What happened
On August 24, 2015, at approximately 12:30 UTC, a Discus CS glider was involved in an accident during a winch launch on the grass runway 08 at Innsbruck Airport, Austria. The flight was being conducted under Föhn weather conditions, characterized by strong winds.
During the takeoff roll, the winch operator applied continuous power. As the aircraft began to lift off, the left wingtip made contact with the ground. This contact caused the glider to enter a leftward yaw. Following liftoff, the aircraft experienced further rotation and subsequently crashed from an altitude of approximately 15 meters onto the grass runway.
The investigation
The Austrian Federal Safety Investigation Board (SUB) conducted an investigation into the occurrence. The investigation reconstructed the flight sequence using eyewitness accounts, as the pilot had no memory of the flight following the impact.
Technical inspections of the Discus CS revealed no pre-existing mechanical defects. The investigation confirmed that all control surfaces, including the ailerons, elevators, and rudder, were properly connected and functioned correctly. The damage observed on the fuselage and wings was determined to be a direct result of the impact with the ground. The investigation also verified that the aircraft's weight and center of gravity were within permissible limits and that all required documentation and pilot certifications were valid at the time of the accident.
Findings
- The primary cause of the accident was the high grass growth on runway 08, which caused the left winglet to snag during the takeoff phase.
- Severe wind conditions, including gusts up to 37 knots, contributed to the accident. Specifically, strong gusts of up to 32 knots exacerbated the rotation of the aircraft around its longitudinal axis after liftoff.
- The combination of the wingtip catching the tall grass and the intense wind gusts caused the aircraft to enter an uncontrolled flight state, leading to a crash in an inverted position.