Investigation Summary
Flight 1661 was climbing through 5,400 meters when it struck a radiosonde launched by the Soviet Hydrometeorological Service. The collision was catastrophic, instantly destroying the radome and shattering the cockpit windshield. The sudden loss of the nose structure and the resulting aerodynamic disruption caused the aircraft to pitch down into a violent, uncontrolled dive. As the Antonov reached a speed of 700 km/h at approximately 2,000 meters, the aerodynamic loads exceeded the airframe's design limits, causing the wings and horizontal stabilizers to tear away from the fuselage. The remaining fuselage section impacted the ground at a high vertical velocity, leaving no survivors among the 40 passengers and 5 crew members.
Final Conclusions
The investigation concluded that the primary cause was a collision with a foreign object, specifically a radiosonde/balloon assembly. Evidence included parts of two radiosondes found in the wreckage and damage to the nose cone consistent with a solid object impact. The collision occurred 131 km from the departure airport while the aircraft was in its climb phase.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Aeroflot 1661 — Antonov An-24B · CCCP-47751
Systems & Failure Modes
Radome / Nose Cone
The forward-most structure of the aircraft which was destroyed upon impact with the radiosonde, leading to loss of aerodynamic stability.
Weather Radar
Located within the nose cone, this system was destroyed during the initial collision.
Horizontal Stabilizer
Separated from the aircraft during the high-speed descent when aerodynamic limits were exceeded.
Interesting Facts
- 01The aircraft was carrying a youth ice hockey team traveling to a 'Golden Puck' tournament game.
- 02Parts of the aircraft's nose cone were found 6 km away from the main crash site.
- 03The flight lasted exactly 25 minutes and 25 seconds from takeoff to impact.
- 04The collision occurred approximately 131 km from Tolmachevo Airport.
- 05The aircraft had completed 3,832 cycles at the time of the accident.
Safety Actions & Advisories
Radiosonde Launch Coordination
The investigation led to recommendations for better coordination between the Hydrometeorological Service and civil aviation authorities to ensure radiosonde launch times and locations do not conflict with active flight corridors.