Flight History
On 2 April 1997 at 0945 hours, the pilot departed Zurich Airport in a Mooney M20J, registration HB-DHR, accompanied by two colleagues. They landed in Lugano at 1106 hours and had lunch at the airport restaurant. At 1247 hours, after filing a flight plan, they departed Lugano for Zurich, with a planned route via Luino, Simplon, Jungfraujoch, and Brunnen. Landing at Zurich was scheduled for 1400 hours.
Accident Sequence
Around 1420 hours, several witnesses observed HB-DHR flying up the Aletsch Glacier. A witness near the Sphinx recorded the final 11 seconds on video. The footage showed the aircraft following the glacier line at low altitude. Approximately 750 meters before the Jungfraujoch, the pilot initiated a left turn. The turn became progressively tighter, and the aircraft entered a spiral dive. It struck the glacier about 500 meters before the pass.
Aircraft and Pilot Information
The pilot, a Swiss citizen born in 1939, held a valid private pilot license. He had accumulated 307 total flight hours, with 167 hours on the accident type. In the 90 days prior, he had flown 5 hours. The aircraft was a Mooney M20J, privately owned and operated, with a valid airworthiness certificate. Weight and balance were within limits.
Findings
- The pilot had experienced dizziness in 1991 and 1995, for which he received medical treatment, but reported no further episodes after 1995.
- Autopsy revealed fatty deposits in the coronary arteries, with up to 40% narrowing, and microscopic scars in the heart muscle, indicating previous reduced oxygen supply. The report noted that these pre-existing cardiac findings, combined with flight altitude without cabin pressurization and circulatory load from digestion, could potentially have caused a rhythm disturbance affecting pilot performance. However, the autopsy found no direct link between the pilot's health and his control of the aircraft at the time of the accident.
- No alcohol, drugs, or medications were detected.
- Examination of the airframe, control cables, pulleys, bearings, and control surface connections revealed no pre-existing defects.
- Weather at the accident site was sunny with visibility over 60 km, light winds, and a temperature of -4°C. The sun was behind the pilot, so glare was not a factor.
Probable Cause
The accident resulted from loss of control and subsequent collision with terrain due to incorrect flight tactics.