What happened
On August 10, 2008, at approximately 06:52 UTC, a Fascination D4BK ultralight aircraft, registration OK-LUF 16, crashed into a field near the village of Prostřední Svince, Czech Republic. The flight, which was intended to be a sightseeing flight, originated from the LKCS airfield.
Witnesses observed the aircraft performing a series of high-performance maneuvers at a very low altitude. The aircraft was seen performing steep turns with bank angles exceeding 60 degrees, followed by a vertical climb. During the maneuver, the aircraft transitioned from an inverted position into a steep dive. The aircraft struck the ground at a slight angle, causing the airframe to disintegrate and resulting in a post-impact fire. Both the pilot and the passenger sustained fatal injuries.
The investigation
The ÚZPLN investigation reconstructed the flight sequence using eyewitness accounts, as the aircraft was not equipped with any flight data recorders. Investigators established that the pilot, an experienced ultralight instructor, had performed the maneuvers at high engine power.
Technical analysis of the wreckage and weight calculations revealed that the aircraft was significantly overweight. The investigation also noted that the pilot's intended flight plan—a training flight—did not match the actual flight profile observed by witnesses. While the pilot was highly skilled and familiar with the Fascination D4BK, the aircraft's design is not certified for aerobatic flight.
Findings
- The primary cause of the accident was the pilot's decision to perform unauthorized aerobatic maneuvers in an aircraft not certified for such flight.
- The maneuvers were performed at an altitude insufficient to safely recover from the steep dive.
- The aircraft was overweight, exceeding its maximum takeoff mass (MTOW) by at least 44.5 kg due to the combined weight of the occupants and fuel.
- The aircraft's structural limitations for ultralight category (ULLa) aircraft were exceeded by the high-G maneuvers performed.
- The pilot did not utilize the onboard emergency parachute system during the descent.