Factual Information
The accident aircraft was a Piper J3C-65/L-4, registration HB-OXI, operated by Motorfluggruppe Thurgau. The pilot, an Austrian national born 1942, held a private pilot license (PPL(A)) with a single-engine piston (SEP) class rating and a medical certificate with restrictions. The flight instructor, a Swiss national born 1952, held a commercial pilot license (CPL(A)) and a flight instructor rating. The flight was conducted under VFR by day as a training flight, specifically tailwheel conversion training.
Circumstances of the Accident
On 22 July 2011, the pilot began differential training on the Piper J3C at Lommis airfield. Two flights were conducted that day, totaling 79 minutes with nine approaches and landings, including two full-stop landings. Training resumed on 26 July 2011. After a briefing, six circuits were flown, followed by three control circuits and a forced landing exercise. Finally, two circuits with full-stop landings were completed. The flight instructor then exited the aircraft and positioned himself near the landing T to observe solo flights.
At approximately 10:55 local time, the pilot took off from runway 06. A witness reported that the aircraft exhibited a pronounced zigzag motion during the takeoff roll, at times nearly sideways, but it eventually lifted off. During the subsequent solo circuit, the approach was made at about 100 km/h without a sideslip. At about 15 m above ground, the pilot reduced engine power to idle and began to flare. A three-point landing occurred within the first 150 m of the runway, centered. Shortly after touchdown, the aircraft pulled to the right. The pilot applied left rudder and aileron. The aircraft then yawed left, crossed the runway centerline, and rolled toward the left edge of the runway. The right wheel overran a white plastic runway marking. The aircraft then nosed over and came to rest inverted. The pilot sustained no injuries and exited the aircraft unaided.
Meteorological Information
The general weather situation was characterized by flat pressure distribution at the surface, with Switzerland remaining at the southern edge of a trough over central Europe.
Damage
The aircraft was seriously damaged. A runway marking was destroyed.
Probable Cause
Loss of control on landing leading to a lateral runway excursion followed by a nose-over. Contributing factors were an overly optimistic assessment of the pilot's skills by the flight instructor and inappropriate use of brakes.