What happened
On April 2, 1997, a private Mooney M20J, registration HB-DHR, was conducting a private training flight from Lugano toward Zurich. The flight path was intended to pass over the Simplon and Jungfraujoch regions. At approximately 14:20 local time, the aircraft was observed flying at a relatively low altitude following the terrain of the Aletsch Glacier.
Video footage captured by a witness near the Sphinx recorded the final seconds of the flight. Approximately 750 meters before reaching the Jungfraujoch, the pilot initiated a left-hand turn. As the turn tightened, the aircraft entered a steep spiral dive, ultimately impacting the glacier approximately 500 meters short of the pass. The impact resulted in three fatalities, as all occupants of the aircraft were killed.
The investigation
Investigators examined the aircraft's mechanical condition and the pilot's medical history. The investigation confirmed that the Mooney M20J was in an airworthy condition, with the weight and balance within limits and no mechanical failures found in the control cables, pulleys, or rudder connections. The engine performance appeared normal based on both the aircraft's state and audio recordings from the video.
The pilot's medical history was reviewed, noting previous episodes of dizziness in 1991 and 1995. An autopsy revealed evidence of prior cardiac issues, including coronary artery narrowing and myocardial scarring. While these findings suggested a potential for cardiac arrhythmia—especially when combined with the physiological strain of high-altitude flight without a pressurized cabin—the investigation found no direct link between the pilot's health and the accident.
Findings
Several contributing factors were identified regarding the flight execution:
- The pilot likely flew too low into the glacier terrain, potentially misjudging the altitude.
- An optical illusion may have occurred; flying over a steadily rising snow surface can lead a pilot to unconsciously adjust the aircraft's attitude to match the slope, creating a false perception of obstacle height.
- The difficulty of executing a reversing turn below the natural horizon may have contributed to the loss of control.
- The high speed and performance characteristics of the aircraft require precise handling during steep turns to prevent entering a spiral dive.
- Excellent visibility and sunny weather may have acted as a distraction, reducing the pilot's concentration on the terrain.
Safety action
No specific safety recommendations were recorded in the final report.