What happened
On September 27, 2015, during the French ULM Championship at Chauvigny, a Skyranger ultralight, identified as 13-IR, was performing a final circuit following a precision landing on an unpaved runway. After departing runway 05, the aircraft climbed at a shallow angle and low speed. Witnesses observed the aircraft executing a right turn into a crosswind, stabilizing at approximately 300 feet, and then initiating a second right turn with a high nose attitude to join the downwind leg. Instead of leveling out, the aircraft intensified the right turn and entered a descending spiral that continued until it struck the ground. The engine was still functioning at the moment of impact.
The investigation
The investigation examined the aircraft wreckage, flight data, and witness testimonies. Examination of the wreckage revealed no mechanical malfunctions, and the fuel tanks contained approximately 4 to 5 liters of remaining fuel. Analysis of GNSS data confirmed the flight path was consistent with the competition requirements. While previous landings during the event showed controlled flight at low approach speeds, the final landing occurred under slightly stronger and more turbulent wind conditions.
Investigators also looked into potential physiological factors. Witnesses reported that the pilot and passenger had complained of headaches and nausea during the two evenings preceding the accident. It was noted that a carbon monoxide detector, which was installed in the aircraft, had turned black during those previous nights, though the detector was not recovered from the crash site. Blood analysis performed on the passenger was negative for carbon monoxide.
Findings
- The aircraft likely experienced an asymmetric stall while exiting the right turn at a low altitude and low airspeed.
- A loss of consciousness or physical impairment of the pilot due to carbon monoxide poisoning, following a long-duration flight, could not be ruled out.