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VIEWS: 18 PAGES: 59

									NS/LA/03/                                                      14/05/03

                           CNS Circular 1 of 2003

 Subject:            Lightening Arrestor for CNS facilities

       It has been observed that at times the failure of the CNS facilities is due to
lightening, which indicates poor earthing systems. This problem has to be
handled expeditiously to avoid the facility failure due poor earthing. It is
suggested that the following points should be checked for proper earthing of a
CNS facility.

DVOR:

      1. Counter poise should have four independent earthing pits for proper
         earthing. This earthing system should not be looped with any other
         earthing systems.
      2. The equipment should have independent earthing system.
      3. DVOR counterpoise should also have four lightening arrestors and their
         heights should be more than side band antennas.
      4. DVOR monitor antenna should have independent earthing system and
         provision of lightening arrestor should be made above the monitor
         antenna.
      5. Co-located DME (HP) antenna should have independent earthing
         system for lightening arrestor and it should be kept above the antenna
         height.
      6. The earthing strips joint should be brazed instead of joining with nut
         and bolts.
      7. The earthing resistance should be kept less than one ohm.

RADAR:

    1. Radar equipment should have independent earthing systems and should
       not be looped with any other earthing system.
    2. Radar antenna building should have two earthing pits diagonal to each
       other and lightening arrestor should be connected to this earthing pits.
    3. The earthing strips joint should be brazed instead of joining with nut and
       bolts.
    4. The height of the lightening arrestor should be kept more than the radar
       antenna height.
INSTRUMENT LANDING SYSTEM (ILS):

  a. Localizer

       1. The equipment should have independent earthing system.
       2. Antenna system should have two earthing pits and should not be
          looped and lightening arrestor should be connected with it.
       3. Height of the lightening arrestor should be more than height of the
          LLZ antenna.
       4. The earthing strips joint should be brazed instead of joining with nut
          and bolts.
       5. The height of the lightening arrestor should be kept more than LZ
          antenna height.


  b. Glide path

       1.    The equipment should have independent earthing system.
       2. Antenna system should have one earthing system and lightening
          arrestor should be connected with this.
       3. DME antenna should have independent earthing system.
       4. The earthing strips joint should be brazed instead of joining with
          nuts and bolts.
       5. The height of the lightening arrestor should be one feet above the
          GP mast.


  c. Marker and locators

       1. The Marker and Locator equipment should have their independent
          earthing system.
       2. The antennas of the both system should have their own
          independent earthing pits.
       3. The lightening arrestor should be placed above the antenna or the
          highest point in vicinity of equipment building.
       4. The earthing strips joint should be brazed instead of joining with
          nuts and bolts.


NON-DIRECTIONAL BEACON (NDB):

      1. The NDB equipment should have their independent earthing system.
       2. The antenna should have its own independent earthing pits.
       3. The lightening arrestor should be placed one foot above the antenna.
       4. The earthing strips joint should be brazed instead of joining with nut
          and bolts.

      The equipment and its associated earthing system should be checked as
per above checklist and report the compliance to the CHQ at the earliest.


                                                                         Sd/-
                                                                   (A. K. Misra)
                                                  Executive Director (CNS-OM)
                                                                      14.5.2003
No. NS/4Gen/240/03                                          Dated: Sep 4, 2003


                        CNS Circular No. 2 of 2003

                   Subject :- VOR Aerodrome Check points
As per the guidelines contained in Annexure 10, Volume-I, Attachment-E and para 5.2.11
& 5.4.4 Annexure 14, the detail information on VOR aerodrome checkpoints is appended
below for reference.

            SELECTION AND USE OF VOR AERODROME
                       CHECK-POINTS

               1. GENERAL

1.1   When a VOR is suitably located in relationship to an aerodrome, the pre-flight
      checking of an Aircraft VOR installation can be facilitated by the provision of suitably
      calibrated and marked CHECK-POINTS at convenient parts of the aerodrome.

1.2    Following guidelines are provided for consideration in selecting the points to be used.

              2. SITING REQUIREMENTS FOR CHECK-POINTS
2.1    The signal strength of the nearby VOR has to be sufficient to ensure
       satisfactory operation of a typical aircraft VOR installation. In particular, full flag
       action (No flag showing) must be ensured.

2.2    The check-points should, within the limits of operating convenience, be located
       away from buildings or other reflecting objects (Fixed or Moving) which are
       likely to degrade the accuracy or stability of the VOR signal.

2.3    The observed VOR bearing at any selected point should ideally be within + or –
       1.5 degrees of the bearing accurately determined by survey or chart plotting.

       Note:- The figure of plus or minus 1.5 degrees has no direct operational
       significance in that the observed bearing becomes the published bearing :
       however where a larger difference is observed, there is some possibility of poor
       stability.
 2.4     The VOR information at a selected point should be used operationally only if
         found to be consistently within + or - 2 degrees of the published bearing. The
         stability of the VOR information at a selected point should be checked
         periodically with a calibrated receiver to ensure that the + or – 2 degrees tolerance
         is satisfied, irrespective of the orientation of the VOR receiving antenna.

         Note:- The tolerance of + or – 2 degrees relates to the consistency of the
         information at the selected points and includes a small tolerance for the accuracy
         of the calibrated VOR receiver used in checking the point. The 2-degree figure
         does not relate to any figure for acceptance or rejection of an aircraft VOR
         installation, this being a matter for determination by Administrations and users in
         the light of the operation to be performed.

 2.5     Check-points, which can satisfy the foregoing requirements, should be selected in
         consultation with the operators concerned. Provision of check-points in holding
         bays, at runway ends and in maintenance and loading areas, is usually desirable.

         MARKING OF VOR CHECK-POINTS

2.6 Each VOR check-point must be distinctively marked. This marking must include the
     VOR bearing which a pilot would observe on his aircraft instrument if his VOR
     installation were operating correctly

         USE OF VOR CHECK-POINTS

2.7 The accuracy with which a pilot must position his aircraft with respect to a check-
     point will depend on the distance from the VOR station. In cases where the VOR is
     relatively close to a check-point, particular care must be taken to place the aircraft’s
     VOR receiving antenna directly over the check-point.




                     VOR AERODROME CHECKPOINT MARKING

 2.8     When a VOR aerodrome checkpoint is established it shall be indicated by a
         VOR aerodrome checkpoint marking and sign. A VOR aerodrome checkpoint
         marking shall be centered on the spot at which an aircraft is to be parked to
         receive the correct VOR signal. A VOR aerodrome checkpoint marking shall
         consists of a circle 6 meter in diameter and have a line width of 15 cm. as shown
         below.
A. – WITHOUT DIRECTIONAL LINE                    B. – WITH DIRECTIONAL LINE




      When it is preferable for an aircraft to be aligned in a specific direction, a
      line should be provided that passes through the center of the circle on the
      desired azimuth as shown above. The line should extend six meters outside
      the circle in the desired direction of heading and terminate in an arrowhead.
      The width of the line should be 15 c.m.


Note: - VOR aerodrome checkpoint marking should preferably be white in color but
should differ from the color used for taxiway markings. To provide contrast, marking
may be bordered with black.




            VOR AERODROME CHECKPOINT SIGN
2.9   A VOR aerodrome checkpoint sign shall be located as near as possible to the
      check point and so that the inscriptions are visible from the cockpit of the
      aircraft properly positioned on the VOR aerodrome check-point markings.
      Note: A VOR aerodrome check-point sign shall consist of an inscription in black
      on a yellow background.
2.10   The recommended inscriptions on a VOR check-point sign should be in
       accordance with one of the alternatives shown below: -

       VOR          is an abbreviation identifying this as a VOR check-point;
       116.3               is an example of the radio frequency of the VOR concerned
       147          is an example of the VOR bearing, to the nearest degree, which
                    should be indicated at the VOR check-point; and
       4.3 NM       is an example of the distance in nautical miles to a DME
       collocated
                    with the VOR concerned.




The guidelines mentioned above should be examined for establishing the VOR check-
point at your airport.
                                                                              Sd..
                                                                        (A.K.MISRA)
                                                        Executive Director (CNS-OM)
Ref No. NS /SA/410/03                                              Dated 24 -11- 03


                               CNS Circular No. 3 of 2003


    PROVISION OF INFORMATION ON THE OPERATIONAL STATUS OF
                      NAVIGATIONAL AIDS

        As per Annex-11, Para 7.3.1, ATS units shall be kept currently informed of the
operational status of non-visual navigation aids & those visual aids essential for take –off
, departure, approach & landing procedure within their area of responsibility and those
visual & non-visual aids for surface movement.

