or      inductance /n d ktəns/ noun a


point out A lamp on the instrument           measure of a conductor’s ability to
panel will indicate when the pump is         bring a voltage into itself when carrying
operating.      The needle indicated to      a changing current, e.g. during short
zero. 2. to serve as a sign or symptom       times when the circuit is switched on or
Black smoke from the exhaust may indi-       off At low frequencies, the rate of col-
cate a rich mixture or worn piston           lapse of the magnetic field will be slow
rings.                                       and the inductance will be low.
induction                                                        120
induction /n d kʃən/ noun 1. the                                    inflammable /n fl məb(ə)l/ adjec-
induction                                                            inflammable

                                                     |                                                 |

process by which the fuel/air mixture is                             tive easily set on fire   Petrol is an
drawn into the cylinders of an internal                              inflammable liquid. (NOTE: Flammable
combustion engine The four strokes of                                and inflammable mean the same
the engine are induction, compression,                               thing.) highly inflammable very eas-
combustion and exhaust. 2. the produc-                               ily set on fire, and therefore hazardous
tion of electrical current in a conductor                            inflate /n flet/ verb to blow air into


by a change of magnetic field A trans-                               something and thereby increase its size
former is a static device that changes                                  A sharp pull on the cord will dis-
the amplitude or phase of an alternat-                               charge the gas bottle and inflate the life
ing voltage or current by electro-mag-                               jacket. Opposite deflate
netic induction.                                                     inflation /n fleʃ(ə)n/ noun 1. the act


inductive /n d ktv/ adjective refer-

                                                 |                   of blowing air into something, e.g. a
ring to the production of electrical cur-                            balloon or a tyre, and so increasing its
rent in a conductor by a change of mag-                              size Tyre inflation pressures should be
netic field     One side effect of low                               maintained within 4% limits. 2. a con-
frequency in an inductive circuit is that                            tinuing increase in the price of things
excess heat may be produced.                                         and a decrease in the buying power of
inductor /n d ktə/ noun a compo-

                                                                     money Annual inflation is 4%. Oppo-
nent in the ignition system that pro-                                site deflation
                                                                     in-flight / n flat/ adjective taking

duces electrical current in itself by a
change of magnetic field                                             place during a flight in-flight emer-
                                                                     gency in-flight oil loss
inert / n t/ adjective not reacting

                                                                     influence / nfluəns/ noun a power

with other substance
                                                                     which affects people or things The
inert gas / n t s/ noun a gas that
inert gas

                                                                     Atlantic Ocean has a great influence on
does not react with other substances                                 the climate of the British Isles. í verb to
Inert gases, dust, smoke, salt, volcanic                             have an effect on, to change In an
ash, oxygen and nitrogen together con-                               emergency, a crew member’s power of
stitute 99% of the atmosphere. (NOTE:                                command will influence the reaction of
The inert gases include helium, neon,                                passengers.
argon, krypton and xenon.)
                                                                     inform /n fɔ m / verb to tell some-


inertia / n ʃə/ noun the tendency of

                                                                     body something After a particularly
a body at rest to stay at rest or of a mov-                          heavy landing, the pilot should inform
ing body to continue moving in a                                     an engineer so that checks can be made
straight line unless acted on by an out-                             to the aircraft structure.
side force      Inertia switches operate                             information / nfə meʃ(ə)n/ noun a


automatically when a particular g                                    collection of facts or data Meteorolog-
(acceleration due to Earth’s gravity)                                ical visibility gives information on the
loading occurs.                                                      transparency of the atmosphere to a sta-
inertial / n ʃ(ə)l/ adjective referring

                                     |                               tionary ground observer. (NOTE: Infor-
to inertia                                                           mation has no plural form.)
inertial navigation system /                                        infra- /nfrə/ prefix below or beneath
inertial navigation system                                           infra-


 n ʃ(ə)l      n v eʃ(ə)n         sstəm/               |
                                                                     infrared / nfrə red/, infra-red adjec-


noun a navigation system which calcu-                                tive referring to the range of invisible
lates aircraft position by comparing                                 radiation wavelengths from about 750
measurements of acceleration with                                    nanometres to 1 millimetre         Solar
stored data, using gyros rather than                                 radiation is short wave and of high
radios. Abbreviation INS                                             intensity while terrestrial radiation is
inferential /nfə renʃ(ə)l/ adjective                                infra-red.


                                                                     infrequent /n fri kwənt/ adjective

obtained by deduction The inferential                                                              |

method of ice detection is used in flight                            not often In northern Europe, thun-
trials for aircraft certification.                                   derstorms are infrequent in winter time.
                                                             121                                   input
ingest /n d est/ verb to take in, or to                       members must be able to act collec-


absorb into, something such as a jet                           tively and with initiative in unusual sit-
engine through the intake Jet engines                          uations.
may be damaged by ingested chunks of                           inject /n d ekt/ verb to force or drive


ice.                                                           a fluid into something An accelerator
ingestion /n d estʃən / noun the act                          pump, operated by the movement of the


of taking something into something                             throttle lever, injects fuel into the choke
such as a jet engine through the intake                        tube.
                                                               injection / n d ekʃən/ noun the forc-

Ingestion of birds may seriously dam-                                                 |

age the blades of turbo-fan engines.                           ing of fluid into something Power out-
inherent /n hərənt/ adjective exist-

                                                               put can be boosted to a value over
ing as a basic or fundamental character-                       100% maximum power, by the injection
istic A boiling point of 100°C is an                           of a water methanol mixture at the com-
inherent characteristic of water.                              pressor inlet or at the combustion
                                                               chamber inlet.
in hg noun the unit for measuring
in hg

                                                               injector /n d ektə/ noun a device

absolute pressure. Full form inch(es)                                             |

of mercury                                                     that will force or drive a fluid into
inhibit /n hbt/ verb to prevent or to

                                                               injury / nd əri/ noun damage or harm
                             |                                 injury

limit the effect of something Cloud
cover inhibits cooling of the Earth’s                          done to a person Escape slides are
surface at night.                                              designed to minimise the risk of injury
                                                               to passengers when leaving the aircraft.
inhibition / nh bʃ(ə)n/ noun the

                                                               inland / nlənd/ adjective, adverb
                                                         |     inland

prevention or limitation of the effect of                      referring to the interior of a country or
something Fuel contains chemicals                              land mass Sea fog can extend for con-
for the inhibition of fungal growth.                           siderable distances inland.
inhibitor /n hbtə/ noun a device or

                                                               inlet / nlet/ noun 1. an opening which

substance which prevents or limits the                         allows an intake of something turbine
effect of something icing inhibitor a                          inlet combustion chamber inlet Air
substance added to fuel to prevent fuel                        enters the cabin through an inlet. 2. a
system icing                                                   coastal feature such as at the mouth of a
initial / nʃ(ə)l/ adjective relating to

or occurring at the beginning, the first                       inlet valve / nlət v lv/ noun the
                                                               inlet valve

initial climb the period of climb imme-                        valve in a piston engine which allows
diately after take-off initial letter the                      fuel to enter the cylinder
first letter of a word initial stage first                     inner / nə/ adjective positioned far-

stage í noun the first letter of a word                        ther inside inner wing the part of the
initials /  nʃ(ə)lz / plural noun the

                                                               wing near the fuselage
first letters of a name His name is                            inner marker / nə mɑ kə/ noun an
                                                               inner marker

John Smith, his initials are JS.                               ILS marker beacon placed between the
initiate / nʃiet/ verb to get some-

                                                               middle marker and the end of the ILS
thing going by taking the first step, to                       runway
start In a serious emergency, a mem-                           inoperative /n ɒpərətv/ adjective


ber of the cabin crew may initiate an                          not functioning To prevent accidental
evacuation of the aircraft.                                    retraction of the undercarriage, a safety
initiation / nʃi eʃ(ə)n/ noun the act

                                 |                   |         switch is fitted in such a way to the oleo,
of getting something going by taking                           that when it is compressed on the
the first step, starting Normally speak-                       ground, the ‘undercarriage up’ selec-
ing, the captain is responsible for the                        tion is inoperative.
initiation of emergency procedures.                            input / npυt/ noun something such as

initiative / nʃətv/ noun the power

                                     |                         energy, electrical power or information,
or ability to begin or to follow through                       put into a system to achieve output or a
competently with a plan or task Crew                           result Pumps require high input cur-
INS                                         122
rent. If the number of turns on the sec-      installation / nstə leʃ(ə)n/ noun 1.


ondary winding is greater than the            the act of putting equipment or devices
number of turns on the primary, the out-      into position and connecting them for
put voltage from the secondary will be        use The installation of the computer
greater than the input voltage to the pri-    took three hours. 2. equipment or
mary. pilot control input movements           devices which are installed In some
on the flying controls made by the pilot      auxiliary-power-unit installations the

INS abbreviation inertial navigation          air intake area is protected against ice
system                                        formation by bleeding a supply of hot
                                              air from the compressor over the intake
insert /n s t/ verb to put in or into

