Accident Overview
On 8 December 1962 at 1500 hours local time, a Piper Cub J3 (registration HB-OWS) departed Ecuvillens aerodrome with the pilot and his six-year-old son on board. The flight, originally planned as a circuit, was extended towards Bulle. Upon return, the pilot found the Ecuvillens area covered by fog. Noting that the fuel gauge indicated empty, he attempted to land on the aerodrome. While maneuvering, the engine stopped due to fuel exhaustion. The pilot, at approximately 100 m above ground, leveled the aircraft and attempted a forced landing in low visibility. The aircraft struck a fence in flight and crashed into a field at 1545 hours.
Aircraft Information
The aircraft was a Piper Cub J3 (L-4), serial number 11204, built in 1943. It was powered by a Continental C90-8F engine (90 hp) installed in 1960. The fuel system consisted of a 45-liter main tank in the fuselage and a 30-liter auxiliary tank in the right wing, feeding the main tank by gravity. The fuel gauge was a visible rod with no graduations. The aircraft had accumulated 1103 hours since entering Swiss service; the engine had 340 hours total. The aircraft's weight and center of gravity were within limits. The fuel tanks were found empty after the accident.
Pilot Information
The pilot, born in 1918, held a private pilot license issued on 31 July 1962, valid until 1 August 1964. He had approximately 53 flight hours and 379 landings total, with about 5 hours and 16 landings in the previous three months. He had no prior accidents or incidents. His last medical examination on 1 August 1962 certified him fit to fly. On the day of the accident, he was in good physical condition.
Weather and Terrain
Weather conditions in the accident area: ground fog or strong mist, visibility below 1 km according to the pilot. Winds were light from the west. The accident site was near Ecuvillens, approximately 400 m southeast of runway 28 threshold, at field elevation 700 m. The aircraft struck a wooden fence with barbed wire before coming to rest in a field.
Technical Findings
Examination of the wreckage revealed: the altimeter was set to QFE; dual controls were removed; stabilizer neutral; ignition off; throttle retracted; mixture rich; carburetor heat on; fuel pump locked; both fuel valves open; main and auxiliary tanks empty and undamaged. Damage patterns indicated the aircraft struck the fence in a left sideslip, then impacted the ground on its landing gear, rotating left.
Conclusion
The accident was due to fuel exhaustion. The pilot had been warned before departure that fuel was low but intended only a short circuit. He later extended the flight, and upon encountering fog, the engine failed when fuel was exhausted.