Accident Summary
On 19 August 1968, at approximately 1625 hours MEZ, a glider pilot flying Ka 8 B HB-679 collided with two stationary gliders while landing on runway 35 at Schänis airfield. The pilot sustained injuries requiring a five-week hospitalization. The accident aircraft was heavily damaged, one parked glider (HB-806) sustained slight damage, and another (HB-586) had only scratches.
Investigation
The airfield chief immediately notified the Swiss accident investigation bureau by telephone. Due to the late hour, the investigator arrived the following day to interview witnesses. The pilot of HB-679 could not be questioned until February 1969 because of his extended hospital stay. Cantonal authorities did not participate in the investigation.
Aircraft and Pilot Information
The accident glider was a Ka 8 B, manufacturer Schleicher/Kaiser, built in 1961, registered HB-679, owned by Segelfluggruppe Lägern. Its airworthiness certificate was valid until 23 March 1969. Weight and center of gravity were within limits.
The pilot, born in 1944, held a glider pilot license issued on 22 June 1967, valid until 30 April 1969. He had a total of 22 flight hours (130 glider flights), including 13 hours solo. On the accident type, he had flown 12 hours over 32 flights. In the last three months, he had flown 4 hours (4 flights). His training began in summer 1965 at Schänis. At the time of the accident, he was in good mental and physical condition, with no adverse records.
Accident Sequence
The pilot departed Schänis at 1552 hours by aerotow for a slope soaring flight at Schäniserberg. He released at about 1000 m. Weak thermals prompted a return to the airfield. After eight full circles to lose altitude on the eastern side, he set up a long, high final approach to runway 35.
At the start of runway 35, on the right side, another pilot sat ready in Ka 8 B HB-806, waiting for the towplane. About 20 m further right, perpendicular to the runway with its leading edge above the runway edge, stood the Rhönlerche HB-586. Two witnesses sat back-to-back on an old tire nearby, one facing the final approach direction, the other facing the landing direction.
During final approach, the pilot of HB-679, seeing he was too high, initiated a sideslip. After the sideslip, he perceived he was too low. A witness, an experienced glider instructor, considered the altitude after the sideslip still sufficient. The pilot decided to land short of the runway and extended the spoilers halfway. Realizing he would inevitably collide with the stationary gliders on roll-out, he retracted the spoilers and veered slightly right to fly between and over the gliders.
Despite this, the collision was unavoidable. The right wingtip of HB-679 contacted the left wing of the parked Rhönlerche. The left wing of HB-679 struck the right wing of the waiting HB-806, rotating that glider 90 degrees. HB-679 then flew about 30 m further, impacted the ground with a nose-down attitude of about 30°, rotated 130°, and came to rest with its left wing detached.
One witness threw himself to the ground as HB-679 passed overhead; the other remained seated, with the glider passing just 1 m above him.
Discussion
The pilot held a valid license and sufficient experience for the intended flight. The glider was airworthy and certified. Weather conditions (clear, cloudless, calm) posed no difficulty for the final approach.
The pilot corrected his high approach with a sideslip, after which he believed he was too low. Although he must have seen the parked gliders, he initially continued the approach toward HB-806, despite a 60 m clear area to the left. He could not explain this behavior. Deciding to land short was erroneous given the parked gliders. After retracting the spoilers, he had already lost too much height to safely overfly them. The only correct action would have been to turn left into the clear area, but he concentrated on clearing the gliders and overlooked that option.
Conclusion
The accident is due to incorrect corrections during the final approach.