What happened
On the morning of June 2, 2013, a Robinson R22 helicopter, registration F-GMLZ, was positioned near a fueling station at the Brest Bretagne Aerodrome. After refueling, the pilot started the engine. Due to high humidity in the cockpit, fog formed on the windscreen. The pilot attempted to clear the fog by activating the fresh air intake, but did not pull the control to its maximum position.
While attempting to wipe the windscreen with his right hand, the pilot released the cyclic control. During this period, the helicopter began an unintended takeoff, lifting off the ground and translating backward. The aircraft climbed to a height of approximately 1 to 2 meters before tilting sharply to the left. The helicopter then struck the roof of the fueling station, resulting in the destruction of the aircraft and damage to the station.
The investigation
Investigators examined the wreckage and reviewed airport surveillance footage. The analysis of the aircraft revealed no mechanical malfunctions that contributed to the accident. The investigation established that the fresh air intake control was only halfway pulled, the door ventilation windows were closed, and the heating system was turned off.
Surveillance footage confirmed that the helicopter's right skid left the ground first, followed by a lateral movement and a backward translation. The pilot, who had approximately 258 total flight hours, stated that he had placed the collective pitch in the high position out of habit when preparing for takeoff. He also noted that the low angle of the sun and the fog prevented him from realizing the aircraft had actually left the ground.
Findings
- High humidity in the cockpit, likely caused by the crew's activities prior to flight, led to significant fogging on the windscreen.
- The pilot's failure to fully engage the fresh air intake slowed the defogging process.
- The pilot's habit of positioning the collective pitch lever in the high position during takeoff preparations caused the unintended takeoff.
- The pilot's lack of active control input while wiping the windscreen allowed the aircraft to drift and eventually lose stability, leading to the collision.