What happened
On May 9, 2024, a BRM AERO Bristell B23, registration OE-AMK, was performing a cross-country flight from Austria to Italy. While preparing for takeoff from the paved runway 32 at Chambéry - Challes-les-Eaux, a glider winch launch was simultaneously occurring on the adjacent grass runway 32R.
As the pilot of the Bristell B23 applied power for takeoff, a glider began its winch-assisted ascent. During the initial climb, the aircraft deviated to the right, causing the propeller to strike the tensioned winch cable at an altitude of approximately 50 meters. The impact caused the pilot to lose control, leading to a ground collision and a subsequent post-impact fire. The pilot and one passenger were fatally injured, and the aircraft was destroyed.
The investigation
The BEA examined webcam footage, wreckage, and statements from the winch operator, runway supervisor, and glider pilot. The investigation focused on the simultaneous use of the two parallel runways, which is prohibited under local aerodrome regulations.
Technical examination of the wreckage was limited by fire damage, but investigators confirmed that the ailerons, elevator, and flap controls were functional and set for takeoff. A section of the winch cable was found in the debris, having been sliced by the aircraft's propeller. Analysis of the aerodrome's video recordings confirmed that the aircraft crossed the runway threshold while the glider was already airborne, and that the aircraft's deviation to the right occurred shortly after rotation.
Findings
Several factors contributed to the accident, most notably the simultaneous takeoff of a motorized aircraft and a winch-launched glider. Key contributing factors included:
- The potential haste of the pilot to depart after being warned of approaching traffic.
- The difficulty for the winch operator to monitor the paved runway threshold from the winch position.
- The runway supervisor's decision not to abort the winch launch due to the perceived risks of rejecting an active launch.
- Possible language barriers, as the pilot's ability to fully comprehend French radio instructions was uncertain.
- The presence of high-volume winch activity at an aerodrome used by non-based pilots who may be unfamiliar with local coexistence procedures.