What happened
On 31 March 2013, a Pitts S-1T Special, registration G-WILD, was completing a private aerobatic flight at White Waltham Airfield. During the final approach to Runway 11, the pilot maintained a right sideslip to keep the runway centreline visible, as the edges of the runway were unmarked. The aircraft touched down at approximately 85 to 90 mph, with the tailwheel followed quickly by the main wheels.
Immediately following touchdown, the aircraft experienced a sudden nose-down pitch. This motion progressed into a full somersault, where the aircraft rotated onto its back before coming to rest in an upright position. The aircraft sustained damage beyond economic repair, though the pilot escaped without injury.
The investigation
Investigators examined the runway surface and found that the aircraft had landed amongst ruts created by a vehicle used for the deployment and retrieval of portable night-flying lighting. Examination of the wreckage revealed that the propeller tips had struck the ground, and grass was found lodged between the tyre wall and the wheel rim, indicating significant lateral forces.
While there was initial concern regarding a potential landing gear failure, the investigation established that the right main landing gear strut distorted due to compression forces during the impact with the ruts, rather than a structural failure. The investigation also noted that the airfield's air/ground radio operator was not immediately aware of the accident because they were stationed in an operations room that lacked a view of the accident site and were occupied with other tasks.
Findings
- The primary cause of the somersault was the impact of the main landing gear with ruts left by airfield maintenance equipment.
- The propeller strike likely intensified the pitching motion that led to the aircraft flipping.
- The pilot's use of a sideslip to maintain visual contact with the runway edges placed the aircraft's path directly over the disturbed ground.
- The airfield's radio communications response was delayed because the operator was not positioned in the visual control room and was distracted by other duties.