What happened
On October 11, 2007, a Piper PA 28-161 Warrior 2, registration F-GGPO, was conducting a cross-country navigation flight departing from Pontarlier, France. The crew consisted of a pilot, an instructor, and one passenger. The intended route included several aerodromes, including Oyonnax, Chambéry, and Annecy.
As the flight progressed, weather conditions deteriorated. After passing Annecy, the visibility decreased significantly. To avoid entering controlled airspace in Geneva, the instructor decided to divert the aircraft into a valley to the east. During this maneuver, the aircraft entered a cloud layer. The instructor took control of the aircraft and attempted to climb to clear the cloud base. While maneuvering, the instructor spotted a patch of light through the clouds and mistakenly believed it was a break in the overcast layer. He reduced the rate of climb to reach this perceived opening, but the aircraft instead struck trees and subsequently collided with the ground at an altitude of 3,700 ft.
The investigation
The BEA investigation focused on the flight preparation and the decision-making process of the crew. Investigators examined the meteorological data used for the flight, noting that while the pilot had consulted METAR and TAF reports via an online service, he had failed to consult significant weather charts (TEMSI) or wind charts. The investigation also looked into the instructor's role, noting that he did not verify the pilot's flight preparation and did not establish a clear flight objective.
Furthermore, the investigators reviewed the flight club's oversight and training environment. It was noted that the instructor's previous military background may have influenced his acceptance of flying without visual references, a practice he had previously employed. The investigation also found that the flight club lacked a formal procedure for reporting and learning from previous incidents, such as a similar encounter with fog during a flight the previous week.
Findings
- The primary cause of the accident was the decision to continue the flight in deteriorating weather conditions.
- Inadequate flight preparation, specifically the failure to properly interpret meteorological charts and assess terrain constraints.
- A failure to execute an appropriate diversion or return to a safe airfield when visibility degraded.
- The instructor's decision to fly into a valley with a constant cloud ceiling, which reduced the margin of safety relative to the terrain.
- The crew's attempt to navigate through clouds without visual references, which was not a safe or reliable practice.