What is cabin air pressure set at

[scm]

In a commercial airline, I realize that the cabin is pressureizd, but I know
that it is not kept at a sea level pressure. What effective "altitude" is
the passenger cabin kept at? Is it the same for all air liners?

The reason I am asking is that I have to use a CPAP machine to breath while
I sleep, (Continuous positive air pressure) for sleep apnea. I am
contemplating a trip to Hawaii where I will have to sleep during the flight.
Issues about whether I can power my equipment asside, I would need to know
what my effective altitude is to know how to set up my CPAP machine.

Thanks
Stephen

[Gord Beaman]

"scm" > wrote:

>In a commercial airline, I realize that the cabin is pressureizd, but I know
>that it is not kept at a sea level pressure. What effective "altitude" is
>the passenger cabin kept at? Is it the same for all air liners?
>
>The reason I am asking is that I have to use a CPAP machine to breath while
>I sleep, (Continuous positive air pressure) for sleep apnea. I am
>contemplating a trip to Hawaii where I will have to sleep during the flight.
>Issues about whether I can power my equipment asside, I would need to know
>what my effective altitude is to know how to set up my CPAP machine.
>
>Thanks
>Stephen
>
I'm fairly sure that it's around 8,000 feet in most cases.

I use oxygen and I needed to know for that reason. I flew across
the Continent and back last year and did some research on it
then.

Incidentally, the airlines have some quite weird rules governing
stuff like that, some allow you to bring aboard your own oxygen
in limited amounts. Some will rent their own equip to you only,
(and they know bugger-all about it themselves so you better know
how to handle it etc...)

I'd also suggest that you not get too snippy about it, they have
a million rules so as to cover all contingencies and they'll just
leave you on the ramp. I see their point too. You can't make an
omelet without breaking the odd egg.
--

-Gord.
(use gordon in email)

[David Cartwright]

"scm" > wrote in message
...
> The reason I am asking is that I have to use a CPAP machine to breath
> while I sleep, (Continuous positive air pressure) for sleep apnea. I am
> contemplating a trip to Hawaii where I will have to sleep during the
> flight. Issues about whether I can power my equipment asside, I would need
> to know what my effective altitude is to know how to set up my CPAP
> machine.

I've heard it's about 6,000 feet, though another poster has mentioned 8,000
and it sounds like they've done more research than me. My reason for
posting, though, is to say that I'd thoroughly recommend talking to the
airline(s) you're thinking of flying with. I'm sure they come across
instances like your own from time to time, and will be able to answer all
your questions not just with regard to what altitude to set but also
concerning the logistics of boarding your equipment, powering it, etc.

D.

[jmk]

Both sets of numbers are correct. Early pressurized airliners were at
6000 MSL. Later, as they started flying higher and higher (especially
for oceanic routes) it was raised to 8000 MSL. This saves lots of
money - it increases airframe life and reduces fuel bills. Now all the
major carriers are flying with an 8000 foot cabin pressure.

There are talks about the newest generation of superliners being able
to give a superior "coach experience" by being back to 6000, but don't
hold your breath. [Pun intended.]

[Gord Beaman]

"jmk" > wrote:

>Both sets of numbers are correct. Early pressurized airliners were at
>6000 MSL. Later, as they started flying higher and higher (especially
>for oceanic routes) it was raised to 8000 MSL. This saves lots of
>money - it increases airframe life and reduces fuel bills. Now all the
>major carriers are flying with an 8000 foot cabin pressure.
>
>There are talks about the newest generation of superliners being able
>to give a superior "coach experience" by being back to 6000, but don't
>hold your breath. [Pun intended.]

And don't expect to be able to tell the difference either. I flew
some pressurized but mostly unpressurized aircraft for over 25
years and I defy anyone to tell the difference between sealevel
and 15,000 as long as they're not physically working, are in
average physical shape, cannot see outside the aircraft and have
no instruments...so this particular 'coach experience' claim is
just hype...
--

-Gord.
(use gordon in email)

[Dave]

So passing out counts as "not physically working" at 15k right?

