Accident Overview
On 23 July 1989 at approximately 1500 local time, a Piper PA-38-112, registration HB-PFU, operated by a private pilot with his son as passenger, crashed at L'Auta Chia-d'en Haut in the canton of Fribourg, Switzerland. The aircraft was destroyed and a parked car was damaged. Both occupants sustained minor injuries and were hospitalized for 24 hours.
Flight History
The pilot departed from Gruyères airfield at 1454 hours, intending to fly to Beromünster. After takeoff, he turned right, flew over Lake Gruyères, and entered the Javro valley toward the Col de la Patta. While climbing northeast, the pilot realized that his altitude was insufficient to clear the terrain ahead. Despite sufficient space to the right, he initiated a 360° left turn. During the turn, airspeed dropped to 60 kt. To avoid stalling, he lowered the nose slightly, but speed did not increase and altitude continued to decrease. The aircraft struck the ground with its landing gear, bounced, hit a stationary car, overturned, and came to rest on its belly. The fuselage broke behind the cabin and the engine was ejected 50 m away.
Investigation Findings
The pilot held a valid private pilot license and was authorized for the flight. No health issues were indicated. The aircraft was properly maintained with valid documents, and technical inspection revealed no pre-accident defects. Mass and center of gravity were within limits, and fuel tanks were two-thirds full at departure. The average climb rate of the aircraft was 470 ft/min, which matched the maximum achievable under the conditions. However, to clear Col de la Patta with 1000 ft of safety margin, a climb rate of 650 ft/min would have been required following the same route. Meteorological conditions were summer-like, with cumulus clouds, warm temperatures, and southwesterly winds of 15 kt at altitude.
Cause and Contributing Factors
The accident was attributed to flight in mountainous terrain without sufficient altitude reserve. Contributing factors included inadequate mountain flying tactics, poor flight preparation, ignorance of aircraft performance, and insufficient training. The pilot had logged only 24 minutes and three landings since November of the previous year, indicating lack of recent practice.