FLIGHT SAFETY AN IN-HOUSE NEWSLETTER OF OPERATIONS DEPT. IN- NEWSLETTER Vol.2, No.4 Flight Safety & Quality Assurance Division April 2007 Editorial 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 landing 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 NEWSLETTER TEAM 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, firstname.lastname@example.org 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 Links International Airport, Chicago, Illinois. The time limitation. He then telephoned the flight kacops.kuwaitairways.com first officer and the captain checked in for the dispatcher to suggest that he get another www.ntsb.gov flight around 1018 and 1038 respectively. airplane for the flight or cancel it. Afterwards, www.bea-fr.org/anglaise/ 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 www.bst.gc.ca/en/index.asp Flight 2080, from Salt Lake City to Dallas/Fort departure time was 2 hours 12 minutes later www.bfu-web.de Worth, departed at 1647 and arrived at 2010, than the scheduled departure time. Captain www.aaib.gov.uk/home/index.cfm www.atsb.gov.au/ 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 exceeded. - 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 http://avsp.larc.nasa.gov information about NASA's Aviation Safety and Security Program— turbulence detection http://www.airbus.com/en/corporate/ethics/safety_lib - “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 email@example.com 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.