Investigation Summary
The Tu-104, a civilian derivative of the Tu-16 strategic bomber, suffered from aerodynamic instabilities at high altitudes that were not fully understood at the time of its introduction. During this flight, the aircraft was cruising at 10,000 meters when it encountered a massive updraft, described by the crew as the plane 'standing on its hind legs.' This forced the jet to climb rapidly to 12,000 meters, where it lost airspeed and entered a spin. The crew, led by Captain Garold Kuznetsov, remained at the controls until the end, providing a calm and detailed radio transmission of the aircraft's behavior during the fall. These final transmissions were instrumental in helping investigators understand the 'grab' phenomenon, where the Tu-104 would become pitch-unstable in turbulent air, leading to a redesign of the flight control systems and operational limits.
Final Conclusions
The investigation concluded that the loss of control was caused by severe atmospheric turbulence (updrafts and downdrafts) that pushed the aircraft beyond its critical angle of attack. The Tu-104's design, particularly its horizontal stabilizers and swept-wing configuration adapted from a bomber, was found to be insufficient for maintaining stability in such extreme high-altitude conditions. The crash was the deadliest in Aeroflot's history at the time.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Horizontal Stabilizers
The design of the stabilizers was found to be inadequate for recovering from high-alpha excursions caused by turbulence.
Tupolev Tu-16 Airframe
The Tu-104 was a direct derivative of the Tu-16 bomber, inheriting aerodynamic characteristics that proved dangerous in civilian high-altitude cruise.
Interesting Facts
- 01The aircraft had accumulated only 465 flight hours and had been in service for less than three months.
- 02The passenger list included a 16-person Chinese delegation led by scholar Zheng Zhenduo and the Cambodian ambassador to China.
- 03The crew managed to provide a detailed description of the aircraft's loss of control over the radio while descending, which helped solve the 'grab' phenomenon.
- 04The crash site was located approximately 400 miles east of Moscow near the Apnerka rail station.
- 05It was the second fatal accident involving the Tu-104 jetliner and the deadliest in Aeroflot's history at the time.
Safety Actions & Advisories
Flight Level Restrictions
Authorities imposed a maximum flight level of 9,000 meters for the Tu-104 fleet to avoid the most severe high-altitude turbulence zones.
Stabilizer Redesign
The aircraft's horizontal stabilizers were redesigned to improve pitch control and recovery characteristics.
Angle of Attack Modifications
Changes were made to the aircraft's wing and control surfaces to increase the margin before reaching a critical angle of attack.