Date & Time:
Jul 10, 1985 at 2346 LT
Type of aircraft:
Tupolev TU-154
Operator:
Registration:
CCCP-85311
Flight Phase:
Flight
Flight Type:
Scheduled Revenue Flight
Survivors:
No
Site:
Desert
Schedule:
Karshi – Ufa – Leningrad
MSN:
78A311
YOM:
1978
Flight number:
SU5143
Country:
Uzbekistan
Region:
Asia
Crew on board:
9
Crew fatalities:
9
Pax on board:
191
Pax fatalities:
191
Other fatalities:
0
Total fatalities:
200
Aircraft flight hours:
12443
Aircraft flight cycles:
5660
Circumstances:
After takeoff from Karsi Airport, the aircraft climbed at an insufficient speed of 470 km/h with a max speed of 515 km/h. The cruising altitude of 11,600 meters was reached after 40 minutes and 20 seconds. The speed dropped to 400 km/h then the aircraft reached a critical angle of attack (+20°) when vibrations started. The crew misinterpreted these vibrations and failed to judge properly the situation in reducing the engine power to idle. The speed dropped to 290 km/h when the aircraft stalled and entered a spin. The aircraft eventually went into a flat attitude and crashed in an isolated and desert area located in the region of Ushquduq. The aircraft was totally destroyed upon impact and all 200 occupants were killed.
Probable cause:
It was determined that the climb configuration was incorrect and the crew led the aircraft adopting a critical angle of attack once the cruising altitude was reached. This situation affected the air flow into the three engines and the aircraft went into inappropriate flight conditions. The crew misinterpreted the situation and failed to identify the wrong flight configuration until the aircraft entered stall condition.
