Nepal Aircraft Accident Investigation Commission: Yeti Airlines 691 (YT691) ATR72-500 9N-ANC - Final Report
Aviation Herald - News, Incidents and Accidents in Aviation
On Mar 28th 2024 Nepal's Aircraft Accident Investigation Commission (AAIC) released their final report via the French BEA concluding the probable causes of the crash were:
The most probable cause of the accident is determined to be the inadvertent movement of both condition levers to the feathered position in flight, which resulted in feathering of both propellers and subsequent loss of thrust, leading to an aerodynamic stall and collision with terrain.
The contributing factors to the accident are:
- High workload due to operating into a new airport with surrounding terrain and the crew missing the associated flight deck and engine indications that both propellers had been feathered.
- Human factor issues such as high workload and stress that appears to have resulted in the misidentification and selection of the propellers to the feathered position.
- The proximity of terrain requiring a tight circuit to land on runway
- This tight circuit was not the usual visual circuit pattern and contributed to the high workload. This tight pattern also meant that the approach did not meet the stabilised visual approach criteria.
- Use of visual approach circuit for RWY 12 without any evaluation, validation and resolution of its threats which were highlighted by the SRM team of CAAN and advices proposed in flight procedures design report conducted by the consultant and without the development and approval of the chart by the operator and regulator respectively.
- Lack of appropriate technical and skill based training (including simulator) to the crew and proper classroom briefings (for that flight) for the safe operation of flight at new airport for visual approach to runway 12.
- Non-compliance with SOPs, ineffective CRM and lack of sterile cockpit discipline