Interest in this incident, which made headlines in the USA several years ago, was rekindled by the presence at a recent aviation medical examiner seminar of the doctorpilot involved.
Interest in this incident, which made headlines in the USA several years ago, was rekindled by the presence at a recent aviation medical examiner seminar of the doctorpilot involved.
Dr Robert Frayser of Hoisington, Kansas, had departed from Great Bend Airport in his Comanche 400 at 7 a.m.. Bound for Topeka, Kansas, he settled the aircraft on autopilot in the cruise at 5,500 feet. It was a clear, sunny day and the flight seemed to be going routinely, until Frayser switched tanks and set up the GPS for his destination. ‘Then I lost about an hour and a half of my life,’ he recalled.
During that time, the Comanche, guided by its autopilot, flew on in a straight course until the tank ran dry. With no input from the unconscious pilot, it then glided down to a deadstick landing in a snowcovered farm field near Cairo, Missouri. Touching down wingslevel, the Comanche slid 525 feet before coming to rest in a wire fence along a line of small trees.
Unaware that he was already on the ground, a groggy Dr Frayser automatically went through his landing precautions as he came to. When he realised the aeroplane was already down, with its engine stopped, he climbed out and made his way to the nearby farm. Pilot and aircraft were but lightly damaged: Dr Frayser had cuts, bruises and what turned out to be a broken wrist; the Comanche’s right wing had been damaged when it struck a tree.
The severe headache that Dr Frayser was also suffering was a symptom of what had gone wrong. Investigators discovered that a cracked manifold had allowed exhaust gases to escape into the heater muff. Though exposure to carbon monoxide (CO), loss of consciousness has occurred in individuals suffering carboxyhaemoglobin (CoHg) levels of forty per cent. It was estimated that Dr Frayser’s CoHg was as high as 44 per cent when he exited the aeroplane; luckily, he had given up smoking six months earlier, significantly reducing his susceptibility to CO poisoning. His escape was, though, a narrow one. Had the aeroplane been carrying more fuel and the engine run longer, he might well have died as a result of the exhaust gas poisoning. Equally, gusting winds or alternative field ‘selection’ could have made the landing unsurvivable.
As it is, Dr Frayser who now must surely take aircraft maintenance very seriously indeed still flies a replacement Comanche, this time equipped with a CO detector in the cockpit.
From an item in Aviation International News.
