What happened
On October 31, 2013, a B&F Technik FK9 ultralight, registration 31-SQ, was performing a solo instructional flight at the Muret Lherm aerodrome. Following a dual instruction flight, the instructor permitted the student pilot to conduct two circuits alone. The instructor had previously reviewed the student's approach and landing speeds, deeming them appropriate for the mission.
During the landing roll on runway 12, the student pilot applied significant braking force. This action caused the aircraft to veer to the left, crossing the lateral boundaries of the unpaved grass runway. The aircraft subsequently struck a ditch, resulting in the destruction of the aircraft, specifically damaging the propeller, the nose gear, and the right wing.
The investigation
The investigation focused on the environmental conditions and the pilot's control inputs during the landing roll. Investigators noted that the grass runway was covered in morning dew, which reduced surface friction. The student pilot indicated that the engine power may not have been fully reduced prior to braking. The instructor, who was monitoring the flight via portable radio, stated that the excursion occurred too rapidly for any intervention to be possible.
At the time of the accident, weather conditions were CAVOK with a light wind from 220 degrees at 3 knots, a temperature of 10°C, and a dew point of 6°C. The student pilot had accumulated 14 hours of flight experience in dual instruction.
Findings
- The loss of directional control was caused by an inappropriate coordination of braking and power inputs.
- The student pilot's lack of experience prevented them from effectively correcting the resulting veer.
- The presence of morning dew on the grass surface contributed to the aircraft sliding during the braking maneuver.