NCSA club rules specify that: ":Members who fly at altitudes higher than
18,000' are required to have attended a high altitude FAA-USAF
physiological training course." This was easy to arrange until some
years ago, as the nearby Air Force Bases offered these courses several
times a year and initially only cost $20 or less. When this was no
longer an option, members could do what Walter did last year and go to
Van Nuys for the 'normobaric training', where there was no pressure
change, which remains at sea level. The oxygen level is controlled via
piped air which the trainee breathes through a mask, to simulate a climb
to high altitude. The only other option for this training is through
the FAA CAMI in Oklahoma City.
Maja chose that option and describes her experiences:
"Hi all,
For civilian pilots who want to test their own tolerance to hypoxia in
the controlled environment, only two kinds of options are available
these days:
a)going to CAMI - Civilian Aeronautical Medical Institute in Oklahoma
City, an FAA establishment, for a hypobaric and hypoxic chamber ride or
b) commercial normobaric hypoxia testing in Van Nyues in Southern
California or few other and more distant places.
CAMI high-altitude chamber ride obviously means hypoxia with
concomittant decompression, as if one is really climbing in the
atmosphere. Normobaric testing, like in Van Nuys, means ground level
pressure at all times, and the oxygen-starved air is supplied via the
face mask.
The other relevant difference between these two options is the
distribution of cost for the test and travel. CAMI offers morning of
lectures and a chamber ride plus the spatial disorientation course with
the simulator the same afternoon for zero dollars. Two hour normobaric
testing in SoCal was close to $300. Travel to OKC does cost money,
though: but if one flies to Dallas and then drives the rental car to
OKC, that costs about $300. A night in the hotel is needed for either
option. So, finances being about the same, I have opted for the hypoxia
physiology training in CAMI in Oklahoma City.
For those who have never done it, "the chamber" really is a sealed
walk-in chamber, fits about 12 students plus 2 staff. It is connected
via valves in the walls to large compressors (?) which can take out or
whoosh in the air at different speeds and of different O2 pressure.
The first part of the "ride" takes you to 5000 ft AGL and back to ground
level, at 3000 ft/min (just like lazy Byron thermal), as a test of the
health of ones sinuses and ability to clear the ears. Whoever finds this
part painful should leave the chamber, because it will only get worse
after that. First real "ascent" is to 8000 ft (3000 ft/min), O2 mask
hanging on the wall above your left shoulder. About that altitude an
unannounced rapid decompression (10-15 s) to 18.000 ft occurs and one
has to recognize that moment and jump for the O2 mask. This is supposed
to simulate the loss of cabin door in an airliner. Such a rapid
decompression is a very violent sensation, at least it was for me, so
there is really no way that it cannot be noticed.
What follows is the real test of your hypoxia tolerance. Masks on, we
"climbed" to 25.000 ft at 3000 ft/min. Once 25.000 ft is reached, half
of the students take off the masks for up to 5 min, while the other half
sitting across with masks on and watching and writing down symptoms they
see in other people. Everyone has a worksheet, most important part of
which is to check your symptoms during the first, second ... fifth
minute while without the O2 mask. The goal is to identify 3-4 symptoms,
some more some less obvious. However, the moment one has a very obvious
symptom the mask should go back on, and you should record both that
symptom and the O2 saturation reading from the pulse oxymeter. I had
identified 3 symptoms, all within the first minute: blurry vision - not
too obvious, very obvious heart racing, and finally rapidly developing
dizziness. The last made me put the mask back on at 47 s: did not think
I could detect anymore symptoms if I actually fainted.
After that I "enjoyed" watching men getting silly by refusing to put the
mask back on. At the end of minute 3, it looked like the collective IQ
of all the students which still had the mask off was about 70. They
grinned very happily when addressed by staff, but could not execute the
simple tasks given, like stretch your arms and pretend to fly around.
Some could execute tasks - one guy was asked to put plastic pieces into
his hood or front of the sweatshirt, which he did quite well, but later
could not recall that it was him who did it, rather the staff person.
Temporary amnesia is apparently common in hypoxia. Eventually, all these
men needed help to put the O2 masks back on. Time of useful
consciousness at 25.000 ft is said to be between 3-5 minutes. However,
if one cannot put the mask back on, that consciousness if not very
useful. Two minutes at 25.000 ft without O2 seemed like a better
approximation, which was also mentioned during the morning lectures.
The last test was back at 18.000 ft for five minutes, demonstrating the
effect of hypoxia on night vision. Once the lights were out, we were
given a chart with 5-color printed pin-wheels (color vision testing),
with "Z"s around the periphery (peripheral vision testing), and small
sectional chart legends to focus on (foveal focusing). I did not think I
noticed much of an effect of O2 deprivation on night vision: could still
tell apart yellow from white and green from neighboring blue, could see
all "Z"s and focus on most of the text. It's just that it became much
easier when I put the O2 mask back on: the colors got brighter, and I
could tell apart more of those sectional chart legends.
Other interesting tidbits: 1)For CAMI, one needs a current FAA Medical,
which can be older than 1 year (mine was). 2) The session is recorded on
a video (ours wasn't by mistake), so if you end up being really silly it
will go to YouTube and go viral around the globe :-)
3) Men with beards: if you have one like President Larry, it will be
hard to seal the O2 mask to your face; goatees and mustaches are manageable.
4) I was the only female in the group.
If one can afford taking couple of days off during the work week to go
to OKC, it is definitely worth it. I learned a lot: I have not expected
those particular symptoms of hypoxia that I have noticed. Also, even
though I thought I would be more susceptible to hypoxia than most men, I
did not think I could "last" only 47 sec. Teachers and instructors are
doing a good job, and I found it useful to do it in a large and
interactive group of people.
Maja
Links for you:
http://www.faa.gov/pilots/training/airman_education/aerospace_physiology/
http://en.wikipedia.org/wiki/Hypobaric_chamber
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