What happened
On June 23, 2002, a Piper PA-28-181, registration HB-PMD, departed from Bex airfield for a scenic flight through the Alps with three passengers. During the flight, the pilot performed several low-altitude maneuvers, including varying engine power and briefly cutting the magnetos to demonstrate engine-off flight capabilities.
As the aircraft progressed through the valley toward the Prélagine ridge, the pilot attempted a left turn toward Lake Tanay. Realizing the altitude was insufficient, the pilot executed a right turn to cross the ridge from the north. During this maneuver, the aircraft lost altitude and struck trees on a steep slope, crashing into rocky terrain. The impact resulted in two fatalities and two serious injuries.
The investigation
Investigators examined the wreckage and the aircraft's maintenance history, finding no evidence of mechanical failure. The engine was found to have been producing power at the moment of impact. While the aircraft's takeoff weight exceeded the maximum allowable limit by approximately 67 lbs, investigators determined this was not the primary cause of the crash.
The investigation also reviewed the pilot's background and physiological state. The pilot had a total of 270 flight hours, but his recent training progress was noted as slow. Additionally, the pilot had only had approximately five hours of rest following a late-night social event prior to the flight.
Findings
- The primary cause of the terrain collision was inadequate flight tactics during mountain operations.
- The pilot's limited flight experience and low level of training contributed to the accident.
- Pilot fatigue, resulting from a short period of rest, may have played a role.
- The pilot's decision to perform maneuvers that exceeded the aircraft's climb performance in the valley was a critical factor.