Accident Details
On 12 May 1963, at approximately 1640 local time, the Rhönlerche glider HB-572 crashed near Niedermuhlern, about 8 km west-southwest of Bern-Längenberg airfield. The aircraft was owned and operated by ALPAR AG Bern. The pilot, a male student born in 1941, held a learner's permit issued on 10 September 1958 and valid until 30 November 1963. He had accumulated about 10 hours of flight time over 73 flights, including two dual-instruction flights: a 57-minute hill-soaring introduction on 30 May 1958 in Bern and a 41-minute dual flight on 3 June 1962 in Colombier. No other occupants were on board.
Flight History
The flight was a training mission, authorized as a half-hour soaring flight. The student pilot departed Bern-Längenberg at approximately 1545 local time. According to the pilot's report, he launched and released over Kehrsatz at about 600 m altitude, then climbed steadily in ridge lift to approximately 1800 m above sea level. He noted another Rhönlerche (HB-664) in the area. After a spiral, he lost sight of the other glider and continued flying parallel to the Langenberg ridge. He encountered sinking air and lost altitude, and after attempting a spiral near Niederscherli without gaining height, he continued toward Niedermuhlern. At about 200 m above ground, he realized he could not return to the airfield and prepared for an out-landing. Seeing houses, a power line, and a wooded depression ahead, he initiated a turn to avoid the power line but lost too much height; the left wing struck a tree, causing the glider to spin and become entangled in the branches. The pilot exited the aircraft uninjured and reported the accident by telephone.
Investigation Findings
The accident site was at Brönni, west of Niedermuhlern, coordinates 600.300/190.200 at 850 m above sea level, in a group of 20–30 trees 12–15 m high in strongly hilly terrain. Weather conditions included a Bise wind, horizontal visibility 50 km, cumulus clouds with base at 1800 m, coverage 2/8, and wind 10 knots from 60°. The glider sustained heavy damage to both wings; estimated repair costs were 6000 Swiss francs, about 15% of the aircraft's value. No ground damage occurred.
The investigation concluded that the accident resulted from the student pilot allowing himself to be carried too far behind the ridge by the ridge lift and, while attempting to return, stalling the aircraft at low altitude above ground. The report characterized this as a typical beginner tactic error: the pilot was overly optimistic and believed he could force a return, causing the glider to stall when he tried to avoid the power line.
Probable Cause
The accident was caused by the student pilot allowing himself to drift too far behind the ridge due to ridge lift, and stalling the aircraft at low altitude while attempting to return.