Incident Overview
On Sunday, July 2, 1967, at approximately 14:30 local time, a glider student operating a Rhönlerche II with registration HB-598 collided with infrastructure on the southern slope of the Pilatus mountain in Obwalden, Switzerland. The aircraft struck the telephone cable of the aerial tramway connecting Aeschi (Grunderberg) to Chretzenalp. The impact resulted in the death of the pilot and the total destruction of the glider.
Aircraft and Personnel
The aircraft was a two-seat Rhönlerche II, manufactured in 1959, owned by the Segelfluggruppe Obwalden in Sarnen. It featured a steel tube fuselage and wooden wings. The pilot was a student born in February 1935, who had completed basic glider training at Kägiswil airfield. At the time of the accident, he had logged 19 hours and 10 minutes of flight experience, including 77 landings, all conducted on this specific aircraft type.
Sequence of Events
The student launched from Kägiswil at 13:42 for a training flight. After releasing from the tow plane, he flew toward the western part of the Pilatus south face. Another pilot, flying a Ka-8 glider, observed the Rhönlerche circling near the Schwändi-Längenmatt huts before it moved eastward toward the Chretzenalp area. Witnesses reported seeing the glider fly close to the mountain slope below Chretzenalp. The aircraft then collided with the 6 mm diameter telephone cable of the tramway, which severed a portion of the right wing. The glider subsequently crashed into the steep rock bed of the Giessbach stream.
Investigation Findings
The investigation determined that the collision occurred because the student pilot entered a hazard zone near the mountain slope while flying in weak lift conditions. He failed to see the cable obstacle. Although the tramway was marked on standard maps and the group had begun compiling a local hazard inventory, the specific map detailing all cables was not yet finalized at the time of the accident. The flight instructor had briefed the student on the tow path and minimum return altitude but did not explicitly prohibit entry into the cable zone, assuming the student would remain in the safer, obstacle-free western sector.