Flight Details
On 21 September 1967, at approximately 1415 local time, a Piper J3C aircraft, registration HB-ONE, was conducting a takeoff from La Chaux-de-Fonds Airport (Les Eplatures) in Switzerland. The aircraft was operated by Fliegerschule Birrfeld der Sektion Aargau des Ae.C.S. The pilot, a student pilot born in 1930, had departed earlier from Birrfeld Aerodrome at 1035 with the intention of completing navigation and altitude flight requirements for a private pilot license. The planned route was Birrfeld–Granges–Lausanne–Birrfeld. After landing at Granges at 1127, the pilot departed for Lausanne at 1147. Encountering strong headwinds, he realized fuel would be insufficient and diverted to La Chaux-de-Fonds to refuel. He landed without incident at 1310.
Accident Sequence
After refueling and a brief rest, the pilot taxied to runway 24 for departure. At 1415, the aircraft was aligned at the start of the runway, ready for takeoff. The pilot applied full throttle, progressively pushing the control column forward and compensating for a left crosswind using the controls. After rolling approximately 50 meters along the runway centerline, a wind gust suddenly lifted the left wing, destabilizing the aircraft. The pilot immediately moved the control column left to counteract, but was unable to overcome the wind effect. The right wingtip contacted the ground, the aircraft turned 180 degrees, and then entered a pylon-like maneuver at the runway edge. As the pilot prepared to evacuate, another gust flipped the aircraft onto its back.
Aircraft and Pilot Information
The aircraft was a Piper J3C, a high-wing, strut-braced monoplane with tandem seating, fixed landing gear, and a tailwheel. It was powered by a Rolls-Royce 0-200A engine (100 hp). The airworthiness certificate was valid until 22 April 1968. At the time of the accident, the aircraft weighed 510 kg (maximum authorized 580 kg), and the center of gravity was within limits. The airframe had accumulated 5671 flight hours, and the engine had 978 hours since last overhaul. The student pilot had a student pilot card issued 31 July 1967, valid until 27 July 1969, with an extension for cross-country flights from 2 September 1967. He had begun flight training on 26 July 1967 and had logged 23 hours 37 minutes and 225 landings on the Piper J3C, including 3 hours 38 minutes and 37 landings solo.
Weather Conditions
On the day of the accident, a deep depression centered over central and northern France moving northeast at 25–30 knots influenced the weather over Switzerland. Wind, light in the early morning, increased during the day with gusts in low layers. At La Chaux-de-Fonds in the early afternoon, wind was from the southwest at 15–20 knots, gusting to 30–35 knots. Temperature was +20°C, QNH 999 mb. The pilot encountered wind at various altitudes en route from Granges to La Chaux-de-Fonds: at 500 m, 240°/5–10 knots; at 1000 m, 220°/15 knots; at 1500 m, 220°/25–30 knots; at 2000 m, 220°/40 knots. The aeronautical forecast issued by Kloten Airport for 0600–1200 had warned of strong southwest wind in low layers and gusts over the Alps.
Damage
The pilot exited the aircraft uninjured. The aircraft sustained 75% damage. No ground damage occurred.