"Gord Beaman" > wrote in message
...
> "jmk" > wrote:
>
>>Both sets of numbers are correct. Early pressurized airliners were at
>>6000 MSL. Later, as they started flying higher and higher (especially
>>for oceanic routes) it was raised to 8000 MSL. This saves lots of
>>money - it increases airframe life and reduces fuel bills. Now all the
>>major carriers are flying with an 8000 foot cabin pressure.
>>
>>There are talks about the newest generation of superliners being able
>>to give a superior "coach experience" by being back to 6000, but don't
>>hold your breath. [Pun intended.]
>
> And don't expect to be able to tell the difference either. I flew
> some pressurized but mostly unpressurized aircraft for over 25
> years and I defy anyone to tell the difference between sealevel
> and 15,000 as long as they're not physically working, are in
> average physical shape, cannot see outside the aircraft and have
> no instruments...so this particular 'coach experience' claim is
> just hype...
> --
>
> -Gord.
> (use gordon in email)

[[email protected]]

: And don't expect to be able to tell the difference either. I flew
: some pressurized but mostly unpressurized aircraft for over 25
: years and I defy anyone to tell the difference between sealevel
: and 15,000 as long as they're not physically working, are in
: average physical shape, cannot see outside the aircraft and have
: no instruments...so this particular 'coach experience' claim is
: just hype...
: --

If you said the difference between sea level and 5000', or 6000' and 8000' I
may believe you. You must have some Sherpa blood in you to not be affected at all at
15k. I know lots of pilots in "average" shape or better that report headaches and
diminishing concentration at 10K for a few hours, and impaired judgement at 12-14k for
a few hours. Just because you're not gasping for breath doesn't mean you're not
impaired.

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Gord Beaman]

"Dave" > wrote:

>So passing out counts as "not physically working" at 15k right?
>

I haven't any idea what you're asking about...what does it mean
in English?...










>"Gord Beaman" > wrote in message
...
>> "jmk" > wrote:
>>
>>>Both sets of numbers are correct. Early pressurized airliners were at
>>>6000 MSL. Later, as they started flying higher and higher (especially
>>>for oceanic routes) it was raised to 8000 MSL. This saves lots of
>>>money - it increases airframe life and reduces fuel bills. Now all the
>>>major carriers are flying with an 8000 foot cabin pressure.
>>>
>>>There are talks about the newest generation of superliners being able
>>>to give a superior "coach experience" by being back to 6000, but don't
>>>hold your breath. [Pun intended.]
>>
>> And don't expect to be able to tell the difference either. I flew
>> some pressurized but mostly unpressurized aircraft for over 25
>> years and I defy anyone to tell the difference between sealevel
>> and 15,000 as long as they're not physically working, are in
>> average physical shape, cannot see outside the aircraft and have
>> no instruments...so this particular 'coach experience' claim is
>> just hype...
>> --
>>
>> -Gord.
>> (use gordon in email)
>

--

-Gord.
(use gordon in email)

[Gord Beaman]

wrote:

>: And don't expect to be able to tell the difference either. I flew
>: some pressurized but mostly unpressurized aircraft for over 25
>: years and I defy anyone to tell the difference between sealevel
>: and 15,000 as long as they're not physically working, are in
>: average physical shape, cannot see outside the aircraft and have
>: no instruments...so this particular 'coach experience' claim is
>: just hype...
>: --
>
> If you said the difference between sea level and 5000', or 6000' and 8000' I
>may believe you. You must have some Sherpa blood in you to not be affected at all at
>15k. I know lots of pilots in "average" shape or better that report headaches and
>diminishing concentration at 10K for a few hours, and impaired judgement at 12-14k for
>a few hours. Just because you're not gasping for breath doesn't mean you're not
>impaired.

You're probably quite right about the effects that happen at
those altitudes AFTER a few HOURS.

It's quite possible that those symptoms 'may' appear, I wouldn't
know, having never flown for 'several hours' at these altitudes.

