What happened
On 19 April 2010, a Centrair 101 Pégase glider, registration F-CHLU, was conducting a local private flight at the Pont-sur-Yronne aerodrome. After a towed takeoff, the pilot spent approximately two hours soaring at altitudes ranging between 1,200 and 2,300 m. Around 15:00, the pilot began a descent, eventually reaching 800 m while approximately 5 nautical miles from the aerodrome.
During the final approach, the glider's flight path transitioned into a steady downward trajectory. Data from the aircraft's FLARM computer indicated that one minute before impact, the vertical speed increased abruptly from -500 ft/min to -4,000 ft/min. The aircraft entered a smooth turn with a radius of approximately 1,000 m before colliding with the ground. The impact resulted in one fatality and the destruction of the glider.
The investigation
Investigators examined the wreckage and the accident site, noting that the glider struck the ground with high horizontal speed, a significant nose-down attitude, and a slight right bank. The aircraft came to rest 30 meters from the initial impact point. Analysis of the FLARM data allowed for a reconstruction of the final flight path, confirming the rapid increase in descent rate.
Medical examinations and an autopsy were also conducted. The investigation focused on the pilot's physiological state, specifically looking for evidence of cardiovascular issues that could have led to incapacitation. The autopsy revealed cardiomegaly and coronary atherosclerosis, with arterial narrowing reaching 66% in certain areas.
Findings
Technical examination of the wreckage revealed no mechanical failures contributing to the accident. However, the flight data suggested the pilot was likely no longer in control of the aircraft during the final minute of flight.
The investigation concluded that the pilot's underlying cardiovascular condition may have led to a dizzy spell or loss of consciousness. The investigation highlighted that flying at altitudes exceeding 1,500 m for several hours can cause physiological adaptations to hypoxia. In a pilot with rigidified coronary arteries due to sclerosis, these adaptations may fail, potentially triggering an acute coronary event.