What happened
On May 9, 2015, a Schleicher ASK 13 glider departed from the Iserlohn-Sümmern airfield via aero-tow for a circuit flight. The flight, which included a student pilot, proceeded normally for approximately five minutes before the approach for landing began.
During the final approach, witnesses observed the aircraft flying lower than usual. Approximately 100 to 200 meters before the runway threshold, the glider experienced a significant change in direction toward the right. The pilot attempted to correct this deviation but reported that the flight controls had become "soft." Consequently, the left wing struck a tree at an altitude of roughly 15 meters. The impact caused the aircraft to rotate 270 degrees counter-clockwise, after which it struck the ground approximately 25 meters further on, colliding with a parked car. The impact resulted in two serious injuries to the occupants and heavy damage to the aircraft.
The investigation
The BFU examined the wreckage and flight data recorded by the onboard Flarm device. The investigation focused on the aircraft's mechanical condition and the sequence of events leading to the loss of control. Investigators inspected the airframe, noting that the cockpit area was destroyed and both wings were broken near the brake flap housing. All observed structural failures were attributed to the impact with the trees and the subsequent ground collision. No technical defects were identified in the aircraft's systems or components.
Findings
- The pilot experienced a loss of control characterized by a sudden rightward deviation and a noticeable loss of control effectiveness (described as "soft" controls).
- Wind conditions at the time were significant, with gusts ranging from 10 to 22 knots from directions between 210° and 300°.
- The aircraft's structural damage was entirely consistent with the impact with vegetation and the ground.