On July 31, 1992, at 07:00:26 UTC (12:45:26 NST; 14:00:26 ICT), the Airbus A310-304 operating the route crashed into the side of a mountain 37 kilometres (23 mi; 20 nmi) north of Kathmandu, killing all 113 passengers and crew members on board.

[5] Shortly after reporting the Sierra fix 10 kilometres (6.2 mi; 5.4 nmi) south of the Kathmandu VOR, the aircraft called ATC asking for a diversion to Calcutta, India, because of a "technical problem".

The aircraft crashed into a steep rock face in a remote area of the Langtang National Park at an altitude of 11,500 ft (3,505 m) and with a ground speed of 300 knots (560 km/h; 350 mph), killing all 113 people on board.

Concerned that the complex approach into Kathmandu in instrument conditions would be difficult with malfunctioning flaps and frustrated by ATC and his first officer's inconclusive and weak answers to his questions, the captain decided to divert to Calcutta.

[7] The flaps suddenly began to work properly, but the captain was forced to resolve more aspects of the difficult approach himself due to his first officer's lack of initiative.

Only after numerous extremely frustrating exchanges with ATC was the captain able to obtain adequate weather information for the airport, but by that time he had overflown Kathmandu and the aircraft was headed towards the Himalayas.

[7] Nepalese authorities found that the probable causes of the accident were the captain and air traffic controller's loss of situational awareness; language and technical problems caused the captain to experience frustration and a high workload;[7] the first officer's lack of initiative and inconclusive answers to the captain's questions; the air traffic controller's inexperience, poor grasp of English, and reluctance to interfere with what he saw as piloting matters such as terrain separation; poor supervision of the inexperienced air traffic controller; Thai Airways International's failure to provide simulator training for the complex Kathmandu approach to its pilots; and improper use of the aircraft's flight management system.