What happened
On September 28, 2008, a single-seat Ultralair Espace 462 ultralight, registration 01-WQ, was performing post-maintenance testing in Lompnas, France. The pilot had recently restored the aircraft and intended to perform a simple takeoff and landing sequence in a local field. After completing ground engine tests and taxiing without the wing assembly, the pilot decided to reattach the wing and proceed with the flight.
During the climb, once the aircraft reached an altitude of approximately 50 to 100 meters, the pilot attempted to level the aircraft by pulling the control bar backward. At this moment, the pilot felt themselves sliding forward in the seat and realized the seatbelt had become unfastened. This movement caused an involuntary input on the control bar, resulting in a steep nose-down attitude while the engine remained at full power.
As the aircraft descended at approximately seven meters per second, the pilot struggled to reach the throttle located on the side of the seat. Although the pilot eventually managed to reduce the engine to idle, the aircraft entered an uncontrolled right turn. The aircraft subsequently struck trees at a high angle of descent, causing the pilot to be ejected from the cockpit. The impact resulted in one serious injury and the destruction of the aircraft.
The investigation
The investigation focused on the mechanical state of the restraint system and the sequence of the pilot's movements. Investigators examined the seatbelt buckle and found no apparent defects in the hardware. The pilot noted that while they had checked the belt before takeoff, the buckle did not provide a clear, audible click when fastened. The investigation also reviewed the pilot's experience, noting they had approximately 40 flight hours, but had not flown in ten years and had no prior experience with this specific model.