Incident
On Sunday, 1 October 1989, at 1104 local time, an instructor and a student took off from Schaffhausen aerodrome in a SZD-50-3 "Puchacz" glider, registration HB-1516, for a training flight. After release at about 900 m above mean sea level east of Siblingen, the glider was observed by witnesses entering a spin. Seven to eight rotations were seen. The glider recovered near the ground, crossing a railway embankment at about 10 m above ground. It then stalled again and crashed from about 10 m onto its left wing. The accident occurred at 1124 hours at coordinates 683 000 / 282 800, elevation 430 m/M.
Aircraft and Crew
The glider, a two-seat shoulder-wing aircraft with a fixed main wheel, was manufactured in 1979 by PZL-Bielsko, Poland. It had accumulated 1812:23 hours on the airframe. The maximum takeoff mass was 570 kg; the mass at the time of the accident was about 558 kg, within limits. The aircraft was operated by Segelfluggruppe Schaffhausen.
The instructor, a Swiss citizen born in 1940, held a glider pilot license issued in 1963, with aerobatic endorsement from 1972. His total glider experience was 1338:19 hours, with 55:41 hours on the accident type. His aerobatic experience was low. The student, a Swiss citizen born in 1973, held a student pilot license issued in August 1989. He had 5:38 total glider hours, with 4:45 on the accident type.
Investigation
Examination of the wreckage revealed no pre-existing technical defects except the left trim control, which appeared to have been loose before the accident. Both pilots were wearing lap and shoulder belts, which remained intact. Autopsies showed both died from impact injuries; no pre-existing conditions or alcohol/drugs were found. Foot injuries indicated the right rudder pedal was depressed. The glider had minimal forward speed at impact; the nose section showed no sliding marks, indicating a near-vertical descent.
Causes
The investigation concluded that the accident was due to:
- Exceeding the minimum speed near the ground.
- An intentional or unintentional spin initiated too late to recover.
- The instructor's low aerobatic experience.
- A likely unlocked or misadjusted left trim control.