Accident Overview
On 12 August 1966, a Piper Cub J3C, registration HB-ONK, operated by the Motorfluggruppe der Sektion Thurgau des Aero-Clubs der Schweiz, was involved in an accident near Niederbüren, Switzerland. The aircraft was substantially damaged; the pilot was uninjured.
Flight History
The student pilot, born in 1947, held a student pilot certificate issued on 25 February 1966. His total flight experience at the time of the accident was 11 hours and 51 minutes, including 113 landings, of which 3 hours and 11 minutes were solo in 21 flights. His first solo flight had occurred on 10 August 1966.
The instructor, born in 1929, held a private pilot license (issued 24 June 1952) with an extension for training private pilots (28 October 1958). He also held a restricted commercial pilot license (23 December 1954) and a commercial pilot license (24 August 1959). His total flight experience as of 17 June 1966 was 3,195 hours with 19,702 landings.
The accident flight was a training mission. The student was instructed to fly from Lommis airfield to Frauenfeld, then Wil, then Weinfelden, and return to Lommis, maintaining visual contact with the airfield. The flight distance was approximately 40-50 km. Takeoff occurred at 1919 MEZ, and a landing before 2000 was expected.
Accident Sequence
After reaching Weinfelden, the student lost sight of Lommis airfield, despite it remaining within his visual range but with a different and unfavorable lighting angle. He searched for about 15 minutes, drifting southeast toward Niederbüren. As darkness approached, he decided to attempt a forced landing.
The approach was misjudged, resulting in a too-high and too-long final. At an altitude of about 5 meters, the pilot noticed an unevenness in the terrain and decided to go around, simultaneously banking left. During this maneuver, the aircraft stalled ("durchsackte") and made unintentional ground contact with the left wheel. The aircraft then veered and came to rest tail-first, 30-40 meters beyond the initial touchdown point.
Findings
The student had not yet received the endorsement for solo cross-country flights on his student certificate. The instructor's assignment did not conform to the 1962 pre-training program because it constituted a cross-country flight where the instructor could no longer maintain direct supervision.
The forced landing field was a stubble field near Niederbüren, on the southern bank of the Thur river, about 15 km east-southeast of Lommis. The field measured approximately 200 m by 150 m. Coordinates: 731'500/258'125, elevation 480 m.
Weather
The weather was characterized by high pressure, 1/8 cirrus clouds, visibility about 30 km, and calm wind.
Damage
The aircraft sustained substantial damage to the fuselage, left wing, landing gear, engine, and propeller. Repair costs were estimated at 6,000 to 8,000 Swiss francs. No ground damage occurred.
Probable Cause
The accident is attributed to the student pilot losing his way on a flight inappropriate for his training level, and during an attempted forced landing, the aircraft stalled and made unintentional ground contact.