What happened
On August 4, 1974, a Piper PA-28-180 Cherokee, registration HB-OMR, departed from Grenchen airport for a scenic Alpine tour. The flight, which included the pilot and two passengers, proceeded through various landmarks including the Gemmi Pass and Leukerbad.
As the aircraft approached the Jungfraujoch region, the flight path became increasingly precarious. Witnesses and onboard film footage indicate that after passing the Sphinx Observatory, the pilot attempted several turns to navigate the terrain. During these maneuvers, the aircraft encountered thickening clouds and fog. While attempting to execute a turn near the Trugberg, the aircraft lost sufficient altitude to clear the terrain. The aircraft eventually disappeared into the fog and reappeared in a steep, 70-degree descent, impacting a glacier approximately 600 meters southeast of the Sphinx tunnel exit. The impact resulted in three fatalities and the total destruction of the aircraft.
The investigation
The investigation, conducted with assistance from the Bern Cantonal Police, examined the aircraft's wreckage, meteorological records, and passenger film footage. Investigators confirmed that the aircraft was airworthy, with its weight and center of gravity within legal limits. The engine and flight controls showed no signs of mechanical failure prior to the impact.
Meteorological data revealed that while visibility was initially good, cloud cover was increasing. By the time of the accident, fog had descended to approximately 3,300 meters, and winds from the southeast were gusting at 16 knots. The investigation also reviewed the pilot's credentials, noting he held a valid private pilot license but had very limited experience with this specific aircraft type and lacked mountain flying experience.
Findings
- The pilot entered an area where the combination of topography and meteorology made a safe turnaround impossible.
- The pilot's focus on providing a scenic view for the passengers may have led to a delayed reaction to the encroaching cloud bank on the western side of the Mönch.
- The aircraft entered a downdraft zone caused by the terrain and southeast winds, which, combined with the necessity of tight turns in low visibility, depleted the aircraft's altitude.
- The pilot lacked sufficient mountain flying experience to navigate the complex terrain and weather conditions effectively.