Date & Time:
Dec 21, 1955 at 0645 LT
Type of aircraft:
Lisunov LI-2
Operator:
Registration:
CCCP-L4981
Flight Phase:
Flight
Flight Type:
Cargo
Survivors:
No
Site:
Desert
Schedule:
Almaty – Balkhash – Moscow
MSN:
2 34 433 07
YOM:
22
Flight number:
SU090
Country:
Kazakhstan
Region:
Asia
Crew on board:
5
Crew fatalities:
5
Pax on board:
1
Pax fatalities:
1
Other fatalities:
0
Total fatalities:
6
Aircraft flight hours:
4023
Circumstances:
The aircraft left Almaty Airport at 0515LT bound for Moscow via Balkash, carrying one passenger, five crew members, 763 kilos of various goods and 683 kilos of mail. Upon departure, the total weight of the aircraft was 10,722 kilos, 22 kilos above MTOW. Enroute to Balkash, the crew encountered poor weather conditions. While flying in clouds, some instruments failed. The pilot-in-command lost his orientation and then the control of the aircraft that dove into the ground and crashed in a snow covered area located about 105 km southeast of the Balkash Lake. It was determined that the aircraft hit the ground in a 65° nose-down angle at high speed and disintegrated on impact, causing the debris to be scattered on more than 200 meters. All six occupants were killed.
Probable cause:
Failure of a vacuum regulator which cause the dysfunction of the gyrocompas and then the automatic pilot system. While cruising in very low visibility (night and clouds), the crew suffered a spatial disorientation and lost control of the airplane.
