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					                                          FLIGHT SAFETY
                                                AN IN-HOUSE NEWSLETTER OF OPERATIONS DEPT.
                                                   IN-      NEWSLETTER
                                    Vol.2, No.4            Flight Safety & Quality Assurance Division                    April 2007

                                        We hope you enjoyed reading the                 even result in serious injuries. We address
       In this issue                March issue.                                        managing turbulence in this issue.
                                        In this issue we look at the American Air-          As always, we look forward to your feed-
American Airlines MD 82         1
                                    lines MD82-1 runway overrun accident, an            back, suggestions and contributions in the
runway overrun during
                                    example where fatigue, ignoring company             form of articles, anecdotes, pictures, etc.
                                    minima and weather plays havoc resulting in         which can be sent to our office address given
Managing turbulence             3   many deaths including the captain.                  in this page.
                                        Turbulence is something the pilots always           Happy reading and many more safe
                                    encounter, but the severe ones can result in        landings.
Web watch                       4
                                    discomfort to crew and passengers and could

                                    American airlines MD 82
                                    runway overrun during landing
                                    Based on Aircraft Accident Report NTSB/AAR-01/02
                                         On June 1,1999, at 2350:44 Central Day-
                                    light Time, American Airlines (AA) flight 1420,
  Capt. Shawki Al-Ablani
                                    a     McDonnell     Douglas     DC-9-82(MD-82),
    Dr.M.S.Rajamurthy               N215AA, crashed after it overran the end of
                                    runway 4R during landing at Little Rock
          Contact:                  National Airport in Little Rock, Arkansas.
   Flight Safety & Quality               Flight 1420 left Dallas/Fort Worth Inter-
     Assurance Division,            national Airport, Texas, at 2240 with 145 on-
                                    board and touched down in Little Rock at
      Operations Dept.
                                    2350:20. After departing the end of the
        P.O.Box.394,                runway, the airplane struck several tubes
    Safat 13004 Kuwait              extending outward from the left edge of the
                                    instrument landing system (ILS) localizer
   Phone:+965- 4725475              array, located 411 feet beyond the end of the
   Fax: +965- 4749823               runway; passed through a chain-link security        officer was the flying pilot for flight 2080.
          E mail:                   fence and over a rock embankment to a flood             The scheduled departure and arrival of
                                    plain, located approximately 15 feet below the      Flight 1420 was 2028 and 2141. However,
                                    runway elevation; and collided with the             before their arrival at Dallas/Fort Worth, the
                                    structure supporting the runway 22L approach        flight crew received an Aircraft Communica-
                                                       lighting system. The captain     tion Addressing and Reporting System
                                                       and 10 passengers were           (ACARS) message indicating a delayed
                                                       killed; the first officer, the   departure time of 2100 for flight 1420. After
                                                       flight attendants, and 105       deplaning from flight 2080, the flight crew
                                                       passengers received serious      proceeded to the departure gate for flight
                                                       or minor injuries; and 24        1420. The trip paperwork for the flight
                                                       passengers were not injured.     received      included an American Airlines
                                                       The airplane was destroyed       weather advisory for a widely scattered area
                                                       by impact forces and a post-     of thunderstorms along the planned route and
                                                       crash fire (see the wreckage     two National Weather Service (NWS) in-flight
                                                       photo).                          weather advisories for an area of severe thun-
                                                           Flight 1420 was operating    derstorms along the planned route.
                                                       under the provisions of 14           The airplane originally intended to be used
                                                       CFR Part-121 on IFR flight       for this flight was delayed in its arrival to
                                                       plan.                            Dallas/Fort Worth due to adverse weather in
                                         Flight 1420 was the third and final leg of     the area. After 2100, the first officer notified
                                    the first day of a 3-day sequence for the flight    gate agents that flight 1420 would need to
  Flight Safety/aircraft Accident   crew. The flight sequence began at O’Hare           depart by 2316 because of company duty
                                    International Airport, Chicago, Illinois. The       time limitation. He then telephoned the flight         first officer and the captain checked in for the    dispatcher to suggest that he get another                flight around 1018 and 1038 respectively.           airplane for the flight or cancel it. Afterwards,         Flight 1226, from Chicago to Salt Lake City,        the     accident    airplane,     N215AA,     was
           index.htm                Utah, departed at 1143 and arrived at 1458.         substituted for flight 1420. The flight’s 2240        Flight 2080, from Salt Lake City to Dallas/Fort     departure time was 2 hours 12 minutes later
                                    Worth, departed at 1647 and arrived at 2010,        than the scheduled departure time. Captain
                                    39 minutes late due to an airborne hold             was the flying pilot for this flight.