        Annex-11, Para 7.3.2, states that information received on the operational status,
and any changes thereto, of visual and non-visual aids referred to in Annex-11, Para 7.3.1
should be received by the appropriate ATS unit(s) on a timely basis consistent with the
use of aid(s) involved.

        Major types of equipment associated with ATC services include:

   1)      NDB (Non Directional Beacon)
   2)      DVOR/VOR (Doppler VHF Omni Range / VHF Omni Range)
   3)      DME (HP)/DME(LP) (Distance Measuring Equipment – High Power / Low
           power)
   4)      ILS (Instrument Landing System)
   5)      Markers/ Locators

The respective functional and operational requirements for the equipments listed above
are discussed below:

   1)      NDB :

As per Doc. 9426 (Air Traffic Services Manual) Para 3.1.1, NDB transmits non-
directional signals in the low & medium frequency bands, between 190 to 1750 KHz.
With appropriate airborne equipment, the pilot can determine the bearing of the station or
can “home” on the station. The specific identification of NDB is normally broadcast in
Morse code. As per Doc.9426, Para 3.2.1.b, NDBs used in conjunction with ILS are
designated as “Locators”.
As per Annex-10, Vol-I , Para 3.4.8.1 for each NDB suitable means shall be provided to
enable detection of any of the following conditions at an appropriate location :

     a) Decrease in radiated carrier power of more than 50 % below that required for the
        rated coverage.

     b) failure to transmit the identification signal

     c) Malfunctioning or failure of the means of monitoring itself.

Failure of any of the above results in alarm indication in the local / remote unit installed
at appropriate locations.

2)       DVOR/ VOR:

As per Doc.9426, Para 2.1.1, the VHF omni-directional radio range (VOR) is an omni
directional (3600 of azimuth) range station which operates in the very high frequency
(VHF) band of the radio spectrum between 108 to 118 MHz , sharing the band from 108
to 112 MHz with the localiser component of ILS. The basic navigation guidance derived
from a VOR is a radial line of position (magnetic) w.r.t. a known geographic point (the
VOR site). The radial line is read in degrees of azimuth from magnetic North & is
technically accurate to within ± 2.00.
        Doc.9426, Para 2.1.2 states that the identification of specific VORs is provided by
means of Morse code identifier or by voice recording. VORs can be remotely operated by
means of telephone lines from the control facility. Where standby or dual equipment is
provided, an automatic transfer between the equipment is made whenever the operating
VOR is subject to malfunction.

        As per Annex-10, Vol-I, Para 3.3.7.1 , suitable equipment located in the radiation
field shall provide signals for the operation of an automatic monitor . The monitor shall
transmit a warning to a control point , and either remove the identification & navigation
components from the carrier or cause radiation to cease if any one or a combination of the
following deviations from established conditions arises :

     a) a change in excess of 10 at the monitor site of the bearing information transmitted
        by the VOR.
     b) a reduction of 15% in the modulation components of the radio frequency signals
        voltage levels at the monitor of either sub carrier , or 30 Hz amplitude modulation
        signals or both.

   Annex-10 , Vol-I Para 3.3.72 states that failure of the monitor itself shall transmit a
warning to a control point & either
   a) remove the identification & navigation components from the carrier ; or
   b) cause radiation to cease.
3)        DME (HP)/DME (LP)

        As per Doc. 9426, Para 2.1.6, DME is a useful adjunct to, & is normally co-
located with VOR. In such cases, the VOR is referred to as “VOR/DME”. A DME
provides a continuous digital read out of the slant range distance, in nautical miles,
between the aircraft and the DME site. DME operates in the UHF band between 962
MHz & 1213 MHz.

       As per Annex-10 , Vol-I, Para 3.5.4.7.1 , means shall be provided at each
transponder site for the automatic monitoring and control of the transponder in use.

        Annex-10 Vol-I Para 3.5.4.7.2.1, states that in the event of any of the conditions
specified below occur, the monitor shall cause following action to take place:

     a)     a suitable indication shall be given at a control point ;
     b)     the operating transponder shall be automatically switched off ; and
     c)     the standby transponder , if provided, shall be automatically placed in
            operation.

     As per Annex-10 , Vol-I , para 3.5.4.7.2.3 , the monitor shall cause the actions
     specified in 3.5.4.7.2.1 above if the spacing between first and second pulse of the
     transponder reply pulse pair differs from the nominal value by 1μs or more.

         As per Annex-10 , Vol-I , Para 3.5.4.7.2.4 , the monitor should also cause a
     suitable indication to be given at a control point if any of the following conditions
     arise :

     a) a fall of 3 dB or more in transponder transmitted power output;
     a) a fall of 6 dB or more in the minimum transponder receiver sensitivity;
     b) the spacing between the first and second pulse of the transponder reply pulse pair
        differs from the normal value specified in Annex-10 , Vol-I , Para 3.5.4.1.4 by
        1μsec or more ;
     c) variation of the transponder receiver & transmitter frequencies beyond the control
        range of the reference circuit.

     The monitor system shall provide a Normal/Warning/Alarm indication at a control
     point. Same status shall be extended to ATC tower.

     d) ILS
         As per Doc.9426, Para 5.1.1.1, the ILS is the ICAO standard, non-visual
     navigation aid to final approach and landing. Ground equipment consists of two
     highly directional transmitting systems and two marker beacons aligned along the
     approach. The directional transmitters are known as localiser and glide slope
     transmitters. The total landing system of which ILS is an integral part generally
     provides the pilot with:
   a) guidance information regarding the approach path derived from the localiser and
      the glide slope ;
   b) range information at significant points along the approach path by marker beacon
      or continuous range information from Distance Measuring Equipment (DME) ;
   c) visual information in the last phase of flight from approach lights , touch down
      and center line lights , runway lights.

   Doc.9426 Para 5.1.1.2 states that at selected locations where the provision of marker
   beacons at the defined locations creates difficulties, they may be replaced by a DME
   which is associated with ILS.

   As per Annex-10 , Vol-I , para 3.1.2.1 the ILS shall comprise the following basic
   components :

        a) VHF Localiser equipment, associated monitor system, remote control and
           indicator equipment;

        b) UHF Glide path equipment, associated monitor system, remote control and
        indicator equipment ;

        c) VHF Marker beacons, associated monitor systems, remote control and
        indicator equipment

       As per Doc 9426, Para 5.1.1.4 the localiser provides course guidance throughout
   the descent path to the runway threshold from a distance of 18 NM from the antenna
   between a height of 300 m above the highest terrain along the approach path and
   1350 m above the elevation of the antenna site. Distinct off-course indications are
   provided throughout the areas of the operational service as under:

           a. 10 º either side within a radius of 18 NM from the antenna ;
           b. 35º either side within a radius of 10 NM from the antenna.

As per Annex-10 Vol-I Para 3.1.3.11.1, of , the automatic monitor system shall provide
a warning to the designated control points and cause one of the following to occur ,
within the period specified in Annex-10 , Vol-I, Para 3.1.3.11.3.1, if any of the conditions
stated in Annex-10 Vol-I Para 3.1.3.11.3.2 below persists:


   a)      radiation to cease ;
   b)      removal of the navigation & identification components from the carrier ;
   c)      reversion to a lower category in case of facility performance Categories II &
           III localisers where the reversion requirement exists.


As per Annex-10, Vol-I, Para 3.1.3.11.2, the conditions requiring initiation of monitor
action shall be the following:
a) for Facility Performance Category-I localisers , a shift of mean course line from
   the runway center line equivalent to more than 10.5 m or the linear equivalent
   0.015 DDM , whichever is less , at the ILS reference datum ;
b) for Facility Performance Category-III localisers , a shift of the mean course line
   from the runway center line equivalent to more than 6 m at the ILS reference
   datum ;
c) in the case of localisers in which the basic functions are provided by the use of a
   single -frequency system , a reduction of power output to less than 50% of the
   normal ;
d) in the case of localisers in which the basic functions are provided by the use of a
   two- frequency system , a reduction of power output for either carrier to less than
   80% of the normal , except that a greater reduction to between 80% and 50% of
   normal may be permitted.
e) change of displacement sensitivity to a value differing by more than 17% from
   the nominal value for the localiser facility

    As per Annex-10 , Vol-I , Para 3.1.3.11.2.1 , in the case of localisers in which the
basic functions are provided by the use of two – frequency system , the conditions
requiring initiation of monitor action should include the case when the DDM in the
required coverage beyond ± 10 0 from the front course line , except in the back course
sector, decreases below 0.155.

