Pilot loses terrain clearance circling a turbulent ridge in an SZD-30 Pirat
The pilot of an SZD-30 Pirat was fatally injured when the glider struck a slope above Zweisimmen; aircraft destroyed. On a 50 km FAI distance flight from Gruyère, the freshly licensed, low-time pilot worked the pre-alpine ridges for over two hours. Near the Fromattgrat, struggling to climb at ~1400 m, he circled at least three times close to the slope in gusty south-westerly turbulence. Instead of breaking off he kept circling low until the glider lost its terrain margin and hit the 25° grass slope almost vertically. The probable cause was unsuitable ridge-soaring tactics; turbulence, low experience and fatigue may have contributed.
- Cross-country thermaling: After an aerotow launch from Gruyère and release over the Schopfenspitze, the pilot flew a normal cross-country flight via Gros Mont, Gastlosen, Spillgerten and Stockhorn in good thermals.
- Low, turbulent ridge thermaling: Near the Fromattgrat ridge above Zweisimmen, the pilot began circling along the slope in strong, gusty south-westerly turbulence while struggling to gain height.
- Low terrain clearance: The glider was flown close to the sloping terrain, with a probable misjudgment of the distance to the ground during ridge circling.
- Limited experience and fatigue: The pilot had relatively low overall and pre-alpine experience and may have been fatigued after about 2.5 hours in a warm cockpit.
- Continued tight circling: The pilot circled at least three times along the ridge in the turbulent air instead of breaking off to a safer height and terrain clearance.
- Loss of safe margin: While circling close to the slope in turbulence, the glider lost its remaining safety margin to the terrain and descended toward the hillside.
- Crash - fatal: The glider struck the 25° grass slope almost vertically at about 2007 m near the Fromattgrat, was destroyed, and the pilot sustained fatal injuries.