Rans S-7 N55893 accident near Spirit Lake, Idaho

Probable cause

The pilot’s exceedance of the airplane's critical angle of attack during the initial climb after takeoff, which resulted in an aerodynamic stall.

NTSB analysis

The pilot and pilot-rated passenger were departing from a grass runway. The passenger stated that the airplane remained in ground effect for a large duration of the takeoff and then climbed above the treeline. At an altitude of about 75 ft above ground level, the airplane’s left wing stalled, and the airplane collided with terrain.

Analysis of video of the accident takeoff and GPS data indicated that the airplane’s wing reached its critical angle of attack before it began to lose altitude and descend into terrain. Sound spectrum analysis of the engine indicated that it was producing power at the time of the accident. Given the weights of the pilot, passenger, and fuel onboard, the airplane was under its maximum gross weight and within its center-of-gravity limits at the time of the accident. The circumstances of the accident are consistent with the pilot’s exceedance of the airplane’s critical angle of attack during the initial climb, which resulted in an aerodynamic stall and loss of control.

Text from the NTSB. Open the NTSB docket for WPR21LA011 for the full record.