To prevent tyre explosion due to over-
                                              instance / nstəns/ noun an example

heating, fusible plugs are inserted into
the wheel assemblies. Insert your tel-        which is used to provide evidence of
ephone number in the space provided           something Failure to check fuel levels
on the form. Insert the key in the lock       before take-off is an instance of bad air-
and turn it.                                  manship. for instance e.g.
                                              instant / nstənt/ adjective immedi-

insertion /n s ʃ(ə)n/ noun the act


                                              ate, happening immediately í noun a
of putting in or into There is a space        very short period of time The pilot has
on the form for the insertion of a postal     to act in an instant to counteract the
address. When the contours for a par-         severe downdraughts of a microburst.
ticular pressure level have been drawn
                                              instinctive /n stŋktv/ adjective

in, the chart is completed by insertion of                                     |

spot temperatures and wind speed              natural, rather than thought-out        In
information.                                  most modern light aircraft, use of the
                                              trim wheel is instinctive, i.e. forwards
                        / ns nfkənt/

insignificant                           |
                                              for nose down and backwards for nose
adjective not important, of no conse-         up.
quence Minor changes in wind speed
                                              instruct /n str kt/ verb to give infor-

or direction are insignificant.                                    |

                                              mation or knowledge, usually in a for-
inspect /n spekt/ verb to look at

                                              mal setting such as a lesson or briefing
something closely and to check for              The safety officer instructs employees
problems or defects Propellers should         on the use of the breathing equipment.
be inspected prior to flight.                 The training captain instructs trainee
inspection /n spekʃ(ə)n/ noun a              pilots in the simulator.


careful check for problems         Before     instruction /n str kʃən/ noun 1. the


flight, the pilot should carry out a care-    act of giving information or knowledge,
ful inspection of the aircraft.               usually in a formal setting such as a les-
instability / nstə blti/ noun a con-

                                              son or briefing Trainees receive first-
dition in which a body or mass moves          aid instruction. 2. information on how
easily, and with increasing speed, away       something should be operated or used
from its original position Atmospheric        You must follow the instructions.
                                              instruction manual /n str kʃən
                                              instruction manual

instability often results in strong verti-                                             |

cal currents of air. The built-in insta-       m njuəl/ noun a book containing
bility of some modern fighter aircraft        information on how something should
makes them highly manoeuvrable but            be operated or used
difficult to control without fly-by-wire      instructor /n str ktə/ noun a person


technology.                                   who gives information or knowledge,
install /n stɔ l/ verb to put in posi-       usually in a formal setting such as a les-


tion, connect and make ready for use          son or briefing
                                              instrument / nstrυmənt/ noun a

Most carburettors are installed in a
warm position to help against icing.          device for recording, measuring or con-
installed battery a battery in position       trolling, especially functioning as part
in the aircraft                               of a control system Airspeed is given
                                                                123                                          intake
on an instrument called the airspeed                                    and distance from cloud ceiling which
indicator.                                                              are less than those for visual meteoro-
instrument approach procedure
instrument approach procedure
                                                                        logical conditions The basic licence
/ nstrυmənt ə prəυtʃ prə si d ə/          |            |
                                                                        does not permit the pilot to fly in instru-
noun a set of procedures which a pilot                                  ment meteorological conditions. Abbre-
must follow when approaching an air-                                    viation IMC
                                                                        instrument rating / nstrυmənt
                                                                        instrument rating

port under instrument flight rules

                           / nstrυmen                              |
                                                                         retŋ/ noun an additional qualifica-
 teʃ(ə)n/ noun a set of specialised                                    tion added to a licence, such as PPL,
instruments on an aircraft Instrumen-                                   allowing a pilot to fly in instrument
tation in some basic light aircraft is                                  meteorological conditions He gained
restricted to a few instruments only.                                   his instrument rating in 1992. Abbrevi-
Some modern light aircraft have very                                    ation I/R
sophisticated instrumentation.                                              COMMENT: An instrument rating is
instrument error / nstrυmənt                                               required for operating in clouds or
instrument error

 erə/ noun the difference between indi-                                     when the ceiling and visibility are less
                                                                            than those required for flight under
cated instrument value and true value                                       visual flight rules (VFR).
instrument                                     flight       rules
instrument flight rules

                                                                        insufficient / nsə fʃ(ə)nt/ adjec-

/ nstrυmənt flat ru lz/ plural noun                                                               |

regulations which must be followed                                      tive not enough   Insufficient height
when weather conditions do not meet                                     resulted in the pilot landing short of the
the minima for visual flight The flight                                 runway.
                                                                        insulate / nsjυlet/ verb 1. to prevent

from Manchester to Prestwick was con-
ducted under instrument flight rules.                                   the passing of heat, cold or sound into
Abbreviation IFR                                                        or out of an area 2. to prevent the pass-
instrument flying / nstrυmənt
instrument flying
                                                                        ing of electricity to where it is not
 flaŋ/ noun flying using no references                                required, especially by using a non-con-
other than the flight instruments Some                                  ducting material Bus bars are insu-
conditions require instrument flying.                                   lated from the main structure and are
When in cloud, instrument flying is                                     normally provided with some form of
required. Abbreviation IF                                               protective covering.
                                                                        insulating / nsjuletŋ/ adjective

instrument landing / nstrυmənt
instrument landing

 l ndŋ/ noun the landing of an aircraft                                preventing the unwanted passage of
when a pilot is relying on information                                  heat, cold, sound or electricity
                                                                        insulating tape / nsjυletŋ tep/
                                                                        insulating tape

obtained from instruments rather than
from what can be seen outside the air-                                  noun special adhesive tape which is
craft                                                                   used to insulate electrical wires Insu-
instrument landing system

                                           landing      system          lating tape was used to prevent the elec-
/ nstrυmənt l ndŋ sstəm/ noun                                        trical wires from touching.
                                                                        insulation / nsjυ leʃ(ə)n/ noun an

aids for an instrument landing approach                                                         |

to an airfield, consisting of a localiser,                              act of or state of preventing the passing
glide slope, marker beacons and                                         of heat, cold, sound or electricity from
approach lights The instrument land-                                    one area to another For continuous
ing system provides both horizontal and                                 supersonic flight, fuel tank insulation is
vertical guidance to aircraft approach-                                 necessary to reduce the effect of kinetic
ing a runway. Abbreviation ILS                                          heating.
                                                                        insulator / nsjυletə/ noun a sub-

    COMMENT: The ILS is the most used
    precision approach system in the                                    stance which will insulate, especially
    world.                                                              which will not conduct electricity
instrument meteorological con-
instrument meteorological conditions
                                                                        Wood is a good insulator.
ditions / nstrυmənt   mi tiərə                                         intake / ntek/ noun an opening

lɒd k(ə)l kən dʃ(ə)nz/ plural noun   |                                through which a fluid is allowed into a
meteorological conditions of visibility                                 container or tube
intake guide vane                                      124
intake guide vane / ntek             ad                 intercept / ntə sept/ verb to stop or
intake guide vane                                          intercept


 ven/ noun a device to direct the flow                    interrupt the intended path of something
of air at the air-intake                                      When a radio transmission is made
intake lip / ntek lp/ noun the rim or                   from a moving platform, there will be a
intake lip

edge of the air intake of a jet engine As                  shift in frequency between the transmit-
sonic speed is approached, the effi-                       ted and intercepted radio signals.
ciency of the intake begins to fall                        interconnect / ntəkə nekt/ verb to


because of shock waves at the intake lip.                  connect together The fire extinguish-
intake                         temperature         gauge   ers for each engine are interconnected,
intake temperature gauge

/ ntek temprtʃə         ed / noun an                   so allowing two extinguishers to be
instrument to indicate the temperature                     used on either engine.
of air entering an engine                                  inter-crew / ntə kru / adjective

integral / nt rəl/ adjective which

                                                           inter-crew communications commu-
completes the whole or which belongs                       nications between members of the crew
to a whole Meteorology is an integral                         The lack of inter-crew communication
part of a flying training course. inte-                    contributed to the accident.
gral fuel tanks tanks which are located                    interfere / ntə fə/ verb to inter-


within the structure of the aircraft                       fere with to get in the way of something
integrity /n te rti/ noun the state of

                                   |                       or come between things and thus create
being complete and in good working                         a problem An engine intake close to
condition      The engine fire warning                     another surface, such as the fuselage
system is checked to test its integrity.                   tail section, must be separated from that
The integrity of an aid used to conduct                    surface so that the slower boundary
procedural approaches must be high.                        layer air does not interfere with the reg-
intend /n tend/ verb to have a partic-                    ular intake flow.


ular plan, aim or purpose A battery is                     interference / ntə fərəns/ noun


intended to supply only limited amounts                    the prevention of reception of a clear
of power.       intended track desired                     radio signal Some equipment, such as
course of flight                                           generators and ignition systems, will
intense /n tens/ adjective 1. extreme                     cause unwanted radio frequency inter-


in amount intense heat very high heat                      ference.     precipitation interference
   intense wind very strong wind 2.                        interference caused by rain, snow or
intense concentration very hard or                         hail
deep concentration                                         interlock / ntə lɒk/ noun a series of


intensity /n tensti/ noun the

                                           |               switches and/or relays          Interlocks
amount or strength of heat, light, radia-                  operate in a specific sequence to ensure
tion Surface air temperatures depend                       satisfactory engagement of the autopi-
mostly on the intensity and duration of                    lot. í verb to connect together parts of a
solar radiation.                                           mechanism, so that the movement or
intention /n tenʃən/ noun the course                      operation of individual parts affects


of action one means or plans to follow                     each other The two parts interlock to
It is not the intention of this chapter to                 create a solid structure.
give a detailed description of world                       intermediate / ntə mi diət/ adjec-


weather. Our intention is to provide                       tive 1. in a position between two others
safe, cost-effective flying.                               2. between beginners and advanced
inter- /ntə/ prefix between                               he is at an intermediate stage in his

interact / ntər kt/ verb to act on                        studies he is in the middle of his course


each other Angle of attack and the                         of study an intermediate level lan-
profile of the wing section interact to                    guage student a second language
produce lift. Direct and reflected path                    learner who has reached a level between
signals can interact to cause bending of                   elementary and advanced level
                                                           intermediate approach

the localiser and/or generation of a                                                                           approach
false glidepath.                                           / ntəmi diət ə prəυtʃ/ noun the part
                                                                      125                                                                     interrupt
of the approach from arriving at the first                                    international standard atmos-
                                                                              international standard atmosphere

navigational fix to the beginning of the                                      phere / ntən ʃ(ə)nəl st ndəd
final approach                                                                   tməsfə/ noun an internationally
intermediate frequency

