Moscow oblast

Investigations were unable to determined the exact cause of the accident. All four engines were functioning properly at impact and some vibrations may have occur on both wings, maybe following ailerons issues.

It was determined that control was lost when severe turbulences were encountered in flight, causing the left wing and the elevators to partially detach as the forces exceeded their certification.

It was determined that the crew decided to attempt to takeoff with a visibility limited to 1,000 meters due to fog and snow, which was well below the minima. In such conditions, the aircraft was not properly aligned on the runway centerline, causing the left main gear to struck a snow wall. Investigators believe that Sheremetyevo Airport officials also bear some responsibilities for the accident because they failed to take the appropriate actions to ensure that the runway was properly cleared of snow. At the time of the accident, most elements of the lighting system fitted to both sides of the runway were covered with snow and therefore did not constitute pilot assistance.

It was reported the pilot-in-command positioned the rudder in a 25° angle without reducing speed. The airplane a steep turn and went out of control.

It was determined that the accident was the consequence of an error on part of the technicians who failed to reconnected the rudder control system according to the manufacturer procedures. It was reported that the system was cross-connected by mistake, causing the aircraft to be uncontrollable.

Poor flying techniques on part of the crew who decided to take off with one engine off in difficult flight conditions.

Loss of control on final approach due to loss of thrust on engine number one after the propeller went into autorotation, causing negative thrust.

The investigations revealed that there were no technical deficiencies in the aircraft itself or a meteorological phenomenon involved in the accident. The Austrian observers participating in the investigation of the accident were of the opinion that the accident was related to altitude measurement, inasmuch as it was apparent from radio communications as well as from the examination of the wreckage that that the crew believed that they were flying at the normal approach altitude. The erroneous altitude measurement may be attributed to:
- A technical deficiency of either of the two altimeters,
- The divergent settings of the altimeters or,
- Omission of altimeter reading or erroneous reading of altimeters.
The internal mechanism of both altimeters was so heavily damaged that it could no longer be ascertained whether, at the time of the accident, the altimeters were functioning accurately. Both altimeters were set to the correct atmospheric pressure but their settings differed, namely the left altimeter was set at QFE 990 millibars and the right altimeter at 1013 millibars, which in view of the prevailing atmospheric pressure conditions, could have corresponded both to QNH and to the standard pressure setting. Such divergent settings are at variance with the usual procedure of Austrian Airlines. The reasons prompting the flight captain to depart from the usual practice could not be ascertained. It was not possible to reach a categorical conclusion as to which of the three causes were responsible for an approach below the minimum flying altitude.

The accident was the consequence of poor approach techniques on part of the flying crew who allowed the aircraft to descent below the glide in poor visibility until the airplane struck obstacles. Following factors were considered as contributory:
- The crew was tired and failed to observe a sufficient rest time,
- At the time of the accident, the crew was on duty since 13h50 with 5h53 cumulated flying hours,
- The pilots performances were diminished by fatigue and work overload,
- The copilot's experience was insufficient,
- Poor visibility due to the night and a cloud layer down to 60 meters from the ground.