Accident Details
On 29 October 1969, at 1552 hours local time, a Piper J3C aircraft registered as HB-OXS crashed at Yens, Vaud, Switzerland. The aircraft was operated by the Ecole de Pilotage de La Côte S.A. and was being used for training. The instructor and student pilot were uninjured, but the aircraft was destroyed. The accident occurred during landing practice on outlying fields.
Aircraft and Occupants
The aircraft was a Piper J3C, a single-engine, high-wing monoplane with fixed landing gear, constructed of mixed materials. Its empty weight was 363 kg, and it carried 3 kg of oil, approximately 25 kg of fuel (35 liters), and occupants weighing 175 kg, totaling 566 kg, within the maximum authorized weight of 580 kg. The center of gravity was within limits. The engine was a Continental C90-8F, and the propeller was a metal Sensenich M76AK-2-42. The aircraft had a valid certificate of airworthiness and was regularly maintained.
The instructor, born in 1925, held a private pilot license with instructor and night ratings, and a professional pilot license. He had 859:57 hours total flight time with 3868 landings. The student pilot, born in 1928, had a student pilot card and a glider pilot license, with 42:03 hours of powered flight and 278 landings.
Accident Sequence
The instructor and student departed for a tour of outlying fields at La Chaux-de-Fonds, Colombier, and Yverdon. On the return, the instructor decided to demonstrate landing and takeoff procedures at Yens. They landed at Yens at 1545 hours, then took off two minutes later for a traffic pattern. After departure, the pilot turned right to perform a circuit but saw another aircraft ready for departure. He delayed the approach and flew east toward Denens, climbing to about 200 meters above ground. He then made a wide left turn back over the field and performed a simulated engine failure exercise, power at idle. Through a second left turn of 270 degrees, he positioned for a short final but was offset to the right of the runway. To align, he continued the left turn beyond heading 320 degrees, then turned right with a bank of about 20 degrees at a height of 5 to 10 meters. The airspeed was very low. The right wing stalled, and the aircraft struck the ground in a right sideslip. The occupants exited unharmed and moved the aircraft to the runway edge to clear it for another landing aircraft.
Observations
The weather was fair with strong haze; visibility near ground was 5 km, reduced to 2 km toward the sun. The sun at the time was at azimuth 240°, elevation 12°, to the left of the flight path. A local tailwind from the southeast of 2 to 5 knots was reported. The runway at Yens was oriented 140/320, about 450 m by 30 m, with mandatory landing direction 32 due to a railway line. The accident had no witnesses.
Probable Cause
The accident was caused by a stall following a slow approach in a turn.