What happened
On 13 September 2019, a Schleicher ASH26E glider, registered D-KFMH, was performing a local flight near Saint-Pons in the Alpes-de-Haute-Provence region. The pilot had taken off from Puimoisson aerodrome earlier that day to engage in slope soaring near the Soleil Bœuf ridge.
While flying at an altitude of approximately 2,015 meters, the pilot was executing a series of turns, including figure-of-eight maneuvers, along the slope and beneath the ridge line. During the final sequence of maneuvers, the aircraft was positioned facing the slope, very close to the terrain. An eyewitness observed the glider suddenly enter a spin. The aircraft completed two full rotations before colliding with the terrain at an altitude of 1,990 meters. The pilot was fatally injured, and the glider was destroyed.
The investigation
The investigation utilized flight data from the aircraft's LX8000 onboard computer and the Open Glider Network (OGN) to reconstruct the flight path. Analysis of the GNSS data revealed that during the final turn, the glider gained approximately 30 meters in altitude, which likely created a false impression of significant thermal uplift.
Investigators examined the wreckage, noting that the aircraft struck the ground with a high nose-down attitude. At the time of impact, the engine, landing gear, and air brakes were all in the retracted position. The flight control linkages for all three axes, as well as the flap and air brake controls, remained intact upon impact. Meteorological data confirmed a 15-knot westerly breeze with moderate turbulence and clear skies, conditions that can make locating thermals difficult and create deceptive vertical air movements.
Findings
- The pilot likely miscalculated the exit path of the turn, underestimating the impact of the wind and the specific aerological conditions near the spur.
- As the glider drifted toward the slope, it became confined within a gully, facing a steep spur only 200 meters away.
- The glider encountered a tailwind that rapidly decreased its altitude while facing the terrain.
- To avoid the terrain, the pilot likely attempted to tighten the turn by increasing the bank angle and pulling back on the elevator.
- The glider entered a spin following a stall caused by the increased load factor during this recovery attempt.
- Performing spirals while flying below the ridge line and at an insufficient lateral distance from the terrain prevented the pilot from maneuvering away from the mountainside.