What happened
On August 11, 2006, at approximately 15:10 UTC, two gliders engaged in ridge soaring near Curienne, France, collided head-on. The first aircraft, a Rolladen Schneider LS8A with registration F-CGZO, had been conducting a circuit flight since earlier that morning. The second aircraft, a Centrair C101 with registration F-CHLP, had departed via winch launch for a solo ridge soaring flight.
Both aircraft were flying along the western flank of Mont Saint Michel. The F-CGZO was traveling on a southbound route, while the F-CHLP was following a northbound path. The collision occurred at an altitude of approximately 800 to 900 meters. Following the impact, the F-CHLP crashed into a forested area near a road, while the F-CGZO entered a steep dive and struck the ground roughly 100 meters from the first wreckage. The collision resulted in one fatality and one serious injury.
The investigation
The investigation focused on the flight paths, environmental conditions, and the visibility of the aircraft. Investigators utilized GPS data from the F-CGZO to reconstruct the trajectories, which confirmed that the two gliders were on converging paths. The investigation also examined the visibility conditions, noting that both aircraft were primarily white, which, combined with the presence of cumulus clouds, created a low-contrast environment.
Investigators also reviewed the aircraft equipment, noting that neither glider was equipped with a proximity warning system (FLARM). The study of the wreckage revealed that the pilot of the F-CGZO had attempted an in-flight bailout; the harness was found open and the parachute deployment handle was near the pilot, though the canopy had not been jettisoned before impact.
Findings
- The pilots were properly licensed for the intended flights, and both aircraft held valid certificates of airworthiness.
- The meteorological conditions were suitable for flight, though the presence of 7/8th cumulus clouds and the white color of the aircraft made detection difficult.
- The lack of visual detection of the opposing aircraft was the primary factor in the collision.
- The converging trajectories and the low-altitude nature of the ridge soaring flight provided very little time for evasive maneuvers.
- The thin profile of the glider wings and fuselages, combined with a lack of high-visibility markings on the F-CLHP, contributed to the difficulty in perceiving the approaching aircraft.