What happened
On June 5, 1976, a Piper PA-28-140 Cherokee Cruiser, registered HB-OQD, was conducting a private VFR flight from Les Eplatures, Switzerland, to Perpignan, France. After a morning delay due to unfavorable weather, the aircraft departed at 12:20 UTC. The pilot maintained contact with Geneva Information, reporting positions near Lake Lausanne and Lake Annecy. However, upon attempting to transition to Marseille Information frequencies, the aircraft's communications were lost.
While navigating the Alpine terrain, the aircraft deviated significantly from its planned route. Instead of following the intended path through the valleys, the aircraft flew toward the Col de l'Occiput. In conditions of dense fog with visibility reduced to between 10 and 200 meters, the aircraft struck the rocky terrain at an altitude below the surrounding peaks. The impact caused the immediate destruction of the aircraft and a subsequent intense fire. There were 3 fatalities among the occupants, consisting of the pilot and two female passengers.
The investigation
The investigation focused on the flight path, meteorological conditions, and the pilot's navigation. Investigators established that the pilot had consulted weather briefings earlier in the day and was aware of difficult conditions east of Marseille. While the aircraft's equipment and maintenance records were in order, and the aircraft was not overloaded, the investigation noted a significant deviation from the filed flight plan. The aircraft was found approximately 50 kilometers east of its intended route.
Technical analysis of the pilot's wristwatch, which stopped at 13:40 UTC, helped reconstruct the timing of the impact. Furthermore, the investigation examined the lack of radio contact with Marseille Information, noting that the aircraft's position was too low for radar detection and that the VHF coverage in the area was insufficient to maintain contact during the descent into the valley.
Findings
- The primary cause of the accident was the collision with terrain while flying in thick fog.
- The pilot failed to adhere to the VFR (Visual Flight Rules) requirements of the flight plan by operating in conditions that precluded visual reference to the ground.
- A navigation error or undetermined motive led the pilot to fly at an altitude lower than the surrounding mountainous relief.
- The pilot's limited flight experience contributed to an inability to manage the deteriorating weather conditions or seek alternative landing sites.
- The loss of radio contact with regional air traffic services deprived the pilot of vital assistance and weather updates.