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Oxygen Masks Rumors And How They Work  
User currently offlineUSAirALB From United States of America, joined Sep 2007, 3058 posts, RR: 2
Posted (6 years 9 months 2 weeks 6 days 3 hours ago) and read 5816 times:

Do the oxygen masks always work? Can you bet your life on one? I mean if your AC suffers a exposive decompression at about 41000 ft, its very unlikely you'll have time before passing out. What are the chances of me ever having to use one? I've heard stories like that when people pulling down, like the chemical oxygen generator not working. How hard do you have to pull down? How do you know the mask is working? Does the Airline check the oxygen system regulary?


E135/E140/E145/E70/E75/E90/CR2/CR7/CR9/717/732/733/734/735/73G/738/739/752/753/762/772/319/320/321/333
35 replies: All unread, showing first 25:
 
User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 1, posted (6 years 9 months 2 weeks 6 days 3 hours ago) and read 5812 times:



Quoting USAirALB (Thread starter):
I mean if your AC suffers a exposive decompression at about 41000 ft, its very unlikely you'll have time before passing out.

IIRC, the FAR's require one flight crewmember to always have an O2 mask on at or above FL390 for that very reason...that crewmember would be required to initiate an emergency descent should a decompression happen.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 2, posted (6 years 9 months 2 weeks 6 days 3 hours ago) and read 5804 times:



Quoting KELPkid (Reply 1):

IIRC, the FAR's require one flight crew member to always have an O2 mask on at or above FL390 for that very reason..

I know of no FAR Regulation to which you refer.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 3, posted (6 years 9 months 2 weeks 6 days 2 hours ago) and read 5790 times:



Quoting EMBQA (Reply 2):
I know of no FAR Regulation to which you refer.

Okay, so it was FL350.

Here it is:

§ 91.211 Supplemental oxygen.

(a) General. No person may operate a civil aircraft of U.S. registry—

(b) Pressurized cabin aircraft.
(1) No person may operate a civil aircraft of U.S. registry with a pressurized cabin—

(ii) At flight altitudes above flight level 350 unless one pilot at the controls of the airplane is wearing and using an oxygen mask that is secured and sealed and that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL), except that the one pilot need not wear and use an oxygen mask while at or below flight level 410 if there are two pilots at the controls and each pilot has a quick-donning type of oxygen mask that can be placed on the face with one hand from the ready position within 5 seconds, supplying oxygen and properly secured and sealed.

(2) Notwithstanding paragraph (b)(1)(ii) of this section, if for any reason at any time it is necessary for one pilot to leave the controls of the aircraft when operating at flight altitudes above flight level 350, the remaining pilot at the controls shall put on and use an oxygen mask until the other pilot has returned to that crewmember's station.

From:
http://ecfr.gpoaccess.gov/cgi/t/text...ew=text&node=14:2.0.1.3.10&idno=14

 Smile



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 4, posted (6 years 9 months 2 weeks 6 days 2 hours ago) and read 5780 times:

Passenger o2 systems are very reliable, most use oxygen generators that use a chemical reaction to produce the oxygen. Pulling the mask requires very little effort, (trust me, I set one off by accident) and the oxygen will last either 11 minutes or 22, depending on the regulations where you live. Plenty of time for the crew to descend to a safe altitude. It's hard to tell if it's working, as a pax in an emergency, I mean it's just oxygen, it doesn't taste funny or anything. Additionally, the odds of an explosive decompression are very small. I am sure you would have enough concious time left to grab the mask, it only takes a second, it's not rocket science.

User currently offlineUSAirALB From United States of America, joined Sep 2007, 3058 posts, RR: 2
Reply 5, posted (6 years 9 months 2 weeks 6 days 2 hours ago) and read 5767 times:



Quoting Avt007 (Reply 4):
(trust me, I set one off by accident

how can you set one off by accident

what are the odds of me having to use one like 3/10?



