Date & Time: Aug 29, 1979 at 0026 LT
Odessa - Kiev - Kazan
3 35 10 03
Crew on board:
Pax on board:
Aircraft flight hours:
Aircraft flight cycles:
The airplane departed Kiev-Borispol Airport at 2321LT on the second leg of a flight from Odessa to Kazan. While cruising by night at an altitude of 9,000 meters and a speed of 530 km/h, the flaps extended to an angle of 30°. The airplane entered a spin and partially disintegrated at an altitude of 4,000 meters before crashing in a field located near Kirsanov. The aircraft was totally destroyed and debris were found on a wide area. None of the 63 occupants survived the crash.
It was not possible to determine the exact cause of the extension of the flaps to an angle of 30° while the aircraft was in normal cruise with the autopilot system engaged. Various analysis could not define if the extension was the result of an electrical failure or a human action, voluntary or not. The most likely cause for flap release could be moving the handle of the left pilot flap control switch to the 'down' position by an angle sufficient to trigger the switch. The design of the locking device of the ZPPM-45 switch of the left pilot and its geographical situation does not exclude the possibility of an unintentional flap release, which was revealed by a one-time check of these devices on 16 others Tupolev Tu-124 aircraft.