Hypoxia - what is it?

It is correctly said that air flight is less dangerous tan being gored by a Bull on your holiday in Spain None the less, let us look at Hypoxia, a condition of impaired judgment that is caused by lack of sufficient oxygen, and that is rarely recognized by the sufferer at its initial onset. 
Hypoxia is a risk at altitudes of 10,000 feet and higher (Christensen 2010b: 126–127)
 Suppose you are a pilot who does a recalculation while flying, to conclude that you have more than enough fuel to get to an airport fifty miles further than the one in your initial plan.
 

Suppose you then glance at the altimeter to see that you’re at 10,500 feet and remember the phenomenon of hypoxia and its insidious onset. You now have evidence that you might have hypoxia and therefore might have misidentified the support relations between your evidence and your conclusion. 

Are you now justified in believing that you can get to the more distant airport? Are you justified in believing that your evidence supports that claim?