What happened
During a night flight, the aircraft landed at an airport where runway conditions were compromised by recent snow removal operations. A snow plow had cleaned the runway surface; however, the plowing was conducted off-center and did not encompass the full width of the runway. This incomplete clearing left a significant snowbank along one side of the paved surface.
Upon touchdown, the aircraft's left main landing gear struck this remaining snowbank. The impact caused the aircraft to swerve sharply to the left. As the pilot attempted to maintain directional control, the nose gear subsequently contacted the same snowbank. This contact resulted in the aircraft nosing over, coming to rest on its nose.
The investigation
The investigation focused on the runway conditions at the time of the accident. It was determined that the snow removal equipment had not cleared the entire width of the runway. The presence of the snowbank directly contributed to the loss of directional control during the landing roll.