What happened
On the evening of November 13, 2013, a Cessna 150, registration F-HPTC, was preparing for a local night flight at the Le Mans-Arnage aerodrome. After starting the engine, the pilot began performing a checklist using a lamp for illumination. During this process, the aircraft began to move and collided with another aircraft parked approximately 15 meters away. The impact caused significant damage to the engine and propeller of the F-HPTC, as well as severe damage to the elevator of the stationary aircraft.
The investigation
The investigation examined the pilot's experience, the aircraft's braking system, and the procedures used during the pre-flight phase. The pilot, an experienced flyer with over 1,300 total hours, noted that he had intentionally decided to read the checklist thoroughly while the engine warmed up, rather than relying on memory as he usually did.
Crucially, the investigation looked into the pilot's braking technique. The pilot stated that he had not used the parking brake due to a long-standing habit formed during his initial training at the same club over 25 years prior. He had been instructed by a former instructor to avoid the parking brake on these specific models due to potential reliability issues with the mechanism and to use chocks instead. The investigation also reviewed the club's specific maintenance knowledge regarding the master cylinders in the F150 and F152 models, which could cause the parking brake to seize.
Findings
Several factors contributed to the movement of the aircraft:
- The pilot did not apply the parking brake, relying instead on foot pressure on the brake pedals.
- The pilot's attention was diverted by the task of reading the checklist, which led to a reduction in the physical pressure applied to the brake pedals.
- A lack of external visual references and the low-acceleration movement of the aircraft may have created a somatogravic illusion, preventing the pilot from perceiving the motion.
- The pilot's reliance on long-standing habits and experience led to an overconfidence that prevented him from doubting the stability of the aircraft.
Safety action
- The investigation noted that personalized adaptations of flight manual procedures can fail to identify associated risks.
- There is a need to clarify the use of the term "checklist" to ensure it is used as a verification tool for vital actions rather than a procedural guide.
- Improved communication within the flying club regarding the standardized use of the parking brake on F150 and F152 aircraft is necessary.