E135/E140/E145/E70/E75/E90/CR2/CR7/CR9/717/732/733/734/735/73G/738/739/752/753/762/772/319/320/321/333
User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 6, posted (6 years 9 months 2 weeks 6 days 1 hour ago) and read 5748 times:

As a passenger, you can't set them off by accident. During maintenance, I lowered an o2 panel, and the last guy hadn't routed the lanyard properly. It was hooked on the door latch, and when I pulled the door down, it pulled the pin out and fired the o2 generator. Since it was fired already, I used the mask to see what it was like. No smell or taste that I could sense.

User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 7, posted (6 years 9 months 2 weeks 6 days 1 hour ago) and read 5736 times:

Quoting KELPkid (Reply 3):
Okay, so it was FL350

That FAR still doesn't say that a flight crew member must be on 02 above 350. You need to read that closely....It say a crew member must wear the O2 mask....UNLESS a quick don mask is available. ALL passenger aircraft are required to have quick don O2 masks

[Edited 2007-11-13 16:51:30]


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 8, posted (6 years 9 months 2 weeks 6 days 1 hour ago) and read 5722 times:



Quoting USAirALB (Thread starter):
Do the oxygen masks always work? Can you bet your life on one? I mean if your AC suffers a exposive decompression at about 41000 ft, its very unlikely you'll have time before passing out. What are the chances of me ever having to use one? I've heard stories like that when people pulling down, like the chemical oxygen generator not working. How hard do you have to pull down? How do you know the mask is working? Does the Airline check the oxygen system regulary?

In response to you questions in order:

1. No
2. You have too if you fly commerically.
3. No problem, you will have enough time to put on the mask and get the oxygen flowing.
4. Very slim.
5. A firm tug is all it takes.
6. You don't pass out.
7. The oxygen generators are a one time use item. However, they must be replaced every 14 years. Hard line systems are periodically checked. Additionally, there are door drop tests performed to insure the door open. In a door test the door is only allow to open a small amount so you do not have to repack all the masks.


User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 9, posted (6 years 9 months 2 weeks 5 days 23 hours ago) and read 5682 times:



Quoting USAirALB (Thread starter):
I mean if your AC suffers a exposive decompression at about 41000 ft, its very unlikely you'll have time before passing out.

You have plenty of time if you are not mentally challenged (not meant to be funny). See http://en.wikipedia.org/wiki/Time_of_Useful_Consciousness for a pretty table.


User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 10, posted (6 years 9 months 2 weeks 5 days 23 hours ago) and read 5675 times:



Quoting USAirALB (Thread starter):
I've heard stories like that when people pulling down, like the chemical oxygen generator not working.

People in these situations usually misinterpret the lack of the bag filling to be equipment failure. The low flow rate (in chemical oxygen generators, an average of 2 liters per minute) prevents the bag from filling.

Quoting USAirALB (Thread starter):
How hard do you have to pull down?

You will know when the firing lanyard is pulled off.

Quoting USAirALB (Thread starter):
How do you know the mask is working?

There are several ways.
1. A burning smell, generated from the chemical oxygen generator, should be expected.
2. On certain masks, a green bar on the top of the bag inflates, or a green flow "in line" indicator in the tubing becomes visible if there is oxygen flow.
3. You could also pinch the bag where it meets the mask to see if it inflates, but this is really not a good idea if you need the oxygen...
4. There are heat-sensitive stickers stuck on the oxygen generator itself, which change color once the generator is activated. (The generators get very hot, which is reflected by the color change.) Usually only visible by maintenance.



Release your seat-belts and get out! Leave everything!
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 11, posted (6 years 9 months 2 weeks 5 days 20 hours ago) and read 5644 times:

The heat generated by an active chemical O2 Generator is tremendous  Smile

The Inspection of serviceability of both O2 Generators & portable Bottles is the responsibility of Mx.

regds
MEL



Think of the brighter side!
User currently offlineAAR90 From United States of America, joined Jan 2000, 3471 posts, RR: 47
Reply 12, posted (6 years 9 months 2 weeks 5 days 11 hours ago) and read 5572 times:



Quoting EMBQA (Reply 2):
I know of no FAR Regulation to which you refer.

