What happened
On February 7, 1971, a Cessna 150 (registration HB-CSG) departed Locarno for a flight toward Altenrhein. The pilot, accompanied by one passenger, initially crossed the San Bernardino pass at approximately 9,000 feet, encountering only light haze in the Rhine Valley. As the aircraft descended toward Chur, the pilot encountered low-lying clouds and fog.
Upon reaching the Bad Ragaz area, the pilot encountered difficult landing conditions and poor local visibility. Despite having received weather warnings that indicated the valley was closed by fog, the pilot decided to proceed toward Altenrhein. While attempting a turnback maneuver near Trübbach, the aircraft entered a thick layer of fog, resulting in a total loss of ground visibility. In an attempt to climb out of the fog, the pilot initiated a steep ascent under instrument meteorological conditions (IMC). During this maneuver, the aircraft's right wing struck the tops of fir trees on the Alp Lida, causing the plane to flip and strike a steep slope before coming to rest against a large tree. The accident resulted in one fatality (the passenger) and one serious injury (the pilot).
The investigation
The investigation examined the aircraft's technical condition, the pilot's experience, and the prevailing meteorological data. The Cessna 150 was found to be in airworthy condition, with no mechanical failures or fuel issues identified. Investigators reviewed the pilot's flight training and recent flight history, noting that while the pilot was a licensed private pilot, his experience in this specific aircraft type was limited to approximately 9.5 hours. The investigation also analyzed weather reports from the time, including a telephone warning from the Bad Ragaz airfield manager stating that the valley was completely obscured by fog and that landing was impossible.
Findings
- The pilot continued a visual flight rules (VFR) flight into weather conditions that were no longer suitable for VFR.
- The decision to proceed toward Altenrhein should have been replaced by a decision to land or return to Locarno once the weather deteriorated near Bad Ragaz.
- The turnback maneuver over the Rhine was initiated too late, placing the aircraft in an inescapable situation.
- The pilot attempted to climb through the fog to reach the cloud ceiling, a maneuver that was dangerous because the pilot was not trained for IFR flight, the aircraft was not equipped for it, and the local terrain made such an ascent extremely hazardous.