Perhaps you should reread my statements, and try to avoid putting
words (and conditions) in my mouth?.

I base my statements on an experience (among others) of flying on
a Fairchild C-119G (a twin engined cargo a/c). We were pretty
busy moving our whole Squadron from one field to another in
several days in bad weather. Our 'Transport Tech' asked for help
to get the cargo hold ready for the next load on one particular
return trip (about an hour transit time). I went back to help him
untangle the cargo tie-down chains and hang them up on the walls.

I noticed the pilots apply climb power and start climbing and
worked on, noticing after awhile, "Boy, I must be getting out of
shape because I'm puffing and panting like an old man here".

We soon finished and when I went back up to the cockpit I saw
that we were at 20,000 ft and just sneaking over a squall line.

--

-Gord.
(use gordon in email)

[[email protected]]

Gord Beaman > wrote:
: You're probably quite right about the effects that happen at
: those altitudes AFTER a few HOURS.

Don't people spend a few hours on commercial flights in pressurized cabins?

: It's quite possible that those symptoms 'may' appear, I wouldn't
: know, having never flown for 'several hours' at these altitudes.

By several, I mean 3 or 4.... routinely done by passengers on commercial
airlines.

: Perhaps you should reread my statements, and try to avoid putting
: words (and conditions) in my mouth?.

I'm particularly refering to the statement that essentially says it's
impossible for anyone to notice the difference between sea level pressure and 15k. I
call bull**** on that one, because I can tell I'm at 10K in my airplane within 15
minutes.... and I live at 2100', too!

: We soon finished and when I went back up to the cockpit I saw
: that we were at 20,000 ft and just sneaking over a squall line.

You were likely in good physicaly shape, and completely unaware of how
impaired you were. The "average" (overweight) person riding a cattle car for 1 hour
would very likely get lightheaded getting up from his seat to walk to the lavatory at
10-12k cabin altitude.

Hypoxia affects different people quite differently. Sooner or later, however,
everyone gets impaired.

-Cory
--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Dave]

Bright guy.

"Gord Beaman" > wrote in message
...
> "Dave" > wrote:
>
>>So passing out counts as "not physically working" at 15k right?
>>
>
> I haven't any idea what you're asking about...what does it mean
> in English?...
>
>
>
>
>
>
>
>
>
>
>>"Gord Beaman" > wrote in message
...
>>> "jmk" > wrote:
>>>
>>>>Both sets of numbers are correct. Early pressurized airliners were at
>>>>6000 MSL. Later, as they started flying higher and higher (especially
>>>>for oceanic routes) it was raised to 8000 MSL. This saves lots of
>>>>money - it increases airframe life and reduces fuel bills. Now all the
>>>>major carriers are flying with an 8000 foot cabin pressure.
>>>>
>>>>There are talks about the newest generation of superliners being able
>>>>to give a superior "coach experience" by being back to 6000, but don't
>>>>hold your breath. [Pun intended.]
>>>
>>> And don't expect to be able to tell the difference either. I flew
>>> some pressurized but mostly unpressurized aircraft for over 25
>>> years and I defy anyone to tell the difference between sealevel
>>> and 15,000 as long as they're not physically working, are in
>>> average physical shape, cannot see outside the aircraft and have
>>> no instruments...so this particular 'coach experience' claim is
>>> just hype...
>>> --
>>>
>>> -Gord.
>>> (use gordon in email)
>>
>
> --
>
> -Gord.
> (use gordon in email)

[Gord Beaman]

wrote:

> Hypoxia affects different people quite differently. Sooner or later, however,
>everyone gets impaired.
>
>-Cory

Sure..that's correct...you'll likely notice that I didn't mention
anything about endurance at these altitudes, yes?...ever hear of
the expression of RTFQ?, a variation on that applies here...
--

-Gord.
(use gordon in email)

[Gord Beaman]

"Dave" > wrote:

>Bright guy.
huh?
--

-Gord.
(use gordon in email)

[[email protected]]

I hate to even respond to this, but...

