1970 Piper PA-18-150 Super Cub accident in the Bernese Alps (HB-OYK)

Accident Overview and Investigation Status On 22 August 1970, a Piper PA-18-150 “Super Cub” with registration HB-OYK crashed in the Bernese Alps. The accident occurred on the north side of the Petersgrat, in the upper part of the Kanderfirn glacier, at an altitude of 2,940 m above sea level. The aircraft struck the snow-covered slope in landing configuration, with its heading roughly parallel to the contour lines. The local slope had a lateral gradient of about 15%. The accident was reported to the Federal Bureau of Aviation Accident Investigation the following day at 1200 local time by the pilot’s wife. The investigation was opened on 25 August 1970 at 1600 local time at the accident site. The final report was approved with one amendment and circulated between 7 December 1970 and 27 January 1971. ## Aircraft, Pilot, and Operational Context The aircraft was owned and operated by the pilot. It was a Piper PA-18-150 “Super Cub” equipped with a 150 hp Lycoming O-320 engine and a fixed-pitch metal Sensenich propeller. The landing gear was mixed, with wheels and skis. The aircraft’s certificate of airworthiness was issued on 9 February 1966 and was valid until 21 January 1971. The maximum authorized weight was 794 kg; at the time of the accident, the weight was about 710 kg, and the center of gravity was within prescribed limits. The pilot was born in 1923 and held a restricted professional pilot license issued on 4 September 1950, valid until 15 January 1971, with a mountain-landing qualification dated 17 June 1964. His total experience was 4,977 hours and 24,617 landings, including 16,817 mountain landings. In the three months before the accident, he had 140 hours and 640 landings; in the three days before the accident, he had no recorded flying. The report also listed prior incidents and a 1970 fine for insufficient flight preparation and landing beyond civil twilight without night-flight conditions. The pilot held a general operating authorization for commercial, non-scheduled visual-flight-rule flights within Switzerland, with ground visibility, during the day, for occasional transport of persons and goods. The authorization was issued on 12 June 1969 and was valid until 30 June 1971. ## Flight Sequence and Weather At 1430 local time on 22 August 1970, the pilot departed Reichenbach aerodrome in the Frutigtal to pick up a passenger he had dropped off in the morning near the Mutthorn hut. The passenger was a television cameraman from Ticino. The pilot was alone aboard and carried first-aid alpine equipment, 72 boxes of carbonated beverages, and about 40 liters of fuel. About 10 minutes before departure, the pilot had telephoned the hut keeper and was told that conditions on the glacier were expected to be similar to those at 0800: high fog and calm wind. After climbing the Gasterntal, the pilot spiraled between cloud formations and entered the upper Kanderfirn area at about 2,800 m on the altimeter. He found that conditions had deteriorated and that the hut was in fog. About 50 m to the south, the glacier was clear, and he saw his client still working, surrounded by guides. Believing a landing could be attempted, the pilot turned back downstream to get under the cloud cover and climb the glacier while staying beneath the layer. He used numerous crevasses on his right, along the north slope of the Petersgrat, as a visual reference. He then realized he had lost all forward visual contact with the ground. Unable to turn back because fog blocked visibility to his left and terrain prevented escape to the right, he banked toward the slope to keep some ground reference and decided to make a forced landing on the north side of the Petersgrat. The aircraft passed through some fog patches, struck the snow-covered slope first with the right ski, which was torn off, then with the left gear, which also failed, and came to rest on its back. There were no witnesses. ## Injuries, Damage, and Recovery The pilot emerged uninjured from the wreckage. He reached the Mutthorn hut in the late afternoon with a rope team that happened to arrive about an hour and a half after the accident. The extent of damage to the aircraft was estimated at about 70%. The wreckage was evacuated by helicopter four days after the accident. ## Findings and Probable Cause The investigation found that the pilot held the required licenses and authorizations for the flight. The aircraft had a valid certificate of airworthiness, and the investigation did not reveal any deficiencies in the condition of the equipment. The report concluded that the pilot, despite extensive regional experience, attempted to complete the flight under insufficient visibility and ceiling conditions in the approach area. After recognizing the difficult situation, he chose to put the aircraft on the ground as quickly as possible before losing control due to lack of visual reference.