What happened
On August 22, 2014, a single-seat Schempp-Hirth Cirrus 11/75 glider, registration F-CEMM, departed Romorantin aerodrome via winch launch for a cross-country flight. The pilot's planned route included Loches and Briare. Throughout the afternoon, the pilot utilized various thermals to maintain altitude, reaching a peak of 1,815 meters.
By 18:15, the pilot notified Romorantin tower that the aircraft was approximately 30 km southeast of the airfield and expressed difficulty in returning. Despite the deteriorating weather, the pilot continued toward the aerodrome. Approximately one kilometer from the runway threshold, the glider struck the treetops and crashed in a forested area, resulting in heavy damage to the aircraft.
The investigation
The BEA examined the flight path using GNSS data from the glider's onboard computer, which recorded altitude, airspeed, and wind parameters. The investigation also reviewed meteorological reports from Romorantin and interviewed the pilot, a highly experienced aviator with over 5,160 flight hours.
Analysis of the GNSS data revealed that at 18:05, the glider was at approximately 1,600 meters and began a steady descent at a rate of 0.8 m/s. The average indicated airspeed was 95 km/h, which is very close to the aircraft's maximum glide ratio speed of 90 km/h. While the official METAR reported a light wind, the onboard computer showed the pilot actually encountered a headwind component varying between 15 and 20 km/h.
Findings
- The pilot initially considered an out-of-field landing due to degrading weather but decided to attempt a return to the aerodrome after finding a thermal.
- The pilot underestimated the strength of the headwind, which significantly reduced the glider's gliding range.
- The decision to fly over a dense forest meant there were no viable alternative landing sites available once the glide was compromised.
- The aircraft's performance margin to reach the runway was extremely low due to the uncalculated impact of the wind.