Oxygen Masks Are For Decoration

[NSEU]

http://www.pprune.org/forums/showthread.php?t=311535

I'd love to hear a doctor's response to "Eat My Shorts"'s comments :confused:

[obgraham]

A typical ill informed comment. There's a reason the 10,000' altitude is advised.

[BelArgUSA]

And I hope that doctor knows about airline 02 masks, flight crew type and cabin type masks
xxx
And after being briefed as to how they work, he will tell you something to the effect that, indeed cockpit flight crew masks are somewhat adequate for use up to about 32-33,000 feet... if well sealed on the face. He will certainly recommend not to rely on them for any extended amount of time above, shall I say about 25,000 feet. These are not "pressure type" 02 masks.
xxx
And bad news for the cabin type masks, for passengers. The comments of "Eat My Shorts" are no far from the sad truth. Again, these are rubber cups which do not fit well, leak a lot of 02, and the 02 is just a free flow, without pressure. I would say (military pilot aeromedical pressure chamber training) that they help sustain life at a cabin altitude of maybe 14 or 15,000 feet.
xxx
Loss of cabin pressure, yes, an emergency descent is necessary. No doubt about it. Get to these lower 15,000 to 20,000 feet ASAP. Then, hope for the best. If healthy, most people will be ok... hopefully.
xxx
The 10,000 feet is an arbitrary figure... In the FAA, CAA and JAR books.
Maybe other books.
I doubt it means anything to people who live all their life at 10,000 feet in Quito, Ecuador. You and I feel tired when on layover, in Quito, or even only in Bogota's 7,000 feet MSL... And how about of the people living around La Paz in Bolivia at 13,500 feet elevation, maybe with a QNH of 950 mB at times.
xxx
With PanAm, if we had to operate in La Paz, we would have been required to use our masks at all times on the ground. The guys with LAB or Ecuatoriana dont do that (they probably are healthier, munching their coca leaves).
xxx
As to descending to 10,000 feet for your emergency descent, fine and dandy if you are over the Netherlands or Ireland... Watch-out going from Argentina to Chile... The summits are at 24,000 feet. The 10,000 feet rule is the common denominator for most people, yet most of us, healthy pilots, with a Class 1 JAR medical can live perfectly at 14,000 feet. Just very tired if we party and booze a lot... or smoke.
xxx
I crossed the Andes with my little plane, a L-21 Super Cub, from Mendoza, Argentina, to Santiago, Chile, a few years ago (the most scenic flight experience ever of my life). I had an oxygen bottle and mask (remembering the 10,000 feet rule) and had to negotiate a mountain pass at 14,000 feet.
The 02 bottle was there... I have to admit that I did not use it.
xxx
Passenger masks are next to be worthless... that is what I know...
And however excellent JAR training standards are, and your MCCs, and your modular courses or frozen ATPLs might be, I would personally recommend to forget all that and require pressure chamber training for any crewmember who flies an aircraft certificated for operations above FL 250.
xxx

Oh, by the way, in airlines, we keep the cabin altitude generally around 7 or 7,500 feet.
xxx
:)
Happy contrails

[BelArgUSA]

Hola obgraham -
xxx
Indeed - cabin masks are working (let me use the word "somewhat") for typical 10-15,000 feet. I did not say worthless at these cabin altitudes... but I dont count on them to do their job at 20,000 feet.
xxx
One thing we all have to do on Pprune, you, myself and everyone else, is read what the words are and what they mean. According to FAA (and probably JAR 25 since similar), cabin masks sustain life up to 14,000 feet cabin altitude. Beyong that... it is a guess.
xxx
You know, it is funny... What I pass along here in Pprune, as info to people, from aviation enthusiasts to pilots, are official information I teach (or my instructor team teach) with my airline. If I am wrong, realize that my own airline crews are all wrong, and maybe could be subject to a lawsuit for training malpractice...
xxx
Our official policy, in Argentina is...
Maintain cabin altitude below 8,000 feet when possible.
If circumstances dictate, acceptable (unlimited time) at/below 10,000 feet.
In case of system failure, cabin to be maintained at/below 14,000 feet.
If ground elevation does not permit, in function of min. enroute altitude.
xxx
Cockpit crew using O2 if cabin altitude above 14,000 feet.
Recommended use of O2 when cabin altitude exceeds 10,000 feet.
Remember... we operate to La Paz in Bolivia.
We have a circuit breaker to pull to prevent cabin altitude warning.
And to prevent cabin O2 masks to drop at 14,000 feet.
(Boeing high altitude operations STC)
xxx
Hope we get a doctor from the aeromedical branch here... Cheers -
:)
Happy contrails

[obgraham]

BelArg: I decided to withdraw from this discussion.
I did find LaPaz and El Alto an "interesting" location
Regards.

[BelArgUSA]

You should not, obgraham -
xxx
You know, we all learn from each other here, even a lot.
And when you, or someone else does not agree, let us say it in the clear.
I am just a pilot in charge of pilot training where I work.
And I teach following my curriculum, and the manuals I have...
My O2 knowledge comes from a USAF manual "Your body in flight" - 1963 edition.
They gave us that book when student pilots had to go through the pressure chamber.
And sometimes, I learn from others... even from classroom trainees.
All the best to you -
xxx
:)
Happy contrails

[Wader2]

The 10,000 feet is an arbitrary figure... In the FAA, CAA and JAR books.
Maybe other books.
I doubt it means anything to people who live all their life at 10,000 feet in Quito, Ecuador.

I would challenge the 10000 foot rule as arbitary. I would contend that it was obtained from emperical evidence. It is necessarily an imprecise value as evidenced by the acclimatisation of Ecuadorians or the apparent ability of BelArgUSA to fly with unimpaired functions at 14000 feet.

Many thousands of aircrew have flown in unpressurised aircraft and their abilities and functions observed. In a stress free and passive state the rule was that a passenger did not require oxygen until higher than 12500 feet whereas active aircrew needed oxygen above 10000 feet. Certainly moving around the cabin and doing any work, even going to the toilet, was hard work without oxygen.

We had one flight engineer who was sown the back with us with a happy smile on his face. in his own opinion he was 100% AOK. His captain, OTOH was concerned that he had been off oxygen for 20 minutes at an altitude of 15000 feet.

Man is no accurate judge of his abilities when he is hypoxic, just lucky. I am extremely lucky, I feel nauseous and ill long before I sucumb to hypoxia.