                                                              frequency       agreed unit of pressure used in the cali-
/ ntəmi diət    fri kwənsi/ noun the                                         bration of instruments and the measure-
frequency in a radio receiver to which                                        ment of aircraft performance For en
the incoming received signal is trans-                                        route weather the datum chosen is
formed. Abbreviation IF                                                       international standard atmosphere at
intermittent / ntə mt(ə)nt/ adjec-

                                                                              mean sea level. Abbreviation ISA
                                                                              interphone / ntəfəυn/ an internal

tive stopping and starting at intervals
The cycle of induction, compression,                                          telephone communications system
combustion and exhaust in the piston                                          within an aircraft that enables members
engine is intermittent, whereas in the                                        of the crew to speak to one another
gas turbine, each process is continuous.                                      interpolation         /n t pə leʃ(ə)n/

                                                                                                                                      |               |

internal /n t n(ə)l/ adjective refer-                                        noun the estimation of a middle value


ring to the inside or interior of some-                                       by reference to known values each side
thing      internal damage Opposite                                              Spot temperatures at positions other
external                                                                      than those printed are obtained by
internal combustion engine /n
internal combustion engine

 t n(ə)l k m b stʃən end n/ noun                                             interpret /n t prt/ verb to under-


type of engine in which the fuel is burnt                                     stand something presented in code or
within the cylinders of the engine, as                                        symbolic form Aircrew must be able
opposed to the steam engine                                                   to interpret information printed on a

                      / ntə n ʃ(ə)nəl/                       |
                                                                              contour chart.
                                                                              interpretation /n t pr teʃ(ə)n/

adjective between countries interna-                                                                                              |               |

tional call a telephone call between                                          noun an understanding of something
people in two different countries                                             presented in code or symbolic form
International Air    Transport
International Air Transport Association
                                                                              Synoptic charts require interpretation
Association / ntən ʃ(ə)nəl eə                                                in order to understand the information
 tr nspɔ t ə səυsieʃ(ə)n/ noun an            |
                                                                              interrogate /n terə et/ verb to

international organisation that super-                                                                                    |

vises and coordinates air transport and                                       transmit SSR or ATC signals to activate
to which most major airlines belong.                                          a transponder Secondary surveillance
Abbreviation IATA                                                             radar interrogates the aircraft equip-
International Calling Frequency
International Calling Frequency
                                                                              ment which responds with identification
/ ntən ʃ(ə)nəl kɔ lŋ fri kwənsi/,                                           and height information.
                                                                              interrogation          /n terə eʃ(ə)n/

International Distress Frequency                                                                                                          |   |

/ ntən ʃ(ə)nəl ds tres fri kwənsi/                  |                       noun the transmission of a SSR or ATC
noun 2182 kHz or 500 kHz                                                      signal to activate a transponder       A
International Civil Aviation
International Civil Aviation Organization
                                                                              transponder replies to interrogation by
Organization / ntən ʃ(ə)nəl svl                                            passing a four-digit code.
 evi eiʃ(ə)n ɔ ənazeʃ(ə)n/ noun                                            interrogator /n terə etə/ noun a

                |                                                                                                             |

an organisation established in 1947 by                                        ground-based surveillance radar beacon
governments that ‘agreed on particular                                        transmitter/receiver      The questioner,
principles and arrangements in order                                          better known as the interrogator, is fit-
that international civil aviation may be                                      ted on the ground, while the responder,
developed in a safe and orderly man-                                          also known as the transponder, is an
ner…’ Air navigation obstructions in                                          airborne installation.
the United Kingdom are shown on                                               interrupt / ntə r pt/ verb to break


ICAO aeronautical charts. Abbrevia-                                           the continuity of something The con-
tion ICAO                                                                     versation was interrupted by a tele-
    COMMENT: ICAO is based in Montreal                                        phone call.      In the northern hemi-
    (Canada).                                                                 sphere, the westerly flow of air is
interruption                                             126
interrupted by variations which occur                      inversion /n v ʃ(ə)n/ noun 1. an


in pressure patterns.                                      atmospheric phenomenon where cold
interruption / ntə r pʃən/ noun a                         air is nearer the ground than warm air


break in the continuity of something                       Smog is smoke or pollution trapped on
Because of the summer holiday, there                       the surface by an inversion of tempera-
was an interruption in the flying train-                   ture with little or no wind. 2. turning
ing course.                                                something upside down Inversion of
intersect / ntə sekt/ verb to cut

                                                           the aircraft in flight may result in fuel
across each other Meridians intersect                      stoppage.
                                                           inversion layer /n v ʃ(ə)n leə/
                                                           inversion layer

at the poles and cross the equator at                                                                        |

right angles.                                              noun a layer of the atmosphere in which
intersection / ntə sekʃən/ noun the

                                                           the temperature increases as altitude
point at which two lines cross each                        increases
                                                           invert /n v t/ verb to turn upside

other The aircraft came to a stop at                                         |

the intersection between runways 09                        down A glass tube is sealed at one
and 16. The intersection of the drift                      end, filled with mercury and then
line and the wind vector gives the drift                   inverted so that the open end is
point.                                                     immersed in a bowl containing mer-
intertropical convergence zone                             cury.
intertropical convergence zone
                                                           investigate /n vest et/ verb to

/ ntətrɒpk(ə)l kən v d əns zəυn/           |

noun the boundary between the trade                        examine or look into something in great
winds and tropical air masses from the                     detail If the starter engaged light stays
northern and southern hemispheres                          on after starting, it means that power is
The intertropical convergence zone is                      still connected to the starter and, if it is
the zone in which the trade winds from                     still on after 30 seconds, the cause must
the two hemispheres approach each                          be investigated.
                                                           investigation         /n vest eʃ(ə)n/

other. Abbreviation ITCZ                                                                                 |       |

interval / ntəv(ə)l/ noun 1. the
                                                           noun a detailed inquiry or close exami-
amount of space between places or                          nation of a matter accident investiga-
points The intervals at which contours                     tion process of discovering the cause of
are drawn depends on the scale of the                      accidents
chart and this interval, known as the                        ‘…accident investigation by the FAA and
vertical interval, is noted on the chart.                    the German LBA revealed that the
2. the period of time between two                            crashed aircraft had been completely
events A precise interval is essential                       repainted in an unauthorized paint shop’
to obtain correct ignition timing on all                     [Pilot]
                                                           investigator /n vest etə/ noun a

cylinders.                                                                                           |

introduction / ntrə d kʃ(ə)n/ noun

                                                           person who investigates        Accident
1. something written which comes at                        investigators found poor coordination
the beginning of a report, chapter, etc.,                  between controllers.
                                                           invisible /n vzb(ə)l/ adjective

or something spoken which comes at                                                           |

the beginning of a talk In his introduc-                   impossible to see Oxygen is an invisi-
tion, the chief executive praised the                      ble gas.
efforts of the workforce over the previ-                   involve /n vɒlv/ verb to include In


ous 12 months. 2. the act of bringing                      large transport aircraft, because of the
into use The introduction of fly-by-                       distance and numbers of people
wire technology has made the pilot’s                       involved, effective and rapid communi-
task easier.                                               cations are required between flight
inverse /n v s/ adjective reversed in                     crew and cabin crew and between cabin


order or effect There is an inverse                        crew and passengers.       Two aircraft
relationship between altitude and tem-                     were involved in an accident.
                                                           involved /n vɒlvd/ adjective over-

perature, i.e. temperature decreases as                                              |

altitude increases.                                        complex, difficult The procedure for
                                                              127                                     item
replacing a lost passport is very                                 their work irrespective of the weather
involved.                                                         conditions.
inward / nwəd/ adjective directed to                             ISA / asə/ abbreviation international
inward                                                            ISA

or moving towards the inside or interior                          standard atmosphere
   To provide protection against smoke                            isobar / asəυbɑ / noun a line on a

and other harmful gases, a flow of                                weather chart joining points of equal
100% oxygen is supplied at a positive                             atmospheric pressure         Isobars are
pressure to avoid any inward leakage of
                                                                  analogous to contour lines.
poisonous gases at the mask.
                                                                  isobaric /asə b rk/ adjective refer-

inwards / nwədz/ adverb towards

                                                                  ring to or showing isobars isobaric
the inside or the interior The door
opens inwards. Opposite outwards                                  charts
                                                                  isolate / asəlet/ verb to separate

ion / aən/ noun an atom or a group of

atoms that has obtained an electric                               something from other things or some-
charge by gaining or losing one or more                           body from other people The low-pres-
electrons negative ion positive ion                               sure fuel cock isolates the airframe fuel
Ultra-violet light from the sun can                               system from the engine fuel system to
cause electrons to become separated                               enable maintenance and engine remov-
from their parent atoms of the gases in                           als to be carried out.
                                                                  isolated / asəletd/ adjective sepa-

the atmosphere, the atoms left with
resultant positive charges being known                            rate      isolated rain showers well
as ions.                                                          spaced out rain showers
ionisation / aəna zeʃ(ə)n/, ioni-                              isolation / asə leʃ(ə)n/ noun the


zation noun the process of producing                              state of being separated from something
ions by heat or radiation The intensity                           or somebody        Isolation of the air-
of ionisation depends on the strength of                          craft’s passengers and crew from the
the ultra-violet radiation and the den-                           reduced atmospheric pressure at alti-
sity of the air.                                                  tude is achieved by pressurisation of the
ionosphere /a ɒnəsfə/ noun the