    As per Doc. 9426 , Para 5.1.1.5 , the UHF Glide slope transmitter within the
frequency band from 329.15 MHz to 335 MHz radiates its signals only in the
direction of localiser front course .

    As per Annex-10 ,Vol-I, Para 3.1.5.7 ,the automatic monitor system shall provide
warning to the designated control points and cause radiation to cease if any of the
following conditions persist :
a) shift of the mean ILS glide path angle equivalent to more than minus 0.075 θ to
    plus 1.10 θ from θ ; (Typical value of θ is 30 )
b) in the case of ILS glide paths in which the basic functions are provided by the use
    of a single - frequency system , a reduction of power output to less than 50% of
    the normal;
c) in the case of ILS glide paths in which the basic functions are provided by the use
    of a two - frequency systems , a reduction of power output for either carrier to less
    than 80% of the normal , except that a greater reduction to between 80% and 50%
    of normal may be permitted.
d) for Facility Performance Category I- ILS glide paths , a change of the angle
    between the glide path and the line below the glide path (150 Hz predominating)
    at which a DDM of 0.0875 is realized by more than ± 0.0375 θ ;
e) for Facility Performance Category III - ILS glide paths , a change of displacement
    sensitivity to a value differing more than 25 % from the nominal value ;
f) lowering of the line beneath the ILS glide path at which a DDM of 0.0875 is
    realized to less than 0.7475 θ from horizontal;
 g) a reduction of DDM to less than 0.175 within the specified coverage below the
    glide path sector.

e) VHF Marker Beacons

     As per Annex-10 , Vol-I , Para 3.1.7.1.a &b, there shall be two marker beacons in
 each installation . When the installation comprises only two marker beacons, the
 requirements applicable to the middle marker and to the outer marker shall be
 complied with.
     Annex-10 , Vol-I Para 3.1.7.1.c of states that the marker beacons shall produce
 radiation pattern to indicate predetermined distance from the threshold along the ILS
 glide path.

 As per Annex-10 , Vol-I , Para 3.1.7.6.2 , the middle marker shall be located so as to
 indicate the imminence , in low visibility conditions , of visual approach guidance.

 Annex-10 , Vol-I Para 3.1.7.6.3 ,states that outer marker shall be located so as to
 provide height , distance and equipment functioning checks to aircraft on intermediate
 and final approach.

 As per Annex-10, Vol-I Para 3.1.7.7 , suitable equipment shall provide signals for
 the operation of automatic monitor . The monitor shall transmit a warning to control
 point if either of the following conditions arises:

 a) failure of the modulation or keying ;
 b) reduction of power output to less than 50 % of normal .

 As per Annex -10 , Vol-I Para 3.1.7.7.2, for each marker beacon , suitable
 monitoring equipment should be provided which will indicate at the appropriate
 location a decrease of the modulation depth below 50%.

             In addition to above, Status Indication of the facility shall be provided at
 ATC center which will indicate the status of navigational aids on real -time basis. The
 status Indicator at ATC center shall work in conjunction with the remote control and
 status unit of the facilities installed in the equipment room. The provision of status
 indication in ATC center is one of the basic requirements for aircraft operation from
 safety point of view. The compliance report of the provision of the status indictor in
 ATC center may be sent to CHQ at the earliest.




                                                                                Sd..
                                                                         ( A. K. Misra)
                                                         Executive Director (CNS-OM)
Ref No. NS /SA/410/03                                           Dated: 2 -12- 2003
                          CNS Circular No. 4 of 2003
                     Subject:-Time in Air Traffic Services


      To maintain correct and synchronized time for different operational units of ATS,
  the following systems are in operation at the Airports.


  1. Digital Master/Slave system of clocks.
  2. Clock system through GPS.
  3. Stand alone clock systems.


  The following requirements are listed in ICAO Annexure 11 Para 2.24, for provision
  of time in air traffic services.


  3.24.1 Air traffic services units shall use Coordinated Universal Time (UTC) and
         shall express the time in hours and minutes and, when required, seconds of the
         24-hour day beginning at midnight.


  3.24.2 Air traffic services units shall be equipped with clocks indicating the time in
         hours, minutes and seconds, clearly visible from each operating position in the
         unit concerned.


  3.24.3 Air traffic service unit clocks and other time recording devices shall be
         checked as necessary to ensure correct time to within ± 30 seconds of UTC.
         Wherever data link communication are utilized by an air traffic services unit,
         clocks and other time recording devices shall be checked as necessary to
         ensure correct time to within 1 seconds of UTC.


  3.24.4 The correct time shall be obtained from a standard time station or, if not
         possible, from another unit which has obtained the correct time from such
         station.


  3.24.5 Aerodrome control towers shall, prior to an aircraft taxiing for take off,
         provide the pilot the correct time, unless arrangements have been made for the
          pilot to obtain it from other sources. Air Traffic services units, shall in
          addition, provide aircraft with the correct time on request. Time checks shall
          be given to the nearest half minute.
   The above ICAO guidelines are required to be followed strictly in maintaining the
   time in different operational units:-


   i)     Where master / slave system is in operation, the master clock is to be
          corrected/ synchronized every day in the morning at 0230 UTC from the time
          signal obtained from All India Radio ( before start of the news bulletin) or
          from a standard time station. All the slave clocks are required to be
          synchronized with the master clock. The clocks can also be corrected and
          synchronized through GPS wherever such system is installed.


   ii)    The time of stand alone working positions like RADAR,AMSS,DVTR &
          other positions is required to to be synchronized with the time of the master
          clock.


   iii)   The stations where stand alone clocks are provided at working positions, the
          time is to be corrected/synchronized with the time signal obtained from All
          India Radio OR from a standard time station.


   iv)    The clocks and other time recording devices shall be checked as necessary to
          ensure correct time to be within specified limits.


   v)     An entry in the daily shift log book is to be recorded for correcting/
          synchronizing of all operational clocks.


      The compliance report on the provision of time in Air traffic services may be sent
to CHQ at the earliest.



                                                                              Sd..
                                                                    ( A. K. Misra)
                                                    Executive Director (CNS-OM)
Ref No. NS /SA/410/03                                                   Dated: 5-12-2003



                             CNS Circular No. 5 of 2003
           Subject:- Use of Standard Language for communication in ATS

It has been observed that regional language and non-standard phraseology is being used
excessively for inter-unit communication for co-ordination and exchange of ATS
messages by the HFRT controllers as well as other ACS units.


The following requirements are listed in Para 2.27.1 & 2.27.2 of Annex 11 of ICAO.


       2.27.1     An air traffic services provider shall ensure that air traffic controllers
                  speak and understand the language(s) used for radiotelephony
                  communications as specified in Annex 1.
       2.27.2     Except when communications between air traffic control units are
                  conducted in a mutually agreed language, the English language shall be
                  used for such communications.


In view of above it is required to follow the following instructions.


   a) Use “English” as the only language for exchange of communications for co-
      ordination with air traffic control units.


   b) Use Standard phraseology for exchange of communications between air traffic
   control units.


                The compliance of the above may please be ensured.




                                                                                           Sd..
                                                                              (A.K.Misra)
                                                                             E.D.(CNS-OM)
 Ref. No. NS/SA/410/03                                         Dated: 15/12/03


                              CNS CIRCULAR No. 6 of 2003.


Sub: Air Traffic Services Requirements for Communication – Back up
      capabilities thereof.


    Wherever required, the “State” has implemented the requirements listed in Para 6.1 to
6.3 of ICAO Annex 11 and para 8.3.1 of ICAO DOC 4444** regarding provision of
Aeronautical Mobile Service, Aeronautical fixed service and Movement control service
at various airports under the control of Airports Authority of India. A copy of the above
relevant para is enclosed as Annex – I for ready reference.

  To ensure high degree of reliability and availability of various Communication
Channels and equipment, the following have been provided:-

   a) Redundancy of equipment (main & stand by)
   b) Stand by power supply/Battery back up over and above the dedicated power
      supply.
   c) Inherent reliability of equipment.
   d) Controlled temperature & humidity
   e) Adequate test equipment.
   f) Quality maintenance by trained/skilled personnel.

    It is required to maintain/comply the above provision strictly for optimum efficiency
of operation.


