What happened
On July 16, 2015, a Beechcraft 58 Baron, registration F-GKZA, was performing a private VFR flight from Nantes to Toussus-le-Noble. The flight included one passenger. During the landing roll on runway 07L, the pilot experienced a loss of braking effectiveness, causing the aircraft to veer to the left. The aircraft struck several runway edge lights at the threshold of runway 25R, exited the paved surface, and came to a stop in the grass approximately 3 to 33 meters beyond the end of the runway. The aircraft sustained slight damage.
The investigation
The BEA examined several factors contributing to the excursion. The pilot, a professional with 2,243 total flight hours, had only 10 hours of experience specifically on the Beechcraft 58. While the pilot had recently completed a flight training session on this model, the investigation found that the differences training was insufficient, consisting only of a brief ground briefing rather than a formal theoretical and practical course.
Technical inspections of the aircraft revealed no mechanical failures in the braking system. However, investigators found flat spots on each main landing gear tire, indicating that the wheels had locked during the landing roll. Analysis of the runway surface showed skid marks from both the left and right tires. The investigation also considered environmental factors, noting an extremely high ambient temperature of 35°C, which significantly impacts tire adhesion.
Findings
The investigation established that the runway excursion resulted from a combination of a long landing and late braking. Several contributing factors were identified:
- Inadequate training: The pilot lacked sufficient differences training to understand the specific landing and braking techniques required for the Beechcraft 58, such as maintaining aft elevator pressure to keep the main gear loaded.
- Delayed braking application: The pilot waited approximately six seconds after touchdown before applying brakes, intending to clear the runway via a taxiway.
- Wheel lock-up: The application of heavy braking caused the wheels to lock, leading to a loss of directional control.
- Environmental conditions: High surface temperatures on the runway reduced the coefficient of friction between the tires and the pavement.
- Misunderstanding of performance data: The pilot underestimated the required landing distance, likely due to a lack of familiarity with the specific certification testing methods used for the aircraft's flight manual performance figures.