Try FAR121.333



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineUSAirALB From United States of America, joined Sep 2007, 3058 posts, RR: 2
Reply 13, posted (6 years 9 months 2 weeks 5 days 4 hours ago) and read 5451 times:

do they throw the masks out after people use them?


E135/E140/E145/E70/E75/E90/CR2/CR7/CR9/717/732/733/734/735/73G/738/739/752/753/762/772/319/320/321/333
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 14, posted (6 years 9 months 2 weeks 5 days 3 hours ago) and read 5448 times:

Quoting AAR90 (Reply 12):
Try FAR121.333

...and where in that section does it state a crew member must wear an O2 mask when above 350... as was stated above...?? It states a quick don O2 mask must be avaliable

Quoting USAirALB (Reply 13):
do they throw the masks out after people use them?

Well...... The mask is part of the O2 generator. After it's used it is removed as an assembly. With th e cost to re-cert over just replacing... I'm sure the used O2 mask is just destroyed (they are just rubber and plastic)

[Edited 2007-11-14 14:04:02]


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineAAR90 From United States of America, joined Jan 2000, 3471 posts, RR: 47
Reply 15, posted (6 years 9 months 2 weeks 5 days 3 hours ago) and read 5437 times:



Quoting EMBQA (Reply 14):
...and where in that section does it state a crew member must wear an O2 mask when above 350... as was stated above...?? It states a quick don O2 mask must be avaliable

Classic government lawyer writing. Read carefully {quoted with emphasis added}:

(2) When operating at flight altitudes above flight level 250, one pilot at the controls of the airplane shall at all times wear and use an oxygen mask secured, sealed, and supplying oxygen, in accordance with the following:

(i) The one pilot need not wear and use an oxygen mask at or below the following flight levels if each flight crewmember on flight deck duty has a quick-donning type of oxygen mask that the certificate holder has shown can be placed on the face from its ready position, properly secured, sealed, and supplying oxygen upon demand, with one hand and within five seconds:

(A) For airplanes having a passenger seat configuration of more than 30 seats, excluding any required crewmember seat, or a payload capacity of more than 7,500 pounds, at or below flight level 410.

(B) For airplanes having a passenger seat configuration of less than 31 seats, excluding any required crewmember seat, and a payload capacity of 7,500 pounds or less, at or below flight level 350.


Translation: Above the listed flight levels one pilot is STILL REQUIRED to use supplemental oxygen. The mask type "exception" does NOT apply.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 16, posted (6 years 9 months 2 weeks 5 days 3 hours ago) and read 5428 times:

Quoting HAWK21M (Reply 11):
The heat generated by an active chemical O2 Generator is tremendous


 checkmark  A fire resultant from the heat of illegally shipped and unintentionally-set off O2 generators in the cargo hold, along with them supplying oxygen, is what brought down ValuJet 592.

[Edited 2007-11-14 14:57:00]

User currently offlineJetstar From United States of America, joined May 2003, 1645 posts, RR: 10
Reply 17, posted (6 years 9 months 2 weeks 5 days 2 hours ago) and read 5416 times:
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I believe there is another regulation which requires that if one pilot leaves the cockpit while at altitude for whatever reason, then the remaining pilot must wear and use oxygen until that other pilot returns.

User currently offlineAAR90 From United States of America, joined Jan 2000, 3471 posts, RR: 47
Reply 18, posted (6 years 9 months 2 weeks 5 days 1 hour ago) and read 5397 times:



Quoting Jetstar (Reply 17):
I believe there is another regulation which requires....

Sub-section 3 of the same FAR 121.333.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 19, posted (6 years 9 months 2 weeks 5 days 1 hour ago) and read 5392 times:



Quoting USAirALB (Reply 13):
do they throw the masks out after people use them?



