What happened
On 14 July 2015, an Aquila AT01, registration PH-DHB, was performing a cross-country flight from the Moutiers private aerodrome in France. The aircraft, operated by Aero Club Maritime, was carrying a pilot and one passenger.
Prior to the accident, the pilot had conducted a solo takeoff from the same aerodrome to familiarize himself with the runway conditions. The runway, a grass strip, featured a 3% downward slope from south to north. Following the initial solo flight, the pilot returned to the south end of the runway to prepare for the flight with the passenger.
During the takeoff roll on runway 35, the aircraft accelerated but began to deviate slightly to the right. After approximately 300 meters of ground roll, the pilot noted that the indicated airspeed was only 35 knots, well below the required 50-knot rotation speed. Realizing the aircraft was not accelerating as expected and facing a fence located only 30 meters beyond the runway end, the pilot opted to continue the takeoff rather than attempt to abort. During the rotation, the main landing gear made contact with the top of the fence. The pilot maintained control and performed a forced landing in a nearby field. During the subsequent landing roll, the nose gear struck a hole in the ground and collapsed. There were no injuries to the occupants, though the aircraft sustained damage to the propeller, the right wing leading edge, and the nose gear.
The investigation
The BEA examined several factors regarding the aircraft's performance and the aerodrome environment. The investigation noted that the aircraft's weight was near its maximum takeoff weight of 750 kg. While the pilot had calculated performance based on the flight manual, the calculations did not account for the downward slope of the runway.
Investigators also looked into the runway conditions, noting that the grass had been mowed two days prior, and clippings remained on the field. The investigation also reviewed the pilot's familiarity with the aerodrome, noting that the pilot had used a person on the runway shoulder to estimate the takeoff lift-off point during his earlier solo flight, but lacked fixed references to judge distance during the actual accident flight.