What happened
On March 28, 1976, a Fuji FA-200-180 (registration HB-ESP) departed from Luzern-Beromünster for a private alpine flight. The aircraft was carrying the pilot and three passengers. While flying near the Schilthorn region, the aircraft was observed approaching the Schilthorn Restaurant from the southwest, maintaining an altitude between 50 and 100 meters.
After a brief period of straight flight, the pilot initiated a sudden and aggressive right-hand steep turn. The aircraft reached a bank angle of approximately 80 degrees. Witnesses noted that the airspeed appeared to be extremely low during this maneuver. This maneuver caused the aircraft to undergo a 180-degree direction change, leading it into a right-hand spin. After three to four rotations, the aircraft struck a steep, snow-covered slope at an altitude of approximately 2500 meters, roughly 700 meters northwest of the Schilthorn Restaurant. All four occupants sustained fatal injuries, and the aircraft was destroyed.
The investigation
The investigation, conducted in collaboration with the Bern Cantonal Police, examined the aircraft's flight path, mechanical condition, and the pilot's credentials. Investigators found that the aircraft's weight and center of gravity were within permissible limits, and there was sufficient fuel remaining for several hours of flight.
Technical examination of the wreckage showed that the landing gear was retracted, the engine power was at idle, and the mixture was pulled back. No mechanical defects in the control linkages, cables, or pulleys were identified. The pilot held a valid private pilot license and was medically fit. The investigation also noted that while the pilot was wearing a seatbelt, the front passenger's belt had torn, and the two rear passengers were not restrained.
Findings
- The primary cause of the accident was the underspeeding of the aircraft below its minimum required velocity while executing a steep turn.
- The pilot's limited flight experience may have contributed to the loss of control.
- The aircraft's maneuverability and performance margins are significantly reduced at altitudes around 3000 meters.
- Turbulence or wind gusts may have facilitated the onset of the spin.