                                                                                 Sd…
                                                                            (A.K. Misra)
                                                                          ED ( CNS -OM)

                       Para 8.3.1 of ICAO Document 4444**

8.3.1   The level of reliability and availability of communication systems shall be such
        that the possibility of system failures or significant degradations is very remote.
        Adequate backup facilities shall be provided.

Note: Guidance material and information pertaining to system reliability and availability
are contained in Annex 10, Volume I and the Air Traffic Services Planning Manual
(Doc. 9426).
Ref. No. NS /SA/410/03                                              Dated: 26 -12-2003


                               CNS Circular No. 7 of 2003
                     Subject: Radar Systems –Backup Capabilities

       Airports Authority of India (AAI) has provided Radar Systems at various Airports
used in provision of the Air Traffic Services (ATS). The systems are being maintained to
provide high level of availability, reliability and integrity of ATS. The requirement of
Para 8.1.1 of ICAO Doc-4444 on radar systems capabilities is given below:-

8.1.1    Radar systems used in the provision of air traffic services shall have a very high
level of reliability, availability and integrity. The possibility of system failure or
significant system degradations which may cause complete or partial interruptions of
service shall be very remote. Back-up facilities shall be provided

Note 1:- A radar system will normally consist of a number of integrated elements,
including radar sensor(s), radar data transmission lines, radar data processing system,
radar displays.

Note2: Guidance material and information pertaining to use of radar and to system
reliability and availability is contained in Annex -10, Volume 1 and the Air Traffic
services Planning Manual ( Doc 9426)

       To ensure high level of availability, reliability and integrity in operation of the
Radar systems, the following have been provided in the Radar installation at stations.
       1. Redundancy of equipment.( Mains and Standby)
       2. Standby power supply / battery back up over and above dedicated power
             supply.
       3. Inherent reliability of equipment
       4. Controlled temperature and humidity ( Air conditioning)
       5. Installation of fixed targets at known locations and processing the data
             received from targets.
       6. Adequate test equipment & spares
       7. Maintenance schedules as per requirement s of the equipment maintenance.
       8. Quality maintenance by trained / skilled personnel.

                It is required to maintain / comply the above provisions to achieve high
           level of efficiency in operation. It is also required to document the data on
           faults observed in the equipment serviceability and performance of the
           equipment in the form of Log book and Maintenance Schedule etc.

                                                                                         Sd..
                                                                               ( A. K. Misra)
                                                               Executive Director (CNS-OM)
Ref No. NS /SA/410/03                                                   Dated 5-01-2004

                            CNS Circular No. 1 of 2004.
                  Subject: Automatic recording of Surveillance Data.

   Surveillance data from Primary and Secondary radar equipment provided at different
airports is being recorded automatically and continuously in the hard disc of computer. It
is required to take back-up of the recorded data files everyday for retention as is being
done in the case of voice recorded tapes.

  The recommendations of Para 6.4.1 of ICAO Annex -11 on recording of surveillance
data is given below:-
6.4.1 Automatic recording of surveillance data.

6.4.1.1 Recommendation:—Surveillance data from primary and secondary radar
equipment or obtained through ADS, used as an aid to air traffic services, should be
automatically recorded for use in accident and incident investigations, search and rescue,
air traffic control and surveillance systems evaluation and training.

6.4.1.2 Recommendation: --- Automatic recording should be retained for a period of at
least fourteen days. When the recordings are pertinent to accident and incident
investigations, they should be retained for longer periods until it is evident that they will
no longer be required.

To meet the above recommendations, the following instructions are required to be
followed:--

   1.   A back-up of the previous day recorded files is to be taken every day on the
        prescribed tape, from the Hard disk.

   2.   The previous day backup is to be taken every day at a fixed time. The day is to be
        reckoned from midnight to midnight.

   3.   The files of the previous day data should be deleted, after backup of the data is
        taken on the tape.

   4.   The recorded tapes are required to be labeled properly with date of recording and
        details of the recorded files.

   5.   The recorded tapes are required to be preserved in the tape library under safe
        custody of a designated responsible officer.

   6.   To reduce the number of empty/recorded tapes in circulation, it is required to
        erase the recorded tapes after a period of 30 days from the date of recording
        except when the tapes are required to be preserved for a longer period.
7.   When the recordings are pertinent to accident and incident investigations, they
     should be retained for longer periods until it is evident that they will no longer be
     required.

8.   Till such time, a stand alone tape replay display position is provided at every
     radar station, the recorded tapes, whenever required may be replayed from
     maintenance position or from one of the operational position without interrupting
     the normal operation, as far as possible.




                                                                                Sd…
                                                                           (A.K. Misra)
                                                                          ED (CNS-OM)
Ref: CNS/SA/410/03                                  Dated: 16th January, 2004


                       CNS Circular No.2 of 2004


                     Sub: VOLMET Broadcasts service



       As per recommendations of Para 4.4.1 of ICAO Annex 11 and as
determined by Regional Air Navigation agreements for the requirements of
VOLMET Broadcasts from Kolkata and Mumbai, VOLMET broadcast service is
provided on High Frequency (HF) radiotelephony as per details provided in Para
11.6 of ICAO Annex 3.

      The standard Radiotelephony phraseology is required to be used in the
broadcasts of VOLMET as recommended in Para 4.4.2 of Annex 11 and the
guidance material provided in coordination between ATSs, Aeronautical
Information services and Aeronautical Meteorological Services (DOC 9377),
Appendix I.




                                                                       Sd..
                                                                 (A.K.MISRA)
                                                 Executive Director (CNS-OM)
      Ref : CNS/SA/410/03                                                  Dated: 20.01.2004.

                                       CNS Circular No.3 of 2004.

      Sub: Aeronautical fixed service - (ground-ground communications)

       Airports Authority of India (AAI) is providing ground-ground communications
facilities by direct speech / or data link communication for air traffic services purpose.
Depending upon the requirements at each airport, for the provision of communication
facilities in accordance with the provisions of Para 6.2.1, 6.2.2, and 6.2.3 of ICAO
Annex 11 (copy enclosed), and to meet the requirement of times for establishment of
communication, the following communication channels have been provided.

         1. Dedicated hot lines.
         2. Value added hot lines.
         3. Direct speech circuits.
         4. Direct telephones.
         5. Subscriber trunk dialing (STD).
         6. International trunk dialing.
         7. Speech switching system (SSS).
         8. Voice communication control system (VCCS).
         9. Intercom. Telephones.
         10. EPABX telephones.
         11. Automatic message switching system (AMSS).
         12. Voice logging systems (digital and analogue)

              The stations are required to maintain the assigned communication channels
      efficiently so that ground to ground communication for air traffic services can be
      established within the desired time limits as stipulated in above paras. Stations are
      also required to keep a proper record of assigned channels.



                                                                                Sd…
                                                                          (A K Misra)
                                                                          ED (CNS-
OM)
Ref No. CNS/DW/205/03                                           Dated: 17th March, 2004


                     CNS Circular No. 4 of 2004
                    Sub: Disposal of Old / Dismantled Equipment

It has been observed that disposal action is not being taken for a long time for the CNS
Equipment withdrawn from operation. Such inventory continues to be maintained at the
station for a long time, thereby increasing the unnecessary inventory and blocking the
useful space. The dismantled equipment sometimes is stored even in the operational area
/ equipment room, which adversely affects the maintenance and operation of the
equipment in use.

       In order to avoid such situation, it is advised that the following action on obsolete
/ dismantled equipment be taken immediately.

   1.      The concerned station will initiate the necessary survey report action of all
           such equipment, which is replaced, and the new equipment is commissioned
           within a month through proper channel to seek CHQ approval in principle.
   2.      The GM (Com) of the region to monitor that the dismantled / old equipment is
           disposed of quickly.
   3.      A consolidated list of all equipment, which have been withdrawn from
           operation more than three years ago in the region and not yet disposed off,
           shall be submitted by the GM concerned to CHQ for information and review.
   4.      The list of dismantled / old equipment stocked at the station shall be submitted
           along with six monthly returns.



                                                                                  Sd…
                                                                            ( A.K. Misra)
                                                            Executive Director (CNS-OM)
  File No. NS / ILS–workshop / 267 /04                   Dated12-08-2004


                     Circular No.5 of 2004


   Normarc ILS General Maintenance - Workshop held at
                 Chennai on 4-5th July 2002.

