Josh-Daniel S. Davis (joshdavis) wrote,
Josh-Daniel S. Davis
joshdavis

Civil AeroMedical Institute

I went for the Physiological Training course at the CAMI, which is in the FAA's Mike Monroney Aero Center in OKC today.

We covered spatial disorientation, Night Vision Goggles, and Hypoxia.

One of the videos we watched:
http://www.youtube.com/watch?v=NSN4oOxBcfY

The guy is in an altitude chamber set to 30kft and they're measuring his Time of Useful Consciousness. Basically, that's how much time you have to get your oxygen mask on before you're too stupid to do it for yourself. Four of Spades, all the way.

Anyway, we had 4 min sim time each, that was demonstrating somatogyral illusion and coriolis effect. SG is, if you're spinning, after 20-30 seconds, you won't feel like you're spinning anymore. Then, if you stop, you'll feel like you're spinning the other way. Coriolis is where you're spinning in one plane, and then you tilt or lean in another, and you get a huge feeling perpendicular to how you moved your head. Roger ran the sim for all of us and endured the repetition well without rushing us, but without subjecting us to the exact same words each time. We all watched each of our half-group. The effects were much more surprising than I'd expected, since I did my BFR with unusual attitudes earlier this year. The sim was in B32

For NVG, we got to play with some 3rd gen monoculars and see how they work, plus the limitations (too bright, and it washes out. No light, and it doesn't work. Colors all look the same, except red and IR which may halo at lower light levels. Quarter moon brightness is the best detail. Fine details, like power lines, will be invisible. Trees with no leaves will be invisible unless a fairly bright light source is on them. Take the NVG off and you see you've lost night vision from its brightness. Etc. Nice tech, but monoculars are $5k, binoculars are $15k, and 3G Binoculars are the min allowed for NVG flight. Plus, NVG can lead you into IMC, and can be a problem if your panel lights are too bright. Best to have 2 pilots, one with, one without, so you can see VASI/PAPI/Runway light colors, etc. JR did the NVG demo and it was a great setup in B34.

We had a bunch of classroom lecture, and JR (last initial B but I forgot his actual last name) made things amusing. The lecture was in B33 and had plenty of breaks, including lunch. The cafeteria was really nice, and was next to the "Multi Purpose Building".

Then, off to the altitude chambers. We tested climb to 6k, sit, then drop to ambient (1800') to make sure no one had any ear or sinus blockages, then spent about 30 mins on 100% oxygen to get about a 50% denitrogenation of our blood. Then, up to 18k, then rapid to 25k, then testing our hypoxia signs with a watcher, then recovery, then back to 18k to see how it affected our night vision, and then done.

Baseline blood oxygenation was 95-98 and pulse 68-71, depending on my breathing. In the chamber, before the testing or preparations, 98% and 77bpm.

During de-nit, I was at 100%, but didn't record pulse. 100% O2 makes me a little sleepy, strangely enough, though maybe it's tied to restless sleep last night, long drive the day before, and dim lights for a video on spatial awareness. I am normally a mouth breather, but I switched to nasal because the O2 was so dry. It was easier because there was pressure behind it.

At 18k, mask on, exposed skin felt a little cool. It would have been clammy, but moisture evaporated quickly.

At 25k, no mask, first sign was tingling fingertips, bloaty feeling from gas expansion in my gut, and some dizziness. At minute 1, I was down to 71% and 116bpm. I did one crossword line, but was agitated and expectant. External observer recorded that I went from fairly pink to very pale.

At second minute, my eyes felt a little wattery and blurry, with some blotchy, almost scintilation to my vision. Tingling was gone or not noticeable. I was a little more dizzy, but could control it with proper breathing. I was tense, and couldn't do another crossword. I'm not good at crosswords, don't do them, and got lost. I didn't think to shift to the math problems. I was at 68%. Observer reported that my breathing rate increased.

At minute 3, I didn't/couldn't record my O2 saturation, and was confused. I picked up the mask, but wasn't sure if I should put it on. I could still process sensory input just fine, but complex tasks were out. Observer said my breathing was deeper.

At minute 4, or 4 seconds prior to it, I put on the mask. Dizziness went away within seconds, and I recorded 96% and 95bpm, though I wasn't with it enough to record O2 levels prior to putting on the mask.

I got confused about my times, because I initially started my tach, instead of stopwatch, and it was counting down from 7:35. Oops.

For the 18kft test, lights were dimmed. My bright light vision is 20/20, or thereabouts, though the font was too thick and the letters bled a bit. In the dim light, my vision was 20/50. Pulling off the mask for minor hypoxia (TUC is ~30m at 18kft unless you live in the mountains) lead to colors dimming a little in the first minute. Red/orange greying a little and closing in on similar color. Also, blue/green closed in on similar color. Some swimmies in the first 2 minutes, but adjusting breathing mostly fixed that. I didn't lose any text, and didn't lose 20/50 status after 4 mins. Handwriting was a little poor. Generally less details observed. Putting the mask on gave the color back within 30 seconds, reduced tension and heart-rate, and otherwise wasn't overly noticeable.

We were told to expect possible post-chamber ear blocks, and fatigue from negative nitrogen balance, which would lead to some toxins being released. This all seems to be true, but nothing major.
Tags: altitude, cami, faa, hypoxia, pilot
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