: Sure..that's correct...you'll likely notice that I didn't mention
: anything about endurance at these altitudes, yes?...ever hear of
: the expression of RTFQ?, a variation on that applies here...
: --

Your original post:

"And don't expect to be able to tell the difference either. I flew
some pressurized but mostly unpressurized aircraft for over 25
years and I defy anyone to tell the difference between sealevel
and 15,000 as long as they're not physically working, are in
average physical shape, cannot see outside the aircraft and have
no instruments...so this particular 'coach experience' claim is
just hype..."

You said nothing about endurance. Simply that it's impossible for normal
people who aren't working hard and cannot see outside to determine that cabin altitude
is at 15k feet. Had you said short periods of time, I would agree with you. In the
context of the original post (i.e. travel on commercial airlines), that is most
decidedly NOT the case. Multiple hours of travel are the norm and would most
certainly cause impairment and potentially other health problems.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Dave]

Exactly.

"Gord Beaman" > wrote in message
...
> "Dave" > wrote:
>
>>Bright guy.
> huh?
> --
>
> -Gord.
> (use gordon in email)

[Gord Beaman]

wrote:

> I hate to even respond to this, but...
>
>: Sure..that's correct...you'll likely notice that I didn't mention
>: anything about endurance at these altitudes, yes?...ever hear of
>: the expression of RTFQ?, a variation on that applies here...
>: --
>
>Your original post:
>
>"And don't expect to be able to tell the difference either. I flew
>some pressurized but mostly unpressurized aircraft for over 25
>years and I defy anyone to tell the difference between sealevel
>and 15,000 as long as they're not physically working, are in
>average physical shape, cannot see outside the aircraft and have
>no instruments...so this particular 'coach experience' claim is
>just hype..."
>
> You said nothing about endurance. Simply that it's impossible for normal
>people who aren't working hard and cannot see outside to determine that cabin altitude
>is at 15k feet. Had you said short periods of time, I would agree with you. In the
>context of the original post (i.e. travel on commercial airlines), that is most
>decidedly NOT the case. Multiple hours of travel are the norm and would most
>certainly cause impairment and potentially other health problems.
>
>-Cory

Ok Cory.
You're right.
I'm wrong.
Happy now?
--

-Gord.
(use gordon in email)

[[email protected]]

Gord Beaman > wrote:
: > You said nothing about endurance. Simply that it's impossible for normal
: >people who aren't working hard and cannot see outside to determine that cabin altitude
: >is at 15k feet. Had you said short periods of time, I would agree with you. In the
: >context of the original post (i.e. travel on commercial airlines), that is most
: >decidedly NOT the case. Multiple hours of travel are the norm and would most
: >certainly cause impairment and potentially other health problems.
: >
: >-Cory

: Ok Cory.
: You're right.
: I'm wrong.
: Happy now?
: --

Funny.. I was planning on having a very similar response to any rebuttal.... :)

'nuff about this crap

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Gord Beaman]

wrote:

>Gord Beaman > wrote:
>: > You said nothing about endurance. Simply that it's impossible for normal
>: >people who aren't working hard and cannot see outside to determine that cabin altitude
>: >is at 15k feet. Had you said short periods of time, I would agree with you. In the
>: >context of the original post (i.e. travel on commercial airlines), that is most
>: >decidedly NOT the case. Multiple hours of travel are the norm and would most
>: >certainly cause impairment and potentially other health problems.
>: >
>: >-Cory
>
>: Ok Cory.
>: You're right.
>: I'm wrong.
>: Happy now?
>: --
>
> Funny.. I was planning on having a very similar response to any rebuttal.... :)
>
>'nuff about this crap
>
>-Cory

I agree...life's too short for this stuff...you can be happy in
thinking that you're right, I can be happy in knoXXX thinking
that I'm right... :)

(just kidding, it's a pretty subjective problem)
--

-Gord.
(use gordon in email)

[Andrew Koenig]

"Gord Beaman" > wrote in message
...

