USAirALB
Topic Author
Posts: 1672
Joined: Tue Sep 11, 2007 4:46 am

Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 10:13 pm

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/738/739/752/753/762/772/77W/319/320/321/333/343
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 10:28 pm



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 :-)
 
EMBQA
Posts: 7798
Joined: Sat Oct 25, 2003 3:52 am

RE: Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 10:42 pm



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"
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 11:08 pm



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 :-)
 
avt007
Posts: 1989
Joined: Mon Jul 10, 2000 4:51 am

RE: Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 11:27 pm

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.
 
USAirALB
Topic Author
Posts: 1672
Joined: Tue Sep 11, 2007 4:46 am

RE: Oxygen Masks Rumors And How They Work

Tue Nov 13, 2007 11:44 pm



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/738/739/752/753/762/772/77W/319/320/321/333/343
 
avt007
Posts: 1989
Joined: Mon Jul 10, 2000 4:51 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 12:17 am

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.
 
EMBQA
Posts: 7798
Joined: Sat Oct 25, 2003 3:52 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 12:46 am

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"
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 12:55 am



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.
 
pilotboi
Posts: 711
Joined: Thu Sep 06, 2007 8:16 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 2:41 am



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.
 
Markhkg
Posts: 838
Joined: Mon Dec 05, 2005 4:13 pm

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 2:51 am



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 avatar
HAWK21M
Posts: 29929
Joined: Fri Jan 05, 2001 10:05 pm

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 5:53 am

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
I may not win often, but I damn well never lose!!! ;)
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 2:19 pm



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!
 
USAirALB
Topic Author
Posts: 1672
Joined: Tue Sep 11, 2007 4:46 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 9:54 pm

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/738/739/752/753/762/772/77W/319/320/321/333/343
 
EMBQA
Posts: 7798
Joined: Sat Oct 25, 2003 3:52 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 9:59 pm

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"
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 10:30 pm



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!
 
N231YE
Posts: 2620
Joined: Tue Jul 25, 2006 9:24 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 10:52 pm

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]
 
jetstar
Posts: 1374
Joined: Mon May 19, 2003 2:16 am

RE: Oxygen Masks Rumors And How They Work

Wed Nov 14, 2007 11:18 pm

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.
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 12:11 am



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!
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 12:18 am



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.
 
EMBQA
Posts: 7798
Joined: Sat Oct 25, 2003 3:52 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 2:41 am



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"
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 2:45 am



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.
 
CF188A
Posts: 680
Joined: Sun May 07, 2006 12:27 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 5:26 am



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
Dream as if you'll live forever. Live as if you'll die tomorrow~ RIP ... LJFM
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 6:24 am



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!
 
pilotboi
Posts: 711
Joined: Thu Sep 06, 2007 8:16 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 6:41 am

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]
 
N231YE
Posts: 2620
Joined: Tue Jul 25, 2006 9:24 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 3:52 pm



Quoting EMBQA (Reply 20):
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

Thus they were shipped illegally?  smile 
 
User avatar
HAWK21M
Posts: 29929
Joined: Fri Jan 05, 2001 10:05 pm

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 8:18 pm



Quoting N231YE (Reply 25):
Thus they were shipped illegally

Rather Not conforming to the Criteria for Packaged goods as Cargo.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
USAirALB
Topic Author
Posts: 1672
Joined: Tue Sep 11, 2007 4:46 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 10:40 pm



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

what do you mean pass out?
E135/E140/E145/E70/E75/E90/CR2/CR7/CR9/717/732/733/734/735/73G/738/739/752/753/762/772/77W/319/320/321/333/343
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Oxygen Masks Rumors And How They Work

Thu Nov 15, 2007 11:19 pm



Quoting HAWK21M (Reply 26):
Rather Not conforming to the Criteria for Packaged goods as Cargo.
regds
MEL

Which, in the USA, would be a federal offense (violation of the FAR's).
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
jetstar
Posts: 1374
Joined: Mon May 19, 2003 2:16 am

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 2:46 am

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, then the depleted containers can be scrapped.

