Allison was piloting the last airworthy Second World War German Messerschmitt Bf 109 when he made a forced landing at an air show in Duxford in October 1997. The incident occurred on the aircraft's last planned flight before being placed as permanent static display at RAF Duxford. Allison had 4,612 hours of flying experience across his career, though only 18 hours on this particular aircraft type. A report by the Air Accidents Investigation Branch concluded that Allison had manually operated the cooling system of the Daimler Benz DB605A engine into a level of overheating, and had interpreted the thermostat-controlled release of coolant fluid to be an indicator of imminent engine failure. Allison made an attempt to land at the designated airstrip but approached too fast, aborting landing and climbing to an altitude to pass over the M11 motorway. Allison then attempted to land in a ploughed field nearby, but the aircraft nosed over and the pilot became trapped until rescue workers arrived. Alison was unharmed.