1951-11-17: Ilyushin II-12 (CCCP-L1775) — Aeroflot - Russian International Airlines — Novosibirsk, Russia

23 fatalitiesNovosibirsk, RussiaTakeoff (climb)

An aircraft crashed shortly after departing Novosibirsk for Moscow due to heavy ice and snow accumulation on the airframe.

What happened

Following the addition of passengers arriving from Yakutsk, a secondary flight was scheduled to travel from Novosibirsk to Moscow. Throughout the day, heavy snowfall occurred, resulting in approximately 15 mm of ice buildup across all aircraft at the airport. During the taxiing process, an additional 8 to 10 mm of snow settled on the plane.

During the takeoff roll, the flight appeared normal; however, after rotation, the aircraft reached an altitude of roughly 100 meters before experiencing a stall. The plane crashed approximately 900 meters beyond the runway threshold, resulting in a massive explosion. The impact and subsequent fire destroyed the aircraft, leading to 23 fatalities.

Findings

Investigations revealed that the aircraft's surfaces were heavily contaminated with ice and snow. Specifically, accumulation was noted on the wings, fuselage, tail, stabilizers, ailerons, and both the leading and trailing edges. This contamination prevented the aircraft from maintaining a safe climb gradient.

Several contributing factors were identified during the investigation:

  • The crew did not follow established flight preparation procedures.
  • There was a failure to inspect the aircraft properly before departure.
  • Appropriate deicing protocols were not implemented.
  • Inadequate organizational and flight preparation efforts.
  • Failure to clear snow and ice from the airframe prior to takeoff.

Probable cause

The accumulation of ice and snow on critical flight surfaces, combined with a failure to perform proper deicing procedures, led to an aerodynamic stall during the initial climb.