Quoting EMBQA (Reply 14):
Well...... The mask is part of the O2 generator. After it's used it is removed as an assembly. With th e cost to re-cert over just replacing... I'm sure the used O2 mask is just destroyed (they are just rubber and plastic)

One would assume that all masks that were used during an actual emergency would be replaced. However, masks that are inadvertently dropped (due to malfunction or a test) are repacked and re-stowed. Additionally, the masks and the hoses are removable from the O2 generators.


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 20, posted (6 years 9 months 2 weeks 4 days 23 hours ago) and read 5348 times:



Quoting N231YE (Reply 16):
A fire resultant from the heat of illegally shipped and unintentionally-set off O2 generators in the cargo hold

They were not illegally shipped. Up until then it was legal to ship them. You just had to follow the safety guidelines. In the case of Valuejet 592 the units were marked as depleted and were not. Also, they were not shipped with the required safety caps



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 21, posted (6 years 9 months 2 weeks 4 days 23 hours ago) and read 5346 times:



Quoting USAirALB (Thread starter):
Do the oxygen masks always work?

No.

Quoting USAirALB (Thread starter):
Can you bet your life on one?

Yes. If it malfunctions you'll pass out, but you won't die before the crew gets the aircraft down to a breathable altitude.

Quoting USAirALB (Thread starter):
I mean if your AC suffers a exposive decompression at about 41000 ft, its very unlikely you'll have time before passing out. What are the chances of me ever having to use one?

You'll have time. But the chances of you having to use one are very very low.

Tom.


User currently offlineCF188A From , joined Dec 1969, posts, RR:
Reply 22, posted (6 years 9 months 2 weeks 4 days 20 hours ago) and read 5317 times:



Quoting KELPkid (Reply 1):

From the little knowledge I have on this Topic, I was told it varies airline to airline . I could be wrong but I am pretty sire this is correct as well


User currently offlineAAR90 From United States of America, joined Jan 2000, 3471 posts, RR: 47
Reply 23, posted (6 years 9 months 2 weeks 4 days 19 hours ago) and read 5301 times:



Quoting CF188A (Reply 22):
From the little knowledge I have on this Topic, I was told it varies airline to airline . I could be wrong but I am pretty sire this is correct as well

Please read the above quoted FAR. An airline may have a policy more restrictive than the FAR, but may not operate less restrictive than the FAR.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 24, posted (6 years 9 months 2 weeks 4 days 19 hours ago) and read 5296 times:

Quoting Tdscanuck (Reply 21):
If it malfunctions you'll pass out, but you won't die before the crew gets the aircraft down to a breathable altitude.

That's if the pilots don't fail to put their masks on (or realize they need to put them on) and just keep flying until they pass out as well, then the autopilot keeps flying until it runs out of fuel: Helios Airways Flight 522.

[Edited 2007-11-14 22:44:10]

25 Post contains images N231YE : Thus they were shipped illegally?
26 HAWK21M : Rather Not conforming to the Criteria for Packaged goods as Cargo. regds MEL
27 USAirALB : what do you mean pass out?
28 KELPkid : Which, in the USA, would be a federal offense (violation of the FAR's).
29 Jetstar : The normal procedure when the O2 generators time out is to put them in a metal bucket filled with sand and pull the firing pin and let them discharge,
30 Tdscanuck : Lose consciousness. Tom.
31 Pilotboi : Pass out is when your brain is not getting enough oxygen and decides it needs to go on standby. You still breathe, just less then normal. After an ex
32 TristarSteve : 2 or 3 years ago there was an incident with a B737 in the UK. They were near Top of Descent when there was a decompression. The crew donned their mask
33 BAe146QT : USAirALB: I don't know whether your question comes from; a) idle curiosity b) a genuine fear c) journalistic intentions Whatever the case, (it's none
34 TristarSteve : I would like to second that. I have worked with airliners since 1970, and have only once been invoved with all the masks dropping. And that was on an
35 TZTriStar500 : While this is logically true, the FAR 121 does require 30% extra masks over the cabin configuration capacity to "make-up" for some failure, allow lim
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