The truth on Yeti Air flight #YT691

??On 15 January 2023, Yeti Air Flight YT691 en-route from Kathmandu to Pokhara in Nepal, crashed while performing an approach, killing all 72 occupants on board. The aircraft was seen as approaching the airfield at a high angle of attack, and eventually sharply banking to the left. This is the deadliest accident involving an ATR 72.

??The first data collected from the aircraft’s black boxes indicate that the propellers of both engines were put into the feather position prior to the crash. On many variable pitch propellers, the blade pitch can be increased to the point that the chord line of the blade is approximately parallel to the airflow. This process is referred to as feathering.

??Shortly before the accident, the Pilot Flying disconnected the autopilot system, and called for “Flaps 30” a few seconds later. However, the Pilot Monitoring inadvertently set the propeller pitch to feather, instead of setting the flap position to 30 degrees. On ATR 72 aircraft, the levers responsible for propeller pitch are located near the flap lever on the throttle quadrant.

??For the time being, the investigation is continuing, with a particular focus on human factor issues.