What happened
On July 29, 2017, during the Regional Glider Competitions at the Grudziąlarz-Lisie Kąty (EPGI) aerodrome, a pilot was completing a long-distance task of 109/221 km. After crossing the finish line, the ASW20FL glider was flying at approximately 250 m altitude with an indicated airspeed of 180 km/h.
As the pilot approached the airfield, they noted an excess of altitude and attempted to reduce speed to 120 km/h by deploying flaps, landing gear, and air brakes. However, while on the final approach, the aircraft entered an area of intense thermal-rotor induced downdrafts. In an attempt to mitigate the sink rate and reduce aerodynamic drag, the pilot retracted the air brakes, the landing gear, and set the flaps to the zero position.
While flying over a wooded hill approximately 500 m from the runway threshold, the glider maintained only about 50 m of clearance above the treetops. To avoid a collision with a tall tree identified on the flight path, the pilot used terrain features to gain speed and then pulled up to clear the forest edge. Following this maneuver, the pilot pushed the nose down to maintain airspeed but was unable to reach the runway threshold. The glider subsequently landed in an uncultivated area of the airfield, specifically a clearing of felled trees. The aircraft struck uneven ground with the left wing, causing it to spin 180 degrees and come to a stop approximately 100 m from the runway threshold. The aircraft sustained serious damage, though the pilot escaped without injury.
The investigation
The investigation examined the flight path, the meteorological conditions provided by the Institute of Meteorology and Water Management (IMGW-PIB), and the pilot's actions during the encounter with the downdrafts. The investigation confirmed that the atmospheric conditions at the time presented a moderate to strong turbulence potential due to wind gradients and atmospheric stability.