Simviation Forum - Hypoxia?

Aug 16^th, 2005 at 3:32pm

spirit1flyer Offline
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While the extremes at 30,000 feet are foreign to most general aviation aircraft, the issues are not as far removed from the typical single-engine pilot as you might think. Any time you fly above 10,000 feet (5,000 feet at night), you need to think about hypoxia — what effect diminished oxygen levels can have on you and your ability to fly the aircraft safely.

why is the oxygen levels different at night? ???

spirit

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Reply #1 - Aug 16^th, 2005 at 3:44pm

C Offline
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Quote:

why is the oxygen levels different at night?

I have absolutely no idea - that's the first I've ever heard of it.

Quote:

what effect diminished oxygen levels can have on you and your ability to fly the aircraft safely.

Hypoxia is an interesting beast. I've experienced it inside a decompression chamber at an equivalent altitude of 25000ft, at which you're really looking at a maximum of 3-4 minutes before you're going to die (because if you haven't taken action by 3 to 4 minutes, you'll pass out, and not recover). We conducted a series of simple exercises, starting with adding shapes (where different shapes represented different numbers), then relatively simple arithmatic, then copying patterns and so on and so forth. The key thing was you could feel yourself having to really concentrate on completing each task, but as time progressed (2 to 3 mins, by which time you're feeling light headed and slightly euphoric) you still thought you were doing rather well. When the doc finally gave you your mask back (somewhere between 3-4 minutes) and you took on oxygen again you realised how badly you had done, how bad your copied shapes were, and how scruffy your writing became.

It was an interesting an enlightening experience - certainly I feel that I am as well equipped as I can be if I ever feel I am experiencing the symptoms.

The worst thing about GA aircraft is as they'll be flying lower (say up to 15-20000) is that the onset of Hypoxia will be a lot slower, so potentially much more difficult to recognise, and therefore prevent.

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Reply #2 - Aug 16^th, 2005 at 3:54pm

Fozzer Offline
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...interesting read here...>>>

http://www.mountainflying.com/hypoxia.htm

Useful page to keep... Wink

...?

Cheers...!

Paul.

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Reply #3 - Aug 16^th, 2005 at 7:37pm

beaky Offline
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Thanx Paul; never knew there were so many different types of hypoxia. Perfect hangar-talk stumper... Grin

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Reply #4 - Aug 16^th, 2005 at 9:59pm

Boss_BlueAngels Offline
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It's different at night because of your eyesight. Has nothing really to do with hypoxia itself.

Your eyes take up more oxygen than any other part of the body, and the first thing to go when you're flying at higher altitudes is vision acuity.

I took a class on aviation physiology which included a lot of study into high altitude flight, and even required going to the local Air Force base to take the offical FAA High Altitude Training and a "flight" in their altitude chamber. We experienced rapid de-compression up to 18,000 feet (so weird to watch fog form right in front of your eyes!) and then went up to 25,000.

My TOC was about 3 minutes. I "lasted" about 7 though. I was certainly wasted by the 3rd minute though. I swore the entire thing lasted 30 seconds.

Also, we went down to 18,000 feet, turned the lights down and we all took the oxygen masks off and for about 4 minutes... then began staring at this color chart. We were told to put the oxygen back on, and within the first breath the color chart went from completely black and white, to beautiful, vivid color!

Some people had photographs, and when whey had no oxygen, it looked solid gray... but within that first breath of 100% oxygen, it was actually a very detailed satellite photo of the base!

The FAA class was about 6 hours long and was an extremely condensed version of my college class... so it was great hearing everything twice, to reinforce the concepts.

If any of you ever have the chance of taking one of these, I HIGHLY recommend it! IT'll save your life someday!

The day is always better when you're flying upside down.&&&&www.fight2flyphoto.com&&&&Canon RebelXT&&Canon 18-55mm&&Sigma 10-20mm F/4-6.3&&Sigma 100-300mm F/4-6.3&&Sigma 50-500mm F/4-6.3

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Reply #5 - Aug 16^th, 2005 at 10:03pm

Boss_BlueAngels Offline
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Oh yeah, and as for symptoms... too many to count! The list goes on and on and they are as different as the individual. For one person, they may get all happy and excited... the person next to them may get angry and start throwing things, while the person yet beside them gets a bad headache... etc.

If you ever fly even in the 8-9,000 foot levels study up on this! ESPECIALLY if you smoke! The average smoker even at sea level is physiologically at 8,000 feet with regard to oxygen use.

Oh yes, and even with all the lights on, you could certainly tell a difference in color once that oxygen hit!

The day is always better when you're flying upside down.&&&&www.fight2flyphoto.com&&&&Canon RebelXT&&Canon 18-55mm&&Sigma 10-20mm F/4-6.3&&Sigma 100-300mm F/4-6.3&&Sigma 50-500mm F/4-6.3

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Reply #6 - Aug 17^th, 2005 at 1:31am

RitterKreuz Offline
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Texas

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i remember a recent flight at FL250 at about 11:00PM it was a clear night except for a few cirrus clouds high in the flight levels. we were IFR GPS direct but could see for what seemed like miles. Mobile Alabama was about 15 miles to the 3 O'Clock position. I hit the oxygen mask for a couple of minuts, just because thats something i do on such flights. almost immediately i saw several fairly large cities that had previously gone un-noticed.

Another similar Event between Richmond and Dallas at around 38,000 feet ish. I hit the mask for a few minutes and noticed several towns dotting the dark landscape that i hadnt previously seen.

Thats about the time the Master Caution Light went to flashing. Annunciator # 12 was illuminated... Battery Overtemp (Citation V). we spent the night in Nashville. Home would have to wait another day Sad

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