                                   General
        1. Maintenance Schedule shall be followed meticulously.
        2. On-line UPS shall be provided for both LLZ and GP. The
           provision of the UPS is to be made by respective RHQ.
        3. Spares of programmed EPROM’s should be available at site.
           Programming of EPROMs is the responsibility of SMU. Stations
           if not having the spare EPROMs may demand the same from
           SMU.
        4. All stations should configure the CAT-I ILS to COLD standby
           mode instead of HOT standby mode and necessary configuration
           shall be made in the system accordingly.
        5. No unserviceable card should be kept at station and it should be
           sent immediately to SMU for repair, with fault report and
           observations.

   Hub Center for distribution of ILS cards / Modules.

            For storing the spares of Normarc ILS 3500 / 7000 series, HUB
     stations suggested are as follows:

For Normarc 3500 Series ILS

               HUB Station        Stations to be covered by HUB
                  where
            spares to be stored
            Trivandrum          Trivandrum, Calicut, Mangalore
            Chennai             Chennai,    Bangalore,     Hyderabad,
                                Coimbatore
            Kolkata             Kolkata, Udaipur
            Nagpur              Nagpur, Rajkot, Indore, Aurangabad
For Normarc 7000 Series ILS

               HUB Station            Stations to be supplied by HUB
                   where
                spares to be
                   stored
            Jaipur                  Jaipur, Varanasi, Lucknow, Jammu,
                                    Khajuraho, Amritsar
            Chennai                 Chennai, Vizag, Trichy, Madurai
            Kolkata                 Kolkata, Patna, Bhubaneshwar, Ranchi
            Ahmedabad               Ahmedabad,       Bhopal,   Bhavnagar,
                                    Baroda
            Guwahati                Guwahati,     Dibrugarh,     Dimapur,
                                    Imphal, Lilabari, Agartala




Decision Taken:

        1. Fault logbooks containing detection of fault, observation, action
           taken for rectification of fault with tests carried out, shall be
           maintained and kept up to date.

        2. Flight inspection schedule shall be finalized 3 months in
           advance and should be sent by FIU to all regions and stations so
           that the stations are aware of the inspection dates and
           accordingly plan their maintenance/ checks schedule well in
           advance.

        3. It shall be ensured that in case of deviation from the schedule
           date of flight inspection, the station shall be given at least seven
           days prior notice to plan and test the system and keep the
           system ready for flight inspection.

        4. During flight inspection, there were difficulties faced in
           communication phraseology used. After deliberation it was
           decided that a document like the one which was developed by
           FIU for GCEL ILS, should be made by FIU and circulated to all
           stations. The document will include the pre-calibration checks to
           be carried out, site conditioning etc. Similar document should be
           made for all facilities i.e. VOR, DME, & ILS.
        5. In CATC training, arrangements shall be made to train the
           officials on Ground (field) adjustments and handling of required
           test equipments including vector voltmeter.

Advisory note for Upkeep of ILS Equipment:

         1.   To protect the system from the surge and transients, which
              are the major causes for breakdown, the feasibility of
              operating the facility on battery or On-Line UPS operation
              shall be explored and implemented.

         2.   All module/card level maintenance should be carried out using
              anti-static kit. Proper grounding of the system should be
              ensured.

         3.   All steps should be taken for protecting the system from
              lightening. The standard lightening arresters shall be
              provided at all sites and periodical inspection shall be carried
              out. If any deviation from previous reading is found, corrective
              action shall be initiated.


         4.   De-humidifiers shall be installed to control humidity. The
              provision of wall paneling, double door and cubical before the
              entrance to equipment room using antistatic measures shall
              be ensured to have dust free environment.


         5.   The critical area for ILS system should be properly graded.




                                                                       Sd….
                                                                 (A.K.Misra)
                                               Executive Director (CNS-OM)
File No. NS-07/ILS/General/701/04                         Dated:24-08-2004

                       Circular No.6 of 2004


            Identification Signal of ILS Localizer.

   It has been decided to implement amendment related to Identification
signal of Localizer as per amendment no. 74 dated 04.11.1999 Para
3.1.3.9.3 of Annex. 10 Vol.I as mentioned below:

3.2.3.9.3 The identification signal shall employ the International
          Morse Code and consist of two or three letters. It may be
          preceded by the International Morse Code signal of the
          letter “I”, followed by a short pause where it is necessary
          to distinguish the ILS facility from other navigational
          facilities in the immediate area.

   The short pause will be equivalent to interval between letters and shall
not be less than the duration of 3 dots. For details of dots and dashes, their
duration and rate of transmission, refer to Para 3.1.3.9.4 of Annex. 10 Vol. I
                           (amended 04.11.1999).

    All ILS stations are to carry out changes in localizer identification code
accordingly, if not done hitherto. De-briefing reports should be taken
immediately after carrying out the changes. A compliance report to this
effect may be sent to this office.




                                                                       Sd..
                                                                   (A.K.Misra)
                                               Executive Director (CNS – OM)
Ref. No. NS/Circular/03                                             Dated: 28/10/2004

                                Circular No. 7 of 2004

                  Subject: Operation of DVOR / DME (HP)

            Based on the recommendation of workshops on maintenance of DVOR /
DME (HP) held at Delhi from 29th April to 1st May, 2004 for ASII DVOR / DME and at
Ahmedabad from 7th to 8th May 2002 for GCEL & AWA DVOR / DME, the following
guidelines are issued:

1.         Maintenance Schedules of the equipment are to be strictly followed.

2.         The temperature inside the Nav-aid room should be maintained at 22º ± 1º
           temperature and humidity measuring device should be installed in equipment
           room.

3.         Provision of adequate voltage stabilization either by use of electronic voltage
           stabilizers cascaded with spike suppressors or using constant voltage
           stabilizer (CVT).

4.         Equipment and Airconditioner should not be connected to the same phase of
           AC mains power supply.

5.         Provision of “Lightning arrestors” on the counterpoise and monitoring
           antenna and “Surge Protectors” across remote lines for protection of
           equipment from lightning.

6.         Provision of anti-static kit on the working table and anti-static flooring in the
           equipment room to avoid the anti-static discharge. This should be mandatory
           for all new installations.

7.         Provision of “Smoke detectors” at site to auto cut-off the power supply and
           warning at Equipment room.

8.         Area below the counterpoise should be concretized to stop wild vegetation.

9.         As far as practical, power supply system to equipment may be kept ‘ON’ H-
           24 basis irrespective of watch hours of station. After watch hours, R.F
           radiation may be switched ‘OFF’ from remote and switched ‘ON’ 30 minutes
           prior to commencement of watch hours to enable stabilization of radiated
           parameters. Airconditioner should be kept ‘ON’ on H – 24 basis of possible.
10.   Power output of each DVOR other than enroute DVORs may be reduced to
      70 Watts to avoid overheating of RF power amplifier. This should be done
      during next flight calibration and parameters particularly coverage limits, to
      confirm that required coverage requirement is fully met, be checked. If
      reduction of power output reduces coverage requirement, the power should
      be increased till the coverage is met and proper records should be kept in this
      regard. This supersedes the earlier CHQ letter No. 19019/6/99-COM(M)
      dated 24/07/2001.

11.   All stations should immediately send the unserviceable modules/PCBs to the
      respective SMU for repair and return.

12.   Spare PCBs / modules shall be stocked at four regional centres one in each
      region i.e. Kolkata, Delhi, Bangalore & SMU Ahmedabad.

13.   Regular interaction between SMU and field stations for efficient and prompt
      maintenance support through internet and other means should be done.

      All Station-in-Charges should ensure strict compliance of the above for
      optimum efficiency of VOR/DVOR/DME (HP) operation.


                                                     Sd….
                                                     ( A.K. MISRA )
                                            Executive Director (CNS – OM)
File No. AAI/NS/Maint-Schedule/251/04/                            Date     /01/2006

                                      CNS Circular No. 01 Of 2006

 Sub: Documentation and preservation of maintenance records of CNS facilities.

       Following guidelines will be followed for documentation and preservation of
maintenance records of CNS facilities: -

                     1.Preservation of maintenance records of CNS facilities.

     (i)       Routine Maintenance Schedules: - Reports on Routine Maintenance
               Schedules i.e Daily, Weekly, Monthly, Quarterly, Half Yearly and Annual as
               applicable to CNS equipment shall be maintained and retained as per below: -

                      (a) Daily, Weekly and Monthly                :- One Year.
                      (b) Quarterly, Half Yearly and Yearly       :- Five Years.

     (ii)      Handing over report (Proof of Performance), History /Fault Log Book: -
               These records shall be maintained and retained throughout the life of facility.