                                    during the approach resulting from adverse               At 2254, the flight dispatcher sent the
                                    weather in the airport area. The captain was        flight crew an ACARS message indicating that
                                    the flying pilot for flight 1226, and the first     the weather around Little Rock might be a
 Page 2                                              FLIGHT SAFETY                                         Volume 2, No.4

                                                                                        received, the flight crew should have
                                                                                        recognized that the approach to runway
                                                                                        4R should not continue because the
                                                                                        maximum crosswind component for
                                                                                        conducting the landing had been
                                                                                        - Because of the flight crew’s failure to
                                                                                        adequately prepare for the approach
                                                                                        and the rapidly deteriorating weather
                                                                                        conditions, the likelihood of safely
                                                                                        completing the approach was decreas-
                                                                                        ing, and the need to take a different
                                                                                        course of action was progressively
                                                                                        increasing; as a result, the flight crew
                                                                                        should have abandoned the approach.
                                                                                        - Dynamic or reverted rubber hydro-
                                                                                        planing did not occur during the
                                                                                        accident airplane’s landing rollout.
                                                                                        - The auto spoiler system operated
                                                                                        properly, and the spoilers did not auto-
                                                                                        matically deploy because the spoiler
                                                                                        handle was not armed by either pilot
                                                                                        before landing.
                                                                                         - The flight crew failed to verify that
                                                                                        the spoilers had automatically deployed
                                                                                        after landing, and the captain failed to
                                                                                        manually extend the spoilers when they
                                                                                        did not deploy.
                                                                                         - The lack of spoiler deployment led
                                                                                        directly to the flight crew’s problems in
                                                                                        stopping the airplane within the remain-
                                                                                        ing available runway length and main-
                                            Flight 1420’s approach path to the          taining directional control of the air-
                                            airport and key CVR comments                plane on the runway.
                                                                                        - The use of reverse thrust at levels
                                                                                        greater than 1.3 engine pressure ratio
                                                                                        significantly reduced the effectiveness
                                                                                        of the airplane’s rudder and vertical
                                                                                        stabilizer and resulted in further direc-
                                                                                        tional control problems on the runway.
factor during the arrival and suggested     and :30, respectively, and both pedals      - The lack of spoiler deployment was
that the flight crew expedite the arrival   reached full travel at 2350:31. About       the single most important factor in the
to beat the thunderstorms if possible.      the time that the brakes were applied,      flight crew’s inability to stop the
The flight crew acknowledged this mes-      the thrust reversers were deployed          accident airplane within the available
sage. According to the pre-departure        again. At 2350:32, the CVR recorded an      runway length.
trip paperwork, two alternate airports-     unidentified voice in the cockpit stating    -The flight crewmembers’ performance
Nashville Int. Airport, Tennessee, and      “on the brakes.” The left & right engine    during the accident flight was degraded,
Dallas/Fort Worth—were specified as         reverse EPR reached a maximum               as evidenced by their operational errors
options in case a diversion was needed.     setting of 1.98 and 1.64 respectively.      and impaired decision-making (see the
    Figure above shows flight 1420’s            The left brake pedal was relaxed at     CVR comments in the figure)
approach path to Little Rock along          2350:34 before returning to its full         - The flight crewmembers’ focus on
with key CVR comments and the               position 2 seconds later. About the time    expediting the landing because of the
airplane’s location when the comments       that the left brake pedal was relaxed,      impending weather contributed to their
were made.                                  the reversers were returned to the          degraded performance.
