Champion 7AC N84462 accident near Darby, Montana

Probable cause

The pilot's failure to maintain airspeed while maneuvering in gusting wind conditions, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall.

NTSB analysis

The commercial pilot reported that he was attempting to land the light sport airplane on a private grass airstrip surrounded by mountainous terrain. While maneuvering for landing, the airplane suddenly entered into a steep, right-wing-low bank. The wings then leveled momentarily before the airplane impacted the ground. The passenger in the rear seat of the airplane stated that he felt a downdraft or windshear just prior to impact. A post-accident examination of the airplane found no anomalies that would have precluded normal operation.

The pilot reported the wind as light and variable with 5-10 knot gusts; however, he stated that during previous flights in the area, he experienced unexpected severe gusts and terrain-induced turbulence, followed by complete calm.

The airplane was not equipped with a stall warning system or flaps. Since the airplane was maneuvering for landing approach at low airspeed, a sudden gust of wind or shift in wind speed or direction could have resulted in a rapid loss of airspeed, followed by an aerodynamic stall as the airplane reached its critical angle-of-attack. Due to the airplane's low altitude, the pilot likely did not have sufficient time to recover from the stalled condition prior to impacting terrain.

Text from the NTSB. Open the NTSB docket for WPR15LA036 for the full record.