What happened
On 20 June 2017, a Rans S6-116 Coyote II, registration G-BUOK, was performing a private flight departing from Bagby (Thirsk) Airfield in Yorkshire. During the takeoff roll from Runway 24, the aircraft reached an altitude of roughly 20 feet before the left wing dropped. This caused the aircraft to bank sharply to the left, lose altitude, and strike the ground. The pilot escaped the incident without any injuries, though the aircraft suffered extensive damage to the propeller blades, landing gear, engine, cockpit, windscreen, and right wing.
The investigation
Investigators examined the airfield environment and meteorological conditions at the time of the accident. The runway at Bagby features a 2.5% downslope. At the time of departure, the wind was reported as a 150°/8 kt crosswind, with gusts reaching 120°/12 kt. These backing winds resulted in a gusting tailwind component.
At this airfield, there is a local recommendation to complete the takeoff and become airborne on the grass portion of the runway before reaching the concrete section, which begins approximately 230 m from the threshold. The investigation looked into whether the pilot's attempt to meet this recommendation influenced the aircraft's airspeed. While the Rans S6-116 Coyote II is capable of taking off in a 60 m run, the investigation focused on how the combination of wind and airspeed affected the flight path.
Findings
- The pilot likely attempted to become airborne as quickly as possible to clear the concrete section of the runway.
- This urgency may have resulted in the aircraft lifting off with a lower than normal airspeed.
- The presence of a gusting tailwind component of approximately 5 kt, combined with the low airspeed, likely reduced the relative airspeed over the left wing to a critical level.
- The low inertia and low altitude of the aircraft made recovering from the resulting wing stall extremely difficult.