                                      |                           cabin.
part of the atmosphere 50 km above the                            isotach / asəυ t ʃ/ noun a line of


surface of the earth Since the strength                           equal wind speed on charts (NOTE: Wind
of the sun’s radiation varies with lati-                          speed is normally given in the form of
tude, the structure of the ionosphere                             isotachs.)
varies over the surface of the earth.
                                                                  isotherm / asəυθ m/ noun a line of

ionospheric /a ɒnə sferk/ adjec-

                                              |           |
                                                                  equal temperature on charts Ascent of
tive referring to the ionosphere                                  stable air over high ground may result
                     attenuation /a
ionospheric attenuation

ionospheric                                                   |   in a lowering of the 0°C isotherm.
 ɒnəsferk ə tenju eiʃ(ə)n/ noun loss
                          |                       |

                                                                  issue / ʃu / noun a number or copy

of signal strength to the ionosphere                              The article was in last month’s issue of
ionospheric refraction

ionospheric           refraction                              |
                                                                  the magazine. í verb 1. to give out The
 ɒnəsferk r fr kʃən/ noun a change
                                                                  captain issued the evacuate command.
in direction as the wave passes through                           2. to publish The magazine is issued
an ionised layer                                                  monthly. 3. to give out, to grant The

I/R abbreviation instrument rating                                Civil Aviation Authority issue licences.
irregular / re jυlə/ adjective not

                                                                  ITCZ abbreviation intertropical conver-


regular Pilots of long-haul flights are                           gence zone
subject to an irregular sleep pattern.                            item / atəm/ noun a single article or

irrespective /r spektv /, irrespec-

                                          |                       unit in a collection, on a list, etc.
tive of preposition taking no account of,                         Before practising stalls, the pilot should
regardless of Rescue flights continue                             secure all loose items in the cockpit.
J symbol joule

                                           takes in air at the front, mixes it with
JAA abbreviation

                       Joint   Aviation    fuel, burns the mixture and the resulting
Authorities                                expansion of gases provides thrust
jack /d

            k/ noun a powered device to    The turbo jet engine was invented by
move heavy components, such as con-        Frank Whittle in 1941. 3. a type of air-
trol surfaces of large aircraft            craft which has jet engines The de
                                           Havilland Comet was the first commer-
jacket / d kt/ noun 1. a short coat

                                           cial jet.
with long sleeves worn with trousers or
                                           jetbridge / d etbrd / noun same as

skirt 2. an outer covering or casing
Liquid cooling of a piston engine is       loading bridge
                                           jet fighter / d et       fatə/ noun a
                                           jet fighter

achieved by circulating a liquid around
the cylinder barrels, through a passage    fighter plane that is powered by a jet
formed by a jacket on the outside.         engine or engines
jam /d m/ verb to cause moving             jet lag / d et l / noun the temporary
                                           jet lag

parts to become locked and unable to be    disturbance of body rhythms such as
moved a jammed door a door which           sleep and eating habits, caused by high-
has become fixed and unmovable The         speed travel across several time zones
investigation revealed that the accident   When I fly to Canada, it always takes
had been caused by the controls being      me a couple of days to recover from jet
jammed due to a spanner caught in the      lag.
control cables.
                                           jetliner / d etlanə/ noun a large pas-

JAR abbreviation Joint Aviation

                                           senger aircraft powered by jet engines
                                           jet plane / d et plen/ noun an air-
                                           jet plane

jato / d etəυ/ noun an auxiliary jet or

rocket designed to aid the combined        craft powered by jet engines
                                           jet-propelled aircraft / d et prə
                                           jet-propelled aircraft

thrust of aircraft jet engines during                                                  |

take-off                                    peld eəkrɑ ft/ noun aircraft powered
jeopardise / d epədaz/, jeopardize
                                           by jet engines
                                           jet propulsion / d et prə p lʃ(ə)n/
                                           jet propulsion

verb to put in doubt or danger Injury                                    |

to a crew member will seriously jeop-      noun jet power which provides thrust
ardise the successful evacuation of the    for an aircraft The first known exam-
aircraft.                                  ple of jet propulsion was when Hero, a
Jeppesen chart / d epəs(ə)n tʃɑ t/         Greek engineer, made a machine as a
Jeppesen chart

noun a type of aeronautical chart pro-     toy in the year 120 BC.
duced by a US company and widely           jet stream /d et stri m/ noun 1. a
                                           jet stream

used in aviation                           band of strong winds at high altitude
jet /d et/ noun 1. a strong fast stream

                                           The occurrence of the equatorial jet
of fluid forced out of an opening a jet    stream is due to a temperature gradient
of water from a pipe 2. a type of engine   with colder air to the south. 2. the flow
used to power modern aircraft which        of gases from a jet engine
                                                      129                                         junction box
jettison / d ets(ə)n/ verb to throw                          states, including all the countries of the

off or release from a moving aircraft                         European Union.
The undercarriage failed to retract and                   Joint Aviation Requirement

                                                          Joint                        Aviation   Requirement
the captain had to jettison the fuel over                 / d ɔnt evieʃ(ə)n r kwaəmənt/       |

the sea before landing the aircraft.                      noun a JAA requirement concerning
join /d ɔn/ verb 1. to connect Join                      design, manufacture, maintenance and

the two wires. With a pencil and ruler,                   operation of aircraft. Abbreviation JAR
join point A to point B. 2. to bring                      (NOTE: JARs of relevance to mainte-
together to make one whole part Wing                      nance staff are JAR-145, JAR-OPS 1
panels are joined by rivets. 3. to                        and JAR-OPS 3.)
become a member of a club, etc. She                       joule /d u l/ noun an International

had to pay a membership fee to join the                   System unit of electrical, mechanical,
gliding club.                                             and thermal energy Ignition units are
joint /d ɔnt/ noun the place at which

                                                          measured in joules (1 joule = 1 watt per
two or more things are joined together                    second). (NOTE: It is usually written J
Fuselage frame rings are formed with                      with figures: 25J.)
only one joint. í adjective combined,                     jumbo / d

                                                                         mbəυ/ noun same as
with two or more things linked together                   jumbo jet (informal )
or shared by two or more people a
                                                          jumbo jet / d mbəυ d et/ noun a
                                                          jumbo jet

joint effort
                                                          large wide-bodied aircraft capable of
Joint                        Aviation       Authorities
Joint Aviation Authorities

                                                          carrying several hundred passengers
/ d ɔnt evi eʃ(ə)n ɔ θɒrətiz/ noun
                                                          jump jet / d mp d et/ noun a jet air-
                               |        |                 jump jet

a body, consisting of European repre-
sentatives, set up to control and regulate                craft with fixed wings that can take off
aspects of civil aviation in Europe The                   and lands vertically
                                                          junction / d ŋkʃən/ noun a place

Joint Aviation Authorities is an
arrangement between European coun-                        where two things meet the junction of
tries which has developed since the                       two wires
1970s. Abbreviation JAA                                   junction box / d ŋkʃən bɒks/
                                                          junction box

       COMMENT:      The     Joint  Aviation              noun electrical unit where a number of
       Authorities currently has 37 member                wires can be connected together
                                             kilo / ki ləυ/ noun same as kilogram
K                                            kilo

K symbol kelvin
katabatic /k tə b tk/

                     |          adjective    This piece of luggage weighs 15 kilos.
                                             kilo- /kləυ/ prefix one thousand

referring to a cold flow of air travelling
down hillsides or mountainsides Due          kilogram / klə r m/ noun a meas-

to katabatic effects, cold air flows         ure of weight equal to one thousand
downwards and accumulates over low           grams This piece of luggage weighs
ground. Compare anabatic                     15 kg. Abbreviation kg (NOTE: It is writ-
katabatic wind /k tə b tk wnd/
katabatic wind

                          |                  ten kg after figures.)
noun a wind which occurs when the air        kilohertz / kləh ts/ noun a unit of

in contact with the slope of a hill is       frequency measurement equal to one
cooled to a temperature lower than that      thousand Hertz. Abbreviation kHz
in the free atmosphere, causing it to        kilometre /k lɒmtə / noun a meas-


sink. Compare anabatic wind                  ure of length equal to one thousand
kelvin / kelvn/ noun the base SI unit

                                             metres (NOTE: It is written km with fig-
of measurement of thermodynamic              ures: 150 km. The US spelling is kilom-
temperature. Symbol K (NOTE: Temper-         eter.)
atures are shown in kelvin without a         kilowatt / kləwɒt/ a unit of measure-

degree sign: 20K. Note also that 0°C is      ment of electricity equal to 1000 watts.
equal to 273.15K.)                           Abbreviation kW
kerosene / kerəsi n/, kerosine noun

                                             kilowatt-hour / klə wɒt aυə/ noun


a thin fuel oil made from petroleum          a unit of 1000 watts of electricity used
Kerosene will only burn efficiently at, or   for one hour. Abbreviation kW-hr
close to, a ratio of 15:1.
                                             kinetic /k netk, ka netk/ adjec-

