What happened
On 8 September 2006, a Luton LA4A Minor, registration G-AYSK, was prepared for a local flight at Barton Aerodrome, Manchester. After moving the aircraft from its hangar to a grass area near the tower, the pilot performed pre-flight inspections and engine power checks.
Following the completion of these checks, the pilot exited the cockpit to manually swing the propeller. During this process, the engine ignited and immediately began accelerating. As the aircraft moved forward, the pilot attempted to steer the plane toward an open area by gripping the left wing strut. However, the pilot eventually lost his grip, causing the aircraft to climb steeply, bank to the right, and enter a loop. The aircraft ultimately crashed inverted in a rough area on the airfield's south-western edge. The pilot sustained minor injuries.
The investigation
The investigation focused on why the engine started while the pilot was outside the cockpit. The pilot reported that after closing the throttle and exiting the aircraft, his left leg may have struck the top of the throttle lever. Due to the thick, padded flying suit the pilot was wearing, he did not realize this contact had occurred.
While the pilot had verified the magneto settings during the manual starting sequence, he had not verified the position of the throttle. This oversight allowed the engine to run at a high RPM upon ignition, providing enough thrust to move the aircraft forward toward a parked plane located approximately 150 ft ahead.