Schempp-Hirth STANDARD CIRRUS N7880 accident near Aguila, Arizona

Probable cause

The pilot's exceedance of the glider's critical angle of attack while attempting a thermal climb at low altitude, which resulted in an aerodynamic stall/spin at an altitude that precluded recovery.

NTSB analysis

The glider pilot departed the airport via a tow winch for a local area flight. The tow winch driver reported that the takeoff and flight in the pattern were normal. When he observed the glider again, about 3 minutes later, it was crossing the approach end of the runway at an altitude of about 400 ft. The glider made a right 360° turn, abruptly pitched 60° nose-down and completed two spins. The glider came to rest inverted on the desert floor.

An examination of the glider revealed no mechanical malfunctions that would have precluded normal operations. Investigators established flight control continuity, and all breaks were attributed to impact forces. Given the glider's circling at low altitude, it is likely that the pilot encountered atmospheric lift (thermal) and was attempting to climb when he inadvertently exceeded the glider's critical angle of attack and entered an aerodynamic stall/spin. The glider's low altitude at the time of the spin entry would have precluded recovery.

Text from the NTSB. Open the NTSB docket for WPR18FA178 for the full record.