What happened
On May 29, 1977, a private pilot departed from Geneva-Cointrin airport in an AS 202/15 Bravo, registration HB-HFC, accompanied by two passengers. The intention of the flight was a scenic tour over the Jura Mountains. During the flight, the pilot attempted to fly at a very low altitude to observe a friend's residence near the village of Péron, France.
To approach the house, the pilot performed a descent with reduced engine power and executed a turn of more than 180 degrees. This maneuver placed the aircraft directly facing a mountain ridge with an elevation of approximately 1,100 meters, while the aircraft was flying at an altitude significantly lower than the terrain. As the pilot attempted to climb and apply power to clear the rising terrain, the aircraft entered a sudden left-hand stall. The aircraft subsequently entered a spin, descending vertically into the trees and terrain at an altitude of 750 meters. The impact resulted in the destruction of the aircraft and 3 fatalities.
The investigation
The investigation examined the aircraft's mechanical condition, the pilot's experience, and the environmental factors at the time of the accident. Technical analysis of the Lycoming engine and propeller indicated that the engine was producing power at the moment of impact. While the operator had previously noted intermittent power drops related to fuel types, laboratory testing showed no significant mechanical defects that would have caused a sudden failure.
Investigators also reviewed the pilot's flight records. Although the pilot held valid licenses, he had not flown this specific aircraft type for approximately 18 months and had only accumulated a small number of flight hours on the type in the preceding months. The aircraft was also operating near its maximum takeoff weight.
Findings
- The primary cause of the accident was the impact with the mountainside following a loss of airspeed.
- The pilot engaged in highly dangerous flight maneuvers at an extremely low altitude relative to the terrain.
- The pilot's recent experience with the AS 202/15 Bravo was insufficient to manage the aerodynamic demands of the low-altitude turn, especially while the aircraft was heavily loaded.
- While a potential loss of engine power or carburetor icing could not be entirely ruled out as a contributing factor, the investigation concluded that the pilot's chosen flight path and maneuvers were the decisive factors.