Accident
On Saturday, 7 October 1967, a student pilot was conducting solo training flights in a Jodel D-11, registration HB-SOV, at Speck-Fehraltorf airfield in Switzerland. After two uneventful circuits under supervision, the pilot initiated a third approach. Following a brief right glissade (slip), the aircraft suddenly pitched nose-down from an altitude of approximately 20 to 30 meters. It struck the ground at a steep angle about 175 meters short of the southeastern runway threshold at around 1130 hours. The pilot sustained fatal injuries and the aircraft was destroyed. No significant ground damage occurred.
Pilot and Aircraft
The student pilot, born in 1922, held a learner permit for powered and glider aircraft issued on 20 July 1967. His training began on 6 July 1967 at Speck-Fehraltorf, with his first solo flight on 13 September 1967. At the time of the accident, he had logged 18 hours and 59 minutes of flight time with 228 landings, including 2 hours 35 minutes and 36 landings solo. All training had been conducted on type at the same airfield. No previous incidents were recorded, and his qualifications were satisfactory. The investigation found no evidence of any health issues at the time of the accident.
The aircraft was a Jodel D-11, a single-engine low-wing monoplane with a 90 hp Continental engine, constructed in 1961. It was owned by the Flugsportgruppe Zürcher Oberland. The airframe had accumulated 1403 hours and 6590 landings. Two previous damage events in 1962 and 1964 had been properly repaired. Its last periodic inspection on 10 November 1966 rated its condition as "very good." Weight and center of gravity were within limits. The aircraft was equipped with airbrakes on the underside of the wings, which increased drag but did not change lift or trim significantly. The trim controls for pitch and yaw were located between the seats.
Investigation
Post-accident examination of the wreckage revealed no pre-existing technical defects. The flight control surfaces and tail assembly showed no prior issues. The tachometer was stuck at 640 rpm, corresponding to engine idle. Impact marks indicated a slight left turn in the final moments. It could not be determined whether the airbrakes were extended at impact due to extensive damage. Both trim levers were found bent in their neutral positions.
Flight tests conducted on 17-18 October 1968 with the same aircraft type under comparable conditions showed that at speeds around 75 km/h, the aircraft could stall and enter a spin, particularly during right glissades with an aft center of gravity. The tests indicated that stall characteristics were generally mild, but the aircraft required careful speed management during glissades to avoid critical low speeds.
Probable Cause
The accident was attributed to the aircraft entering an uncontrolled dive for undetermined reasons shortly before landing.