What happened
On April 30, 1970, a Piper PA-28 Cherokee (HB-OLV) departed Lugano-Agno for a private VFR flight to La Côte with three passengers. During the flight, the pilot encountered heavy cloud cover and turbulence while attempting to cross the Alps. After being unable to navigate through the Simplon, Nufenen, or Gotthard passes due to weather, the pilot climbed to 12,500 feet to fly above the cloud layer.
While flying over Lake Geneva, the aircraft experienced a total engine failure, likely due to fuel exhaustion. The pilot lost control of the aircraft while flying through thick clouds at approximately 10,000 feet. After regaining visual contact with the ground at 7,000 feet, the pilot realized there was insufficient altitude to reach the intended destination. The pilot attempted to reach the French shore near Excenevex but instead performed an emergency landing on the water, approximately 200 meters from the shore.
Upon impact with the water, the aircraft capsized and began to sink. The occupants were unable to open the cabin doors, but one passenger managed to break a rear window, allowing everyone to escape. The occupants were rescued by nearby fishermen. While one passenger suffered trauma, the others were uninjured. The aircraft was destroyed.
The investigation
The investigation, conducted by the Swiss authorities despite the accident occurring in French waters, focused on the sequence of events leading to the engine failure and the subsequent loss of control. Investigators examined the aircraft's fuel system, including the two 95-liter wing tanks and the electrical fuel pump. The investigation also reviewed radio communications between the pilot and Geneva radar, noting that the pilot had reported being "short of fuel" while the engine had already failed.
Findings
- The primary cause of the engine failure was fuel exhaustion.
- The pilot encountered significant weather challenges, including heavy clouds and turbulence, which forced a change in flight path and altitude.
- The loss of engine power led to the failure of the autopilot, as the artificial horizon was powered by a vacuum pump driven by the engine.
- The pilot lost visual references and spatial orientation while descending through a dense cloud layer.