Event Sequence
The flight began at 1136 hours MEZ from Saanen airfield with a glider tow. The pilot had completed an instructional flight with a dual-control instructor earlier. After releasing the tow rope at Hornberg, he flew in company with other gliders. Around 1215, rain started. The sky cleared after about fifteen minutes but darkened again around 1330. At that time, flying at approximately 2300 meters above sea level, the pilot noticed several gliders returning to Saanen and decided to abandon his flight. While descending with airbrakes extended, at an indicated airspeed of 130 km/h and a sink rate of 5 m/s, rain and strong gusts began. The glider flew east, passing north of the airfield, then turned right toward runway 26 with the airbrakes still deployed. The impaired visibility and gustiness challenged the pilot, who forgot to retract the airbrakes. While overflying the Montreux-Oberland-Bahn (MOB) railway, the glider's tail skid contacted the overhead power line. The glider then became stuck in the crown of a tree at about 3 meters above ground, south of Saanen station, at 1340 hours.
Damage
The pilot was uninjured. The glider sustained severe damage. Minor third-party damage occurred.
Findings
The pilot, born in 1952, held a valid glider pilot license. His total flight experience was 25 hours and 48 minutes, including 8 hours on the accident type. In the preceding 90 days, he had flown 15 hours and 2 minutes, of which 8 hours on type. No evidence indicated any health impairment at the time of the accident. Before the flight, an instructional flight was conducted and the pilot was briefed on the weather conditions. The glider was airworthy and certified for flight. No pre-existing technical defects were found that could have influenced the event. Weight and balance were within permissible limits.
Weather according to the Meteorological Central Institute: General situation: a thunderstorm zone over central France was expected to reach Switzerland in the afternoon. At the accident time: 1/8 cumulonimbus, base at 2000 m; 7/8 stratocumulus and cumulus, base 2000-2500 m. Horizontal visibility 8-15 km. Surface wind from west to north at 10 knots (mean); at 1500 m, wind from south at 15 knots; at 3000 m, wind from south at 30 knots. Weather phenomena: showers and thunderstorms. Meteorological flight hazards: highly variable wind influences from foehn and thunderstorm activity. Weather development before the accident: increasing clouds with foehn conditions, first showers or thunderstorms around midday.
Probable Cause
Collision with obstacles, with contributing factors: misoperation of the airbrakes and the pilot's low flight experience, especially in alpine gliding.