What happened
On March 6, 2013, at approximately 20:20 local time, a Piper PA28-161, registration F-GHPN, departed Persan Beaumont aerodrome for a night VFR flight to Pontoise. About seven minutes after takeoff, the pilot notified the airfield's self-information frequency that the flight to Pontoise had been canceled due to a GPS issue and that they were returning to the airfield to perform touch-and-go landings. During the final approach to runway 10, the aircraft struck a small grove of trees approximately 660 meters from the displaced threshold. The impact occurred at a height of about 5 meters while the aircraft was in a slight descent. The aircraft was destroyed, and the pilot was killed.
The investigation
The BEA examined the wreckage and the site, noting that the engine was producing power at the moment of impact. Several cockpit switches, including the landing light, navigation lights, and GPS, were found in the "OFF" position. The transponder was also turned off. An instructor flying nearby reported seeing the aircraft flying very low during its final approaches but did not intervene to avoid disturbing the pilot.
Medical examinations of the pilot revealed the presence of a lens opacity, which may indicate early-stage cataracts, and cardiac enlargement, which can lead to fatigue. The investigation also considered the "Kraft illusion," a phenomenon where a pilot performing a night approach without sufficient visual references maintains a constant visual angle between runway lights, resulting in a concave, descending flight path that is perceived as straight.
Findings
- The pilot was experiencing fatigue, which likely contributed to the decision to cancel the flight and the lack of situational awareness.
- Visual impairments, specifically a lens opacity that could affect vision in extreme luminance, likely hindered the pilot's ability to maintain the correct glide path.
- The use of the "black hole" illusion (Kraft illusion) led the pilot to descend below the nominal glide path without realizing the proximity to the ground.
- The absence of the landing light and navigation lights made it more difficult for the pilot to perceive the aircraft's altitude relative to the terrain.
- The pilot's seatbelt was not fastened at the time of the accident.