Introduction
On 14 August 2011, at approximately 11:35 UTC, a DG-400 glider registered as OK-2154 crashed in a field about 250 meters north-northwest of the village of Bystřice in the Benešov District, Czech Republic. The pilot, a 44-year-old male, sustained no injuries and landed by parachute about 500 meters from the crash site. The glider was destroyed upon impact.
Flight History
The pilot intended to conduct a thermal soaring flight in the vicinity of Benešov Airport (LKBE). He was towed aloft by a towplane, departing from Runway 27. After a 6-minute aerotow, the glider released at an altitude of 600–650 meters above ground level (AGL) in a thermal with an updraft of 3–5 m/s. After release, the pilot spent about 20 minutes circling in weak thermals with flaps set to +6°. While transitioning to straight flight, the pilot felt the glider pitch forward and enter a steep descent. He was unable to arrest the descent despite repeatedly pulling back on the control stick. The angle of descent increased continuously. At approximately 400 meters AGL and an indicated airspeed of 150–160 km/h, the pilot jettisoned the canopy and bailed out. The glider impacted the ground at a shallow angle of 10–15°, coming to rest inverted on an uncut wheat field. The pilot descended by parachute and landed safely on the same field.
Technical Findings
Post-accident technical inspection revealed that the glider's damage was consistent with impact forces. All flight control systems, including linkages and attachments, were found to be functional and in good condition before the accident. The glider had a valid certificate of airworthiness and was deemed airworthy at the time of the event. The on-board flight data recorder (LX 7007 PRO IGC) was damaged beyond data retrieval.
Meteorological Information
Surface wind was from 150° at 7 knots, visibility exceeded 10 km, and the towplane pilot reported strong thermal activity.
Probable Cause
The accident investigation commission determined the probable cause to be the pilot's limited experience on the DG-400 type and his use of a stall recovery technique that differed from the procedure specified in the flight manual. The stall likely occurred at low speed, and the pilot's repeated back-stick inputs exacerbated the situation instead of applying forward stick as recommended.