    FDR and CVR data indicated that the     unlocked status. As the right thrust        - The flight crew’s degraded perform-
airplane touched down on the runway         reverser was being moved to the             ance was consistent with known effects
at 2350:20. At 2350:22, the first officer   unlocked status, the right engine           of fatigue.
stated “we’re down;” about 2 seconds        reached a maximum setting of 1.74               The NTSB concluded that the
later, he stated, “we’re sliding.” FDR      reverse EPR.                                probable causes of accident were the
data indicated that, both thrust                Following     are the NTSB findings     flight crew’s failure to discontinue the
reversers were deployed for 7 seconds       related to the flight crew.                 approach when severe thunderstorms
after touchdown, and the left and right     - During the descent into the terminal      had moved into the airport area and the
engines’ engine pressure ratios (EPR)       area, the flight crew members could         crew’s failure to ensure that the spoilers
reached settings of 1.89 and 1.67,          have reasonably believed that they          had extended after touchdown.
respectively. The thrust reversers were     could reach the airport before the              Contributing to the accident were
subsequently moved to the unlocked          thunderstorm.                               the flight crew’s (1) impaired perform-
status (neither deployed nor stowed).       - As the first officer was able to          ance due to fatigue and the situational
FDR data showed that the flight spoilers    maintain visual contact with the runway     stress associated with the intent to land
did not deploy symmetrically at touch-      as the airplane was vectored for the        under the circumstances, (2) continua-
down, but a momentary 8° deflection of      final approach course, both flight crew     tion of the approach to a landing when
the left outboard flight spoiler concur-    members might still have believed that      the company’s maximum crosswind
rent with a left aileron deflection. FDR    flight 1420 could arrive at the airport     component was exceeded, and (3) use
data indicated that the right and left      before the thunderstorm.                    of reverse thrust greater than 1.3 EPR
brake pedals began to move at 2350:25       - When the second wind shear alert was      after landing.
 Volume 2, No.4                                         FLIGHT SAFETY                                                           Page 3

 Managing severe turbulence
 Based on an article of the same title by Panxika CHARALAMBIDES in Safety First Airbus magazine, FAA and other literature
      Turbulence encounters are not                 STANDARD TERMINOLOGY FOR                     tions in indicated airspeed. Aircraft may be
 uncommon, but when the encountered                     TURBULENCE (FAA)                         momentarily out of control. Occupants are
 turbulence is so severe as to cause                                                             forced violently against seatbelts. Unsecured
 large, abrupt changes in altitude, atti-      TURBULENCE INTENSITY                              objects are tossed about. Food service and
 tude and speed it could be hazardous.                                                           walking are impossible.
                                                Light Chop. Slight, rapid, and somewhat          Extreme. Aircraft is violently tossed about
      Severe turbulence encounters rarely      rhythmic bumpiness without         appreciable    and is practically impossible to control. May
 lead to fatal accidents, but could result     changes in altitude or attitude.                  cause structural damage.
 in serious injuries to un-buckled passen-     Light Turbulence. Slight, erratic changes in
 gers and cabin crew. These encounters         altitude and/or attitude. Occupants may feel      TURBULENCE TYPES
 generate trauma among passengers and          a slight strain against seatbelts. Unsecured      Thunderstorm Turbulence
                                               objects may be displaced slightly. Food ser-      Turbulence associated within and in the vi-
 is an economical issue as substantial         vice may be conducted and little to no diffi-
 aircraft damage could occur. An AOG                                                             cinity of thunderstorms or cumulonimbus
                                               culty is encountered in walking.                  clouds. A cumulonimbus cloud with hanging
 situation with associated repair costs        Moderate Chop. Rapid bumps or jolts with-         protuberances is usually indicative of severe
 may makes it very costly.                     out appreciable changes in aircraft altitude or   turbulence.
      As severe turbulence encounter           attitude.                                         Clear Air Turbulence(CAT)
 causes damage to the aircraft, it is nec-     Moderate Turbulence. Changes in altitude          High level turbulence (above 15000’) not
 essary to inspect the aircraft after the      and/or attitude occur but the aircraft remains    normally associated with cumuliform cloudi-
                                               in positive control at all times. It usually      ness. Typically windshear turbulence even
 encounter. This makes it mandatory for        causes variations in indicated airspeed.
 the pilots to report such encounters.                                                           when in cirrus clouds.
