What happened
On May 24, 2009, at approximately 09:33, a Rolladen-Schneider LS 8-18 glider, registration HB-3357, was performing a winch launch at Birrfeld aerodrome (LSZF) in Switzerland. During the launch sequence, the winch operator applied full power. As the aircraft transitioned into its climb, it reached an extremely steep pitch angle of approximately 60 degrees relative to the horizon. At an altitude of roughly 40 meters, the glider began to drop its right wing. The winch operator subsequently reduced power, causing the cable to release via the automatic mechanism. The aircraft then struck the airfield ground with its nose and right wing, resulting in one serious injury to the pilot.
The investigation
Investigators examined the wreckage and the winch equipment, finding no evidence of mechanical failure in the glider's flight controls or the winch mechanism itself. The winch cable and the breaking link were found to be undamaged. The investigation also reviewed the aircraft's configuration, noting that the center of gravity was positioned at the most rearward limit. Meteorological data indicated a light tailwind component during the launch. The pilot's recent flight history was also reviewed, noting that while the pilot held the necessary licenses, there had been a significant gap in recent winch launch training.
Findings
- The primary cause of the accident was the aircraft entering a flight attitude so steep during the winch launch that it resulted in a stall at low altitude.
- The aircraft was operating with its center of gravity at the most rearward position.
- A light tailwind contributed to a slower acceleration phase, making the transition to the climb more difficult.
- The pilot had a lack of recent training, particularly regarding winch launch procedures.
- The breaking link used in the cable had a nominal breaking load slightly higher than the maximum recommended in the aircraft's flight manual.