World Record 31,000 feet

Now this is a great subject with lots of good info.
How about some more!

So, Are they any hard data on the ascent rates that
would be acceptable? Or the altitudes that they apply?
In other words If I were climbing in 1500fpm lift thru
18K to 24K am I likely to develop DCS? Are there any
warning signs before damage would occur? I used these
figures because I have been in them and have a hopt
to be in them again






Arnie,

1) Rates of ascent above, say, 100 fpm is way too fast
to equilibrate. Thus
you are building a supersaturation (increased body
burden of nitrogen). By
comparison, climbing is much slower, and you're exercising
the whole time
(thus moving blood around and clearing tissue compartments
more efficiently
than sedentary pilots). The recent record setting climb
of Everest from base
camp to summit in 8 hours, works out to about 24 fpm.
Rate of ascent is not particularly predictive or protective,
above a certain
threshold. Exercising and prebreathing are better than
adjusting rates of
ascent.

2) Trapped gas problems, like bowel gas, or gas in
the middle ears, or gas
under a new dental filling, are not DCS. They are certainly
aeromedical
issues of which pilots and others should be aware,
but not DCS. In military
altitude chambers, trainees are told not to try to
hold their gas out of
politeness, rather to let 'er rip.


nafod40 (Mike) also asked:
Does breathing 100% O2 from chocks to chocks help lower
the N2 in the
body? In other words, is there a secondary benefit
to breathing 100% O2
other than that you don't pass out?

Answer: In the studies I did, my test subjects pre-breathed
100% oxygen at
ground level for a full hour before going to altitude.
They kept breathing
100% oxygen the whole time they were there (at 25,
30 or 40 thousand feet)
and they STILL got DCS.

Even my inside observers, who prebreathed for two full
hours before ascent,
occasionally got DCS. They got it at a lower rate,
though. My most severe
cases of DCS came from this group, though (a case of
chokes: resolved
quickly in a hyperbaric chamber).

Short answer: prebreathing is good, but not perfect.

Thanks again.