                                               Occupants feel definite strain against seat-      Mountain Wave Turbulence
 The pilot must make a logbook/ tech log       belts. Unsecured objects are dislodged. Food      Turbulence as a result of air being blown
 entry for maintenance action initiation.      service and walking are difficult.                over a mountain range or a sharp bluff
      As per FAA and aircraft maintenance      Severe. Large, abrupt changes in altitude         causing a series of updrafts and downdrafts.
 manuals (AMM):-                               and/or attitude. Usually causes large varia-
      Excessive/severe turbulence is iden-
 tified as turbulence which causes large,      at the pilots’ disposal to localize the           Flight briefing, reported turbulence,
 abrupt changes in altitude and/or atti-       turbulence as early as possible in order          updated weather forecast).
 tude. It usually causes large variations      to have enough time to properly avoid it               The investigation of a turbulence
 in airspeed. Passengers and crew are          or at least to secure the cabin when it is        event where six cabin crew and three
 moved violently against their seat belts      unavoidable.                                      passengers were seriously injured
 and loose objects move around the air-            Analysis of several turbulence events         concluded that—"It is highly probable
 craft.                                        show that there is scope for improving            that the flight crew were not presented
      Airbus specifies a flight in excessive   pilot awareness on the appropriate use            with the optimum weather radar picture
 turbulence as a flight in which the verti-    of available means.                               that would have enabled a full apprecia-
 cal load factor is out of range –1g to            Firstly, weather forecast information         tion of the intensity and extend of the
 +2.5g(inclusive) in clean configuration       available before taking-off as well as            weather in the vicinity of the aircraft.
 or is out of the range 0g to +2g              the weather briefing have to be as com-           As a result the deviation was not
 (inclusive) with the flaps extended.          plete as possible and, depending on the           initiated early enough nor large enough
      Boeing while mentioning these            weather context, this information has to          to avoid the weather". This event is
 vertical loads notes that for severe/         be updated in flight as often as neces-           not an isolated case!
 excess turbulence cases, inspection is        sary. In some severe turbulence events,                The analysis of a large percentage
 required for conditions that do not           analysis has shown that an appropriate            of turbulence events in convective
 exceed these limits as well.                  update of weather information in flight           environment shows a sudden heading
      The following Airbus examples give       would have very likely allowed the de-            change demand just before encounter-
 an idea of the severity of these encoun-      tection and consequently the avoidance            ing the turbulence that has made the
 ters.                                         of the area of turbulence.                        radar tuning and picture interpretation
 - An A340 in cruise had a vertical load           Modern aircraft are equipped with             questionable.
 factor excursion of +2.3g to -0.9g            airborne weather radars. The principle                 For example it is important to notice
 recorded near the centre of gravity           of these radars is to detect precipitation        that a tilt setting in cruise too close
 within few seconds.                           such as wet turbulence and wet hail but           from horizon will only scan in a high
 - An A320 within 10 seconds had               these radars will not detect wind, ice,           range of altitude where humidity is in
 vertical     load     factor    excursions    fog and Clear Air Turbulence (CAT).               ice shape and so not reflective.
 of_1g/1.4g/ 0.2g/3g/0.3g/+1.6g/-0.8g/             Despite weather radar efficiency to                Turbulence      associated   with    a
 +2.6g. During the same period of time         detect convective clouds, in-service              cumulonimbus is not limited to inside
 lateral     load     factor    excursions     events analysis has shown that a large            the cloud. Thus, as current weather
 were_+0 .2 g/-0 .08g/+0.06g/-0.2g/            part of turbulence events comes from              radars cannot detect dry turbulence it is
 +0.2g/-0.22g/ +0.13g.                         aircraft incursions into cumulonimbus             essential     to   take    adequate    pre-
      In case of severe turbulence it is       (CB) that were either not localized by            cautionary measures:
also recommended to inform the aircraft        the crew or not avoided with sufficient                In particular, to minimize the risk of
manufacturer because in some remote            margin.                                           encountering severe turbulence, a
cases, limit loads might have been locally         Weather radar is only helpful if:             cumulonimbus should be cleared by a
exceeded which calls for some additional       - It is properly tuned (tilt, weather             minimum of 5000 feet vertically and
inspections (On top of what is recom-          mode and range           control on the           20NM laterally. Furthermore, if the top
mended in AMM section 05-51).                  Navigation Display) to present an                 of cell is at or above 25000 feet, over-
      Only the most severe turbulence          optimum weather radar picture.                    flying should also be avoided due to the
 encounters are reported to the aircraft       - The flight crew performs regularly              possibility of encountering turbulence
 manufacturer. Airbus annually receives        vertical scan, and correctly interprets           stronger than expected.
