Longitudinal runway excursion during takeoff roll of a Robin DR400-120 at Chauvigny (F-GOKQ)

Accident overview and flight details On 22 November 2014 at approximately 17:00 local time, a Robin DR400-120 registered F-GOKQ, operated by a club, was on a local general-aviation flight from the aerodrome of Chauvigny (86). The aircraft carried a pilot and two passengers. The aircraft was destroyed. ## Runway and operational context The preferred runway was 05, an unpaved runway measuring 740 m by 80 m, with a takeoff distance available (TODA) of 740 m. The pilot, with two passengers, lined up for takeoff on runway 05 for a local flight. He applied maximum power while holding the brakes, then released them. As the aircraft approached the runway end, it was still rolling and had not reached rotation speed. Believing he could benefit from the slight slope of the safety area, the pilot continued past the runway end in the safety area and extended the second flap setting. The aircraft crossed the perimeter fence while rolling, crossed the embankment of the road at the aerodrome boundary, and performed a somersault before coming to rest. ## Site and wreckage examination Examination of the landing-gear marks on the runway showed that the pilot had lined up at the offset threshold chevrons for runway 05 rather than at the beginning of the runway, leaving approximately 670 m of available takeoff roll. The runway was wet and greasy. Deep ruts were present over a large part of the runway. Examination of the wreckage did not reveal any malfunction that could explain the accident. Forward deformation of the tips of both propeller blades indicated that the engine was delivering significant power for takeoff. ## Pilot experience The pilot held a British CPL/A licence from 1990, expired since 2000, a British PPL/A licence from 2001, and a British pilot-instructor qualification from 2010. Residing in France, he converted his PPL/A licence in 2011 and his instructor qualification in 2013 in accordance with the 2008 decree. He had approximately 1,950 flight hours, including about 450 hours on type and about 530 hours as an aircraft instructor. ## Meteorological conditions Estimated meteorological conditions at the site were: wind from 150° at 4 kt to 8 kt; temperature 16 °C; QNH 1,014 hPa. ## Performance and aircraft limitations During the takeoff phase, the aircraft mass was 860 kg, below the maximum takeoff mass of 900 kg. The centre of gravity was aft but within the manufacturer’s recommended limits. The takeoff roll distance was 270 m and the takeoff distance (over 15 m) was 580 m. The flight manual specified that the first flap setting was used for takeoff and the second for landing. The flight manual’s takeoff performance chapter stated that for a dry grass runway, 15% should be added to all distances in the performance table; no specific provision was given for a greasy runway. ## Club instructions and prior flight The aeroclub’s special instructions recommended that pilots limit flights in the DR400-120 to two persons on board during the winter period because of the runway condition, which could limit takeoff performance. In 2015, the special instructions attached to the landing card were modified, including a note that the first 100 m of runway 23 were unusable after heavy rain. The pilot had reserved the aircraft online in the afternoon. At the club, he noted in the logbook that the previous flight had been cancelled, without a stated cause. He completed his mass and balance calculation and decided not to apply the club instruction limiting the number of persons on board to two during the winter period, as the field did not appear particularly greasy to him. ## Pilot account and prior pilot account The pilot lined up at the offset threshold 05 and performed a power check on brakes. The engine parameters at takeoff seemed normal to him. At mid-runway, the engine tachometer indicated 2,400 rpm but the indicated airspeed was only 60 km/h, insufficient for takeoff. He decided to continue, hoping to reach takeoff speed before the runway end. After threshold 23, the aircraft was still rolling and had not reached rotation speed. In the safety area, on a slight slope, the speed was 100 km/h but the aircraft still did not take off. The pilot then extended an additional flap setting, thinking it would help. The aircraft remained on the ground and came to rest beyond the road. A club pilot with a passenger had performed an acceleration-stop in the early afternoon during a takeoff attempt on QFU 23. He had observed that, despite normal engine parameters, the aircraft had not reached rotation speed (100 km/h) before mid-runway. He had not recorded anything particular in the logbook other than the cancellation of the flight. He had informed the chief pilot, who was to fly with him the next day. ## Findings and conclusion The longitudinal runway excursion was due to: insufficient consideration of parameters that could limit takeoff performance; the decision to continue the takeoff when the acceleration during the takeoff roll was insufficient at mid-runway; and the persistence in continuing the takeoff after the runway end.