What happened
On December 8, 1962, a pilot took off from the Ecuvillens airfield in a Piper Cub J3 accompanied by his six-year-old son. The original intention was a simple circuit of the airfield. However, after noticing improved weather conditions, the pilot decided to extend the flight toward Bulle.
During the return leg, the pilot encountered heavy fog that had settled over the Ecuvillered region, significantly reducing visibility. Upon checking the fuel gauge, the pilot realized the fuel level had reached its lowest point. Attempting to reach the airfield, the pilot performed a wide left turn to descend from 1,400 feet. During this maneuver, the engine failed due to fuel exhaustion.
At an altitude of approximately 100 meters, the pilot attempted an emergency landing straight ahead. While maneuvering through the fog, the aircraft narrowly avoided a group of houses but struck a wire fence. The impact caused the aircraft to skid and crash into a field. The pilot sustained facial injuries, including broken bones, while the child remained uninjured.
The investigation
The investigation examined the aircraft's fuel system and the pilot's flight planning. Investigators found that the aircraft's main fuel tank and auxiliary tank were both empty. The fuel gauge, which used a non-graduated metal rod, provided only a rough indication of remaining fuel.
Technical analysis of the wreckage confirmed that the aircraft had struck the fence with its left wing and bracing wires while in a left slip. The investigation also noted that the pilot had departed with approximately 10 liters of fuel, which was insufficient for the extended flight duration. The weather conditions at the time of the accident involved ground fog with visibility below 1 km.
Findings
- The primary cause of the accident was the pilot's decision to fly with insufficient fuel reserves.
- The pilot's decision to extend the flight beyond the immediate vicinity of the airfield without adequate fuel left no margin for error when weather conditions deteriorated.
- The non-graduated nature of the fuel gauge made it difficult to accurately estimate remaining fuel levels.
- Low visibility due to fog complicated the emergency approach and contributed to the impact with the fence.