What happened
On May 17, 1965, a Beech 95-A-55 "Baron", registration HB-GBA, departed Samedan airport for a flight to Zurich. The aircraft was carrying a pilot, a co-pilot, and two passengers. After an initial attempt to fly over the Flüela Pass was abandoned due to poor visibility, the pilot rerouted through Landeck to enter the Engadin valley.
At approximately 12:34, the aircraft departed Samed and began a climb. Around 12:45, witnesses on the ground near the pass reported hearing a powerful engine noise that abruptly ceased. The wreckage was discovered later that evening in deep snow approximately 700 meters south of the pass summit. All four fatalities were confirmed, and the aircraft was destroyed.
The investigation
Investigators examined the wreckage and the flight conditions at the time of the accident. The aircraft's engines and propellers showed no signs of mechanical failure prior to the impact. The investigation noted that the aircraft was in a climbing configuration with landing gear retracted and the elevator trim set slightly tail-heavy.
Reconstruction flights using a similar aircraft type demonstrated that the terrain near the Susasca valley limits visibility of the pass summit until the final approach, making safe maneuvering difficult. Furthermore, the investigation established that while the aircraft could maintain stability in moderate turbulence, the specific weather conditions at the time involved significant wind fluctuations.
Findings
- The primary cause of the accident was that the aircraft stalled during a climb due to the influence of extraordinarily strong wind gusts.
- The stall occurred at an altitude that provided insufficient margin to recover controlled flight.
- Severe weather conditions were present, characterized by a Föhn weather pattern and a passing warm front, which generated intense turbulence and gusty winds near the mountain slopes.
- The pilot likely encountered sudden airflow separation caused by a powerful gust while attempting to climb through the valley.