Aguila, AZ, USA
N7880
SCHEMPP-HIRTH STANDARD CIRRUS
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.
HISTORY OF FLIGHT On June 23, 2018, about 1408 mountain standard time, a Schempp-Hirth glider, N7880, was substantially damaged when it was involved in an accident near Aguila, Arizona. The pilot was fatally injured. The glider was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to witnesses located at Sampley's Airport (28AZ), Aguila, Arizona, the pilot had arrived at the airport earlier in the day. Witnesses stated the pilot flew one 3-minute flight that morning before departing on the accident flight about 1359. The driver of the glider tow vehicle reported the launch was normal, and no anomalies occurred. He observed the glider depart the upwind leg of the traffic pattern and turn right. He noted that the glider was about 1,000 ft above ground level (agl) while on the downwind leg. About 3 minutes later, he began to reel in the tow winch, and observed the glider near the approach end of runway 17 traveling west. He further reported that the glider made a right 360° turn with about a 30° bank angle, while at 400 ft agl. the turn continued, the glider then abruptly pitched 60° nose down and completed two spins before he lost sight of it about 100 ft agl. WRECKAGE AND IMPACT INFORMATIONA survey of the wreckage site revealed that the glider had impacted flat, desert terrain in a steep nose-down attitude, about 1,375 ft northeast of the approach end of runway 17. The glider came to rest inverted. The first point of impact was a relatively shallow depression in the dirt 7 ft southwest of the main wreckage, which measured about 49-ft long, 1-inch wide, and 1-inch deep. The forward fuselage and cockpit area were destroyed. The aft fuselage remained intact; however, the fuselage-to-empennage section had separated, but the flight control tubes remained connected. Flight control continuity was established from the rudder attach point forward to the rudder pedals. The stabilator remained attached to the top of the vertical stabilizer at all attached points. Flight control continuity was established from the stabilator forward to the control stick. The left wing was partially separated from the fuselage at both attach points. The leading edge exhibited some crushing damage consistent with vertical impact. The aileron control tube was separated at the hollow rivet attach point. Post-accident investigation revealed no pre impact mechanical malfunctions that would have precluded normal operation. The right wing remained attached to the fuselage. The leading edge exhibited some crushing damage consistent with vertical impact. The aileron control tube and spoiler control tube remained attached to their respective bell cranks. MEDICAL AND PATHOLOGICAL INFORMATIONThe Maricopa County Office of the Medical Examiner, Phoenix, Arizona, performed a postmortem examination of the pilot. The cause of death was reported as blunt force injuries. The FAA Forensic Sciences Bioaeronautical Science Research Lab, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the pilot. The results were negative for volatiles and tested-for-drugs.
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.
Source: NTSB Aviation Accident Database
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