What happened
On the morning of September 15, 1959, a Piper Super-Cub HB-OPO departed from a takeoff site near the Sphinx edge at Jungfraujoch for a scheduled aerial photography mission. The pilot had spent the previous night at the Jungfraujoch House due to fog and had noted a thin layer of frozen snow on the aircraft's wings during pre-flight inspections.
Shortly after takeoff, the pilot attempted to maneuver around the Sphinx edge toward the south, intending to catch updrafts over the Konkordiaplatz. During a left turn south of the plateau, the aircraft encountered a downduster and began losing altitude. Despite the pilot's efforts to apply heavy elevator input to recover, the aircraft entered a dive. The aircraft struck the Jungfraufirn glacier at an altitude of 3,480 meters, causing the aircraft to flip and slide 120 meters down the slope. The impact resulted in one fatality (the photographer) and severe injuries to the pilot.
The investigation
The investigation examined the aircraft's mechanical state, the environmental conditions, and the pilot's flight path. Investigators analyzed engine tachometer recordings, which showed a progressive drop in engine RPM from 2450 to just below 2250 during the flight. The investigation also reviewed the presence of snow on the wings and the impact of local wind conditions. Additionally, the investigation noted that wreckage had been moved 500 meters downslope by a rescue pilot prior to the official examination.
Findings
Several contributing factors led to the accident:
- The pilot's decision to fly toward rising terrain immediately after takeoff without a compelling reason, which left no margin for error when encountering unfavorable conditions.
- Carburetor icing, evidenced by the progressive loss of engine power, likely exacerbated by the failure to use the carburetor heat and insufficient engine pre-heating.
- The presence of a residual snow layer on the wings, which negatively impacted aerodynamic performance and added weight.
- The influence of local downdrafts and headwinds that contributed to the loss of airspeed and altitude.
- A lack of sufficient airspeed reserves, evidenced by the pilot's loss of effective elevator control during the final moments of flight.