     (iii)     Shift Log Book and Communication Returns: - These records shall be
               maintained and retained for a period of one year.

     (iv)      Test Equipment Calibration Records: Test equipments such as signal
               generators, oscilloscope etc. must be calibrated on a periodic basis. The
               relevant records shall be retained at station up to five consequent reports.

2.           Retention of Flight Inspection Reports and Data:

               (i)       The commissioning flight inspection report and data recordings shall
                         be retained throughout the life of facility.
               (ii)      Reports and data recordings for last five Flight Inspections shall be
                         retained. Any special flight inspections, carried out during this period
                         shall also be retained.
               (iii)     Five consecutive records of the calibration of flight inspection system
                         shall be retained by Flight Inspection Unit (FIU).

                                           Page ….1/2
3.     Retention of Data required for Investigation: -

     Any of the above records and other related data, if required by
     investigating authority for the purpose of enquiry etc. shall be retained till
     specific written order is issued on matter.

     Note: - Maintenance schedules approved by CHQ are available for CNS
     equipments. If maintenance schedule is not available for any CNS
     equipment, same should be brought to the notice of CHQ for further
     action.
                                                          ..Sd..
                                                    (S C Goswami)
                                                    ED (CNS-OM)
No.AAI/GM(N&S//Misc./05                                              Dt : 4th Jan., 2006

                              CIRCULAR NO. 2 OF 2006

           INTIMATION OF MAJOR FAILURES OF CNS FACILITIES

        In the event of occurrence of following types of major failures of CNS facilities at
an airport/ACS station, immediate intimation shall be given to CHQ.

   1. Communication :-

   1.1 Failure of Air-to-ground VHF and HF channel having adverse impact on flight
       operations.

   1.2 Failure of ground-to-ground communication (including telephone, Direct Speech
       Circuit, Data link circuit etc.) resulting in serious impact on flight operation.

   2. Navigation facilities :-

       Non-availability of navigational facilities like ILS, DVOR, DME, NDB which is
       likely to cause diversion/disruption of flights from the airport.

   3. Surveillance and Automation System :

       Non-availability of facility causing serious impact on the operation of flight
       from/to airport.

             GM(Com) of ACS at Metro airports, Airport Directors and O/In-charge
       of ACS ( where post of Airport Director is not available) will immediately
       communicate the date, time and nature of occurrence to the control room of
       CMG, Corporate Hqrs. through Telephone/ Fax/E-mail is given here under :-

       Ops Control Room:-
                              Tel – 011-24610843/24610848
                              Fax – 011-24693963
                              Email Id- opsctrl@aai.aero

               The duty officer of control room will intimate the occurrence to ED(CNS-
       O&M) at his office/residence telephone number or his Mobile No. as given here
       under :-
                              Mobile: 9810937070
       In case of non-availability of ED(CNS-O&M), the information should be
given to GM(N&S) at the following numbers :

Office 011-24619159,     Residence 011-26124961,       Mobile No. 9818135846

       Please note that the arrangement will be effective immediately and does
not supersede other prevailing means of intimation of events/incidents.



                                                                          Sd-
                                                                (S.C.Goswami)
                                                 Executive Director (CNS-OM)
                                                                       Annexure-I
             Power Supply system for CNS & ATM Automation Facilities.

1 Background:

To ensure continuous availability of CNS and ATM system, it is essential to provide
un- interrupted and clean AC power to the systems. UPS had been provided in
the past for the purpose for CNS and ATM Automation facilities. In the absence
of guidelines on the matter, UPS and power distribution system were left to the
individual stations to design and implement. Proper maintenance system of UPS
and associated Batteries, power input to and output distribution from UPS were
not properly addressed which at times resulted in failure of UPS system resulting
in non availability of vital CNS and ATM system. This resulted in serious set back to
safe operation. It is essential to design power supply system which will ensure
uninterrupted power supply and also single point failure does not result in
catastrophic failure of CNS and ATM facilities. This assumes all the more
importance in view of tremendous increase of flights to/ from metro airports,
other international airports and major airports etc.

2 AIM:

Provision of continuous AC power supply of Three phase 400 volts (phase to
phase) +/- 10% or single phase 230 volts +/-10% , 50 hertz +/- 2.5% sinusoidal
wave shape with harmonic component within 10%              and negligible voltage
surges to CNS and ATM equipments. The power supply system must have
adequate redundancy so that single point failure of power supply system does
not result in non availability of power supply to CNS & ATM equipments.

3. Scope:-

To achieve the aforesaid aim, the power supply system has to be properly
designed and UPS system of adequate capacities is required to be provided.
The responsibilities are divided into followings:

3.1 The power mains up to input of UPS will be the responsibility of Engineering
wing (Electrical). In the event of failure of power mains, the power through
standby generator should be provided within a period not exceeding 2 minutes
as per ICAO Annex 14 provisions. Power supply voltage and frequency to CNS &
ATM automation systems should be continuously monitored with the help of
power loggers. The recorded data should be maintained for a period of at least
24 hrs with a provision to take back up copy of the recorded data for the
purpose of analysis etc.

                                         1
3.2 Provision and maintenance of UPS will be the responsibility of CNS
maintenance wing. Power distribution from the output of UPS to CNS or any
other associated facility will be decided by CNS in charge. Assistance of
Electrical wing is to be taken for UPS electrical distribution wiring provision and
maintenance.

3.3 The power supply system design including power cables and switches etc. as
mentioned in Aim in Para 2 and Scope Para 3.1 above shall be separately
prepared by the Engineering wing (Electrical).

4. The UPS and its power output distribution System:

4.1 General requirements of UPS

  I. UPS system must be compatible with the Battery. Due consideration should
     be given for float charge and charge capability of batteries by UPS. There
     should be provision for enhancing capacity of UPS.

  II. Each CNS system should be supplied by separate small capacity UPS rather
      than large capacity UPS supplying power to several CNS systems. The KVA
      rating of UPS should be adequate to meet the steady state load
      requirement plus switching on transients. Guidelines for calculating
      capacity are given in Attachment- I on “UPS & Battery Maintenance”.
      Scheme of provision of UPS for different CNS & Automation facilities is given
      in Para 5.

 III. UPS should have spike suppressor at the input to suppress spikes and surges
      of supply mains.

 IV. UPS should have remote status indication facility to monitor its functionality
     from central place.

 V. The design of UPS should ensure its proper functioning when AC voltage
    input is supplied from standby generator.

 VI. The service life of UPS should be 8 years and the supplier must ensure
     provision of maintenance support for duration of service life time.

VII. Critical spares of UPS should be procured at the time of procurement of
     UPS itself and should form part of tender conditions for procurement of UPS.

VIII. Preventive and Breakdown maintenance of UPS shall be outsourced to
      OEM or its authorized agency. A maintenance contract will be signed with
      the supplier to come into effect just after completion of warranty period
      and will initially cover 5 year period with option for further extension of next
      5 Years.
                                          2
 IX. Expenditure on account of maintenance contract covering 5 years period
     should be part of tender document.

 X. Where ever CNS equipments & Automation servers are provided with dual
    core power supply input facility, each input should be supplied power from
    different set of UPS.

 XI Wherever a single UPS is installed, the power to the equipment should be
 supplied through a changeover switch – one input from UPS, another from AC
 Mains to facilitate breakdown maintenance of the UPS.

 XII VRLA (Valve Regulated lead Acid) type batteries shall be used with UPS
 systems. At the time of procurement of batteries, all the reference tables
 regarding conductance, discharge voltage, capacity etc. shall be obtained
 from the supplier. This should form part of the tender document.

 XIII Health of batteries should be monitored by methods as described in Para
 4 of attachment –I and should be replaced if their condition deteriorate.
 Further Batteries should be replaced as per life span specified by the
 manufacturer.

 XIV UPS should have minimum back up time of 30 minutes.

 XV In case of single phase UPS, Input supply to each UPS of a UPS set should
 be supplied from two different phases. Further phases of the input to UPS,
 supplying to main and standby equipment viz. FDPS A and FDPS B should be
 chosen to have maximum redundancy.

5) Provision of UPS

5.1 ATC automation system

(i) Separate set of UPS means two UPS working on load sharing basis
configuration. Each UPS should be capable of taking full load.

(ii) Separate set of UPS should provide for:-

(a) Main Surveillance data processor (SDP), Flight data processor (FDP), Direct
    Radar access (DRA) processor, Data Management System (DMS),
    Communication Gateway processor (CGP).

(b) Standby processors in respect of (a) above.

