What happened
On July 1, 2010, a pilot was conducting a triangular flight pattern near Jablonné v Podještědí, Osečná, and Kozákov. During the second circuit, the pilot encountered unfavorable convective conditions west of the Ještěd ridge. Unable to find rising thermals and lacking sufficient altitude to return to LKHD aerodrome, the pilot decided to perform an emergency landing in a field near the village of Rozstání.
The pilot selected a suitable meadow and began a descending turn. As the aircraft passed over the trees bordering the landing area, the pilot deployed the airbrake flaps. During this maneuver, the pilot realized that the landing gear had not been extended and attempted to deploy it. This distraction caused the glider to bank and drift toward the edge of the field. The left wing struck tree branches, causing the aircraft to enter a left-hand rotation, which subsequently led to impacts with tree trunks and a metal fence post.
The investigation
An investigation by the ÚZPLN established that the pilot was fully qualified and experienced, and the ASW 15 B glider, registration OK-6869, was airworthy. Data from a GNSS flight recorder confirmed a continuous descent for approximately 12 minutes prior to the impact.
Investigators examined the aircraft's configuration at the time of the crash and found the airbrake flaps were extended, the trim was set to "heavy nose," and the landing gear lever had been moved to the "extended" position. The investigation focused on the pilot's actions during the final approach and the sequence of mechanical configurations performed just before the collision with the trees.