Causalfactors
patial disorientation was the primary by night instrument meteorological conditions, cause of the Sept. 13, 2008, crash of a as well as by a navigation programming er- Boeing 737-500 at Perm, Russia, accord- ror and a “throttle stagger” that made manual ing to the final report by the Russian Air engine management difficult and led to control AccidentS Investigation Commission (AAIC). problems caused by asymmetric thrust. The Contributing factors were inadequate crew copilot, the pilot flying, abruptly handed over resource management (CRM), a lack of profi- control to the captain when the aircraft was in a ciency in basic aircraft handling and a lack of steep climbing left turn. The captain, whose spa- skills associated with the use of a “Western-type” tial disorientation was exacerbated by alcohol attitude indicator for recovery from an upset. and fatigue, was unable to recover. The aircraft During the approach to Perm’s Bolshoye rolled nearly inverted, entered a steep descent Savino Airport, the flight crew was challenged and fragmented when it struck terrain at high
BY MARK LACAGNINA Misgauged Recovery
An unfamiliar, Western-type attitude indicator was little help to the disoriented Russian captain when an upset occurred.
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speed. All 82 passengers and six crewmembers because the captain’s file did not contain all the were killed. pertinent documents. The copilot was trained The aircraft was operated by Aeroflot- in 2007–2008 at an approved facility in Russia. Nord, which was rapidly adding 737s to its His records reflected inattention to standard fleet and training pilots to fly them. The re- operating procedures and CRM practices, and port said that there were “serious drawbacks” substandard proficiency in flying with a thrust in the transition training that the accident asymmetry. Instructors’ notes recommended pilots had received, and it faulted the airline that the copilot pay more attention to control- for pairing a captain with limited experience ling airspeed and attitude during approach. as a pilot-in-command with a copilot with Both pilots had received English language limited experience in type. instruction at the airline’s training center. Al- The captain, 35, had more than 3,900 flight though they were not engaged in international hours, including 90 hours in an Antonov 2 dur- flight operations, the training was necessary ing his primary training and about 2,700 hours because all the documentation for the 737 was as a Tupolev 134 copilot. His experience in 737s in English. Both pilots received passing grades. comprised 1,190 hours, with 477 hours as cap- However, the report said that the relatively large tain. The copilot, 43, had more than 8,900 flight amount of material included in the training syl- hours, including about 7,000 hours in An-2s and labus and the relatively short period of training 1,600 hours as a Tu-134 copilot. He had logged made it highly doubtful that the pilots assimi- 236 hours in 737s. lated all the instruction. Moreover, analysis of The aircraft that the pilots had flown before recorded statements by the copilot during the transitioning to the 737 — the An-2, a large accident flight indicated that his English pro- utility biplane, and the Tu-134, which has ficiency was not suitable for operating the 737, fuselage-mounted turbofan engines and a flight especially the flight management system (FMS) deck accommodating two pilots and a naviga- and autoflight systems. tor — have “Eastern-type” attitude indicators, in which the horizon remains fixed horizontally Throttle Stagger and the aircraft symbol tilts to show bank angle The accident aircraft was among 12 737s oper- (Figure 1). Conversely, the horizon line in the ated by Aeroflot-Nord. The aircraft was owned 737’s Western-type attitude indicator tilts while by a Bermudan company, previously operated in the aircraft symbol remains fixed horizontally. China and had accumulated about 43,491 flight Neither pilot had any experience with Attitude Indicator Display Differences two-pilot flight crew operations or modern © Andrey Nogin/Airliners.net Western Eastern “glass” flight decks 40
when they began 30 30 40 LRN1 140 IAS The accident aircraft 20 their 737 transition 20 30
landing at Perm 10 20 training. The captain F I 0 10 in happier days. was trained in 2006 10
S 10 20 at a U.S. facility that I 0 30 20
was not approved by 40 30 20
Russian authorities. 40 30 The report said that 40 an adequate assess- Source: Daniel W. Knecht ment of the training was not possible Figure 1
www.flightsafety.org | AeroSafetyWorld | July 2010 | 19 Causalfactors
hours when the airline to the throttle stagger. Despite its designa- began flying it about tion as inoperative, the autothrottle was used four months before during seven subsequent flights, including the the accident. accident flight. The aircraft had a throttle-stagger con- ‘Totally Drunk’ dition that exceeded The captain and copilot were conducting their the limits specified in third flight together. The scheduled departure the aircraft main- time from Moscow’s Sheremetyevo Airport tenance manual was 2112 coordinated universal time (0312 lo- (AMM). This condi- cal time). Both pilots had received 15 hours of tion requires the rest before reporting for duty and had passed throttles to be placed medical examinations before the flight. How- in different positions ever, the report said that the captain’s schedule to match engine set- during the previous three days did not comply tings. Recorded flight with national regulations and was conducive to data showed that fatigue; he had conducted six flights, including during partial-power two night flights, and had taken almost no rest operations, engine at night. fan speeds varied up Before starting the engines, the captain Photo taken on a to 20 percent with the throttles in the same made a public address announcement to the previous flight shows position. Setting the engines to produce identi- passengers. The report said that one passenger throttle stagger cal fan speeds resulted in a throttle stagger of sent a text message to a friend in England, required to maintain up to 15 degrees, with the left throttle ahead of saying that he was frightened because the 83 percent fan speed the right throttle. The report noted, however, captain sounded “like he is totally drunk.” He on both engines. that there was no throttle stagger at idle and said that other passengers were worried but “almost none” at takeoff power. had been assured by flight attendants that The report said that the airline’s mainte- everything was all right. nance personnel did not follow the procedures While completing the initialization of the recommended by the AMM to correct the prob- inertial reference system (IRS), the copilot lem, which initially was identified more than a made two slight errors in entering the stand’s month before the accident. geographical coordinates in the FMS. The im- Maintenance documents indicated that the mediate result was a misposition of 1 minute, or 737 was being operated with an inoperative approximately 1 nm (2 km). The captain, who traffic-alert and collision avoidance system and was supposed to be monitoring the copilot’s an inoperative autothrottle. The autothrottle preflight actions, did not catch the error. was designated as inoperative because it had The 737 departed from Moscow at 2113. disengaged several times during a previous The captain flew the takeoff and then trans- flight. However, maintenance personnel had not ferred control to the copilot. The copilot flew complied with minimum equipment list provi- the aircraft with the autopilot and autothrottle sions requiring the circuit breakers to be pulled engaged. Perm is about 675 nm (1,250 km) east and “collared” to prevent them from being reset, of Moscow. The cruise altitude was 9,100 m and the autothrottle switch to be placarded as (about 29,900 ft). inoperative. Because of the IRS initialization error and Investigators found that the autothrottle normal IRS drift — as well as the inability of actually was functioning properly and that the the FMS to update its position via the global
uncommanded disengagements were related positioning system (the aircraft did not have a Branch Investigation Accidents Air U.K.
