THE HIGHER I GO, THE HAPPIER I FEEL .....???

 Acknowledgements: Thomas P. Turner, Mastery Flight Training, Inc. (Flight Instructor Hall of Fame inductee), & the FAA Aerospace Medical Division

Incident narrative: Little is known so far about the fatal crash of a turbo-charged Beech Bonanza in central Wisconsin. The airplane departed Fort Worth for the north-east .... The pilot initially climbed to 15,000 and levelled off. Approaching a line of weather, he then climbed to approximately 24,000 ... At some point ATC lost contract with the pilot ... Air Force aircraft were dispatched to intercept the Bonanza. Two fighters escorted the airplane at FL240 until it began to descend. Eventually it “flew too low” and the fighter pilots lost sight of it. Dispatchers report the Bonanza pilot had been “unresponsive” to the fighter pilots’ attempt to make contact. The airplane descended, perhaps on autopilot, to a touchdown in a field. Online photos show what appears to have been a survivable impact, although industry sources report the airplane was “written off”. 

Analysis: ... it seems the pilot experienced a problem between the time he returned to course after storm deviations and the point where he was no longer communicating with ATC. Although the airplane appeared to be perfectly flyable the flight was apparently not under the pilot’s control. It’s natural to suspect “pilot incapacitation”. If so, it could have been as the result of hypoxia due to failure of delivery of needed supplemental oxygen to the pilot. Hypoxia may have triggered some other health issue that was not reversed even after the airplane descended into thicker air.

Most GA pilots know something about the effects of hypoxia. With an increase in altitude, the reduction in oxygen will cause impaired judgment, reduced motor function, incapacitation, loss of consciousness, and even death. Vision is first to degrade, and night vision particularly, so the unofficial recommendation is to use supplemental oxygen any time you’re above 6000 feet when flying at night. Most GA pilots also know that the best protection to be gained from the use of supplemental oxygen is at any time above 10,000 feet. 

 Most pilots are also familiar with the concept of “Time of Useful Consciousness (TUC)” - the time between the moment an aviator is exposed to reduced oxygen and the impairment of a pilot’s ability to perform useful flying duties.  

he pilot of an unpressurised aircraft at 15,000 feet (the Bonanza’s initial cruising altitude) has a TUC of 20 to 30 minutes. If oxygen fails, the pilot has up to half an hour to detect the problem and repair it, or to descend to an altitude where hypoxia is unlikely. If that same pilot climbs to FL240 he/she only has between five and 10 minutes ... 

Note: These values were defined using young, very fit US Air Force pilots. Probably, the typical GA pilot’s lifestyle and health factors may not meet that physical standard and so may well result in a reduced TUC! 

 Symptoms: Reaction to loss of oxygen with altitude varies widely among individuals. So, it’s important to get to know your own personal symptoms of the onset of hypoxia. Symptoms include, but not necessarily in this order:

·       Increased breathing rate

·       Headache

·       Light-headedness

·       Dizzyness

·       Tingling or warm sensations

·       Sweating

·       Poor co-ordination

·       Impaired judgment

·       Tunnel vision

·       Feeling of euphoria

Any of the above which starts to occur, or which gets worse as you are climbing, can be an indication of fast-approaching oxygen starvation. So, don’t waste time arguing with yourself over it – get that supplemental oxygen on before you start to fly over that mountain or to climb above that cloud bank which is spoiling your view!

 FLY SAFE!