What happened
On May 21, 2009, a DG 400 glider, powered by a retractable engine, was performing an aeroelectric self-launch from Straubing to participate in a competition at Arnbruck. After approximately 22 minutes of flight, the aircraft arrived at the Arnbruck airfield. The pilot had contacted the airfield controller via radio and was cleared to land on runway 34 with a tailwind.
Witnesses observed the aircraft approaching from the south at an altitude they considered too high. During the approach, the aircraft performed several right-hand turns while continuously losing altitude. During the final phase of the approach, at an altitude of less as 100 meters, the glider tilted sharply to the left. The aircraft struck the ground approximately 160 meters before the start of the asphalt runway with a high longitudinal pitch. The impact resulted in the death of the pilot and the total destruction of the aircraft.
The investigation
The BFU examined the wreckage and the flight data recorded on a carried GPS device. The investigation confirmed that there were no technical defects in the aircraft; all control linkages were intact, and any observed structural breaks were consistent with the impact forces.
While the investigation noted that the aircraft's center of gravity was 0.83 mm beyond the rear limit according to a 2007 weighing report, this was determined to have had no impact on the accident, as the maximum payload was within the required limits. The investigation also confirmed that the aircraft was at its maximum allowable payload at the time of the accident.
Findings
- The pilot was flying at a speed below the stall threshold during a turning maneuver.
- The aircraft entered an aerodynamic stall while in a turn.
- The low altitude at the time of the stall prevented the pilot from recovering the aircraft before impact.