(c) ATC working positions including load of workstation, display subsystem and
    other accessories.


                                          3
(d) Modems, multiplexers, GPS Receivers, network and other communication
    accessories system used with the Automation system should be supplied from
    different set of UPS which are being used for processors as mentioned at (a)
    and (b) Para 5.1 above.UPS input to these should be chosen to have
    maximum redundancy.

5.2 RADAR /ASMGCS System

      RADAR equipment should be provided with separate set of UPS. Each set
      will consist of two UPS working on load sharing configuration.

      Capacity of each UPS should be adequate to take load of RADAR.



5.3 Navigation AIDS ( LLZ, GP,VOR,DME, NDB/LOCATORS & MARKERS)

      Local site of each of the equipment should be supplied by separate set of
      UPS. Each set of UPS will consist of two UPS working on load sharing
      configuration.

      Modems used for RCSU & RMM should be supplied power from the
      aforesaid UPS.

      RMM PC if available at the site should be supplied power from the
      aforesaid UPS.

      Capacity of each UPS should be capable of taking full load of
      equipments as mentioned above.

5.4 VHF system

      UPS should be provided for VHF transmitters and receivers in addition to
      DC supply by batteries to each of the equipment.

      VHF transmitters and receivers of main frequencies should be supplied
      with one set of UPS. The VHF transmitters and receivers for alternate
      frequencies should be supplied by separate set of UPS. Each set of UPS will
      consists of two UPS working on load sharing mode.

      For small airports, VHF equipment for main and alternate frequencies may
      be supplied by one set of UPS.

5.5 VCCS/DVTR/DATIS

      The voice switch equipment should be supplied by separate set of UPS.

      The DVTR & DATIS should be supplied by separate set of UPS.
                                       4
VCCS Control panel provided at ATC working positions should be supplied
by a separate set of UPS. If provision exist for dual core supply of control
panel than supply from the other set of UPS should be provided.

Considering substantial physical separation between Area / Approach
control and ATC control Tower, a separate set of UPS should be used for
Control panels located in the tower.




                                  5
5.6 Automatic Message Switching System

      The Main and Standby Servers of AMSS should be supplied by separate set
      of UPS.

      The Patch panels, Multiplexers, Modems used with AMSS can be supplied
      power from both the aforesaid UPS using suitable changeover switch.

       The AMSS Work Stations and printers provided in Area, Approach ATC
      Tower should be supplied power from the UPS meant for the
      corresponding ATC working positions as mentioned in Para 5.5 above.

      AMSS work stations provided in HFRT should be supplied power from a
      separate set of UPS.

5.7 Remote control & Status Unit (RCSU), Remote Maintenance & Monitor (RMM)
& Remote Status Unit (RSU)

      RCSU of all Nav-Aids installed in Equipment room should be supplied
      power from a separate set of UPS.

      RSU installed at different ATC positions shall be supplied from UPS meant
      for the corresponding ATC working positions as mentioned in Para 5.5
      above

5.8 EPABX, Clock systems, UHF Links & Microwave Links

      EPABX used for operational purpose shall be provided power from a
      separate UPS.

      Site Equipment of UHF & Microwave Links used for Control and Status
      monitoring of CNS facilities shall be provided power from the UPS
      available at the corresponding facility.

      At ATS Building a separate set of UPS should be provided for UHF and
      Microwave links.

      Clock systems used for ATC purpose shall be provided with UPS. This can
      be supplied from any available UPS in the equipment room.

5.9 HF TX & Receivers

      Solid state HF TX and Receivers shall be provided power from separate
      UPS system.


                                      6
                                                                        Attachment –I

                  Guidelines for UPS & Battery Maintenance
Introduction: - UPS system consists of:-


1.     UPS Equipment
2.     UPS Battery Back Up

1.     UPS Equipment Maintenance :-

Preventive & Break down maintenance of UPS will be outsourced to OEM or its
authorized agency as stated at Para 4.1 of the policy.

2.     UPS Battery Back Up Maintenance:-

The batteries provided with UPS are mostly VRLA (Valve Regulated Lead Acid Batteries)
as mentioned in Para 4.1. As these batteries emit extremely low amount of gases,
hence they can be installed in the equipment room itself along with the UPS and do not
require periodic topping up. Thus saving manpower on account of maintenance and
long connecting electrical bus bar or cables. As all these batteries are based on
starved electronic principle, they can be installed in any orientation.

The terminology “Maintenance” free Batteries to VRLA batteries gives the impression to
the users that these batteries are to be installed and no maintenance is required. Due
to this misconception, no proper attention is being given to these batteries which lead
to the failure of these batteries. These batteries have their own problem and limitation,
which require timely monitoring, handling and preventive maintenance. The guidelines
in this regard are as given below:-

2.1   Problems and Limitations of VRLA Batteries :-

Some of the constraints of VRLA batteries are :-

(a)         Self discharge
(b)          Temperature effect
(c)         Difficulties in paralleling of cells
(d)         Special care in charging the batteries.

(a)    Self Discharge: - All these batteries are supplied in charged conditions. These
cells/batteries get discharged of its own on its internal resistance and some localized
action within the cells. This is termed as self discharge. Self discharge of these cells is
about 14% of every 4 weeks.



                                            7
Considering this, it is essential that these cells/batteries are commissioned in the least
possible time so that the cell discharge and subsequent repair is kept to minimum.
Storing period of more than 3 months should be avoided.



(b) Temperature effect:-

(i)    Low Temperature effect: - Batteries are very temperature sensitive. The chemical
reaction increases/decreases in geometric progression with the increase or decrease in
temperature. Battery capacity is diminished at low temperature. Also the charge
acceptance decreases with the decrease in temperature.

(ii)     High temperature: - The Chemical reaction becomes faster and faster with the
rise in temperature above the nominal design temperature of 27 Deg C and give rise to
a chain reaction. High temperature causes loss of life because every 10 degree C rise
in operating temperature, the life is cut to half. The high temperature also causes
gassing, which means dry out and thermal runaway in VRLA cells.

c. Paralleling of cells: - The highest capacity of single cell available for Absorbent Glass
Mat technology batteries is 1500 AH. To achieve high capacity paralleling of cell
become essential. However, for paralleling of cell, it should be ensured that they are
properly matched in capacity, voltage and conductance otherwise premature failure
of cell may take place. Paralleling of cell for VRLA batteries based on GEL technology is
not recommended because of higher internal resistance of these types of cells. It is
recommended that for paralleling, cells below 100AH rating are not used.

(d) Charging Technique: - Special charging technique is required to ensure that
charging of batteries does not result in temperature rise. Float and charge voltages
should be as per the recommendations of the Battery manufacturer. Typically the value
of float voltage is 2.25V and 2.30V as charge per cell. Do not resort to fast charging
setting higher float/charge voltages. A constant voltage technique with battery path
current limited to 0.1 C (Capacity) is recommended.

2.2   Battery capacity calculation: - The battery bank shall be capable of meeting the
load requirements of equipment for specifiedtime. While calculating the battery
capacity for a given load & backup time the following factors are to be taken into
consideration :-

(i)     The battery shall not be allowed to discharge beyond 80% of its rated capacity.
For example if the Load current is L and recommended discharge rate is Lr than:-
L        = Lr x 0.8
i.e. Lr = L/0.8              = 1.25L




                                             8
(ii) The battery capacity depends on the type of discharge application for which it will
used i.e. slow rate of discharge systems or higher rate of discharge systems as given
below :-

   (a) Slow Rate of Discharge system: - In slow rate of discharge systems, battery is
       discharged at Capacity i.e. ‘C’/6 rates or slower. Typically these batteries
       provide back up requirement of 6 Hours or higher. This type of application is
       normally required supplying DC supply to VHF TX/RX.



