What happened
On July 10, 2011, a Schempp-Hirth Duo Discus XLT motor glider departed from the Wilsche glider airfield for a cross-country flight. At approximately 15:00 local time, the aircraft entered the traffic pattern for the Celle-Scheuen airfield at an altitude of roughly 200 meters. At this stage, the engine was running, but the landing gear remained retracted.
Witnesses observed that the engine was running irregularly and that the aircraft was in a continuous descent. As the aircraft continued its approach, the engine performance improved, and the flight path shifted approximately 30 degrees to the left. Data logger records indicated speeds between 113 and 115 km/h. During the maneuver, a steep right turn was observed at an altitude of about 100 meters, which subsequently transitioned into a right-hand spin. The aircraft struck a cornfield at a steep angle, resulting in the destruction of the aircraft and the death of the pilot.
The investigation
The BFU investigation examined the aircraft's flight data, engine performance, and the pilot's experience. The investigation established that the engine was operational during the final flight phase, despite the fuel valve being found in the 'closed' position after the impact; the force of the crash likely moved the lever. The investigation also noted that the engine's automatic electronic throttle, designed to prevent overspeeding the propeller, would have been active at the recorded speeds.
Findings
- The primary cause of the accident was an aerodynamic stall on the wing during a turn, which induced a spin.
- The pilot's ability to recover was severely limited by the low altitude at the time of the stall.
- Contributing factors included the pilot's limited experience with this specific aircraft type and its propulsion system.
- The initial irregular engine running created a complex situation that likely led to inconsistent decision-making.
- The pilot failed to maintain the optimal climbing speed, and the transition between different flight maneuvers contributed to the loss of control.