What happened
On June 17, 2005, a Synairgie Cosmos 14-9 ultralight aircraft, identified as 17-BP, was performing a local flight from a private, non-certified airstrip near Ciré-d'Aunis. During the takeoff roll, which was oriented toward the east, the aircraft experienced an initial loss of engine power immediately after rotation. The aircraft briefly maintained level flight at approximately ten meters of altitude before the engine power returned to normal. As the pilot attempted to continue the climb, a second loss of power occurred.
Determining that the remaining runway length was insufficient for a landing, the pilot maintained level flight and initiated a right-hand turn to avoid trees standing twenty meters high at the end of the takeoff path. During this maneuver, the left wing struck a tree, causing the aircraft to roll and crash into a field beyond a nearby hedge. The accident resulted in one fatality (the passenger) and one serious injury (the pilot), and the aircraft was destroyed.
The investigation
The investigation focused on the engine performance, the takeoff configuration, and the status of the takeoff site. Technical examination of the Rotax 503 engine revealed no mechanical defects or evidence of malfunction that could have caused the power fluctuations; the engine was well-maintained and had seen little use.
Investigators also examined the takeoff site, which was a private 300-meter platform. While regulations allow for occasional use of private strips without prior declaration, the site had previously been denied official authorization for regular use due to obstacles at both ends of the runway and the presence of a protected heron nesting area. This environmental restriction forced the pilot to take off facing east, regardless of wind direction. On the day of the accident, this necessitated a takeoff with a tailwind.
Findings
- The primary cause of the accident was the decision to take off with a tailwind, which reduced the aircraft's climb performance.
- The takeoff mass was high, further degrading the aircraft's ability to clear obstacles.
- The takeoff site contained significant obstacles in the departure path that had previously prevented the site from receiving official certification.
- The passenger's physical position and size in the rear seat were noted as potentially interfering with the pilot's ability to manipulate the control bar.