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GPS receiver) or signals from ground direction finder as a backup. As a assign a heading. The copilot turned navigational facilities (there were result, the aircraft crossed over the the 737 from the 030-degree downwind none on the route) — the misposition runway, rather than the outer marker. heading to a southerly heading to inter- increased to more than 4.5 nm (8.3 km) The controller did not mention this cept the ILS localizer. as the aircraft neared Perm. The crew to the crew. The aircraft was still in the clouds began the descent at about 2245. Following the controller’s radar when it reached 600 m. After the vectors, the copilot maneuvered the 737 copilot advanced the throttles to hold Confusion Reigns onto a right downwind leg for Runway that altitude, the autopilot reached the The automatic terminal information 21 while descending to 2,100 m (about limits of its control travel in coun- system indicated that surface winds at 6,900 ft). The autopilot was in a naviga- tering the left roll moment, and the Perm were from 050 degrees at 6 kt, tion mode, and the copilot became aircraft began turning left. The copilot visibility was 5 km (3 mi) in light rain confused when the aircraft began attempted to use the control wheel and mist, the ceiling was overcast at 240 turning left. “Where’s it going?” he said. steering switch to manually level the m (787 ft) and the instrument landing “I don’t understand where it’s going.” wings while keeping the autopilot system (ILS) approach to Runway 21 The captain told the copilot to use the on line but inadvertently pressed the was in use. autopilot’s heading mode. stabilizer-trim switch, causing the The report said that analysis of When power was increased to level autopilot to disengage. cockpit voice recorder (CVR) data the aircraft at 2,100 m, the throttle The copilot was unable to maintain indicated that the captain likely expe- stagger became so great that the auto- control. The aircraft was in a 30-degree rienced an inordinately high level of throttle automatically disengaged. The left bank and a 20-degree nose-up atti- stress during the final phases of the captain told the copilot to control the tude at 2308, when he told the captain, flight. Conversation between the pilots engines manually. Rather than posi- “Take it. Take it.” often was not related to flight tasks and tioning the throttles to match engine The report said that the captain was replete with expletives and spiteful fan speed, however, the copilot kept the had lost situational awareness during remarks about the flight attendants and throttles together. The resulting asym- a long discussion with the approach the Airport Control Service. No check- metric thrust caused a significant left controller. “Take what?” he asked. lists or mandatory cross-checks were roll moment. “I can’t do it either.” The captain performed, and few required callouts At 2301, the controller issued a fur- abruptly applied left aileron and did were made during the approach. ther descent clearance to 600 m (about not correct the pitch attitude. The The CVR data also showed that the 1,970 ft) and told the crew to main- bank angle increased to 76 degrees, crew was confused by arrival instruc- tain 190 kt. The controller then said, and the aircraft made an almost full tions issued by the approach control- “Are you descending? My radar shows barrel roll before descending to the ler to facilitate an aircraft departing 1,800.” The report said that the ques- ground, the report said. from Perm. The instructions differed tion provoked an “intense reaction” by A postmortem examination of the from the standard arrival route and the captain, who asked “twice emotion- captain revealed that the level of ethyl approach fixes that the copilot had ally” how low they should descend. alcohol in his body before he died entered in the FMS. After lengthy dis- The copilot replied that the assigned exceeded regulatory limits, the report cussions with the captain, the control- altitude was 600 m and then said, “Why said. No alcohol was found in the bod- ler told the crew to navigate directly to doesn’t it descend? I’ve pressed heading ies of the other crewmembers. the outer marker for the ILS approach. select.” The CVR recording indicated The report said that this instruction that the captain was annoyed when he This article is based on the English translation annoyed the pilots. told the copilot to select the autopilot’s of AAIC final report no. B737-505 VP-BKO. Nearing the airport from the west, level change mode. The official report, in Russian, is available at