What happened
On Saturday, January 23, 1999, at 16:00, a Buse Air 150 ultralight aircraft, identified as 78-LF, was involved in a fatal accident near Ecluzelles, approximately 2.5 NM from the Dreux aerodrome. The pilot, who had 400 total flight hours, had recently completed maintenance modifications on the aircraft and intended to perform a local circuit.
During the takeoff roll, fog and condensation formed on the interior of the cockpit windshield, obscuring the pilot's vision. After passing the end of the runway, the pilot transitioned to a downwind pattern. During this maneuver, the aircraft became obscured by clouds, and the pilot descended to approximately 200 feet. While the pilot managed to identify some ground references to the right, they were insufficient for a safe landing. In an attempt to regain orientation, the pilot climbed back into the cloud layer, hoping to find landmarks from above. However, due to the significant thickness of the cloud layer, the pilot attempted a second descent, during which the aircraft entered a loss of control and struck the ground. The impact resulted in one injury to the pilot and the total destruction of the aircraft.
The investigation
The investigation focused on the meteorological conditions and the pilot's decision-making process. At the time of the accident, visibility at the nearby Chartres aerodrome was reported at only 600 meters due to fog, with an overcast ceiling of 100 feet. The investigation examined the pilot's flight path and the impact of the obscured windshield on situational awareness.