Sequence of Events
On December 11, 2008, at 19:34 UTC, a Cessna 510, registration OE-FMZ, was taxiing at Prague Ruzyně Airport (LKPR). The aircraft had been parked at stand S2 on the southern apron (OPJ). The pilot received taxi instructions to proceed via taxiway R to the holding point for runway 31. After leaving stand S2, the pilot turned right and began moving toward the exit to taxiway R, approximately 190 meters away. After turning about 150° to the right and traveling roughly 130 meters, the pilot suddenly turned left, driving onto an unpaved area adjacent to the apron. The aircraft traveled 40–45 meters over the unpaved surface and then re-entered a paved area. While crossing the transition from unpaved to paved surface, the left main landing gear wheel broke off. The pilot reported on the LKPR Ground frequency that he had "hit something" and requested assistance. Airport technical personnel arrived and confirmed the aircraft had left the paved area and sustained damage. The two passengers deplaned using the aircraft steps and left the airport; the pilot remained until technical assistance arrived.
Aircraft Information
The aircraft was a Cessna 510, manufactured in 2008, serial number 0116. At the time of the event, it had accumulated 46 hours and 47 minutes of flight time and 27 landings. It held a valid Certificate of Airworthiness. No previous issues with ground handling or braking were reported. The aircraft's weight was within limits, with 1200 liters of fuel on board.
Personnel Information
The pilot was a 48-year-old male holding a valid Commercial Pilot License with ratings for C510, SEP, MEP, and TMG (including instrument and flight instructor ratings). His total flight experience was 1600 hours, with 150 hours on the Cessna 510 type. He had 48 hours of rest before the flight and held a valid medical certificate.
Weather and Lighting Conditions
The ATIS broadcast at 19:00 UTC reported wind from 320° at 2 knots, visibility 700 meters, light rain, fog, and a temperature of 1°C with a dew point of 0°C. The runway was wet. The pilot estimated visibility at 800–1000 meters. The event occurred at night, and the apron was illuminated by overhead halogen lights. The taxiway was marked with blue edge lights. A rain shower had just passed, leaving standing water on surfaces. The wet asphalt produced glare from the lighting, reducing contrast of yellow taxiway markings.
Investigation Findings
The investigation revealed that after losing visual reference with the yellow taxi line markings, the pilot relied on the aircraft's GPS for navigation. The pilot likely turned left about 40 meters earlier than intended, entering the unpaved area instead of taxiway R. The left main landing gear wheel broke off when the aircraft crossed the 0.17-meter-high concrete edge between the unpaved grass and paved asphalt. A fracture analysis performed by the manufacturer found no fatigue in the wheel axle; the fracture was consistent with bending and shear forces exceeding the axle's critical cross-section.
Probable Cause
The probable cause of the accident was a loss of orientation by the pilot, likely due to distracting reflections from lighting on the wet asphalt surface. After losing orientation, the pilot relied on the GPS indications, and a possible data error in the GPS system led the pilot to decide to turn onto taxiway R earlier than intended.