Glider accident at Benešov airfield (OK-1524)

Incident Overview and Aircraft Details On 3 July 2018, the Czech Institute for Expert Investigation of Causes of Aircraft Accidents (ÚZPLN) investigated an accident involving a VSO 10C GRADIENT glider, registration OK-1524, at Benešov airfield (LKBE). The aircraft, manufactured by Orličan, n. p. in 1981, was a single-seat, high-wing glider with a 15 m wingspan. At the time of the accident, the glider had a total time of 2,557 hours and 44 minutes and was considered airworthy following an inspection on 26 August 2017. The pilot, a 39-year-old holder of a valid glider pilot qualification and a second-class medical certificate, had 93 hours and 56 minutes of glider experience, including 12 hours and 26 minutes on the VSO 10 GRADIENT. ## Flight Sequence and Accident Description The pilot participated in a flying event organized by the Glider Aerobatic Club at Benešov airfield. After reviewing local meteorological and airspace conditions, the pilot took off in an aerotow at 13:32 UTC for a local thermal flight. After more than two hours of thermal soaring, the pilot began the return to the airfield, planning to land on runway 27. During the final approach, the glider entered increased sink and lost the altitude required for a safe approach to runway 27. While attempting to land, the left wing struck a tall crop of rapeseed in a field adjacent to the eastern edge of the airfield, pulling the aircraft to the ground. The impact caused the glider to rotate around its vertical axis, strike the ground with its nose, and perform a somersault over the right wingtip at approximately a 45-degree bank. The aircraft then landed on its main wheel and came to rest on the runway approximately 40 meters west of the runway 27 threshold after a 270-degree turn. The pilot was not injured, and a preliminary breath test by the Czech Police was negative. ## Meteorological and Airfield Conditions At the time of the accident, weather conditions at Benešov were generally clear with visibility exceeding 10 km. The temperature was around 25 °C, and winds from the ground to 5,000 ft MSL were predominantly from the northwest at 4 to 7 kt. The airfield was a public domestic/non-public international airport, and runway 27 was suitable for glider operations. The elevation at the runway 27 threshold was 1,329 ft (403 m). The accident site was located approximately 30 meters east of the runway 27 threshold, near a non-public access road. ## Damage and Investigation Findings The glider sustained severe structural damage, including visible structural integrity violations at both wingtips over a length of approximately 45 cm, complete destruction of the nose up to the rudder pedals, and a broken front organic glass canopy. The forces during the rotation around the vertical axis bent the tail section, broke the tail wheel and its cover, and damaged the lower edge of the rudder. The investigation was conducted in accordance with EU Regulation 996/2010, Czech Act No. 49/1997, and Annex 13 to the Convention on International Civil Aviation, with the sole purpose of preventing future accidents and incidents without determining fault or liability.