What happened
On July 23, 2008, a two-seat Schleicher ASK 13 glider departed from the Butzbach airfield via winch launch for a training flight. The flight, carrying a flight instructor and a student, proceeded normally through the takeoff and the initial circuit. During the landing sequence, the instructor communicated an intention to land on runway 29.
As the aircraft progressed on final approach, it was observed flying notably low and slow over the trees adjacent to the airfield. During this phase, the glider banked to the right, causing the right wing to strike the treetops. The aircraft then entered a steep descent into the forest, striking the ground almost vertically. The impact caused extensive damage to the airframe, including the destruction of the cockpit area and the breaking of both wings.
The investigation
The BFU investigation focused on the flight path and the condition of the aircraft. The investigation confirmed that the aircraft's weight and center of gravity were within permissible limits and that no technical malfunctions were present. Meteorological conditions at the time were favorable, with visual flight rules (VFR) conditions, light winds, and clear visibility.
Findings
- The primary cause of the accident was the incorrect estimation of available altitude during the landing sequence.
- The aircraft was flying at an insufficient height over the wooded area during final approach.
- The glider's airspeed fell below the required minimum, leading to a loss of control and the subsequent wing strike.
- The high-energy, near-vertical impact with the ground resulted in one serious injury and one light injury.