What is cabin air pressure set at

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

"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)

"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.

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.]

"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)

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)

: 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 *
************************************************** ***********************

"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)

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)

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 *
************************************************** ***********************