Incident Overview
On 13 February 1998 at 1445 hours UTC, a Cessna F172L, registration G-AZJV, was operating a private flight from Gloucester to Cardiff, Wales. The aircraft, manufactured in 1972, was powered by a single Lycoming O-320-E2D piston engine. The sole pilot, aged 55, held a Private Pilot's Licence and had 1,194 total flying hours, including 847 hours on type. One passenger was on board.
Engine Failure and Forced Landing
During the flight, conditions were considered conducive to carburettor icing. The pilot selected carburettor heat at frequent intervals but did not detect any evidence of icing. After receiving ATC clearance to descend from 2,000 feet to not above 1,500 feet in the Cardiff Control Area, the pilot applied carburettor heat, reduced power, and descended to 1,400 feet before reapplying cruise power. Approximately four minutes later, the engine suddenly and smoothly ran down to 800 RPM. The pilot immediately transmitted a 'Mayday' call and performed the engine failure drill, including switching the fuel selector from 'right tank' to 'both'. By vigorously pumping the throttle, the engine RPM momentarily increased to around 1,800 for a few seconds before decaying back to 800 RPM. Further throttle pumping produced short bursts of power, reducing the rate of descent. However, it became clear that the aircraft could not reach Cardiff Airport, which was about 6 nautical miles away. The pilot turned away from built-up areas and selected a field for a forced landing, which was executed successfully. The emergency services had been alerted following the Mayday call; a Royal National Lifeboat Institute inshore rescue craft was placed on standby, and a Police Support helicopter landed in the field within 30 seconds of the aircraft coming to rest. Fire, ambulance, and local police vehicles arrived within 20 minutes. There were no injuries to the crew or passengers, and no damage to the aircraft.
Post-Inspection and Possible Causes
A licensed engineer subsequently conducted extensive checks of the induction system and flushed out the carburettor. No fault was found, and the engine ran normally; the aircraft was flown out of the field the following day. The engineer considered that the engine failure may have been the result of severe carburettor icing. The pilot felt there was an additional possibility of a foreign object temporarily causing a blockage within the carburettor.