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Airbus A310-324 Plane crash, [Sibir flight 778]

8 July 06

On July 9, Sibir flight 778 departed Domodeovo (DME) at night for a flight to Irkutsk (IKT). The plane was in full operational order when it landed, but due to a couple of minor human errors, the crew lost control of the plane on the air strip, hit a building and burst in to flames.

There were 193 passengers and 10 crew members aboard. Seventy six passengers and three flight attendants survived the crash, leaving 124 dead. Nearly 60 people were taken to a hospital, some with critical injuries, but others managed to escape with few injuries and 15 were able to continue their journeys. Some survivors said they owed their lives to a flight attendant who managed to open the emergency exit in the rear of the aircraft.

Weather at Irkutsk was poor. It was raining, overcast clouds at 600 feet with a thunderstorm. At 07:38 the co-pilot reported the completion of the final leg at 850m. 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.

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 30m), 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. 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 36.6º (idle) to 59º (~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 10º, 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 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 210m 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 250m 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.

"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.

According to the preliminary results of the investigation, the accident was caused by the left engine thrust reverser's failure to deploy. The thrust reverser in question was known to malfunction prior to the accident. When the pilot attempted to slow down the plane by deploying the right engine thrust reverser, the left engine was inadvertently switched into takeoff mode, causing the plane to accelerate It veered off the runway and hit the concrete barricade at the speed in excess of 100 km/h (62 mph).

Revised accident Section A: According to the final results of the investigation, the accident was not caused by the left engine thrust reverser's non-deployment due to a Minimum Equipment List (MEL)authorized reverser deactivation - The thrust reverser in question was inoperative in line with MEL requirements prior to the accident.

When the pilot slowed down the plane by using wheel braking and deploying the righthand engine thrust reverser, the lefthand engine throttle lever was inadvertently advanced, causing the plane to not de-accelerate as per a normal landing. The crew was unaware the thrust lever had been inadvertently advanced until late in the accident cycle. The aircraft veered off the runway and hit a concrete barricade at the speed of approximately 100 km/h (62 mph).

The preliminary report issued by the Russian MAK the week of September 25, 2006, blaming the accident on pilot error, and finding that there was no problem with the engines or the aircraft.


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