Summary
On August 2, 1972, at approximately 1500 hours, a Ka 8B glider (registration HB-810) crashed on the Ritzingeralp in the Valais region of Switzerland. The pilot, who was on a cross-country mountain soaring flight, was killed. The glider was destroyed. No third-party damage occurred.
Flight History
The pilot, born in 1948, held a glider pilot license issued on September 22, 1971, valid until June 20, 1973. He had a total of 36 hours and 26 minutes of glider flight experience, with 18 hours and 54 minutes on the Ka 8B type. In the preceding 90 days, he had flown 12 hours and 2 minutes, including 11 hours and 39 minutes on the accident aircraft. The pilot had no previous alpine soaring experience. He completed an alpine familiarization flight on July 29, 1972, lasting 23 minutes (including tow), followed by solo flights on July 30 (18 minutes) and August 1 (23 and 44 minutes).
Accident Flight
The accident flight began at 1150 hours on August 2, 1972, from Münster airfield with a tow. The glider was airborne for 3 hours and 10 minutes. Two witnesses observed the glider over the Ritzingeralp. One witness, at Campingplatz Reckingen, saw the glider fly left circles then parallel to the slope; it then shook visibly and pitched over the left wing, entering what appeared to be a spin, and disappeared. Another witness, located 600 meters west of Tränkboden at 2520 m elevation, saw the glider fly low and then pitch over the left wing, executing a half-turn.
The accident site was at 2350 m elevation on the Ritzingeralp (coordinates 659 350 / 147 830). Investigation indicated that the glider encountered a downdraft on the lee side of the main ridge, causing the airspeed to drop below the minimum flying speed. The aircraft entered a left spin. The height above ground at the onset of the stall was estimated between 70 and 120 meters, too low for recovery.
Wreckage and Medical Findings
The glider impacted terrain in a left-turning descent with a nose-low attitude (approximately 75°) and slight left bank. The cockpit was destroyed by frontal impact with a rock, and the rear fuselage was broken. Both wings were severely damaged with broken spars. Control system continuity was confirmed, and no pre-existing technical faults were found. The airspeed indicator needle was stuck at 115 km/h. The pilot's wristwatch stopped at 1500 hours.
Medical examination determined that the pilot's death was solely due to the severe injuries sustained. Toxicology tests were negative. Traces of vomit were found on the fuselage behind the left window and on the pilot's suit, likely from a cocoa-containing drink consumed at 0900 hours. This indicated the pilot had vomited in flight, suggesting a temporary indisposition that may have affected his attention.
Probable Cause
The accident was caused by the aircraft stalling at low altitude. Contributing factors were the pilot's limited mountain soaring experience and his in-flight indisposition.