Investigation Summary
The accident occurred during the 32nd flight of the airframe, which was being prepared for delivery to the Myanmar Air Force. The flight profile included an emergency descent exercise. During this maneuver, the crew permitted the aircraft to accelerate significantly beyond its Never Exceed Speed (VNE), reaching speeds 110 km/h (59 knots) above the design limit. This excessive speed induced severe aerodynamic stress and low-frequency vibrations across all three axes. The resulting alternating accelerations exceeded the structural safety margins of the airframe, causing parts of the horizontal stabilizer and elevator to detach in flight. The investigation highlighted that the crew's coordination was inadequate and they deviated from the procedures established in the flight manual. Furthermore, the basic flight instruments provided misleading indications once the aircraft was pushed outside its normal operating envelope, complicating the crew's ability to recover.
Final Conclusions
The investigation, completed in April 2011, concluded that the primary cause was the inadvertent acceleration of the aircraft to 110 km/h above its maximum design speed during an emergency descent. This led to structural failure and in-flight breakup. Contributing factors included poor crew coordination, deviations from the flight manual, and misleading instrument indications while operating outside the design envelope.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Airframe Structure
The airframe suffered a total structural failure when low-frequency oscillations, caused by excessive airspeed, exceeded the material strength limits.
Flight Instruments
Basic flight instruments provided misleading indications to the crew once the aircraft exceeded its characteristic operating conditions.
Horizontal Stabilizer
Parts of the horizontal stabilizer and elevator were found 2-3 km from the main crash site, indicating they were among the first components to fail.
Interesting Facts
- 01The aircraft was being readied for delivery to the Myanmar Air Force.
- 02The wreckage was strewn along a 3-kilometer-long track.
- 03The aircraft had completed only 31 flights prior to the accident flight.
- 04The type had been granted extended certification just days before the crash.
- 05The crew exceeded the design limit speed by 110 km/h (approximately 59 knots).
- 06The aircraft's Manufacturer Serial Number (MSN) was 41-03.
- 07This was the first hull loss and fatal accident involving the Antonov An-148 type.
Safety Actions & Advisories
Crew Coordination Training
The investigation emphasized the need for improved crew resource management and coordination during high-stress maneuvers like emergency descents.