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AKA 'why is the safety briefing/training inadequate'. I tried Googling my title and got lots of sites explaining the emergency oxygen systems, procedures etc. that I already mostly knew. The briefing: 'Pull sharply on the tube to start the flow of oxygen' is not exactly fully informative or reassuring. The things look so fragile that it must be fairly easy to rip the tube away from the oxygen generator/supply bus pipe/whatever.

How am I supposed to know how hard to pull? Is there some sort of click/detent that can be felt as I pull on the tube that indicates 'OK, you've turned the oxygen on'?

Could not a simple mechanical flag indicate oxygen on, eg 'Pull on the tube until the indicator flag turns green', or the like?

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    $\begingroup$ Perhaps a more informative question would be to ask what the mechanism that triggers oxygen release is. Knowing that should give you an idea what kind of pull would work best to avoid damaging the equipment. $\endgroup$ – Lie Ryan Dec 7 '14 at 2:08
  • $\begingroup$ This is a question that I also thought of, while in the airplane. But just think of it that way: The FAA will only consider the plane airworthy if you can't rip the mask out trying to follow the safety instructions. Their european counterparts even tested it with the average John Doe: They put some John Does into a mockup plane, play them the safety video, and watched whether/how they helped themselves once the oxygen masks fell down. $\endgroup$ – Alexander Dec 8 '14 at 9:07
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When they first fall down they'll be too high to reach your head, pulling on them will release a switch to activate the generator and release enough slack in the line to reach down to your chest comfortably (for children).

Some types are suspended by a cord connected to the switch:

enter image description here
(image source: wikipedia)

Then you will just need to pull until the cord disconnects from the ceiling.

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    $\begingroup$ Any idea how much oxygen is available for the passengers, for example, enough for 5minutes / 15minutes / 30 minutes / 6 minutes $\endgroup$ – Firee Dec 10 '14 at 7:39
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    $\begingroup$ @Firee 15 minutes $\endgroup$ – ratchet freak Dec 10 '14 at 8:44
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    $\begingroup$ Thanks.. One more small query, can't they use re-breather's instead? $\endgroup$ – Firee Dec 10 '14 at 10:46
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    $\begingroup$ @Firee nope you need the oxygen at that altitude by the time you put on the rebreather you are already breathing the thin air, and after a while the air inside the rebreather will be further starved of oxygen. $\endgroup$ – ratchet freak Dec 10 '14 at 10:52
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You can't really pull too hard. The tube (or a separate cord) is held in place by a pin. As you pull down, you will pull the pin out and trigger the oxygen generator.

Once the pin comes out, there will be much more slack tube in your hand and the resistance will drop to zero. At that point, you shouldn't need to pull any more.

Instead of thinking how hard to pull, just think that you need to pull the mask to your face. If you do that, it'll work just fine.

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