The discharge time of batteries depend upon the rate of discharge and is not constant.
A table below indicates the discharge time for various discharge rates for VRLA
batteries for slow discharge applications:-



                                               Table-1
   Rate of                      Cell                                     Mono-Block
  Discharge
              Discharge   Capacity     Discharg    End     Discharg   Capacity    Discharg    End
               Current    expressed        e       cell        e      expressed       e       cell
                           as % of       time     voltag   Current     as % of      time     voltag
                             C/10        (min)      e                    C/10       (min)      e
                          Discharge    Minutes                        Discharge   Minutes
                             rate                                        rate
    C/3        0.333C       71.7         129      1.74V    0.333C       75.0        135      10.44
                                                                                               V
    C/4        0.25C        78.2         188      1.74V     0.25C       81.0        195      10.44
                                                                                               V
    C/5         0.2C        83.3         250      1.75V      0.2C       85.0        255      10.5V
    C/6       0.167C        87.3         314      1.75V    0.167C       91.0        328      10.5V
    C/8       0.125C        95.0         456      1.75V    0.125C       95.0        456      10.5V
   C/10         0.1C      100-120      600-720    1.75V      0.1C     100-120     600-720    10.5V
   C/20        0.05C       120.0        1440      1.75V     0.05C      120.0       1440      10.5V
   C/72       0.014C       130.0        5616      1.75V    0.014C      130.0       5616      10.5V
   C/120      0.0083C      150.0        10800     1.75V    0.0083C     150.0       10800     10.5V




      N.B : It may be noted that if discharge rate is C/10 for slow discharge batteries
      than only it is capable of delivering 100% of its capacity.




                                                  9
   (b) High rate of discharge systems:- These type of batteries can handle higher rate
       of discharge which can be C/0.5 (2C) to C/5 rate depending on the
       requirements of the system. Normally these batteries are used for UPS system. This
       type of application is normally required for UPS system of AAI.

      A table below indicates the discharge time for various discharge rates of VRLA
   batteries for high discharge applications:-

                                                    Table-2
  Rate of                        Cell                                        Mono-Block
  Discharg
  e          Discharg   Capacit         Discharg    End     Discharg   Capacit    Discharge    End
             e          y                   e       cell        e      y          time (min)   mono-
             Current    expresse          time     voltag   Current    expresse   Minutes      block
                        d                 (min)      e                 d as %                  voltage
                        as % of         Minutes                        of C/5
                        C/5                                            Discharg
                        Discharg                                       e rate
                        e
                        rate
    C/0.5    2*C          45             13.5      1.70V        2*C      50          15           10.2V
    C/1      1*C          60              36       1.70V        1*C      65          39           10.2V
    C/2      0.5*C        81              97       1.70V       0.5*C     85         102           10.2V
    C/3      0.33*C       86              155      1.74V      0.33*C     91         164          10.44V
    C/4      0.25*C       95              228      1.75V      0.25*C     96         231           10.5V
    C/5      0.2C        100 -           300 -     1.75V       0.2C     100-      300- 360       10.5V
                          120             360                           120

(iii)   Effective Battery capacity: - Effective battery capacity for a given discharge rate
is as per the tables shown above for slower rate or higher rate of discharge systems.
It may be noted that the VRLA batteries designed for high rate of discharge i.e.
Typically C/5 rate of discharge will give rated capacity only when it is discharged at a
discharge current equal to C/5 (0.2 C) at other discharge rates its capacity will be less
as shown in tables.
(iv)    Sample calculation for high discharge application ( Battery back up 0.5 to 5
        Hours )
        a) Load Current                                         - 50 (Amperes)
        b) Back up time                                         - 0.5 (Hours)
        c) Permissible depth of discharge                 – 80%
From Table 2:-
         Maximum discharge current is C/0.5 i.e. 2C
        Capacity expressed as percentage of C/5 discharge rate = 45%
        Load current = 50A
        Discharge current is = 50/0.8 = 62.5 Amperes
        (Considering 80% permissible depth of discharge)
        Capacity in Ampere Hours = 62.5 X 0.5/0.45 = 69.44 AH




                                                      10
N.B. =The above calculation takes into consideration data from Table 2 i.e. VRLA
batteries from High Rate of Discharge. During technical evaluation the capacity of
battery may be rechecked from the table supplied by the manufacturer.




                                       11
3.   Dos and Do not’s :-

     •   UPS must be fully compatible with the battery, and all the parameters must
         be set at the desired level.

     •   It must be ensured that battery temperature compensation mechanism is
         installed and fully functional and all the terminators are in proper place in UPS
         or Battery charger . Voltages must be set at the desired level compatible with
         the temperatures, as mentioned by manufacturer.

     •   Batteries temperature shall be maintained to such a value that it does not
         affect the life and performance of the battery i.e the average temperature
         shall be maintained around the designed temperature indicated by
         manufacturer or typically at 27 Deg C.

     •   Batteries should not be deep discharged. They shall not be allowed to
         discharge beyond 80 % of their rated capacity. Battery discharge should be
         properly recorded indicating date, time, duration and discharge current to
         have a fair idea about the health of the battery. The guidelines in this regard
         are given in Para 4 below.

     •   Frequent discharge or excessive cycles of discharge of batteries should be
         avoided as this leads to grid corrosion and affects the life of Battery. Each
         and every battery discharge shall be properly logged.

     •   Ensure that battery is not allowed to remain under charged.

     •   Set the float and charge voltages of UPS or Battery charger typically 2.25V as
         float and 2.30V as charge or as per battery manufacturer’s instructions.

     •   Do not resort to fast charging by setting higher/Float/charge voltages.

     •   A fully discharged battery should be charged within 24 to 48 hours otherwise
         it will be damaged and may not be recovered.

     •   Keeping the battery continuously in the undercharged condition due to any
         reason may lead to sulphation of the plates and battery may lose its
         capacity gradually.

     •   Batteries kept in cooler environment gives longer life and better performance

     •   VRLA batteries should be commissioned within three months of
         manufacturing date and in case delay is more than three months it must be


                                           12
ensured that rated capacity has been recovered by giving freshening
charge.




                            13
4.     Preventive maintenance of VRLA batteries:-

The state of health, expected life and expected residual life of a battery can be
predicted by following combining use of following preventive methods :-
(i)      Physical inspection:-Periodical physical inspection of each cell of the battery
for cracks & leakages etc should be carried out. This may be carried out once in a
month and proper record in this regard should be maintained.

(ii)   Battery Partial discharge test:-To carry out this test, discharge battery for a short
duration of time so that 20% (approx) of the battery is discharged and thereafter record
the voltages of each cell in the string by shutting down the mains power supply. The test
discharge tables supplied by the manufacturer with the batteries may be used as a
reference. The test is to be conducted on a fully charged battery if it has not been put
on load for some time. In case the battery is frequently discharged due to frequent AC
mains interruptions, the observations can be recorded during such failures. This test
should be carried out once in a month.

       Digital voltmeter capable of reading three places decimal with accuracy of 1mv
is recommended for this test. By comparing the discharge voltage with the initial
voltages, the loss of capacity of the cell and battery may be decided.

(iii) Conductance Measurement: - Measurement of a mark deviation (> 30 %) in the
impedance or conductance of the cell as compared to the one recorded at the time
of commissioning of the battery. These measurements shall be taken offline. The value
impedance/conductance of each cell given in impedance/conductance table
provided by the manufacturer shall be verified at the time of commissioning and shall
be taken as reference.

        Digital impedance /Conductance meter with online accuracy of 2% and
resolution of 3 place of decimal. Normally change in cell impedance /conductance
less than 30% indicate healthy state of cell/battery, between 30 to 40 % battery
becomes unreliable and above 40 % battery failure is imminent. Digital impedance
/conductance meter power drain from the cell/battery during test shall be not more
than 0.5A. The conductance measurement may be done Quarterly.

(iv)   Current Measurements: - Currents for all the three states i.e. Charge, Discharge
and float of battery are important factors affecting and predicting the life and state of
health of a battery. This test should be carried out monthly.

      Any digital current meter capable to read three places decimal with accuracy
of 1 ma shall be used for this purpose



                                            14
(v)   Float voltage :- Float voltage is another important parameter on which life &
performance of the battery depends. The float voltage shall be so set the
corresponding voltage at 27Deg C shall be 2.25V/cell for float voltage and 2.3V/Cell for
charge voltage taking adjustment factor 3mV/cell/degree centigrade or as
recommended by manufacturer.

Summary: The state of health & expected life of the battery can be predicted more
precisely and reliably by Combining the above methods of preventive maintenance
of batteries as summarized below :-

     (a) Periodical Physical inspection of each cell of the battery for crack & leakages
            etc.
     (b) Discharge of battery for short duration and recording voltages of each cell in the
            string.
     (c) Measurement of a mark deviation ( >30%) in the impedance or conductance of
            the cell as compared to the one recorded at the time of commissioning.
     (d) Float current in fully charged battery.
     (e) Float voltage measurement.



5.      Disposal of unserviceable Batteries

The unserviceable batteries should be disposed off as per the guidelines issued by
Ministry of Environment & forests and available on the website www.envfor.nic.in and
other guidelines issued by department on the subject.




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