What happened
On February 11, 2011, a Raytheon BE 95-B55, registration HB-GDS, departed Lausanne-La Blécherette for a flight through the Alps toward Sion. The aircraft was carrying five occupants. During the flight, the aircraft followed the Rhône Valley before heading toward the Val d'Anniviele. As the aircraft approached the Forcletta peak, the pilot initiated a wide right turn. Radar data and webcam footage indicate that during this maneuver, the aircraft's altitude fluctuated sharply, involving a sudden descent followed by an abrupt climb. The aircraft eventually entered a near-vertical descent, impacting a mountain ridge at approximately 2,900 meters altitude. All five occupants were killed in the crash, and the aircraft was destroyed.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined radar data from Skyguide, passenger photographs, and pilot notes recovered from the wreckage. Investigators analyzed the wreckage and engine components, finding that the engines were at full power at the moment of impact, as evidenced by the deformation of the propeller blades and the position of the fuel injection butterfly valves. The investigation also reviewed meteorological data and webcam footage from St-Luc, which suggested the aircraft was flying within cloud cover at the time of the accident. Technical inspections of the airframe, engines, and instruments revealed no mechanical failures or defects that contributed to the accident.
Findings
- The primary cause of the accident was a collision with terrain resulting from a loss of control.
- This loss of control was likely triggered by the pilot losing visual references while flying in mountainous terrain.
- The pilot likely attempted to avoid cloud masses, leading to extreme banking and rapid changes in altitude.
- These maneuvers likely induced a stall while the engine was at high power, making recovery difficult.
- The flight tactics used were inappropriate for the prevailing meteorological conditions.
- The pilot's experience in this specific aircraft type was relatively low, with fewer than 60 hours of VFR experience, which may have contributed to a lack of anticipation in mountain flying.