What happened
On June 22, 2016, a Centrair ASW20FL glider, registration HB-3128, departed from Puimoisson for a private flight. After an initial period of utilizing thermals, the pilot encountered increasing cloud cover near the mountains and was unable to maintain altitude above 1,950 meters. As the pilot attempted to return toward the original airfield, the strength of the rising air currents diminished.
Seeking to reach the Barcelonnette aerodrome, the pilot entered a valley that lacked suitable emergency landing sites. Realizing that the glider's performance and the lack of lift made reaching the destination impossible, the pilot identified a nearby field for an unplanned landing. During the approach, the pilot spotted an electrical power line directly in the flight path, necessitating a sudden left turn to align the approach parallel to the wires. Due to the low altitude at the time of the maneuver, the pilot began the flare process prematurely. The glider struck the ground with significant force in a field of tall wheat, coming to a halt within ten meters.
The investigation
The investigation focused on the pilot's decision-making process regarding flight path changes and the technical aspects of the final approach. Investigators examined the meteorological conditions, which included a high-pressure system centered over Switzerland, resulting in light winds and varying cloud cover that created significant shadows over the valleys. The investigation also reviewed the pilot's experience, noting a total of 2,770 flight hours, and the specific terrain and obstacles present at the landing site.
Findings
- The pilot decided to leave a known, safe landing area (the Crots ultralight airfield) to pursue a distant aerodrome despite deteriorating aerodynamic conditions.
- The decision to fly toward Barcelonnette led the aircraft into a valley with poor lifting potential and no prepared landing strips.
- The unstabilized approach was caused by the need to avoid an electrical line, which forced a low-altitude maneuver.
- The pilot failed to identify that the chosen landing site was covered in tall wheat, which contributed to the impact dynamics.
- The hard landing was the direct result of the late detection of the power lines and the subsequent lack of altitude to complete a stabilized approach.