Kevlar / kevlə/ noun a trademark for a
Kevlar                                                        |               |

                                             tive referring to motion or something
light and very strong composite mate-        produced by motion kinetic heating
rial Kevlar and carbon fibre account         the heating of aircraft skin by friction
for a large percentage of a modern jet       with the air as it moves through it
airliner’s structure.
                                             kinetic energy /ka netk enəd i/
                                             kinetic energy

key /ki / noun a piece of metal used to
key                                                                       |

                                             noun energy of motion
open a lock
                                             kit /kt/ noun a set of items used for a


kg symbol kilogram                           specific purpose      A physician’s kit

kHz symbol kilohertz                         containing surgical equipment would
kick-back / kkb k/ noun the ten-            be available to a qualified doctor

dency of the engine to suddenly reverse      assisting crew with major medical
the rotation of the propeller momentar-      problems.
                                             knob /nɒb/ noun 1. a rounded handle

ily when being started On most mod-
ern engines the spark is retarded to top-       door knob 2. a rounded control switch
dead-centre, to ensure easier starting       or dial     When the control knob is
and prevent kick-back.                       moved from the central position, the
                                               131                                             kt
ailerons are moved. 3. a round button                 miles per hour. Knot means ‘nautical
such as on a receiver Turn the knob to                miles per hour’. It is therefore incorrect
increase the volume.                                  to say ‘knots per hour’.
knot /nɒt/ noun a unit of speed equal            knowledge / nɒld / noun familiar-
knot                                             knowledge

to one nautical mile per hour, approxi-          ity, awareness or understanding gained
mately 1.85 kilometres or 1.15 statute           through experience or study A knowl-
miles per hour. Abbreviation kt (NOTE:           edge of the factors which affect surface
Wind speeds in aviation are usually
                                                 temperatures will contribute a great
given in knots.)
                                                 deal to the understanding of meteorol-
       COMMENT:     American light aircraft      ogy.
       manufactured prior to 1976 had            kt

       airspeed indicators marked in statute     kt abbreviation knot
label / leb(ə)l/ noun a small piece of       land /l nd/ noun solid ground, as
label                                         land

paper or cloth attached to an article with    opposed to the sea a large land mass
details of its owner, contents, use, desti-   such as Greenland í verb 1. to set an
nation, etc. Hydraulic tubing has a           aircraft onto the ground or another sur-
label with the word HYDRAULIC. í              face such as ice or water, after a flight
verb 1. to identify by using a label          to force land the aircraft to land the
Parts are labelled with the manufac-          aircraft when it can no longer be kept in
turer’s name. 2. to add identifying           the air for any particular reason 2. to
words and numbers to a diagram                arrive on the ground after a flight
There is a standard way of labelling the      Flight BA321 landed at London Heath-
navigation vector.                            row at 1030 hours. crash-land. Oppo-
                                              site take off
lack /l k/ noun the absence of some-

                                              landing / l ndŋ/ noun the act of set-

thing or a need for something The
engine stopped because of a lack of fuel.     ting an aircraft onto the ground or
                                              another surface such as ice or water
lag /l / noun a delay, especially the

                                              after flight Take-off and landing are
time interval between an input and the        normally made into wind in order to
resultant output There is a time lag          reduce the length of the take-off and
between the piston moving down and            landing run. In order to achieve a safe
the mixture flowing into the cylinder.        landing in a cross wind, the correct
jet lag                                       techniques must be used.
Lambert’s projection / l mbəts                landing beacon / l ndŋ bi kən/
Lambert’s projection                          landing beacon

prə d ekʃ(ə)n/ a map projection of the
           |                                  noun a radio transmitter at an airfield
earth based around two standard paral-        that sends a beam to guide aircraft that
lels of latitude. Mercator’s projection       are landing
                                              landing beam / l ndŋ bi m/ noun a
                                              landing beam

laminate / l mnət/ noun a sheet of

man-made material made up of bonded           radio beam from a beacon at a landing
layers      Direction of the fibres and       field that helps incoming aircraft to
types of cloth used in the laminate are       make a landing
                                              landing          charges         / l ndŋ
                                              landing charges

all very important factors. í verb
/ l mnet/ to make by using bonded            tʃɑ d z/ plural noun money paid to an
layers of material     laminated wind-        airport authority by an operator or pri-
screens                                       vate pilot for landing an aircraft
                                              landing field / l ndŋ fi ld/ noun a
                                              landing field

lamp /l mp/ noun a small light

warning lamp a small light, often red,        place where aircraft can land and take
which informs of a possible danger by         off
                                              landing gear / l ndŋ ə/ noun
                                              landing gear

lighting up The switch is connected to
a warning lamp on the instrument panel        same as undercarriage
                                              landing pad / l ndŋ p d/ noun
                                              landing pad

which will illuminate if the oil pressure
falls below an acceptable minimum.            same as helipad
                                                  133                                  latter
landing run / l ndŋ r n/ noun the                  laser ring gyro / lezə rŋ d arəυ /
landing run                                         laser ring gyro

distance on the runway from the touch-              noun an instrument that uses beams of
down point to the stopping point or tax-            laser light in a closed circuit to detect
iing speed                                          whether something is level or not
landing speed / l ndŋ spi d/ noun                  last /lɑ st/ adjective coming or placed
landing speed                                       last

the lowest speed at which an aircraft               after all the others í verb 1. to continue
must be flying in order to land safely              for a period of time A gust is a sudden
landing strip / l ndŋ strp/ noun a                increase in wind speed above the aver-
landing strip

specially prepared area of land for an              age speed lasting only a few seconds. 2.
aircraft to land on                                 to stay in good or usable condition A
landing weight / l ndŋ wet/ noun                  piston engine lasts longer if it is han-
landing weight

the weight of an aircraft when it lands,            dled carefully and serviced regularly.
which is made up of its empty weight,               the last chapter 1. the final chapter in
the weight of its payload, and the                  a book 2. the chapter before the one
weight of its remaining fuel                        being read
landmark / l ndmɑ k/ noun some-                     latent heat / let(ə)nt hi t/ noun
                                                    latent heat

thing on the ground which enables the               heat taken in or given out when a solid
pilot to know where he/she is, e.g. a               changes into a liquid or vapour, or when
noticeable building, bridge, coastal fea-           a liquid changes into a vapour at a con-
ture, etc. Railway lines are usually                stant temperature and pressure latent
useful landmarks.                                   heat of fusion the quantity of heat
landside / l ndsad/ noun the part of
                                                    required to convert ice, at its melting
an airport farthest from the aircraft               point, into liquid at the same tempera-
                                                    ture latent heat of vaporization the
lane /len / noun same as air lane

                                                    quantity of heat required to convert liq-
lapse rate / l ps ret/ noun the rate
lapse rate

                                                    uid to vapour at the same temperature
at which temperature changes accord-                latent heat of sublimation the quantity
ing to altitude adiabatic lapse rate                of heat required to convert ice to vapour
the rate at which air temperature                   at the same temperature
decreases as it rises above the Earth’s
                                                    lateral / l t(ə)rəl/ adjective referring

surface. As the height increases, the
temperature decreases.                              to the side Drift is the lateral move-
                                                    ment of the aircraft caused by the wind.
       COMMENT: It has been found that
                                                    lateral axis / l t(ə)rəl kss/ noun
                                                    lateral axis

       when dry or unsaturated air rises, its
       rate of fall of temperature with height      the axis of the aircraft from wing tip to
       (i.e. lapse rate) is constant at 3°C per     wing tip about which the aircraft
       1,000 feet. Similarly, descending air        pitches up and down. axis, pitch
       warms by compression at that rate.
                                                    latitude / l ttju d/ noun the angular

       This dry adiabatic lapse rate is
       normally referred to as the DALR. Air        distance north or south of the Earth’s
       rising and cooling often reaches its         equator, measured in degrees, minutes
       dew point temperature, becomes               and seconds, along a meridian, as on a
       saturated and any further cooling            map or chart, etc. Parallels of latitude
       results in condensation and the              are imaginary circles on the surface of
       release of latent heat. Release of           the Earth, their planes being parallel to
       latent heat delays the cooling process
       and the lapse rate at low levels is          the plane of the equator. The centre of
       reduced to 1.5°C per 1,000 feet. This        London is latitude 51°30’N, longitude
       temperature change is called the             0°5’W. Compare longitude
       saturated adiabatic lapse rate and is        latter / l tə/ adjective referring to

       normally referred to as the SALR.            something coming at the end or finish
largely / lɑ d li/ adverb mainly,

                                                    the latter part of the take-off run the
mostly Heat is transferred from the                 part of the take-off run immediately
Earth’s surface upwards largely by con-             before the aircraft leaves the ground í
vection.     The southern hemisphere                noun the second of two things men-
consists largely of oceans.                         tioned earlier. Opposite former of the
launch                                    134
Airbus A320 and A340, the latter is           by going first In an emergency situa-
the larger aircraft the A340 is the           tion the aircraft commander may lead
larger of the two                             his passengers to safety. In a smoke-
launch /lɔ ntʃ/ noun a small boat             filled cabin, floor lighting leads passen-

often used to transport people from a         gers to the emergency exit. 2. to cause
larger boat or ship to the shore í verb 1.    In winter, the cold conditions often lead
to slide or drop a boat into the water to     to frost and fog. Contraction of metal
make it ready for use While passen-           parts and seals can lead to fluid leak-
gers are fitting life jackets, crew will      age. (NOTE: leading – led)
                                              lead-acid battery / led                sd
                                              lead-acid battery

open exits and launch the life-rafts. 2. to
force something into motion to launch          bat(ə)ri/ noun a system of lead plates
a rocket                                      and dilute sulphuric acid, used as a
lavatory / l vətri/ noun same as toi-         starter battery or traction battery

