Descent and Navigation Error
The crew initiated the descent to Kathmandu in poor weather conditions. A navigational error on the part of the pilots caused the aircraft to follow an incorrect approach path to Kathmandu Airport, directing it into a valley that did not lead to the runway.
Last-Minute Maneuver and Stall
Realizing the error, the pilot-in-command executed a sharp turn to avoid rising terrain. However, the aircraft's speed was insufficient to sustain the turn, resulting in an aerodynamic stall. The aircraft subsequently crashed on a rocky slope.
Impact and Fatalities
The impact destroyed the aircraft. All 20 occupants on board—comprising passengers and crew—were killed.
Official Findings
Investigators determined the probable cause to be a navigation error on the part of the flying crew. They cited the lack of visibility due to poor weather conditions as a contributing factor.