In the Value Jet incident, the timed out O2 were removed by Sabre Tech, the outside vendor doing the work on the new airplanes that Value Jet acquired, the O2 generators were considered Value Jet company material and were turned over to Value Jet for disposal.

Both parties were found to be responsible, Sabre Tech for not properly tagging and securing the O2 generators and Value Jet for transporting them without properly checking that they were secured. AFAIK it was legal then to transport the O2 generators in the baggage compartment if they were properly secured and packaged so it was not any violation of federal laws at the time. I believe that has now been changed and they cannot be transported on passenger airplanes, I do not know about cargo airplanes

I believe the Value Jet tech rep should have been held the most responsible, they were timed out and not useable anymore and he should have just disposed of them, they were not worth anything other than the value of the scrap metal so there was no need to ship them back to ATL.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 2:51 am



Quoting USAirALB (Reply 27):
Quoting Tdscanuck (Reply 21):
Yes. If it malfunctions you'll pass out, but you won't die before the crew gets the aircraft down to a breathable altitude.

what do you mean pass out?

Lose consciousness.

Tom.
 
pilotboi
Posts: 711
Joined: Thu Sep 06, 2007 8:16 am

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 2:58 am



Quoting USAirALB (Reply 27):
what do you mean pass out?

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 extended period of time, brain cells start dieing, and eventually it turns completly off and you don't wake up.
 
Tristarsteve
Posts: 3373
Joined: Tue Nov 22, 2005 11:04 pm

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 9:41 am

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 masks, but the Captain knocked his glasses off. He leant fwd to get his glasses off the floor, and took his mask off to do it. He passed out and fell on the controls. It was nearly a nasty incident.

Out long haul aircraft are fitted with gaseous oxygen systems, not generators. The problem is flying over the Himalayas you cannot descend to 10000ft in the 22 mins allowed. But our B767 fleet have generators. When they flew on a route that was affected by high ground, we fitted shedfulls of portable oxygen bottles, there were something like 60 bottles for the 180 pax. Perhaps you were meant to share them?
 
BAE146QT
Posts: 981
Joined: Sun Sep 24, 2006 4:58 am

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 6:02 pm

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 of my business) the odds of you not only experiencing a blowout, but also having a mask that fails, are probably on par with you winning the UK lottery two weeks running. With the same six numbers.

Odds don't speak well to fear though - I understand that. So if you want to further mitigate the risk, you can help yourself;

1) Don't smoke
2) Increase your lung capacity through low-impact cardio-vascular exercise, including yoga and step aerobics.
3) Acclimatise yourself to low-oxygen conditions - go find a mountain to climb and do it a couple times a year.

All of this might buy you a few extra seconds.

Remember that, Helios aside, the guys up front will take the aircaft down as fast as they can, to somewhere you can breathe on your own.

One last note - Once upon a time, sex was safe and flying was dangerous. Now you live in a world where it's the other way around.
Todos mis dominós son totalmente pegajosos
 
Tristarsteve
Posts: 3373
Joined: Tue Nov 22, 2005 11:04 pm

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 7:47 pm



Quoting BAe146QT (Reply 33):
Whatever the case, (it's none of my business) the odds of you not only experiencing a blowout, but also having a mask that fails, are probably on par with you winning the UK lottery two weeks running. With the same six numbers.

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 L1011 in 1979 when the captain pressed the wrong button in the cockpit!!!!!!
 
User avatar
TZTriStar500
Posts: 872
Joined: Sat Jan 03, 2004 1:33 am

RE: Oxygen Masks Rumors And How They Work

Fri Nov 16, 2007 11:04 pm



Quoting Tdscanuck (Reply 21):
Quoting USAirALB (Thread starter):
Do the oxygen masks always work?

No.

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 limited movement by crew, and allow for enough masks for lap children. In fact, each lavatory has two and in general on a narrowbody any triple seat has four masks above it.
35 years of American Trans Air/ATA Airlines, 1973-2008. A great little airline that will not be soon forgotten.

Who is online

Users browsing this forum: greg85, ro1960, VictorKJ, Vinka and 18 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos