What happened
On 26 August 2017, an AS350 helicopter, registration F-HLBT, was conducting a commercial sightseeing flight near Guérande, France. The flight, operated by Héliberté, carried a pilot and five passengers. While cruising at approximately 1,500 feet, the pilot experienced a sudden onset of vertigo after moving his head to observe the ground. This led to a loss of control, causing the aircraft to collide flat with the ground at a high vertical speed.
Following the impact, the pilot and four passengers evacuated the aircraft. One passenger, seated in the front left, lost consciousness during the collision. The impact resulted in six persons injured, four of whom sustained serious injuries, and the destruction of the helicopter.
The investigation
The BEA examined the flight data, the aircraft's condition, and the medical history of the pilot. The investigation focused on the cause of the pilot's sudden disorientation and the circumstances surrounding the flight's safety procedures. Investigators also reviewed the medical certification process and the pilot's previous health episodes, including a reported 'vagal disorder' and a separate instance of instability.
Findings
- The primary cause of the accident was the pilot experiencing Benign Paroxysmal Positional Vertigo (BPPV), which induced incapacitating spatial disorientation.
- The pilot's medical records did not include previous instances of dizziness or instability, which may have prevented him from seeking treatment that could have mitigated the condition.
- The medical certificate application process was found to be too restrictive, using a closed-ended questionnaire that does not actively encourage pilots to disclose non-specific health events.
- The injuries to the front left passenger were likely aggravated because the shoulder straps for that seat were not fastened during the flight.
- The ground agent's practice of omitting instructions regarding door operation and seat belts contributed to the unsafe state of the cabin.