What happened
On August 24, 2019, a Schleicher ASH 31 Mi (registration D-KGJM) was performing a self-launch from Herning/Skinderholm (EKHG) under visual flight rules. The pilot, utilizing a rolling takeoff technique to avoid the main wheel sinking into the grass, proceeded to cross an active winch wire laid on the runway. During the takeoff roll, the aircraft's tail skid snagged the steel wire.
While ground personnel attempted to alert the pilot via radio, the pilot did not perceive the transmissions, likely due to intense focus on an unusually long and slow takeoff roll. To prevent a collision with the winch equipment, the winch operator released the wire. However, the aircraft took off with a portion of the wire trailing behind. The drag from the wire's parachute caused the aircraft to lose altitude and airspeed. The pilot attempted to steer toward a clearing in a nearby treeline, but the aircraft sank and struck a stub field heavily, resulting in minor injuries to the pilot and significant damage to the aircraft.
The investigation
The investigation by AIB Denmark focused on why the pilot failed to respond to radio warnings and how the wire became entangled. Investigators examined the aircraft's radio and headset, finding them to be fully functional and capable of two-way communication. The investigation also looked into the club's operational procedures regarding simultaneous winch and self-launch operations.
Findings
- The pilot's primary focus on managing the takeoff roll and the unusual performance of the engine/wind conditions likely depleted his mental capacity, preventing him from recognizing the radio transmissions.
- The aircraft's tail skid, due to its small wheel diameter, was capable of picking up the steel wire.
- The pilot crossed an active winch wire during a rolling takeoff, a practice that had previously occurred without incident, which may have led to an underestimation of the risk.
- The club lacked written procedures for managing simultaneous winch starts and self-launches.
Safety action
Following the accident, the flying club implemented a temporary ban on self-launches while winch wires were deployed. New permanent procedures were established, strictly prohibiting any takeoff that requires crossing an active wire. The club also mandated that instructors be convened immediately following any such incident to review and update operational safety protocols.