> And don't expect to be able to tell the difference either. I flew
> some pressurized but mostly unpressurized aircraft for over 25
> years and I defy anyone to tell the difference between sealevel
> and 15,000 as long as they're not physically working, are in
> average physical shape, cannot see outside the aircraft and have
> no instruments...so this particular 'coach experience' claim is
> just hype...

Once I visited the observatory at Mauna Kea, which is at 13,800 feet
elevation. Based on that experience, I find it hard to believe that
*anyone* couldn't tell the difference between sea level and 15,000 feet --
at least not after returning to sea level.

[Ron Natalie]

Andrew Koenig wrote:
> "Gord Beaman" > wrote in message
> ...
>
>> And don't expect to be able to tell the difference either. I flew
>> some pressurized but mostly unpressurized aircraft for over 25
>> years and I defy anyone to tell the difference between sealevel
>> and 15,000 as long as they're not physically working, are in
>> average physical shape, cannot see outside the aircraft and have
>> no instruments...so this particular 'coach experience' claim is
>> just hype...
>
> Once I visited the observatory at Mauna Kea, which is at 13,800 feet
> elevation. Based on that experience, I find it hard to believe that
> *anyone* couldn't tell the difference between sea level and 15,000 feet --
> at least not after returning to sea level.
>
>
You don't have to physically work very hard to notice. I noticed the
effects of the reduced oxygen content at 12,000 feet just by what I had
to do to turn around and reach back to shut the rear seat air vent in
the Navion.

[Gord Beaman]

Ron Natalie > wrote:

>Andrew Koenig wrote:
>> "Gord Beaman" > wrote in message
>> ...
>>
>>> And don't expect to be able to tell the difference either. I flew
>>> some pressurized but mostly unpressurized aircraft for over 25
>>> years and I defy anyone to tell the difference between sealevel
>>> and 15,000 as long as they're not physically working, are in
>>> average physical shape, cannot see outside the aircraft and have
>>> no instruments...so this particular 'coach experience' claim is
>>> just hype...
>>
>> Once I visited the observatory at Mauna Kea, which is at 13,800 feet
>> elevation. Based on that experience, I find it hard to believe that
>> *anyone* couldn't tell the difference between sea level and 15,000 feet --
>> at least not after returning to sea level.
>>
>>
>You don't have to physically work very hard to notice. I noticed the
>effects of the reduced oxygen content at 12,000 feet just by what I had
>to do to turn around and reach back to shut the rear seat air vent in
>the Navion.

I think it was 'all in your head' Ron (and Andrew) ...you 'knew'
you were at ~12k therefore your body supplied the symptoms that
'you' expected it to...it's similar (in a way) to why the NTSB
etc puts little stock in eyewitness reports unless they're
corroborated by physical or other evidence, your mind/imagination
supplies the expected missing pieces that you thought came from
memory. It's quite common. Not rocket science at all.

Ever hear of the helicopter pilot witnessing a failed tail rotor
crash on the type of a/c that he was very familiar with?...he was
certain that the a/c rotated 6 times, this stood till someone
came forward with a clear video of it rotating 3 times...(these
figures may be in error but the error factor was close to this).

Proving (yet again) that eye witness reports (even seasoned
witnesses) aren't very reliable, this has been proven many times.

In my case, we were at something like 15,000, we worked for
awhile walking around hanging up chains and untangling
rope...after awhile we started climbing and continued working,
really not thinking about the height at all...later on I remember
thinking, gee, I must be out of shape getting tired while doing
light work like this...we finished and I sort of dragged myself
up the steps to the cockpit and found us over 20,000.

We often cruised at 12, 15K. Perhaps it isn't done anymore?
doesn't change the fact that it's true does it?...I doubt that
I'm superman...I did it for quite a few years and I take a bit of
umbrage when someone suggests that I lying in my teeth.
--

-Gord.
(use gordon in email)

[bowman]

Gord Beaman wrote:

> We often cruised at 12, 15K. Perhaps it isn't done anymore?
> doesn't change the fact that it's true does it?...I doubt that
> I'm superman...I did it for quite a few years and I take a bit of
> umbrage when someone suggests that I lying in my teeth.