                                              leading edge / li dŋ ed / noun the
                                              leading edge

let 2
law /lɔ / noun 1. a basic principle           front part of the wing which meets the

describing a relationship observed to be      oncoming air first In icing conditions,
unchanging between things while par-          ice may build up on the leading edges.
                                              leak /li k/ noun the escape of liquid or

ticular conditions are met the law of
gravity 2. a set of agreed rules avia-        gas from a sealed container, or the
tion law                                      amount of liquid or gas that has escaped
layer / leə/ noun 1. one horizontal
                                                 Any failure of the aircraft structure
part The lowest layer of the atmos-           may cause a leak of pressurised air
phere is called the troposphere. 2. a         which might be very difficult to cure.
thickness of something Layers of fluid        exhaust leak an escape of exhaust
next to the surface over which it is flow-    gases í verb to escape from a sealed
ing travels more slowly than layers fur-      container Fuel may leak from a fuel
ther from the surface.                        tank if the drain plug is not seated cor-
layer cloud / leə klaυd/ noun same
layer cloud

                                              leakage / li kd / noun the escape of

as stratus
                                              liquid or gas from a sealed container
layout / leaυt/ noun the way in which

                                              Any internal or external leakage of fuel
things are arranged cockpit layout the        will cause a reduction in the operating
design of the cockpit and the particular
                                              period. (NOTE: Leak is normally used
placement of controls, instruments, etc.
                                              for an individual instance while leakage
LC abbreviation load controller

                                              is used more generally: There is a fuel
LCD / el si di / abbreviation liquid

                                              leak from the central tank; Fuel leakage
crystal display                               is a safety hazard.)
LDA abbreviation landing distance             lean /li n/ adjective referring to a mix-
LDA                                           lean

available                                     ture in which the ratio of air to fuel is
LDR abbreviation landing distance
                                              greater than usual Moving the mixture
required                                      control lever aft to the lean position
lead1 /led/ noun a very heavy soft
                                              reduces the amount of fuel mixing with
metallic element. Symbol Pb lead-             the air.
                                              lean mixture / li n mkstʃə/ noun a
                                              lean mixture

free not containing lead Low-lead or
lead-free fuel is used in most modern         fuel/air mixture in which the ratio of air
piston engines.                               to fuel is greater than usual
                                              LED / el i di / noun a semiconductor

lead2 /li d/ noun 1. an electrical wire

or narrow cable A lead connects the           diode that emits light when current is
monitor to the computer. 2. to take           applied. LEDs are used in cockpit dis-
the lead to take control of a situation       plays. Full form light-emitting diode
                                              lee /li / adjective, noun which is pro-

It is vital in any emergency situation
that a crew member should take the            tected from the wind The air on the
lead. í verb 1. to guide or show the way      lee side is drier than that on the wind-
                                             135                                      level
ward side. The flow of air over and to           lengthwise / leŋθwaz / adjective,

the lee of hills and mountains may               adverb along the length of something
cause particularly severe turbulence.            in a lengthwise direction
Opposite windward                                lengthy / leŋθi/ adjective 1. long,

leg /le / noun part of a flight pattern

                                                 extensive He wrote a lengthy report.
that is between two stops, positions, or         2. long, which lasts for a long time
changes in direction An airfield traffic         (NOTE: Lengthy often suggests a meet-
pattern is divided into take-off, cross-         ing or explanation which is longer than
wind leg, downwind leg, base leg and             necessary and therefore uninteresting.)
final approach.                                     lengthy meeting a long meeting
      ‘…their route was across the States to     lengthy explanation a long explana-
      Canada, Greenland and the North Pole,      tion
                                                 lens /lenz/ noun a normally round

      into Norway, through Europe, back to
      Iceland, then two long legs across the     piece of glass with curved surfaces
      Atlantic via South Greenland and back to   found in microscopes, telescopes, cam-
      Seattle’ [Pilot]                           eras, spectacles, etc.
legal / li (ə)l/ adjective lawful or             lens-shaped cloud / lenz ʃept
legal                                            lens-shaped cloud

within the law Alcohol concentrations             klaυd/, lenticular cloud /len tkjυlə

of 40 milligrams per 100 millilitres, i.e.        klaυd/ noun cloud with slightly out-
half the legal driving limit in the UK,          wardly-curved upper and lower sur-
are associated with substantial                  faces
increases in errors committed by pilots.         lessen / les(ə)n/ verb to make less

legend / led ənd/ noun a list explain-

                                                 Reverse thrust is used to lessen the
ing the symbols on a chart or a map A            loads on brakes and tyres. Clean fil-
legend is usually to be found at the edge        ters lessen the possibility of blockage.
                                                 letdown / letdaυn/ noun the descent

or on the reverse side of most topo-
graphical charts.                                of an aircraft in preparation for landing,
length /leŋθ/ noun 1. a measurement
                                                 before the actual landing approach
                                                 level / lev(ə)l/ adjective 1. level with

along something’s greatest dimension
the length of the aircraft The runway            at the same height or position as some-
length is 3 kilometres. 2. a piece of            thing else In most light aircraft, the
something that is normally measured              aeroplane will be in a climb if the
along its greatest dimension a length            engine cowling is level with the horizon.
of pipe 3. the extent from beginning to          2. having a flat, smooth surface a level
end the length of a book 4. extent or            runway a runway without bumps, etc.
duration, the distance between two               3. on a horizontal plane 4. steady, refer-
points in space or time the length of a          ring to something with no sudden
briefing how much time the briefing              changes speak in a level voice do not
takes the length of the working life             raise and lower the sound of your voice
of components how long the compo-                   the level tone of an engine the
nents last the length of a flight 1. the         unchanging sound of an engine level
time it takes to complete a flight The           head clear thinking It is essential that
length of the flight meant that there was        the crew keeps a level head in an emer-
no time for a meal to be served to the           gency. í noun 1. a position along a ver-
                                                 tical axis     ground level      reference
passengers. 2. the distance of the flight
                                                 level The tropopause is the level at
in nautical miles or kilometres The              which the lapse rate ceases to be so
length of the flight is 100nm.                   important. the fluid level in the res-
lengthen / leŋθən/ verb to make long

                                                 ervoir the point where the surface of
or longer The mercury column short-              the fluid reaches up to         high-level
ens when cooled and, due to expansion,           cloud high-altitude cloud 2. a position
lengthens when heated. Opposite                  on a scale an advanced level of study
shorten                                          3. a relative amount, intensity, or con-
level off                                           136
centration an unsafe level of contami-                ‘to put down’ as in ‘lay the book on the
nation a reduced level of noise A gas                 table’: lay – laid – laid.)
turbine engine has an extremely low                   life jacket / laf d kt/ noun an
                                                      life jacket

vibration level.                                      inflatable device, sometimes resem-
level off / lev(ə)l ɒf/ verb to start to              bling a sleeveless jacket, to keep a per-
level off

fly level with the ground after climbing              son afloat in water Pull down the tog-
or descending, or make an aircraft do                 gles to inflate the life jacket.
this                                                  life raft / laf rɑ ft/ noun a small boat-
                                                      life raft

lever / li və/ noun 1. a device with a                like vessel for use on an emergency

rigid bar balanced on a fixed point and               over water
                                                      life vest / laf vest/ noun same as life
                                                      life vest

used to transmit force, as in raising a
weight at one end by pushing down on                  jacket You will find a life vest under
the other Push the lever fully up to                  your seat.
activate the brake mechanism. Push                    lift /lft/ noun 1. a component of the

the button to release the lever. 2. a han-            total aerodynamic force acting on an
dle used to adjust or operate a mecha-                aerofoil which causes an aeroplane to
nism throttle lever undercarriage                     fly In level flight, a lift force equal to
selector lever Feathering is accom-                   the weight must be produced.          The
plished by moving the pilot’s control                 pilot can achieve maximum lift by pull-
lever. í verb to move as with a lever                 ing hard back on the controls. 2. an
The door would not open so the emer-                  electrically operated machine for mov-
gency services had to lever it open with              ing people or goods between the floors
specialised equipment.                                of a building (NOTE: The US English is

LF abbreviation low frequency                         elevator.) í verb to move to a higher
licence / las(ə)ns/ noun a document
                                                      position A foot-pound is the ability to
which is proof of official permission to              lift a one pound weight a distance of
do or to own something                                one foot.
                                                             COMMENT: Bernoulli’s principle states
      COMMENT : Each licence has its own
                                                             that if the speed of a fluid increases, its
      specific requirements and privileges.
                                                             pressure decreases; if its speed
      In the UK, one of the fundamental
                                                             decreases, its pressure increases.
      differences between a Private Pilot’s
                                                             Wings are shaped so that the high-
      Licence and other types of licence is
                                                             speed flow of air that passes over the
      that the holder of a PPL is not allowed
                                                             curved upper surface results in a
      to fly for ‘hire or reward’, i.e. the pilot
                                                             decrease in pressure. Lift is created
      cannot receive payment for flying.
                                                             because of the pressure differential
licence holder / las(ə)ns həυldə/
licence holder

