What happened
On 22 August 2009, during the 25th World Aerobatics Championship at the Silverstone racing circuit, a Zivko Aeronautics Inc Edge 540, registration N540BW, was performing a competition sequence. The pilot, an experienced competitor, had been conducting practice flights earlier in the day. During the fifth manoeuvre of the sequence—a pull up to vertical followed by a half-eight point roll and a 1¼ turn downwards snap roll—the aircraft failed to recover.
Instead of pulling out of the descent, the aircraft continued to rotate in a nose-low attitude. The flight path was monitored by a portable radar tracking system and handheld cameras, which recorded the aircraft performing several rotations before disappearing behind trees. The aircraft ultimately struck the ground at the race track, causing the destruction of the aircraft and the fatal injury of the pilot.
The investigation
The AAIB examined the wreckage and analyzed video footage from the radar-slaved camera and a handheld camcorder. The investigation focused on the control systems, specifically the rudder pedal assemblies. The aircraft was fitted with adjustable foot extensions to accommodate the pilot's height.
Investigators found that the rudder cables had failed in overload and noted specific wear and witness marks on the rudder pedal pivot tubes. These marks were consistent with the movement of the pip-pins used to secure the pedal extensions. Analysis of the video footage revealed three primary anomalies during the recovery phase: an unusual rudder position, an unexpected aircraft pitch attitude, and the pilot's head position being displaced significantly to the left of the cockpit centerline.
Findings
- The aircraft failed to recover from the downwards snap roll, continuing to rotate in a nose-low attitude until impact.
- A rudder control restriction could have occurred due to the design of the pedal extensions, which allowed the lower attachment to move in a way that could prevent the left rudder from being fully released.
- The pilot's head position was notably off-center during the expected recovery, suggesting either an attempt to investigate a cockpit issue or an impairment in situational awareness.
- The possibility of pilot incapacitation, such as G-induced loss of consciousness (G-LOC), was considered, though no direct evidence of such an event was found.
- The aircraft's engine was rotating under power at the time of impact.