REFLECTOR: Flying High
Jorge Bujanda
jbujanda at dslextreme.com
Fri May 13 20:20:49 CDT 2005
Gentlemen,
The headache is not the problem. What is important is what it means. If
you get a headache, it is likely that you have gone too high. The
headache is a sign of an important and fairly acute decrease of oxygen
delivery to the brain due to sudden decrease in barometric (oxygen)
pressure, due in turn to high altitude.
From a neurological perspective, the onset of headache due to hypoxia
is proven to be accompanied by subtle and unnoticed, but increasing
judgment impairment, coordination loss, decreased reaction time, visual
impairment, drowsiness, excitement, carefree feeling, overestimation of
self-capabilities and exaggerated self-confidence (very dangerous in the
cockpit), disorientation and loss of time sense. As you can see,
although the most uncomfortable, the headache is the least dangerous of
all the events described. It has been proven that there is increasing
“appreciable” neurological handicap between 7000 and 12000 feet and
“considerable” neurological handicap between 12000 and 15000 feet in
physically “normal” individuals.
From a cardiovascular perspective, there is an obvious decrease in the
oxygenation of the heart and any circulatory and cardiac problem (known
or unknown) will be aggravated by such decreased delivery of oxygen to
the heart. Any illness or factor affecting proper tissue oxygenation
such as anemia, hypertension, circulatory problems, heart disease,
emphysema (long-time smokers), asthma, and even simple things such as
been in the process of getting over upper respiratory allergies or
infections may further worsen oxygen delivery to the heart and brain.
This means that, under these circumstances, you might not tolerate
altitudes that you might have tolerated in the past under “normal”
conditions.
More importantly, for reasons I will not detail here, any stressful
situation (i.e., encountering bad, or worse than expected weather and
climbing higher to avoid it) causes rapid and shallow breathing, as well
as increased tissue oxygen consumption which will further decrease
oxygen delivery to the heart and brain and may become the last factor to
precipitate catastrophe.
Pay attention... borderline (high) flying does not come without risk.
The effects of altitude are insidious and are not something to be taken
lightly. A simple headache may be just a warning sign, but also, a
life-saving sign pointing to a bigger underlying problem.
Draw your own conclusions based on what your current physical condition
might be (known or unknown) and the physiological facts stated above.
I hope this helps you increase safety awareness and I highly recommend
that you remind yourselves of all this as you have to take those two
aspirins after landing.
Regards,
Jorge Bujanda
XL FG
Palmdale, CA
"Make your best case... not the best case."
"Spare the noise... convince through silence."
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