Summary
On 15 September 1959 at 0715 local time, a Piper Super-Cub PA-18-150 (registration HB-OPO) took off from a site just east of the Jungfraujoch for a photographic flight. The aircraft was equipped with skis. After reaching an altitude of about 50–70 m above ground, it lost height and struck the Jungfraufirn at 3480 m elevation, about one minute after departure. The aircraft was destroyed. The pilot sustained severe head injuries requiring eight weeks of hospitalization and subsequent partial disability for three weeks, but recovered without permanent effects. The photographer accompanying the pilot suffered severe brain contusions and died the following day.
Aircraft and Occupants
The aircraft was a two-seat high-wing monoplane with a Lycoming O-320 engine (150 hp) and a metal propeller. At the time of the accident, it was fitted with skis. The maximum permissible takeoff weight was 794 kg; the actual takeoff weight was 758 kg (excluding the weight of snow on the wings, which was estimated at about 20 kg). The center of gravity was within limits. The aircraft held a valid certificate of airworthiness.
The pilot, born in 1916, began flight training in 1946 and obtained his private pilot license in 1949, with glacier flight training in 1957/58. He had a total of 545 flight hours and 2326 landings, including about 40 hours and 400 landings on the accident aircraft type, mostly on glaciers. He was well-qualified and had no record of incidents or accidents since 1948. No evidence of fatigue or health issues was found.
The photographer was born in 1937.
Flight and Accident
The pilot had performed transport and passenger flights in the Jungfrau area the previous day. Due to fog, he spent the night at the Jungfraujoch mountain lodge, having anchored the aircraft on the takeoff strip northeast of the Sphinx ridge.
On the morning of the accident, shortly after 0530, the pilot found the wings and control surfaces covered with a thin, fine-grained, frozen layer of snow. He cleaned the controls but could not reach the upper wing surfaces from the ground. He observed that the front third of the wings was snow-free, while the middle third had a gradually increasing snow layer reaching about 5 mm thickness at the trailing edge.
After a warm-up run of about ten minutes, the pilot made three test flights totaling five minutes. The aircraft behaved normally in takeoff and flight, but landed somewhat sluggishly. Afterward, the snow layer appeared unchanged.
Shortly after 0700, the pilot and photographer boarded for a photo flight to the Eiger North Face. The pilot did not re-warm the engine, considering it sufficiently warm. He started the engine and took off at 0715 without further warm-up.
The pilot intended to first gain altitude toward the south (Konkordiaplatz), then turn north to cross the main ridge. He felt a tailwind from the northeast during takeoff. After lifting off, he turned right around the Sphinx ridge to pass near the Joch plateau and then turn south, hoping to find updrafts over the eastward-sloping firn slopes.
He did not activate the carburetor heat; the mixture control was set about 15 mm.
During the left turn south of the Joch plateau, the pilot experienced a downdraft and noticed the aircraft losing altitude despite apparently normal engine power. He continued the turn to the southwest and pushed the elevator forward, causing the aircraft to enter a steep descent. When he attempted to recover, he felt insufficient control pressure and the flight path did not change noticeably. About one minute after takeoff, the aircraft struck the firn at 3480 m elevation while still in a left turn. The left ski touched first, then the aircraft overturned and slid about 120 meters on its back before stopping.
Investigation Findings
Examination of the tachograph chart showed a continuous and progressive drop in engine speed from 2450 to just below 2250 rpm over the minute between takeoff and impact. Under the prevailing meteorological conditions (temperature -2°C, humidity 85%), this indicated the onset and rapid progression of carburetor icing. The pilot had not properly reheated the engine before the final flight and did not use carburetor heat.
The snow layer on the wings, estimated at up to 20 kg, adversely affected aerodynamic performance and weight, though its precise impact could not be quantified.
The pilot's statements suggested local downdrafts and tailwinds, consistent with the terrain.
In the final phase, the loss of normal control pressure indicated insufficient speed margin. The aircraft was likely in transitional airflow zones, losing speed and altitude. The lack of a distinct visual horizon may have hampered the pilot's assessment of the flight condition.
The primary cause identified in the report was that the pilot, after takeoff, immediately turned west toward rising terrain instead of flying south to gain safe altitude quickly. This maneuver, combined with multiple adverse factors, led to a critical situation.
Probable Cause
The probable cause was that the pilot, during the initial climb after takeoff, flew against a mountainside without compelling reason, and under the additional influence of several unfavorable factors—icing-related power loss, residual snow on the wings, and local downdrafts and tailwinds—could not turn away in time.