637
1984-DEC-04 · Near Kostroma-Sokerkino Airport, Russian SFSR, Soviet Union

Aeroflot — Flight 637

On December 4, 1984, an Aeroflot Let L-410MA crashed shortly after takeoff from Kostroma-Sokerkino Airport. During the initial climb in night conditions and low visibility, the aircraft entered a steep bank and crashed into a forest. The accident was attributed to spatial disorientation of the crew, potentially exacerbated by a failure of the aircraft's gyroscopic instruments. All 10 people on board were killed.

Aircraft
Let L-410MA
Registration
CCCP-67225
Phase
Cause
Souls on Board
10
Fatalities
10
Origin → Dest
Kostroma-Sokerkino Airport, USSR → Ivanovo Airport, USSR
Report

Investigation Summary

The flight departed Kostroma at night for a short domestic hop to Ivanovo. Shortly after liftoff, the aircraft began an unplanned bank. The investigation suggested that the crew lost situational awareness and spatial orientation in the dark, possibly due to a malfunction in the flight instruments (gyros). The aircraft lost altitude during the turn and struck trees in a wooded area near the airport. The impact and subsequent fire destroyed the aircraft, resulting in the deaths of all 2 crew members and 8 passengers.

Final Conclusions

The investigation determined the cause to be spatial disorientation during a night takeoff in instrument meteorological conditions. A suspected failure of the gyroscopic systems likely provided the crew with erroneous attitude information, leading to an unrecognized steep bank and subsequent loss of control. The aircraft struck terrain before the crew could recover.

Video Analysis

No video analysis linked for this case file yet.

Airframe & Maintenance

Airframe Hours
16,365
Engines
Walter M601

Systems & Failure Modes

i

Gyroscopic Flight Instruments

A suspected failure of the aircraft's gyroscopic attitude indicators (such as the AGB-3K) likely provided the crew with erroneous bank information during the night climb.

Interesting Facts

  • 01The accident occurred during the initial climb phase shortly after takeoff from Kostroma-Sokerkino Airport.
  • 02The crash site was located in a forested area near the airport.
  • 03All 10 occupants, including 8 passengers and 2 crew members, perished in the accident.

Location

Near Kostroma-Sokerkino Airport, Russian SFSR, Soviet Union · 57.7167, 41.1333

Case File History

  1. New evidenceUpdated findings, systems analysis, event timeline and safety actions.
  2. Final reportUpdated investigation summary, final conclusions, sources and event timeline.

Related Cases

Case ID · aeroflot-3352-1984-gq6Last updated · Filed

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