The pilot stated that the purpose of the flight was to visit an engineering workshop in Charleville, and to demonstrate the aircraft which was for sale. Because he wanted to return from Charleville on the same day, and the flight time each way was approximately 4 hours 30 minutes, he had planned for an early departure. When he arrived at the airport, the aircraft was covered in a thick frost, and it took him over an hour to defrost the aircraft and complete a daily inspection. He departed Orange at 0620, and climbed to 6,500 ft. The weather was fine and sunny, but very cold so he pulled the heater control to full on. After passing Bollon, 120 NM southeast of Charleville, the pilot tuned to the Charleville NDB and noted that the needle rotated to indicate straight ahead. He recalled passing a strip about 25-30 miles from Charleville and made a mental note that he could land there if the weather deteriorated. He said that he then started thinking about the descent and recalled thinking about turning the heater down. It appears that the pilot then lost consciousness as the next thing he remembered was that the aircraft was descending through 1,000 ft at about 1,000 ft a minute.
The pilot said he pulled back on the control yoke and saw the horizon come into view. He banked hard left, and the engine coughed. The pilot then noticed what looked like a very long airstrip ahead and landed. After landing the pilot noticed the time was 1230 and realised that his ETA for Charleville had been about 1100. The pilot said his head was aching and he felt cold and nauseous.
The pilot eventually fixed his position roughly 150 NM northwest of Charleville, and after repairing the aircraft radio, he was able make contact with an overflying jet late the next day and was rescued.
Examination of the cabin heat system revealed a large amount of exhaust build-up in the scat hose leading to the cabin heat selector valve. The muffler was badly cracked around the outlet port and had a white soot stain around it. It was concluded that the pilot may have been effected by carbon monoxide which entered the cabin via the cracked outlet port of the muffler.