What happened
On June 15, 1980, a PIK-20D glider, registration HB-1349, was performing a winch-assisted takeoff at the Dittingen airfield. Following a takeoff roll of approximately 70 to 100 meters, the aircraft entered a shallow climb at an altitude of roughly 30 meters, maintaining a speed between 75 and 80 km/h.
In an attempt to increase airspeed, the pilot abruptly increased the aircraft's pitch angle and adjusted the camber flaps to +4°. This maneuver caused the glider to lose lift and roll onto its right wing at an altitude of approximately 70 to 80 meters. During the upset, the towing cable either detached automatically or was released by the pilot. While attempting to recover the aircraft, the glider struck trees. The pilot sustained serious injuries, and the aircraft was destroyed.
The investigation
The investigation established that the pilot held a valid glider license and was medically fit for the flight. The aircraft's weight and center of gravity were within permissible limits, and no technical defects were found. The weather at the time was clear with good visibility.
Investigators noted that the recommended takeoff speed for a winch launch in the PIK-20D manual is between 110 and 125 km/h, whereas the aircraft was traveling significantly slower at the time of the maneuver. Furthermore, a flight inspector from the Federal Office of Civil Aviation (BZL) conducted subsequent tests at the airfield and observed that the winch operator was initially towing at an insufficient speed.
Findings
- The primary cause of the accident was the failure to maintain minimum flying speed during the winch launch.
- The pilot's abrupt increase in pitch angle placed excessive load on the winch, causing a drop in engine RPM because the winch operator did not increase power accordingly.
- The pilot had limited experience performing winch launches specifically in this aircraft model.
- The winch operator possessed insufficient experience in managing the winch controls.