What happened
On May 14, 2017, a Schempp Hirth CS11 glider, registration F-CEFZ, was participating in a local flight at the Auch aerodrome in France. The flight began with a towed takeoff from unpaved runway 18. At approximately 13:50, the pilot released the tow cable at an altitude of roughly 50 and began flying southeast.
During the flight, the pilot attempted to utilize thermals, performing two spirals to gain altitude. While flying near a hill located southeast of the aerodrome, the aircraft's altitude was recorded at approximately 197 meters. During a left turn near the base of the hill, the glider struck the southern slope of the terrain. The impact occurred with a high pitch-down attitude and significant vertical velocity, resulting in the death of the pilot and the destruction of the aircraft.
The investigation
Investigators examined the wreckage and recovered flight trajectory data via the FLARM system. The investigation established that the aircraft's control linkages and connections were intact, and no mechanical anomalies were found in the wreckage to explain the accident. An autopsy of the pilot revealed no medical causes for the event.
Analysis of the flight path indicated that the glider was flying at a speed very close to its stall speed during the final turn. While the glider's glide ratio theoretically allowed for a return to runway 36, the investigation focused on the pilot's decision-making and the aerodynamic conditions during the maneuver.
Findings
- The accident was caused by a loss of control at low altitude during a turn performed near terrain.
- The pilot was flying at a speed near the aircraft's stall limit, a condition potentially exacerbated by a possible updraft that increased the angle of attack and reduced airspeed.
- The pilot may have been attempting to exploit rising air on the sunny southern slope of the hill, as evidenced by previous maneuvers.
- The investigation suggests the pilot may have experienced significant stress due to the proximity of the terrain, trees, and buildings, which could have impaired decision-making.
- The situation likely stemmed from a late realization that previous attempts to find thermals had been unsuccessful, leaving the aircraft at an excessive distance downwind of the aerodrome.