 around      20    turbulence     encounter    the screen display.                                    In the same way, flight under a
 reports. One third of these caused                This requires a good knowledge of             thunderstorm should be avoided due
 injuries.                                     weather radar which allows to optimize            to possible wind shears, microburst,
      The best way of managing severe          the use of the radar that will be tuned           turbulence or hail.
 turbulence is to use all available means      using all available information (pre-                   When there is a possibility of
 Page 4                                                    FLIGHT SAFETY                                              Volume 2, No.4

 turbulence encounter it is imperative to         - Set the target thrust to follow the            disconnection and activation of the
 secure equipment, passengers and the             speed target (that depends on altitude)          appropriate manual flight control law
 cabin crew. A part of injuries comes             given in QRH 13.04.                              (The VMO/MMO protection or the angle of
 from objects thrown out and coming               - Descent at or below the optimum                attack protection that will command
 down on buckled people. Consequently             altitude given in QRH 17.01. Indeed at           respectively pitch-up and pitch down
 a prime task of the cabin crew is to             the    turbulence    penetration    target       movement to reduce these excursions).
 secure trolleys and any object that can          speed, this optimum altitude must                In order to keep the Autopilot engaged
 be harmful.                                      provide sufficient margin to buffet to           as long as possible, flight controls soft-
     Most of injuries result from non-            face severe turbulence.                          ware modifications have been devel-
 buckled passengers or crew members               - Consider Autopilot disconnection if            oped on fly-by-wire aircraft. They make
 thrown out during the turbulence. This           Autopilot does not perform as desired.           the Autopilot more robust to disconnec-
 could be prevented with seat belts               For Fly-by-wire aircraft:                        tion resulting from a transient VMO/MMO
 fastened. Although the ideal situation           - Keep Autopilot engaged. Keep ATHR              or ‘alpha prot’ exceeding subsequent to
 would be to consider “seat belts                 engaged except if thrust changes be-             a severe turbulence.
 fastened” as a full-time counter-                come excessive.                                       Severe turbulence can induce signifi-
 measure, the minimum recommenda-                 - Recent severe turbulence events have           cant altitude excursions because of the
 tion, which is normally applied, consists        clearly illustrated that potential conse-        severe turbulence itself or as a conse-
 in requiring seat belts fastened when            quences have been minimized thanks to            quence of the triggering of the VMO/MMO
 moderate or stronger turbulence is               the appropriate use of automation by             protection or the Angle of Attack protec-
 anticipated. In this case, fasten seat           the crew, mainly in keeping Autopilot            tion. Without the pilot in the loop these
 belt sign should be illuminated and              engaged instead of possible instinctive          protections will target respectively
 cabin crew should closely check passen-          reaction, which is to take over                  speed and incidence decrease rather
 ger seat belts compliance. But to be             manually. As per FCOM recommenda-                than maintaining the trajectory.
