Investigation Summary
The flight was operating a scheduled service from Hanoi to Bangkok. As the aircraft entered Thai airspace, it encountered deteriorating weather conditions characterized by heavy rain and thunderstorms. During the final approach, the navigator noted lightning activity. The captain later reported that at an altitude of approximately 380 meters (1,250 feet), a bright flash of light occurred, which he claimed incapacitated the crew. The aircraft continued its descent past the outer marker, eventually dropping below the glide path and minimum safe altitude. It struck the ground in a rice field in the Lam Luk Ka District, breaking into three main sections and exploding. Debris was scattered over a 500-meter radius. Among the 14 survivors were the captain, the flight engineer, and one stewardess, while 76 others, including several high-ranking diplomats and the Vietnamese Minister of Public Health, perished.
Final Conclusions
The official cause of the accident is listed as undetermined. However, the investigation highlighted crew actions that led to the aircraft descending below the minimum safe altitude (CFIT). While the crew maintained that a lightning strike or atmospheric electricity played a role in the crash, investigators also considered the possibility of windshear as a contributing factor in the sudden loss of altitude.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Outer Marker
A radio beacon used during approach to indicate the aircraft's position relative to the runway; the aircraft was below safe altitude when passing this point.
Altimeter
Instruments used to monitor altitude; the crew failed to maintain the minimum safe altitude during the final stages of the flight.
Interesting Facts
- 01The crash was the second deadliest aviation accident in Thailand at the time of the occurrence.
- 02The aircraft was a Tu-134A model featuring a glazed glass nose for the navigator, who was the first to report lightning activity.
- 03The aircraft broke into three distinct sections: the nose, the forward fuselage, and the rear section.
- 04Notable fatalities included Vietnamese Minister of Public Health Dang Hoi Xuan and Indian Ambassador Arun Padwardhan.
- 05The captain, Khong Dinh Phuong, survived the impact and subsequent explosion.
- 06Debris from the aircraft was spread over a distance of 500 meters (1,600 feet).
Known Controversies & Unanswered Questions
Lightning Strike vs. Pilot Error
Reference ↗The crew claimed a lightning strike incapacitated them and caused the crash, but investigators focused on the aircraft's descent below minimum safe altitude, suggesting CFIT or windshear as more likely primary causes.