Even though oxygen is flowing...
Even though oxygen is flowing...
(OP)
The usual wording of the oxygen mask portion of the airline "safety briefing" is"
This has always struck me as not quite right. Obviously this leaves open the question:
"If oxygen is not flowing, will the plastic bag still not inflate? If so, how can I really know if oxygen is flowing or not?"
A somewhat better wording might be:
"When oxygen is flowing, the plastic bay may not inflate."
Although this leaves the same question open.
More truthful might be:
"Trust us, some gas will probably be flowing, and if you're lucky it might even be oxygen. The plastic bag may or may not inflate, so you will have no way of telling. Don't worry, if hypoxia sets in you really won't care anyway."
Quote:
Even though oxygen is flowing, the plastic bag may not inflate.
This has always struck me as not quite right. Obviously this leaves open the question:
"If oxygen is not flowing, will the plastic bag still not inflate? If so, how can I really know if oxygen is flowing or not?"
A somewhat better wording might be:
"When oxygen is flowing, the plastic bay may not inflate."
Although this leaves the same question open.
More truthful might be:
"Trust us, some gas will probably be flowing, and if you're lucky it might even be oxygen. The plastic bag may or may not inflate, so you will have no way of telling. Don't worry, if hypoxia sets in you really won't care anyway."





RE: Even though oxygen is flowing...
With this in mind, the advice might as well be:
"Put the mask on and keep it on. If it doesn't work, you won't have the time either to find out, or to do anything about it. If you can't take a joke, you shouldn't have joined"
A.
RE: Even though oxygen is flowing...
What is the general scenario when decompression of an airplane happens? Is there chaos and does everything get sucked out as in the films? Does the plane go out of control and plummet with the pilots wrestling the controls?
Is it survivable (if not then all the oxygen in MintJulep's bag won't matter a damn)?
Should I be worried?
Any offers?
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
"We have supplied a lifejacket for each passenger. Don't bother looking for it, if you ever need it then a miracle has occurred, since in the entire history of civilian jet-liners nobody has ever used one successfully."
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
Back in the eighties, I was cheerfully told (as I climbed aboard) that if we ditched, the latest type-specific modelling had shown there would be a massive snap-down that would subject everyone at the front of the jet to several tens of fast onset G, making a water landing unsurviveable for at least half the crew.
Some years later one of these jets did go into the water and the entire crew walked away from it.
Guess it all depends.
A.
RE: Even though oxygen is flowing...
Myth Busters (TV) explored precisely this aircraft explosive decompression scenario.
Using a fuselage on the ground they pressurised it to the equivalent of 30,000 ft or so and from inside fired a pistol through the window (remote control).
No damage to the dummy in the seat by the window. The window didn't fragment.
The most successful attempt to recreate this scenario was when they exploded a small charge right next to the fuselage. This ripped open the plane like a sardine can. The dummy was not pretty but was still in its seat.
They have similarly debiunked some of the other movie myths such as attaching a wire rope to the back axle of a police car ... when it took off, the rope broke.
Perhaps they will address the Al Gore film next.
JMW
www.ViscoAnalyser.com
RE: Even though oxygen is flowing...
To answer you question "It depends."
I pretty much always leave my seat belt on, both to possibly avoid to being sucked out if a decompression occurs, and more practically, to avoid banging the cabin overhead in case of turbulence.
Regards,
Mike
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
Luis
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
O2 systems are probably in the same boat (plane?), a big investment for a safety system that just about is never used, and probably hasn't saved a significant number of pax. in any case, why give the pax O2 ? the plane will descend quickly enough that the pax will be O2 deprived for only a minute and so (for the most part) suffer no harmfull side effects. and consider the flip side, can you imagine being on O2 (as a pax) where for some horrible reason the pilots aren't ?
RE: Even though oxygen is flowing...
Hg
Eng-Tips policies: FAQ731-376
RE: Even though oxygen is flowing...
How can you kiss your fanny goodbye and still manage to get the mask on at the same time?
50% of the British population couldn't do this.
2 nations divided by a common language...
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
The gotcha with airliner flight is this: If you've been breathing air at a cabin altitude of 0 Ft (as in your breath-holding example - giving a PPO2 of 0.21 bar), or breathing an O2-enriched mix at a cabin altitude of around 10 000 Ft (as you might expect in a modern combat aircraft), then your bloodstream is carrying a significant reservoir of oxygen that can be drawn on - perhaps for up to three minutes - if you suddenly lose the opportunity to breathe in anything helpful.
If instead, you breathe air at a cabin altitude of 10 000 Ft, you're actually getting less than 0.15 bar PPO2, which is right on the border of hypoxia (and this is before anything accidental goes wrong).
Once the window goes and you're at a cabin altitude of 30 000 Ft, the PPO2 in the cabin drops to about 0.06 bar, and you're completely dependent on whatever is stored in your body.
A.
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
RE: Even though oxygen is flowing...
You'd think they could spare a whole can? Naaa.
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RE: Even though oxygen is flowing...
It's a plot I tell you.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Even though oxygen is flowing...
Hg
Eng-Tips policies: FAQ731-376
RE: Even though oxygen is flowing...
Timing has an awful lot to do with the outcome of a rain dance.
RE: Even though oxygen is flowing...
This is the Air Accident Investigation Board's report:
http://w
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Sometimes I only open my mouth to swap feet...
RE: Even though oxygen is flowing...
This despite the fact that from my degree (aero), limited Aero work experience, applying to the air force, flying scholarship etc I probably know far more of the things that can go wrong than most of the other passengers.
JNieuwsma I wouldn't recommend holding your breath during a rapid decompression, for the same reason you don't hold it when escaping from a submarine. The air in your lungs is at the relatively higher pre decompression pressure. This will cause your lungs to tend to expand. Now I'm not sure the effective pressure difference would actually make you blow up but there could be some unpleasant effects, are you sure you want to risk it?
One thing worth mentioning, take the warning not to use cell phones seriously. Despite rumors to the contrary there have been incidents where the cause was believed to be passengers using cell phones. Now obviously if the FAA decides at some point in the near future it's OK then they must know what they are doing but till then...
Also one of the incidents wasn't just navigation aids playing up (which except during instrument landing is fairly unlikely to be fatal). An aircraft fitted with FADEC had trouble with fuel valves intermittently closing causing engine problems, last I heard their best guess was a passenger using a cell phone caused it. (Maybe an aero person has more up to date info on this)
RE: Even though oxygen is flowing...
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Even though oxygen is flowing...