69 fatalities

Aircraft Crash on Mount Thangjing During Approach to Imphal (VT-EFL)

Imphal, IndiaLanding (descent or approach)

On August 16, 1991, a Boeing 737-200 (registration VT-EFL) operated by Indian Airlines was involved in an aviation accident near Imphal, India during landing or approach. 69 people were killed. Investigators recorded the probable cause as: The accident occurred by reason of a grave error on the part of the Pilot-in-Command in not adhering to the operational flight plan and ILS let down chart and not realizing that his early descent to 10,000 feet and turning right for outbound leg without… This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 10 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 2026-06-11Data APIEditorial standards
Aircraft registered VT-EFL
Aircraft registered VT-EFL. Photo: M. Azizul Islam / CC BY 4.0, via Wikimedia Commons

A scheduled flight from Calcutta-Dum Dum to Imphal struck Mount Thangjing during descent in poor weather, killing all 69 occupants. The official report cited the pilot's failure to follow the flight plan and ILS chart.

Flight Details and Accident Sequence The aircraft departed Calcutta-Dum Dum Airport at 1154 local time on a regular scheduled service to Imphal, Manipur. During descent, the crew encountered poor weather conditions with low visibility. After receiving clearance to descend to 10,000 feet, the crew obtained permission to make a direct outbound course in preparation for an Instrument Landing System (ILS) approach to runway 04. While completing a turn to join the approach path, the crew did not recognize that the aircraft's altitude was insufficient. A Ground Proximity Warning System (GPWS) alarm sounded in the cockpit for 6.3 seconds before the aircraft struck the slope of Mount Thangjing, located 39 km southwest of the runway 04 threshold. The aircraft disintegrated on impact, and all 69 occupants were killed. ## Official Findings The official investigation determined that the accident occurred due to a grave error by the Pilot-in-Command. The pilot failed to adhere to the operational flight plan and the ILS let-down chart. The report noted that the pilot's early descent to 10,000 feet and right turn for the outbound leg, without reporting overhead the VOR, resulted in a loss of time reference and misplaced the aircraft in hilly terrain. The investigation also stated that the Pilot-in-Command's actions may have been influenced by extreme familiarity with the terrain.

Probable cause

The accident occurred by reason of a grave error on the part of the Pilot-in-Command in not adhering to the operational flight plan and ILS let down chart and not realizing that his early descent to 10,000 feet and turning right for outbound leg without reporting overhead VOR would result in loss of time reference and as such misplace him in the hilly terrain. The Pilot-in-Command's action may have been influenced by his extreme familiarity with the terrain.