History of the Flight
The accident occurred on 19 February 2011 at 1445 hrs at Dunkeswell Airfield, Devon. The pilot of a Tri Kis, G-BVTA, was receiving tuition from an instructor. At the end of the sortie, the pilot taxied to the threshold end of Runway 23 and turned right onto the embarkation area to allow the instructor to disembark and walk to the hangar. The engine was shut down, and after the instructor left, the pilot restarted the engine and began a 180° left turn to steer towards the taxiway. Due to the confined area, maximum left steering pedal and braking were used.
After completing the turn and coming to a halt to watch for landing aircraft, parachutists, vehicles, or pedestrians, the pilot noticed the nosewheel was cocked well to the left and needed straightening. He applied right rudder pedal and increased engine rpm to 1,300. Just before the aircraft moved, he applied full right pedal, at which point his foot slipped off the pedal. He believes the sudden forward lurch of his body caused his right hand to move the throttle forward, resulting in an increase of 400-500 rpm.
Collision
The aircraft accelerated rapidly in a left turn and, after turning through about 90°, was heading towards a large black twin-engined Beechcraft used for parachuting, parked on the edge of the runway starter extension. The pilot judged that straightening out would likely result in impact with the Beechcraft and also realized he was unable to apply right rudder (possibly due to his shoe being caught behind the right pedal). He tightened the left turn further with left brake application and successfully avoided the Beechcraft.
He was now approaching a Cessna 172, G-ILPY, parked to the left of the Beechcraft. He momentarily hoped to pass between the two aircraft, but the radius of turn had decreased and the aircraft headed diagonally towards the tail of the Cessna. In his struggle to free his right leg, he may have inadvertently nudged the throttle further open. Collision with G-ILPY was inevitable; his left wingtip clipped the rear fuselage, spinning the Tri-Kis to the left and into the right side of the fuselage of the Cessna, just forward of the engine firewall. The engine stalled and the aircraft came to rest with the left wing wedged under the tail of the Cessna, the spinner and remains of the wooden propeller embedded in the nose, and the wing strut of G-ILPY severed.
Aftermath
The airfield owner arrived within seconds, undid the pilot's harness, and switched off the electrics. The pilot, momentarily stunned by his head hitting the upper cockpit hatch cover, reassured the owner he was alright and saw him attend to a fuel leak from a breather tube on the left wingtip. The pilot then realized his right foot was trapped between the right rudder pedal and the centre console. He extricated it and double-checked switches were off. He noted the throttle setting was depressed by an amount equivalent to about 2,200 rpm in flight. After exiting through the left hatch (which was off its hinges due to impact), he returned a few minutes later to remove the keys and recheck the throttle.
Pilot Statement
In a detailed statement, the pilot attributed the accident to his foot slipping off the right rudder pedal and becoming trapped; the resulting lurch of his body also caused him to inadvertently open the throttle. He identified as causal factors the offset of the rudder pedals and the lack of friction material on them to improve grip. He also felt that the throttle friction device, which requires a button to be depressed in the centre of the knob each time a power adjustment is made, would be improved if it was in the form of a collar behind the knob, allowing the throttle to be closed with a single, rearward motion.