What happened
On August 16, 2022, a DG-808 C motor glider, registered as HB-2449, departed from Bad Ragaz aerodrome for a solo flight. The pilot initially flew toward Mont Blanc before turning back. During the return leg, the aircraft flew along a ridge near the Mont Rouge du Giétro at an altitude of approximately 3,500 meters.
Flight data recovered from the wreckage indicates that while traversing the ridge, the aircraft experienced a sharp increase in pitch while initiating a right-hand turn. The aircraft subsequently rolled onto its right wing, leading to a high-speed impact with the Glacier du Giostra at an altitude of 3,280 meters. The impact resulted in the fatal injury of the pilot and the total destruction of the aircraft.
The investigation
Investigators from the Swiss Transportation Safety Investigation Board (SUST) examined the wreckage and flight data recorders to reconstruct the flight path and analyze the aircraft's performance. The investigation confirmed that the aircraft was airworthy, with all maintenance and annual inspections up to date. While the aircraft's center of gravity was noted to be in the aft position, it remained within prescribed limits.
Technical examination of the wreckage revealed no pre-existing mechanical failures capable of causing the accident. Although some loosened locknuts were found on the control rods, investigators determined that these could only cause slight play in the controls and would not have caused a loss of maneuverability. Additionally, an autopsy of the pilot revealed no health issues or presence of substances that could have contributed to the event.
Findings
- The primary cause of the accident was a loss of control due to an aerodynamic stall.
- The stall occurred because the aircraft was executing a turn at a speed below the minimum required for safe flight.
- The pilot was flying at a low altitude relative to the terrain, which prevented any possibility of recovering from the stall before impact.
- Meteorological conditions at the time were favorable, characterized by stable, warm weather with good visibility and light winds.