Incident Overview
The aircraft departed Anapa Airport at 1505 local time and climbed to its assigned altitude of 11,700 metres. Stormy weather was present ahead, prompting air traffic control to clear the crew to modify their route. The crew changed heading to avoid a thunderstorm area with cumulonimbus clouds reaching up to 15 kilometres in height.
Encounter with Turbulence
While deviating around the storm, the aircraft encountered severe turbulence. Within 10 seconds, it climbed from 11,961 metres to 12,794 metres. The angle of attack reached a super critical 46°, and its speed dropped from 350 km/h to zero, causing all three engines to stop.
Loss of Control
The crew managed to send a brief message before the aircraft entered an uncontrolled descent in a flat spin. At an altitude of 3,300 metres, the crew informed air traffic control that control was totally lost.
Crash
The aircraft crashed in a prairie near Novgorodskoye, approximately 45 kilometres northwest of Donetsk. It was totally destroyed by impact forces and a post-crash fire. All 170 occupants were killed.
Probable Cause
The official investigation determined the probable cause to be a loss of control in manual flight mode after the aircraft reached a super critical angle of attack, causing a stall with subsequent transition to a flat spin and collision with the ground with a large vertical velocity. Contributing factors included poor crew coordination, failure of the crew to follow flight manual instructions to identify and prevent a stall condition, and insufficient crew training methods to demonstrate the dangers of manual flight at high altitudes.