Date:	Sunday 9 July 2006
Time:	07:44
Type:	Airbus A310-324
Owner/operator:	S7 Airlines
Registration:	F-OGYP
MSN:	442
Year of manufacture:	1987
Total airframe hrs:	59865 hours
Cycles:	12550 flights
Engine model:	Pratt & Whitney PW4152
Fatalities:	Fatalities: 125 / Occupants: 203
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	Irkutsk Airport (IKT) -   Russia
Phase:	Landing
Nature:	Passenger - Scheduled
Departure airport:	Moskva-Domodedovo Airport (DME/UUDD)
Destination airport:	Irkutsk Airport (IKT/UIII)
Investigating agency:	MAK
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
On its last flight on July 8, 2006, the Airbus A310 F-OGYP was released with six defects as per minimum equipment list (MEL), including the deactivated state of the left engine thrust reverser. The previous two flights had been carried out with a deactivated right engine thrust reverser.
On July 9, Sibir flight 778 departed Domodeovo (DME) at night for a flight to Irkutsk (IKT). Weather at Irkutsk was poor. It was raining, overcast clouds at 600 feet and a thunderstorm in the area. At 07:38 the co-pilot reported the completion of the final leg at 850 m, whereupon he received instructions to contact Irkutsk tower. The Irkutsk tower controller cleared the crew for an approach to runway 30. Descent to the final approach leg was carried out using the airplane captain's navigational display in VOR mode, and that of the co-pilot in ILS mode, to control the airplane's position relative to the course using indications from the localizer beacon. At 07:40:18 the co-pilot reported: "Sibir 7-7-8 descending, landing gear down, ready for landing", whereupon he received the controller's clearance to land. At 07:43:13, 1500 meters short of the runway threshold and at a height of 105 m, the crew disengaged auto-pilot no. 1, and switched off the auto-throttle 2 seconds afterwards.
After breaking through the clouds, the captain obtained visual contact with the runway. He made a small elevator deflection to pitch down, which led momentarily to an increase in vertical speed and activation (at 07:43:30, at 30 m), of the "SINK RATE" ground proximity warning. At 07:43:40 the captain landed the airplane at a speed of 244 kph (132 knots) at a distance of about 200-300 meters from the runway threshold. Immediately after touchdown, with the spoiler handle armed, all spoiler sections were automatically released. 1.5 seconds after touchdown the reverse thrust lever of the right engine was moved to idle by the captain, and 3 seconds after that, after the reverser doors were in their working position, switched to maximum reverse thrust. Engine reverse thrust then started to increase. In violation of SOP’s, the co-pilot did not call out the completion of reverser door movement to the working position (Rev Green). The crew did not activate the reverse thrust lever for the left engine. Afterwards the captain began to shift the reverse thrust lever of the right engine to reduce reverse thrust. Simultaneously with moving the reverse thrust lever of the right engine, the FDR records a change in position of the thrust control lever of the left engine, which in 3 steps, over 16 seconds, increased from 36.6° (idle) to 59° (~60% of the full rated takeoff thrust). The direction and periods of movement of the reverse thrust lever of engine no. 2 to reduce the reverse thrust and the thrust control lever of engine no. 1 to increase forward thrust coincided.
Because of the movement of the thrust control lever to a position greater than 10°, the spoilers retracted automatically. Retraction of the spoilers led to the deactivation of the automatic braking mode. At this time the speed was about 180 kph (98 knots) and, on account of the large asymmetry of engine thrust, the airplane started to turn to the right, which the airplane captain counteracted by depressing the left pedal and forcibly applying the brakes. The speed stabilized at 98 knots. At 07:44:21 the crew (most probably the co-pilot) tried once again to deploy the thrust reverser on the right engine, for which he moved the reverse thrust lever of the engine over to maximum reverse thrust but, per design, the location of the thrust control lever for the left engine in a mode higher than 55° prevented the operation, and the thrust reverser doors failed to unlock. The right engine remained at idle forward thrust. After this attempt to deploy the thrust reverser, the airplane started to swerve to the left. The crew attempted to correct this movement and the airplane started to drift to the right.
The right main bogie exited the runway at a speed of 98 knots, and the nose landing gear and the left main bogie moved along the reinforced concrete portion of the runway. The nose landing gear and the left main bogie exited on to the ground at the end of the reinforced concrete runway at 07:44:36. The airplane traveled over clay soil with a grassy cover. At a distance of 210 m from the threshold of runway 12, the left engine destroyed part of the antenna and the wooden fence of the localizer beacon system. At a distance of 250 m from the threshold of runway 12, the airplane crossed an asphalt bypass road. The airplane stopped at 07:44:40 after colliding with a reinforced concrete airport perimeter fence and with brick structures (garages) behind it. The airplane broke apart during the collision and burst into flames.

CONCLUSION: "The cause of Sibir A-310 F-OGYP accident was the erroneous and uncontrolled actions by the crew during rollout after landing in a configuration with one engine reverser deactivated. After touchdown, the Captain, while acting on the reverse thrust lever of the right engine, inadvertently and uncontrollably moved the throttle lever for the left engine, whose thrust reverser was deactivated, from the "idle" to the significant forward thrust position. Inadequate monitoring and call-outs of airplane speed and engine parameters by the Co-pilot made it impossible for the crew to perform the necessary actions, either by moving the left throttle back to idle or shutting down the engines. The crew had enough time to recognize the situation.
The airplane went off the runway at the high speed of ~180 km/h, hit the concrete fence and buildings, crashed and caught fire. 125 people died as a result of the accident."

MAK Interstate Aviation Committee (IAC)
Ministry of Emergency Situations (MChS) of Russia

photo (c) Stefan Hofecker, via Werner Fischdick; Düsseldorf Airport (DUS); 27 June 2006

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