What happened
On June 25, 2019, a VSO 10 glider, registration OK-8501, was performing a cross-country flight near the Orlické Mountains as part of a junior pilot support project. After being unable to locate sufficient thermal updrafts to continue the flight, the pilot decided to perform an off-field landing in a meadow approximately 2 km northwest of Orlické Záhoří.
During the landing approach, the pilot maintained a higher airspeed to mitigate the potential effects of mountain rotor turbulence. Upon touchdown on the grassy meadow, the pilot observed fence posts protruding from the tall grass. In an attempt to avoid a collision, the pilot applied the brakes and attempted to clear the obstacles. However, the aircraft's landing gear caught an inconspicuous steel wire from the fence, and the right wing trailing edge struck a fence post. This impact, combined with the snagged wire, induced a 180-degree rotation of the aircraft, resulting in structural damage to the fuselage.
The investigation
The ÚZPLN investigation established that the pilot was fully qualified and medically fit for flight. The aircraft was in a condition of airworthiness, with all inspections up to date. The investigation focused on the sequence of events following the touchdown and the visibility of the obstacles within the tall vegetation. The investigation also reviewed the flight path recorded by the aircraft's Oudie device, which confirmed the pilot's attempt to find suitable landing terrain after losing thermal lift.
Findings
- The pilot was unable to maintain flight by finding thermal lift, necessitating an unplanned landing in a field.
- The fence, consisting of steel wire on low wooden posts, was not clearly visible due to the height of the grass at the time of landing.
- The primary cause of the accident was the aircraft striking an inconspicuous obstacle immediately after touchdown.
- The impact with the wire and the post created a rotational moment that caused the deformation of the rear fuselage and damage to the cockpit frame and canopy.