                                                             between upper and lower surfaces of
noun 1. a person who has a licence 2. a                      the wing. Lift is also created because
                                                             the angle of attack allows the airflow to
leather case, etc., in which to keep the                     strike the underside of the wing. Daniel
licence document                                             Bernoulli (1700–82) was a Swiss
license / las(ə)ns/ noun US same as

licence í verb to give somebody a                     light /lat/ noun 1. brightness pro-

licence or official permission to do or to            duced by the sun, the moon, a lamp, etc.
own something                                         2. electromagnetic radiation which can
lie /la/ verb 1. to be in a flat position,

                                                      be sensed by the eyes artificial light
often horizontal         Seat rails are               light made by using electrical, gas, etc.,
attached to the floor beams and lie level             power 3. a source of light such as a lamp
with the flooring. 2. to be situated                     Switch off the navigation lights. í
Great circles are represented by curves               adjective 1. without much weight, not
which lie on the polar side of the rhumb              heavy Aluminium is a light metal. 2.
line. (NOTE: Care should be taken with                of little force or requiring little force a
the verbs to lie, as defined here: lie –              light wind a gentle wind light con-
lay – lain; to lie meaning ‘not to tell the           trols flying controls which do not need
truth’: lie – lied – lied and lay, meaning            much pilot effort to move them 3. of lit-
                                         137                                      link
tle quantity light rain light snow 4.        etc. a line of people a line of cumu-
of thin consistency light oil oil which      lus clouds 4. a row of written or printed
pours easily                                 words Look at line 4 on page 26. 5. a
light aircraft / lat eəkrɑ ft/ noun a       telephone connection to another tele-
light aircraft

small, single engine aircraft generally      phone or system Dial 9 to get an out-
for private not commercial use               side line. 6. an electrical cable or wire
lighting / latŋ/ noun lights or a sys-
                                             telephone line cable supported on
tem of lights         Cabin lighting is      pylons from one telephone exchange to
switched off for take-off and initial        another On final approach to an unfa-
climb.       Emergency floor lighting        miliar airfield, pilots of light aircraft
guides passengers to the emergency           should keep a sharp lookout for power
exits.                                       lines and telephone lines. 7. a system of
                                             pipes a fuel line 8. a company which
lightning / latnŋ/ noun a powerful

                                             owns and manages a system of trans-
and sudden electrical discharge from a       portation routes a shipping line an
cloud Lightning is the most visible
indication of thunderstorm activity.         airline such as KLM or QANTAS
                                             linear / lniə/ adjective referring to a

lightning activity / latnŋ             k
lightning activity


 tvti/ noun a period of time when          line, straight Although air may appear
there are a lot of lightning flashes         to be still or calm it is, in fact, moving
lightning strike / latnŋ strak/
lightning strike                             west to east in space, the linear velocity
noun the hitting of something by a dis-
                                             being zero at the poles and approxi-
charge of lightning                          mately 1,000 mph at the equator. lin-
                                             ear scale a horizontal or vertical
light plane / lat plen/ noun US
light plane

                                             straight-line, rather than circular, scale
same as light aircraft                       on an instrument
likely / lakli/ adjective probable

                                             linear actuator / lniə ktjuetə/
                                             linear actuator

rain is likely rain will probably fall
icing is likely to occur in cumulonim-       noun an actuator which operates in a
bus clouds icing is often a problem if       straight back and forth manner, e.g. to
flying in cumulonimbus clouds                open undercarriage doors
                                             line feature / lan fi tʃə/ noun a use-
                                             line feature

limit / lmt/ noun a point or line past

which something should not go There          ful navigational landmark, e.g. a rail-
is a time limit of one hour for the exam-    way line, road or river
ination. The minimum age limit for           line of position / lan əv pə
                                             line of position


holding a PPL in the UK is 17. the            zʃ(ə)n/ noun same as position line
upper limit of cloud the highest point
                                             line of sight / lan əv sat/ noun a
                                             line of sight

at which there is cloud í verb to restrict
or to prevent from going past a particu-     clear path between sending and receiv-
lar point The amount of cabin bag-           ing antennas. Abbreviation LOS
                                             line up / lan p/ verb to move air-
                                             line up

gage is limited to one bag per passen-
ger.                                         craft into position ready for departure
limitation / lm teʃ(ə)n/ noun the         Line up with the nosewheel on the run-


act of limiting or the state of being lim-   way centre line.
ited      Limitation of the maximum          link /lŋk / noun 1. a connection Light

engine rpm to a little above maximum         aircraft can be steered while taxiing via
engine cruise rpm prevents compressor        a direct link from rudder pedals to nose-
stall at the higher rpm range.               wheel. 2. a relationship There is a link
line /lan/ noun 1. a thin continuous

                                             between alcohol abuse and pilot error
mark as made by a pencil, pen, etc. or       resulting in accidents. í verb 1. to make
printed Draw a line from point A to          a connection, to join The connecting
point B. 2. a real or imaginary mark         rod links the piston to the crankshaft. 2.
placed in relation to points of reference    to establish a relationship between two
   An isobar is a line joining points of     situations They link alcohol abuse and
equal pressure. 3. a long row of people,     pilot error.
linkage                                   138
linkage / lŋkd / noun a system or           increases and, when the aircraft rises

series of mechanical connections such         into the air, the aircraft is supported by
as rods, levers, springs, etc. throttle       the wings. load bearing supporting
linkage rudder linkage The linkage            some weight 2. a force which a struc-
from the control column to the control        ture is subjected to when resisting
surfaces should allow full and free           externally applied forces The load on
movement.                                     the control column is increased when
liquid / lkwd/ adjective having a
                                              the aircraft is flown out of trim. 3.
consistency like that of water Liquid         something that is carried in the aircraft
oxygen is stored in cylinders. í noun a           fuel load       passenger load the
substance with a consistency like water       number of passengers on board 4. the
   Water is a liquid, ice is a solid.         power output of a generator or power
                                              plant 5. the resistance of a device or of
liquid crystal display / lkwd
liquid crystal display

                                              a line to which electrical power is pro-
 krst(ə)l ds ple/ noun liquid crystals

                                              vided í verb 1. to put something into a
that reflect light when a voltage is          container, often for the purpose of
applied, used in many watch, calculator       transportation The aircraft is loaded
and digital displays. Abbreviation LCD        with fuel before take-off. 2. to transfer
liquid fire / lkwd faə/ noun oil or
liquid fire

                                              data from disk into a computer main
petrol fire                                   memory She loaded the software onto
list /lst/ noun a series of names,

                                              the computer.
words, things to do, etc., arranged one       load-bearing structure / ləυd
                                              load-bearing structure

after the other in a vertical column í         beərŋ str ktʃə/ noun a structure
verb to write a series of names, words,       which supports the weight of the air-
etc. one after the other in a vertical col-   craft in flight or on the ground
umn List the advantages of a stressed-
                                              load controller / ləυd kən trəυlə/
                                              load controller

skin construction.                                                                 |

                                              noun a device which monitors the out-
liter / li tə/ noun US same as litre

                                              put of a generator
lithium / lθiəm/ noun a soft silvery

                                              load factor / ləυd f ktə/ noun the
                                              load factor

metallic element, the lightest known
metal, often used in batteries an alloy       stress applied to a structure as a multi-
of aluminium and lithium                      ple of stress applied in 1g flight The
                                              higher the angle of bank, the greater the
litmus / ltməs/ noun a substance

                                              load factor.
which turns red in acid, and blue in
alkali                                            COMMENT:       In straight and level,
                                                  unaccelerated flight, the load factor is
litmus paper / ltməs pepə/ noun
litmus paper

                                                  1. When an aircraft turns or pulls up
small piece of paper impregnated with             out of a dive, the load factor increases.
litmus to test for acidity or alkalinity          An aircraft in a level turn at a bank
litre / li tə/ noun the volume of one kil-        angle of 60 degrees has a load factor

ogram of water at 4°C (= 1,000cc or               of 2. In such a turn, the aircraft’s
                                                  structure must support twice the
1.76 pints) (NOTE: It is written l after a        aircraft’s weight.
figure: 10l; also written liter in US Eng-
                                              loading / ləυdŋ/ noun 1. the act or

live /lav/ adjective carrying electricity
                                              process of adding a load to an aircraft
        live wire                             loading is in progress passengers, bag-
                                              gage, freight, etc., are being put on the
livery / lvəri/ noun the colour scheme

                                              aircraft 2. the total aircraft weight or
and markings on the outside of an air-        mass divided by wing area          Inertia
craft that identify it as belonging to a      switches operate automatically when a
particular airline                            particular g (acceleration due to
LMT abbreviation local mean time

                                              Earth’s gravity) loading occurs. 3. a
load /ləυd/ noun 1. the weight or mass

                                              force or stress acting on an object cen-
which is supported The load on the            trifugal loading centrifugal force act-
undercarriage decreases as lift               ing on something Centrifugal loading
                                        139                                    logic
moves the valve towards the closed          local time / ləυk(ə)l tam/ noun the
                                            local time

position. 4. the act of transferring data   time in the country you are talking
from disk to memory Loading can be          about
a long process.                             locate /ləυ ket/ verb 1. to find the


loading bridge / ləυdŋ brd / noun
loading bridge

                                            position of Survival beacons transmit
a covered walkway from an airport           a signal which enables search air-
departure gate that connects to the door    craft/vessels to rapidly locate accident
of an aircraft, used by passengers and      survivors still in the sea. 2. to position
crew getting on and off the aircraft        The digital flight data recorder is
load manifest / ləυd m nfest/
load manifest
                                            located in the tail section.
                                            location /ləυ keʃ(ə)n/ noun 1. a

noun a detailed list of the cargo on a                            |

flight. Also called load sheet              place where something can be found
                                            Before take-off, cabin staff brief passen-
loadmaster / ləυdmɑ stə/ noun the

