Robin DR400-120 Fence Collision During Touch-and-Go at Chavenay Villepreux

Incident Overview and Damage Assessment On June 26, 2012, at 18:45 local time, a Robin DR400-120 registered F-GGHX, operated by a flying club, collided with a fence during a touch-and-go maneuver at Chavenay Villepreux aerodrome. The aircraft sustained significant damage, including broken wheel fairings, a torn right wing lower surface fabric, and broken wing ribs. Following the impact, the instructor performed a low pass over runway 10 to allow the air traffic controller to assess the damage, before landing safely on runway 23. ## Operational Context and Pilot Actions The instructor and student pilot departed for a local flight and a circuit session. After the first touch-and-go on runway 28, the aircraft struck the top of the fence at the runway end. The instructor reported that the wheels touched down at the displaced threshold. Although the student applied power late, the aircraft's acceleration was normal. When the student did not react at rotation speed, the instructor performed the rotation. The instructor noted a slight jolt when passing the fence but maintained control. The instructor typically used the longer runway 23 for touch-and-goes. At the time, the ATIS indicated runway 28 in use, calm winds, and slippery, wet runways. ## Student Experience and Training Discrepancies The student had been training for less than six months and had approximately 30 flight hours, all in the DR400. The student had begun training with a different instructor who used a different sequence for touch-and-go actions. The first instructor required power application before flap retraction, while the second instructor requested the reverse order. The second instructor observed a hesitation from the student during the maneuver, with a slight movement toward the throttle before retracting the flaps. ## Runway Geometry and Performance Calculations The available landing distance on runway 28 was 560 meters. Passing the displaced threshold at the regulatory height of 15 meters, the wheels touch down 300 meters before the runway end. Considering an immediate takeoff, the 15-meter point would be approximately 10 meters beyond the runway end. The aerodrome fence, 1.20 meters high, was located 8.40 meters from the runway end. Calculations based on the flight manual for the day's conditions (aircraft mass 840 kg, low-pitch propeller, 21°C temperature, and unpaved runway) indicated a minimum distance of 570 meters between two 15-meter passes. Additionally, a 100-meter displaced threshold on runway 10, caused in part by the fence near the physical threshold, meant the obstacle was not accounted for in the available takeoff distance for runway 28. The fence was, however, depicted on the VAC chart. ## Aerodrome Operations and Regulatory Audit The air traffic control chief at Chavenay indicated that runway 05/23 (825 meters long with a 727-meter landing distance) was generally preferred. He noted that aircraft often passed low over the fence when taking off from runway 28. The club had equipped the F-GGHX with a low-pitch propeller to improve performance on short runways, particularly for runway 10/28. An audit of the aerodrome on August 10, 2012, conducted by the DSAC/N, highlighted that the non-frangible fence protruded 50 to 120 cm into the takeoff clearance at all headings. In response, the aerodrome manager proposed indicating the fence height in aeronautical information and enhancing daytime marking of the fence sections in the clearance. The DSAC stated that reducing the declared distances remained the most appropriate solution.