What happened
On a scheduled flight from Vientiane to Pakse, the crew of an ATR72-600 attempted an initial approach to runway 15 but aborted the maneuver because visibility was inadequate. While performing a second approach in poor weather conditions, the aircraft crashed approximately 8 km short of the runway and sank into the Mekong River. All 49 people on board, consisting of 44 passengers and 5 crew members, perished in the accident.
Findings
Investigations into the accident revealed that the flight was operating under instrument meteorological conditions (IMC) without radar service. The crew was required to follow a VOR DME approach procedure, which mandates descending to a specific altitude only if visual ground references are available. Analysis of the flight data recorder indicates that the crew incorrectly set their minimum descent altitude to 600 ft, which was significantly below the published minimum of 990 ft. This error reduced the safety margins by allowing the aircraft to fly a path roughly 345 ft lower than intended.
During the missed approach procedure, the crew attempted to follow the lateral trajectory via a right turn but failed to maintain the necessary vertical profile. Because the altitude was set too low, the aircraft's systems entered altitude capture mode at an unsafe height. As the crew became aware of the proximity to the terrain, the pilot flying responded with an excessive pitch increase to 33 degrees. The aircraft was flying primarily within cloud cover during the final moments of the flight.