Accident Overview
On 14 May 2009 at 1101 UTC, an Aero AT-3 R100, registered G-SACY, was involved in an accident at Sherburn in Elmet Airfield, North Yorkshire. The aircraft sustained significant damage to its fuselage and fin. The pilot, the sole occupant, was uninjured.
Flight Details
The flight was a private circuit training session. The pilot held a Private Pilot's Licence and had accumulated 167 flying hours, of which 10 were on the accident aircraft type. His recent flying experience was limited: 3 hours in the last 90 days and 1 hour in the last 28 days.
Sequence of Events
While flying the fifth circuit of the session, the pilot inadvertently selected the choke control instead of the carburettor heat during the downwind leg. Both controls are located close together on the center panel extension. The choke control features a cylindrical yellow knob, while the carburettor heat control has a square blue knob; both are operated by pulling to engage and turning clockwise to lock.
As the pilot reduced power and turned onto final approach, the engine stopped. The pilot executed a forced landing in a nearby field. During the landing roll, the aircraft nosed over. The pilot, who remained uninjured, was released from the aircraft by the Airfield Fire and Rescue Service.
Possible Causes of Engine Stoppage
Investigators considered two probable reasons for the engine stoppage: an over-rich mixture resulting from the inadvertent selection of the choke, or carburettor icing due to the carburettor heat not being selected. The proximity and similar operation of the two controls likely contributed to the confusion.