PIK-20D incident during winch launch at Dittingen results in collision with trees

On June 15, 1980, a PIK-20D glider was involved in an accident at Dittingen Airfield, Switzerland, during a winch launch. The pilot, who had limited experience with this type of launch, lifted off after a short ground roll. The glider climbed at a shallow angle before the pilot abruptly increased the pitch, causing a stall and a roll to the right. The tow cable released, and the glider collided with trees. The pilot sustained serious injuries, and the glider was destroyed. The report confirmed insufficient airspeed as a cause, with contributing factors including the pilot's and winch operator's limited experience.

1. Winch launch climb: During a winch launch from Dittingen, the glider lifted off after a 70–100 m ground roll and climbed shallowly to about 30 m AGL at only 75–80 km/h, below the handbook’s recommended winch speed.
2. Abrupt pitch increase: At about 30 m AGL the pilot abruptly raised the nose to a relatively steep attitude and extended the flaps to +4°, attempting to gain more speed despite already low airspeed.
3. Low winch speed: The winch driver, who had little experience, towed with insufficient engine power so that the glider never reached the recommended winch launch speed.
4. Limited winch experience: The pilot had only about 30 winch launches in total, including just three on the accident type, reducing his ability to recognize and abort a low-speed launch.
5. Winch not aborted: Despite the low airspeed before transitioning to a steep climb, the pilot did not abort the winch launch and instead increased the pitch, further loading the winch and causing an engine RPM drop.
6. Stall and roll-off: As the glider climbed to about 70–80 m AGL, the airspeed dropped below minimum, the aircraft stalled, and it rolled off over the right wing, with the tow cable releasing automatically or by pilot action.
7. Crash - serious injury: The pilot partially recovered from the upset but the glider struck trees during the recovery, seriously injuring the pilot and destroying the aircraft.