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>> You will pass out in 15 seconds no matter how calm you are. Well, I certainly didn't. In training (military) I did a pressure chamber day with 33,000ft bre

>> You will pass out in 15 seconds no matter how calm you are. Well, I certainly didn't. In training (military) I did a pressure chamber day with 33,000ft breathing (lots of fun, do it if you ever get the chance). They took us to 12,000 in a big chamber and then fed us a reduced oxygen via masks to simulate 33,000ft. After about a minute I certainly felt effects, but I was very much awake long long after 15 seconds. I was playing solitaire on an iPad thing. After everyone noticed their personal symptoms they switched us over to pure O2. Some experienced tunnel vision and such. All I ever felt was as slight headache and that I was doing worse at the ipad game. I was awake enough to remember the Sargent who walked up and down the chamber looking us in the eye to see if we were awake. He was scary.

rezonant 5y ago
You can undergo training to improve function during hypoxic events and some people are naturally better at dealing with it, but that doesn't mean the general population will have the same experience, so I don't think removing this vital tool for aircraft safety is a good call due to a single incident (let me know if you have a reference on that as I'm very curious). It would make more sense to determine why the incident occurred and modify the design of the oxygen generators to avoid that scenario in the future, which is what I assumed happened.
morcheeba 5y ago
There are different kinds of training - it sounds like you got a good one, but it's not fully simulating a blown-door situation. There's a difference between less oxygen @12,000ft and the actual low pressure of 33,000ft: The higher altitude has about 1/3rd the pressure of the lower altitude, so it actively removes oxygen from your body (lungs, blood) faster. But simulating with an abrupt 33,000 feet would cause ear pressure problems, and it's a lot safer (and quickly reversible) to just play with the oxygen concentration. Also, in this thread, I think you all know this, but wanted to make sure - a chemical oxygen generator "burns" to produce oxygen. The exothermic reaction is started with a small explosive; burning means its producing oxygen. Of course, in the 592 crash, they weren't properly packed with heat shielding, so catching other things on fire (plus the excess oxygen) was the cause of the crash. https://en.wikipedia.org/wiki/Chemical_oxygen_generator https://en.wikipedia.org/wiki/Chemical_oxygen_generator
- sandworm101 5y ago
  We did explosive decompression from sea level to 10,000. Fun stuff. Clouds form in the chamber. Going higher than that isnt actually much more violent as the bulk of the atmo is below 10,000. As for oxygen, what matters is the partial pressure of the oxygen rather than the pressure of the other gasses. Breath pure nitrogen at sea level and you will pass out just as quicky as at altitude.

rezonant 5y ago

You can undergo training to improve function during hypoxic events and some people are naturally better at dealing with it, but that doesn't mean the general population will have the same experience, so I don't think removing this vital tool for aircraft safety is a good call due to a single incident (let me know if you have a reference on that as I'm very curious). It would make more sense to determine why the incident occurred and modify the design of the oxygen generators to avoid that scenario in the future, which is what I assumed happened.

morcheeba 5y ago

There are different kinds of training - it sounds like you got a good one, but it's not fully simulating a blown-door situation. There's a difference between less oxygen @12,000ft and the actual low pressure of 33,000ft: The higher altitude has about 1/3rd the pressure of the lower altitude, so it actively removes oxygen from your body (lungs, blood) faster. But simulating with an abrupt 33,000 feet would cause ear pressure problems, and it's a lot safer (and quickly reversible) to just play with the oxygen concentration. Also, in this thread, I think you all know this, but wanted to make sure - a chemical oxygen generator "burns" to produce oxygen. The exothermic reaction is started with a small explosive; burning means its producing oxygen. Of course, in the 592 crash, they weren't properly packed with heat shielding, so catching other things on fire (plus the excess oxygen) was the cause of the crash. https://en.wikipedia.org/wiki/Chemical_oxygen_generator https://en.wikipedia.org/wiki/Chemical_oxygen_generator

sandworm101 5y ago
We did explosive decompression from sea level to 10,000. Fun stuff. Clouds form in the chamber. Going higher than that isnt actually much more violent as the bulk of the atmo is below 10,000. As for oxygen, what matters is the partial pressure of the oxygen rather than the pressure of the other gasses. Breath pure nitrogen at sea level and you will pass out just as quicky as at altitude.