Aeroflot Flight 763

On 14 October 1986, on Aeroflot Flight 763, a Let L-410M regional airliner crashed while taking off from Ust-Maya Airport. The aircraft overran the runway and plunged into the Aldan River. All 14 people on board were killed, as they were unable to open the doors of the sinking aircraft.

Flight history

Flight 763 served a route from Magan to Allakh-Yun with a stopover in Ust-Maya. The flight to Ust-Maya proceeded without any particular incidents. The crew then worked through the checklist for the onward flight to Allakh-Yun. The inspection of the aircraft for the onward flight revealed no deficiencies, the payload was not exceeded and during loading care was also taken to ensure a correct centre of gravity of the aircraft.

Accident sequence

During the takeoff run, after reaching decision speed and only 1.8 seconds before reaching lift-off speed, the left engine faltered; a flameout then occurred. The pilots feathered the propellers of this engine and increased the power of the right engine to 96 percent. Shortly afterwards they rotated the aircraft at a speed of 160 km/h. Because of the measures taken to compensate for the thrust after the engine failure, the pilots forgot to retract the landing gear after lift-off.

At a height of about 10 metres, the aircraft veered to the left. At the end of the runway, the flight path approached obstacles in the form of 10–15-metre-tall trees at a distance of 80 metres beyond the end of the runway. Within six seconds of lift-off, the airspeed first increased to 164 km/h and was then reduced again to 120 km/h within the following 9 seconds. This was presumably due to an attempt by the crew to avoid a collision with obstacles. The pilots managed to climb the aircraft to 40 to 50 metres, but after that the aircraft, with only one engine in operation, could not maintain its altitude, and the airspeed dropped to 140 km/h.

At the same time, on aircraft of the type L-410MU in takeoff configuration with asymmetric engine power at an airspeed of less than 160 km/h, a loss of controllability occurs owing to the lack of full airflow over the rudder to compensate for the torque. The aircraft was in an uncoordinated left turn at a high angle of attack above the water surface of the Aldan River, while its vertical speed changed from 0.7 to 1.1 metres per second and the airspeed, according to the indications, decreased from 125 to 90 km/h. The pilots still tried to increase the airspeed, which, however, only increased the aircraft's rate of descent.

119 seconds after takeoff, at a height of 5 to 10 metres above the Aldan River, a stall occurred. The aircraft plunged into the water 270 metres from the riverbank.

Because of the high water pressure, the occupants could not open the doors of the Let L-410. The aircraft sank in the river within two to three minutes.

Recovery and accident investigation

When rescue teams arrived at the crash site 6 minutes after the crash, they found no trace of the aircraft. The rescue teams moreover had no boats with which to rescue people from the water. Other necessary technical equipment for rescue and evacuation work was also unavailable. Motorboats, vessels of the river fleet and a Mi-8 helicopter carried out the search for the wreck. The wreck was raised the following day, 31 hours after it sank. The accident victims underwent forensic examination after recovery. Since they showed no significant external injuries, the investigators assumed that they had all been wearing their seat belts at the time of the accident. The cause of death for all victims was drowning.