Accident Overview
On a positioning flight from Moscow to Berlin, an aircraft was destroyed after it crashed during takeoff from Runway 06. The three crew members sustained minor injuries. The accident occurred in moderate to strong snowfall.
Sequence of Events
After receiving clearance to start engines, the aircraft was towed to the deicing pad. The crew requested a two-step deicing procedure, consisting of deicing with Type I fluid followed by anti-icing with Type IV fluid. The treatment was completed at 1618 local time. The crew was cleared for takeoff at 1636 local time. During the takeoff roll, after covering 1,500 meters on the runway in snowfall, the pilot-in-command initiated rotation. The aircraft then rolled left and right. The right wing struck the ground, the aircraft went out of control, became inverted, and crashed in a snow-covered area 450 meters further and 35 meters to the right of the runway.
Weather Conditions
At the time of the accident, the reported weather included wind from 130 degrees at 10 knots, horizontal visibility of 1,000 meters in snow, vertical visibility of 300 feet, outside air temperature of -6°C, and dewpoint of -7°C.
Probable Cause
The official probable cause was a loss of control at liftoff due to a loss of lift caused by a stall consecutive to an excessive accumulation of ice or frost on the critical surfaces, despite the aircraft having been deiced and anti-iced prior to takeoff.
Contributory Findings
The following findings were identified in the investigation:
- The aircraft was deiced in a two-step procedure (Type I then Type IV) completed at 1618LT, 19 minutes before the accident.
- At the time of the accident, moderate to strong snowfall was occurring at the airport.
- The crew did not receive the full meteorological bulletin prior to departure and failed to determine the correct holdover time.
- Referring to the actual weather conditions, the crew did not proceed with a second deicing or anti-icing procedure.
- There was a lack of adequate check by crew members and/or airline representatives regarding the quality of the anti-icing treatment.
- The crew failed to comply with the Aircraft Flight Manual (AFM) relating to the actual weather conditions.
- The takeoff was started at a speed 12 knots below the reference speed, increasing the stall condition with leading edges that were slightly contaminated with frost or ice.