Flight History
On Saturday, 30 October 1971, a private visual flight was planned from Bern-Belp to Lugano-Agno with a pilot and three passengers. The pilot had reserved a Cessna 172 F, registration HB-CMR, from Alpar AG. He checked the weather by phone in the morning, and as fog was forecast to lift by midday, he departed Bern at 1221 hours with full fuel tanks. After a flight time of 86 minutes, he landed at Agno.
The stopover in Agno lasted about one hour. The aircraft was not refueled as sufficient reserves remained. The pilot announced his intention to return to Bern but did not consult Agno airport services or the Zurich flight weather advisory for current conditions north of the Alps. He did telephone Alpar AG in Bern to request extended use of the aircraft due to "not particularly good weather," but did not ask about weather in Bern.
Takeoff from Agno for the return flight was at 1451 hours. No further position reports were made. Between 1547 and 1548:30, HB-CMR attempted several times to contact Bern Airport on frequency 118.9 MHz. The pilot's voice was loud and clear, but he did not respond to calls from the ground station.
After 1550 hours, several witnesses in the area of Alp Winterberg, east of Sigriswil, heard an aircraft flying eastbound at low altitude with reduced engine power. The area was covered in fog, so the aircraft was not visible. Shortly thereafter, a crash was heard, and engine noise ceased at 1552 hours. The wreck was found about 30 minutes later, burning.
The accident site was at coordinates 623.400/174.350, at an elevation of 1330 m, on the lower part of the steep, forested northwest slope of the Sigriswilergrat, in the Howald area above Alp Winterberg.
Injuries and Damage
All four occupants—the pilot and three passengers—sustained fatal injuries. The aircraft was destroyed. Significant forest damage occurred.
Pilot Information
The pilot, born 1939, held a private pilot license issued 23 July 1965, valid until 3 February 1972, with limited radiotelephone endorsement. He was rated for all single-engine land aircraft with 1-3 seats up to 2000 kg, including the Cessna 172 (since 27 May 1967). Total flight experience was approximately 131 hours since 1964; his logbook was destroyed in the accident. He had first flown from Bern to Ticino on 3 October 1971, accompanied by a more experienced pilot. He was described as a calm, reliable, rather cautious pilot. No previous incidents were recorded. His last medical examination on 23 January 1970 found him fit.
Aircraft Information
Cessna 172 F, serial number 0086, built 1964 by Reims-Aviation. Engine: Rolls-Royce 0-300-D, 145 hp, serial 30 R 227. Propeller: McCauley fixed-pitch. Owner: Alpar AG. Airworthiness certificate issued 20 October 1970. Total time since new: 2466 hours. Last 50-hour check at 2459 hours on 24 October 1971. The aircraft was properly maintained with complete documentation.
Weather at Accident Area
According to the Swiss Meteorological Institute, a high-pressure system covered the region. The accident area was under 8/8 stratus with base 1200-1400 m/M, top 1800-2000 m. Visibility below the cloud was 2-6 km. Wind was light and variable from west to northwest. Temperature at 1500 m was +2°C with 100% humidity. QNH was 1026 mb. No turbulence or icing.
Around noon, the fog layer lifted toward the Alps; Spiez reported 8/8 stratus base 1350 m at 1245. Beatenberg reported rising fog near noon, visibility 200-500 m. The fog continued to lift during the afternoon.
Probable Cause
The investigation listed the following causes: impact with steeply rising terrain after likely unintentional entry into clouds, where insufficient flight preparation and possibly wrong decisions by the inexperienced pilot may have contributed to the accident.