Incident
While en route from Khatanga to Moscow-Domodedovo Airport, a four-engine aircraft was cruising at an assigned altitude of 7,800 metres in good weather conditions during night. The aircraft entered an uncontrolled descent, reaching an excessive speed of 850 km/h. It then rolled to the left to an angle of 60° and nosed down to an angle of 42°. The aircraft suffered structural failure, losing several elements, and partially disintegrated in the air. It eventually crashed in a snow-covered field located 15 km southeast of Kalyazin. The aircraft was totally destroyed, and all 27 occupants were killed.
Probable Cause
The official investigation determined the probable cause to be a failure of the protection system of the elevator trim, causing a spontaneous deflection of the elevator. This caused the aircraft to enter an uncontrolled descent, and the crew was unable to regain control. Violations about aircraft maintenance, flight organization, and operational aspects were identified within the operator. Excessive G loads during the descent caused the aircraft to partially disintegrate before final impact.