What happened
On May 3, 1998, a pilot was undergoing an introduction program in a DG-100 ELAN, registration HB-1616, at the Winterthur airfield. Following two successful tow-plane flights earlier in the day, the pilot initiated a third flight using a winch launch at 15:42 local time.
During the climb, the aircraft's ascent was relatively shallow, and the glider drifted southeast at an altitude of approximately 300 to 350 meters. While maneuvering in a right-hand turn, the aircraft experienced a sudden loss of lift and entered a spin. Other pilots in the vicinity observed the aircraft banking sharply over the right wing before transitioning into a spiral. Despite radio instructions from another pilot attempting to assist with recovery techniques, the aircraft continued its descent, completing approximately two rotations before impacting a field about 1 km southeast of the airfield. The impact resulted in the death of the pilot and the total destruction of the aircraft.
The investigation
Investigators examined the aircraft's condition, the pilot's background, and the environmental factors present at the time of the accident. The investigation confirmed that the DG-100 ELAN was airworthy, with all control surfaces and bolts properly secured. The aircraft's center of gravity was within permissible limits, though it was positioned in a range where spinning is possible.
The pilot's medical history showed no impairments, and his flight training for this specific aircraft type was current. The investigation also noted that the pilot's seat position allowed for full rudder deflection. Environmental analysis revealed moderate turbulence caused by a combination of thermal activity and gusty Bise winds.
Findings
- The primary cause of the accident was the underspeeding of the aircraft during a turn while flying in turbulent Bise winds.
- The pilot's limited flight experience contributed to the inability to manage the low-speed condition.
- The presence of gusty winds facilitated the wing drop and subsequent stall.
- The sudden nature of the aerodynamic stall likely left the pilot with insufficient time to implement recovery procedures or attempt an emergency egress, as evidenced by the fact that his seatbelts remained fastened and the cockpit canopy remained closed.