I've noticed some shortness of breath at 14K, but I was walking up
Uncompaghre Peak in Colorado at the time. The mountains are a little
shorter around here, and I've never really thought about the quality of the
air at 9 or 10K. I was a little amused when this thread started...

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[Gord Beaman]

bowman > wrote:

>Gord Beaman wrote:
>
>> We often cruised at 12, 15K. Perhaps it isn't done anymore?
>> doesn't change the fact that it's true does it?...I doubt that
>> I'm superman...I did it for quite a few years and I take a bit of
>> umbrage when someone suggests that I lying in my teeth.
>
>I've noticed some shortness of breath at 14K, but I was walking up
>Uncompaghre Peak in Colorado at the time. The mountains are a little
>shorter around here, and I've never really thought about the quality of the
>air at 9 or 10K. I was a little amused when this thread started...
>
Bowman, thanks for your input...it get's frustrating when this
kind of thing happens and it's very gratifying when someone with
similar experiences speaks up...
--

-Gord.
(use gordon in email)

[bowman]

Gord Beaman wrote:

> Bowman, thanks for your input...it get's frustrating when this
> kind of thing happens and it's very gratifying when someone with
> similar experiences speaks up...

For that matter quite a few Sherpas and several Europeans have summitted
Everest without oxygen.

That said, a couple of years ago I was hiking up one of the very popular
local 9K peaks and passed a guy taking a break alongside the trail. I
didn't think much of it until I met up with a woman about a quarter of a
mile further on. She asked me if I'd seen the man. When I said he was
taking a break and would be along shortly, she said with a big grin "he
smokes and I dragged him up here to give him a little taste of what
emphysema will be like."

Another example would be Eisenhower tunnel on I70. I forget the exact
elevation, but it is close to 12K and thousands of people drive over it
without a thought.

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[Brian Whatcott]

On Fri, 14 Oct 2005 23:13:42 -0600, bowman > wrote:

>... a couple of years ago I was hiking up one of the very popular
>local 9K peaks and passed a guy taking a break alongside the trail. I
>didn't think much of it until I met up with a woman about a quarter of a
>mile further on. She asked me if I'd seen the man. When I said he was
>taking a break and would be along shortly, she said with a big grin "he
>smokes and I dragged him up here to give him a little taste of what
>emphysema will be like."...

My lung capacity was never good. 10 minutes playing squash and I would
melt down, panting like a steam loco on a climb. At the age of 25.

At the age of 45 I knew when I was flying at 10K from the slight
breathlessness.
At 60, I was stressed, waiting for the company I worked for to mail me
a ticket to fly to a conference to present a paper I had written.

The ticket finally arrived the day before I was due to fly, a Sunday,
and I had not completed my presentation materials. I got shorter
and shorter of breath, smoking all along, and attempting to set the
material ready, until finally, I could not move without gasping.

My wife drove me 200 yards to the hospital emergency room, and they
stabilized me on oxygen and nebulizers.
I thought it was my dying day. 2 hours later, I could breathe, and
never smoked again. After 40 years.

Brian Whatcott

[Gord Beaman]

Brian Whatcott > wrote:
snip
>My wife drove me 200 yards to the hospital emergency room, and they
>stabilized me on oxygen and nebulizers.
>I thought it was my dying day. 2 hours later, I could breathe, and
>never smoked again. After 40 years.
>
>Brian Whatcott

Yes, I know whereof you speak...I smoked moderately for 45 years
then, noticing increasing shortness of breath I got a few tests
done (PFT - Pulmonary Function Test) etc...

Doctor said "Mr Beaman, you can quit smoking now and have a sort
of acceptable old age, or you can continue smoking, in which case
you WILL quit in about two years...I quit right then.

Diagnosis, emphysema, home oxygen the works.

That was 10 years ago.

I sure wish that I knew then (as a kid) what I know now...
--

-Gord.
(use gordon in email)