Synopsis
On 2 August 2022, the Aviation Accident Investigation Institute (AAII) was notified of an air accident involving a PZL Bielsko SZD-48-3 glider, registered OK-6200, operated by Aeroklub Kralupy nad Vltavou, z. s. The glider entered a spin during a right turn and fell at a sharp angle onto road No. II/232 between Rokycany and Osek, approximately 585 meters northeast of the ARP LKRY. During the fall, the left half of the wing struck the rear part of a vehicle driving on the same road. Vehicle passengers were not injured, but the glider pilot died. The glider was destroyed.
Factual Information
The pilot was participating in a training camp of Aeroclub Kralupy nad Vltavou at LKPS (Plasy). On the day of the accident, he first conducted a short flight as an instructor with a student in an L-23 glider. Less than 30 minutes later, he decided to fly the SZD-48-3 (OK-6200) on a route from Plasy to Tachov, Příbram, and back to Plasy. He took off from LKPS at 11:02 UTC. Approximately from ARP LKPM, he began losing altitude. About 24 km southeast of Plasy airport, he changed direction toward Rokycany airport (LKRY). Near the village of Volduchy, the pilot made two right-hand turns, likely searching for an updraft. He did not find a usable updraft and continued toward LKRY with an average descent rate of about 1 m/s.
Above the crossing of the D5 highway in the direction from Volduchy to Rokycany, the vertical speed was between 0 and +1 m/s. The pilot then made two more right-hand turns, possibly to locate an updraft. During the second turn, approximately in the direction of the D5 highway toward Prague, the glider entered a right-hand spin at a sharp angle. The right half of the wing struck the asphalt surface of road No. II/232, followed by the front upper part of the glider and cockpit, causing the glider to invert. During the fall, the left half of the wing hit the rear part of a car traveling on the same road toward Rokycany. The car's occupants noticed an impact but the driver initially thought it was a flat tire and continued for 65 meters before stopping. After striking the vehicle, the glider continued forward; the tail and cockpit cover frame detached. The fuselage came to rest upside down about 12 meters beyond the car, with the nose pointing south toward Rokycany.
The pilot held a valid SPL flight crew license and a class 1 medical certificate. He had experience on airliners, MEP, SEP, ULA, and gliders. Between 1998 and 2022, he logged 428 hours 29 minutes on gliders, including 91 hours 10 minutes as an instructor. On the SZD-48-3 type, he had flown 33 hours 52 minutes between 2004 and 2022, excluding the accident flight. In the critical phase, the pilot made two turns at low altitude, approximately 100–500 meters from the threshold of runway 27 at LKRY. During the second turn, he likely realized the updraft was insufficient for a return to LKPS and decided to land at LKRY, potentially reducing the turn radius. According to the Flight Manual, paragraph 4.5.3, reducing the circling radius may cause loss of wing lift and a stall-spin.
The glider had undergone annual maintenance on 25 June 2022 with no findings, and an airworthiness inspection on 16 July 2022. No defects were noted on preceding flights. Weather conditions were suitable for the planned flight and had no impact on the accident origin or course. During the first flyover above the D5 highway, the updraft was narrow with a climb rate of 0.5–1 m/s lasting 15 seconds. During the second flyover, the climb rate in the first turn was only 0.1–0.2 m/s for 5 seconds. Pilots familiar with the LKRY area reported that thermal currents there are very narrow and highly turbulent.
Analysis
The investigation found that the pilot had a valid license and medical certificate. He had experience on various aircraft types. However, his recent flight time on the SZD-48-3 was limited: from 2008 to 2022, he flew only 32 minutes on type (excluding the accident flight). During the flight, he did not reduce speed below the stall speed as per the Flight Manual. In the second turn at low altitude, he executed a turn with a large bank angle and decreasing radius, which, per Flight Manual paragraph 4.5.3, could lead to a wing stall and subsequent fall. The glider entered a right spin at a sharp angle. The right wing struck the road, then the cockpit area, causing the glider to invert and subsequently hit the car. Composite forensic medical analysis determined that no health condition contributed to the accident. The technical condition of the glider had no impact.
Aircraft Accident Cause
The cause of the air accident was the sequence of the following events: insufficient hours flown on type; decision to make turns (continuation of flight) at a low altitude instead of landing at LKRY; failure to master the piloting technique when maneuvering at a low altitude with a subsequent spin-stall.