                                            gers on the location of emergency exits
person who is in charge of the work of      and life jackets. 2. finding where some-
loading cargo onto a military or com-       thing is Rapid location of survivors is
mercial transport aircraft                  important.
load sheet / ləυd ʃi t/ noun same as
load sheet

                                            locator /ləυ ketə/ noun a non-direc-


load manifest                               tional beacon used as an aid to final
lobe /ləυb/ noun one of two, four or        approach        Terminal control areas

more sub-beams that form a directional      require charts which show detail on a
radar beam       Any system employing       large scale – terminal VORs, locator
beam sharpening is vulnerable to side       beacons, ILS installations, holding pat-
lobe generation at the transmitter.         terns, arrival/departure and transit
LOC abbreviation localiser
                                            lock /lɒk/ noun a device operated by a

local / ləυk(ə)l/ adjective not broad or

                                            key for securing a door, etc. í verb 1. to
widespread        local meteorological      secure a door by turning a key in the
conditions weather conditions in the        lock Lock the door before leaving the
restricted area of a particular place       building. 2. to be in or to move into a
local authority / ləυk(ə)l ɔ θɒrti/
local authority

                                 |          secure position 3. to block or prevent
noun a government body responsible          moving       Anti-skid braking systems
for the various services of an area         units are designed to prevent the brakes
                                            locking the wheels during landing. 4.
localised / ləυkəlazd/, localized

                                            to lock on to search for, find and follow
adjective restricted in area or influence
                                            a target with a thin radar beam
  a localized fire a fire which has not
                                            locking pin / lɒkŋ pn/ noun a short
                                            locking pin

                                            metal device to prevent a nut from turn-
localiser /ləυkə lazə/, localizer

noun a component of the instrument
                                            log /lɒ / noun a written record of a

landing system that provides horizontal
course guidance to the runway If, dur-      flight, flying hours, maintenance
ing the approach, the aircraft deviates     checks, etc., for an aircraft, engine or
beyond the normal ILS glideslope            propeller í verb to write an entry in a
and/or localiser limits, the flight crew    log book or on a log sheet He calcu-
are alerted. Abbreviation LOC               lates headings to steer for each flight
                                            stage and logs them.
locality / ləυ k lti/ noun a small geo-

                                            logic / lɒd k/ noun electronic circuits

graphical area The highest point in a       which obey mathematical laws Cir-
locality is marked by a dot with the ele-   cuit packs consist of basic decision-
vation marked alongside.                    making elements, referred to as logic
local mean time / ləυk(ə)l mi n
local mean time

                                            gates, each performing operations on
 tam / noun the time according to the      their inputs and so determining the
mean sun. Abbreviation LMT                  state of their outputs.
logical                                  140
logical / lɒd k(ə)l/ adjective refer-       lose /lu z/ verb not to have something
logical                                      lose

ring to something which, because of          any longer (NOTE: losing – lost) to
previous experience or knowledge, is         lose altitude to descend from higher to
natural or expected Pre-flight checks        lower altitude
on light aircraft are made in a logical      loss /lɒs/ noun no longer having

manner from one side of the aircraft to      something The pilot reported loss of
the other.                                   engine power.       loss of control no
longeron / lɒnd (ə)rən/ noun the             longer being able to control loss of

main structural part of an aircraft fuse-    life death in an accident loss of a sig-
lage extending from nose to tail Long-       nal disappearance of a signal       The
erons are normally used in aircraft          term attenuation means the loss of
which require longitudinal strength for      strength of a radio signal.
holds underneath the floor.                  loudspeaker / laυd spi kə/ noun an


long-haul / lɒŋ hɔ l/ adjective trav-        electromagnetic device that converts

elling over a long distance Crew flying      electrical signals into audible noise.
long-haul routes have to adapt to time       Also called speaker
changes. Opposite short-haul                 lounge /laυnd / noun VIP lounge a

longitude / lɒŋ tju d/ noun the
                                             special room at an airport for VIPs.
angular distance on the Earth’s surface,     departure lounge
                                             louvre / lu və / noun thin, horizontal

measured east or west from the prime
meridian at Greenwich, UK, to the            openings for air cooling Cold air can
meridian passing through a position,         be let into the cabin through adjustable
expressed in degrees, minutes, and sec-      louvres. ( NOTE: The US spelling is lou-
onds The centre of London is latitude        ver.)
51°30’N, longitude 0°5’W. Compare            low /ləυ/ adjective 1. not high, not tall

latitude                                       a low building low cloud cloud rel-
                     / lɒŋ  tju dn(ə)l/

longitudinal                |                atively near the surface of the earth
adjective in a lengthwise direction          low ground an area of land which is not
longitudinal axis

longitudinal                          axis   high, as opposed to mountains 2. not
/ lɒŋ tju dn(ə)l      kss/ noun the       high, or below normal an area of low
axis of the aircraft which extends from      pressure low temperature a tempera-
the nose to the tail. axis, roll             ture which shows that it is cold 3. quiet,
                                             not loud í noun an area of low atmos-
long-range / lɒŋ rend / adjective

                                             pheric pressure polar low an area of
1. covering a long distance         long-    low atmospheric pressure over polar
range radar 2. long-range weather            regions
forecast covering a period more than 5       lower / laυə/ adjective 1. referring to

days ahead                                   something that is at a low level or
lookout / lυkaυt/ noun a careful

                                             towards the bottom the lower layers of
watch      Keep a careful lookout for        the atmosphere the lower surface of
other aircraft. to be on the lookout         the wing the underneath surface of the
for to watch carefully for something         wing 2. referring to something which is
loop /lu p/ noun a flight manoeuvre in
                                             below something else of the same sort
which the aircraft rotates, nose up,         Air is cooler high up than at lower lev-
through 360° while holding its lateral       els. Opposite upper í verb 1. to let
position                                     down to a lower position lower the
                                             undercarriage move the undercarriage
loop antenna / lu p n tenə/ noun
loop antenna

                                             into position ready for landing lower
circular-shaped conductive coil which        the flaps set the flaps to a down posi-
rotates to give a bearing to a ground sta-   tion 2. to reduce in amount or intensity
tion                                            to lower the temperature to reduce

LORAN abbreviation long-range air            the temperature to lower the pres-
navigation system                            sure to decrease the pressure to lower
                                         141                               luggage
the volume (of sound) to make some-          lubricate / lu brket/ verb to oil or to

thing such as a radio quieter or less loud   grease moving parts in order to reduce
lower airspace / ləυə eəspes/
lower airspace
                                             friction Oil passes through the hollow
noun the airspace below FL245                crankshaft to lubricate the big-end
(approximately 24,500 ft)                    bearings. Turbo chargers are lubri-
                                             cated by the engine oil system.
                                    / ləυə
lower atmosphere

lower         atmosphere                     lubrication / lu br keʃ(ə)n/ noun

   tməsfə/ noun the layer of the

                                             the act or process of covering moving
atmosphere in which changes in the           surfaces with oil or grease in order to
weather take place. Also called tropo-       reduce friction     lubrication system
sphere                                       the tank, pipes, pumps, filters, etc.,
low frequency / ləυ fri kwənsi/,
low frequency

                                             which together supply oil to moving
low frequency band / ləυ fri kwənsi          parts of the engine
 b nd/ noun a radio communications           luggage / l d / noun baggage, i.e.

range of frequencies between 30–300          cases and bags that somebody takes
kHz. Abbreviation LF                         when travelling
m1 abbreviation metre                         field A freely suspended magnet – not

m2 abbreviation minute
                                              influenced by outside forces – will align
                                              itself with the Earth’s magnetic lines of
Mach /m k/ noun the ratio of the

                                              force which run from the north mag-
speed of an object to the speed of sound      netic pole to the south magnetic pole.
in the same atmospheric conditions
                                              magnetic bearing /m netk
                                              magnetic bearing

Mach 2 equals twice the speed of sound.                                                |

                                               beərŋ/ noun the angle measured in a
       COMMENT : Named after E. Mach, the     clockwise direction of a distant point,
       Austrian physicist who died in 1916.
                                              relative to magnetic north
machine /mə ʃi n/ noun a device               magnetic declination /m netk
                                              magnetic declination

with fixed and moving parts that takes         dekl neʃ(ə)n/ noun same as mag-

mechanical energy and uses it to do use-      netic variation To convert magnetic
ful work A drill is a machine for mak-        bearing into true bearing it is necessary
ing holes in things. An electrical cir-       to apply magnetic variation at the point
cuit is designed to carry energy to a         at which the bearing was taken.
particular device or machine which can        magnetic field /m
                                              magnetic field

                                                                          netk fi ld/

then perform useful work.                     noun area of magnetic influence
Machmeter / m kmi tə/ noun an

                                              magnetic north /m           netk nɔ θ/
                                              magnetic north


instrument for measuring the Mach             noun the direction of the Earth’s mag-
number of an aircraft                         netic pole, to which the north-seeking
Mach number /m k/ noun a number
Mach number

                                              pole of a magnetic needle points if unaf-
that expresses the ratio of the speed of      fected by nearby influences
an object to the speed of sound               magnetic pole /m netk pəυl/
                                              magnetic pole


magnesium /m           ni ziəm / noun a

                                              noun one of the two poles which are the
light, silvery-white metallic element         centres of the Earth’s magnetic field
that burns with a brilliant white flame.      magnetic variation /m netk
                                              magnetic variation