What happened
On April 15, 2013, a Piper PA28, registration F-GHRJ, was conducting a flight instruction session at the Paray-Le-Monial aerodrome. The crew, consisting of an instructor, a student, and one passenger, had arrived from Vichy to practice short-field takeoff and landing techniques. After landing on the grass runway 13, the crew lined up on runway 31 for a takeoff attempt.
During the takeoff roll, as the aircraft approached rotation speed, the crew experienced a slight loss of acceleration. The instructor took control of the aircraft and continued the takeoff roll, as he determined there was insufficient remaining runway to safely abort the maneuver before encountering obstacles located along the runway axis, including a ditch, a road, and a pile of wood. To avoid a head-on collision with the wood pile, the instructor steered the aircraft to the right. During this maneuver, the left wing struck the end of the wood pile, which was approximately 2 meters high and 20 meters long. The impact tore the wing from the fuselage, causing the aircraft to spin 180 degrees and come to a halt approximately 30 meters from the point of impact. The student sustained minor injuries, and the aircraft was destroyed.
The investigation
Technical examinations of the wreckage revealed no engine malfunctions or mechanical failures that contributed to the accident. The aircraft's weight and center of gravity were within manufacturer limits.
The investigation focused on the runway conditions and performance calculations. The instructor had applied a 15% correction factor to his takeoff performance estimates, based on his professional experience, to account for the grass surface. However, the investigation found that a section of the runway was muddy and "sticky," which caused the observed loss of acceleration. While the runway 31 was 600 meters long, the presence of the wood pile—an obstacle not located within the regulatory takeoff clearance area—posed a significant hazard.
Findings
- The primary cause of the accident was the reduction in takeoff performance caused by the aircraft rolling over a muddy section of the grass runway.
- The instructor's decision to continue the takeoff was driven by the lack of remaining runway to perform a rejected takeoff without hitting obstacles.
- The lack of quantified performance data in the Piper PA28 flight manual regarding takeoff on grass surfaces contributed to the incident, as pilots must rely on subjective evaluations or estimated correction factors.
- The instructor's evasive maneuver successfully prevented a direct frontal collision with the wood pile.