What happened
On a scheduled service from Calcutta-Dum Dum Airport to Imphal, Manipur, an aircraft was conducting its descent toward the destination. During the approach, the flight crew encountered adverse weather conditions characterized by low visibility. After receiving clearance to descend to 10,000 feet, the crew was permitted to fly a direct outbound course to facilitate an ILS approach for runway 04.
While the aircraft was executing a turn to intercept the approach path, the Ground Proximity Warning System (GPWS) triggered an alarm in the cockpit, which lasted for 6.3 seconds. Despite the warning, the aircraft continued its descent and struck the slope of Mt Thangjing, situated approximately 39 km southwest of the runway 04 threshold. The impact caused the plane to disintegrating. There were 69 fatalities and no survivors.
Findings
Investigation into the event indicates that the crew was operating in poor visibility and failed to maintain a safe altitude during the maneuvering phase. The inadequate altitude during the turn led to the collision with the terrain.