Cub Crafters PA18 N444GB accident near Basin, Wyoming

Probable cause

The pilot exceeded the airplane's critical angle of attack while maneuvering at low altitude, which resulted in an inadvertent aerodynamic stall and subsequent impact with terrain.

NTSB analysis

The commercial-rated pilot and commercial pilot-rated crewmember were working with a ground crew in animal damage management. These flights typically begin with the surveillance, about 75 to 100 ft agl. Upon identifying a target, the airplane will descend to between 20 and 40 ft agl so that the crewmember can shoot the target. The ground crew lost contact with the airplane about 2 hours into the operation. The airplane wreckage was later located in steep, hilly terrain.

Based upon the location of the wreckage and witness statements from the ground crew, it is likely that the airplane was conducting a low-altitude predator mitigation pass at the time of the accident. Damage to the airplane, witness marks at the accident site, and the position of the wreckage were consistent with the airplane impacting terrain in a nose-low attitude, consistent with an aerodynamic stall and subsequent impact with terrain.

An examination of the airframe, engine, and related systems revealed no anomalies that would have precluded normal operations. It is likely that, while maneuvering at a slow speed, the pilot exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall at an altitude too low for recovery.

Text from the NTSB. Open the NTSB docket for CEN17FA050 for the full record.