 efficient this measure must be used with         tion (section 3.04.91) when encounter-                Indeed, when VMO/MMO protection
 distinction since a too long or too fre-         ing a severe turbulence the following            or Angle of Attack protection has been
 quent use will make it counterproduc-            procedure has to be applied:                     activated, the Autopilot is automatically
 tive as it will not be strictly followed. In     - Follow the speed target (that depends          disconnected. In these conditions, it is
 the same spirit, advise announcement             on altitude) given in Section 3.04.91.           now to the pilot to apply smooth
 requiring passengers to keep their seat-         -Maintain ATHR engaged (target speed)            corrections to manage the aircraft
 belts fastened at all times when seated          except if thrust changes become exces-           trajectory (and to avoid to apply
 is also an efficient measure to prevent          sive. In this case ATHR will be dis-             sudden corrections fighting the turbu-
 non-predictive turbulence such as CAT.           connected and thrust will be set to give         lence). Speed will not be closely
     Except specifically requested by the         the recommended speed (See thrust                targeted. Indeed a number of altitude
 flight crew, when the seatbelt sign is           table versus speed target in the same            bursts is the consequence of pilots
 illuminated, flight attendants usually           FCOM section).                                   targeting a large speed margin after
 continue the cabin service.                      - Keep Autopilot engaged. Indeed,                recovery from VMO/MMO. Keeping aware
     In case of specific announcement of          detailed studies regarding aircraft              of the surrounding traffic, a compro-
 turbulence anticipation by the flight            behavior when crossing such external             mise has to be found since such too
 crew, flight attendants will secure the          perturbations has shown that the less            large speed margins will be obtained at
 trolleys and ensure that all passengers          the aircraft reacts at short term to the         the detrimental of the trajectory.
 are fastened before sitting down and             turbulence, the better it is. Indeed, the             Technologies are under develop-
 buckling up themselves. Consequently             dynamics of such severe turbulence is            ment to make turbulence detection
 they secure themselves quite late,               such that any additional pitch down              precise and reliable.
 which explains that injuries often               reaction to counter the initial up                    Airbus has successfully flight-
 concern flight attendants.                       draught will accentuate in most cases            tested a Laser based Turbulence sensor
     Graduation in the urgency of the             the pitch down effect of the down                system on an Airbus A-340-300. A for-
 flight crew warning properly perceived           draught usually subsequent to the up             ward looking Ultra–Violet Laser sensor
 by the cabin crew could allow them to            draught. This will accentuate the excur-         emits short pulses to obtain adequate
 better adapt their actions to the                sion in negative load factor and so              reflection from clear air found at cruise
 situation.                                       increase the risk and number of inju-            altitudes (not detected by weather
     Because some turbulence are not              ries. To minimize the additional effect          radar) and uses Doppler shift to meas-
 detectable by current onboard weather            of such pitch down order coincident to           ure longitudinal, lateral and vertical
 radar or other cannot be detected early          the down draught, it is recommended              components of turbulence motion up to
 enough to be avoided, aircraft behavior          to the crew not to react to the turbu-           45m ahead of aircraft , and up to 10°
 when crossing a severe turbulence also           lence by short term side stick inputs            from the axis of the flight path.
 has to be considered and optimized.              corrections and to keep Autopilot                     NASA has developed Turbulence
     For this, Airbus has the following           engaged.                                         Prediction     and    Warning     System
 recommendations.                                      A severe turbulence may lead to             (TPAWS) to automatically alert pilots of
 For A300/A310/A300-600:                          excessive high speed excursion (beyond           potentially dangerous turbulence. This
 Disconnect ATHR/Descent at or below              VMO/MMO) or to excessive low speed               system has been evaluated on a NASA
 optimum altitude/does not perform as             excursion (below ‘alpha prot’, angle of          757 research aircraft and will soon
 desired.                                         attack threshold of alpha protection law         undergo commercial flight evaluation
 - Disconnect the ATHR                            activation). This will induce Autopilot          on Delta airlines B737-800.

Web Watch                   information about NASA's Aviation Safety and Security Program— turbulence detection                        - “Optimum use of weather radar” and other briefing notes

The Confidential Aviation Hazard Reporting System (CAHRS) provides a means of reporting hazards and risks in the aviation system before
there is loss of life, injury or damage. It is open to anyone who wishes to submit a hazard report or safety deficiencies confidentially and non-
punitively. Reports help to identify deficiencies and provide safety enhancement in areas of aviation. CAHRS forms can be collected at different
location of KAC (i.e. Flight Dispatch) Premises. Completed forms can be dropped in FS&QA allocated box at Flight Dispatch or e-mailed to or faxed to 00965-4749823 or mail to Flight Safety and Quality Assurance office, Operations Department, P.O. Box
394, Safat 13004, Kuwait Airways –Kuwait.

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