Catastrophic Decompression; Small Place Solo

"G.R. Patterson III" wrote in message
...


Aviation wrote:

On the one hand, passengers need to get denser air to breathe
but large aircraft have oxygen masks that drop down.

If the aircraft is much above 25,000', the masks will do little good. You
need
a pressure mask to survive long at (for example) 35,000'. Those used by
the
airlines for passengers are not good enough for that.

(I could
do some rough estimates that the average fat slob can hold
their breath for less than a minute so, without masks, the jet
would have to go from let's say 30000 feet to 5000 feet in
30-45 seconds. My ears would explode.)

Nobody can hold their breath in that situation - the pressure difference
will
cause you to exhale. Above about 25,000', the air pressure is low enough
that
oxygen actually passes backwards out of your bloodstream into the lungs
and out
of the body. As for your ears, they're already toast. The pressure just
dropped
from the pressure at 8,000' to that at cruise altitude in a few seconds.

Agreed

Basically, the pilots need to get their masks on and get the plane down
below
25,000' as rapidly as it can possibly be done. The descent to 10,000' can
be made
a little more leisurely, but not much - there's always someone in the
cattle
section who panicked and isn't wearing a mask. If that's one of the flight
attendants, you're really in trouble.

Agreed.

There is 1 further issue not yet addressed. Ambient Temp at altitude.
Ambient temps of -30 degrees F or lower are not uncommon at altitudes
25,000 ASL.

Decompression, explosive or otherwise, results in a significant drop in
cabin Temp resulting in ~ fairly rapid freezing.

There have been any number of documented incidents, military & civilian,
over the years where an A/C lost pressure at altitude, disabling the crew,
with the A/C continuing on "Auto Pilot", crashing when fuel exhausted. It is
routine for A/C in this situation to be intercepted/followed/kept under
surveillance/filmed by military A/C. The most recent "Widely/Highly
Publicized Example"of this was the "Payne Stewart" incident.
Ralph Nesbitt
Professional FD/CFR/ARFF Type

Basically, the pilots need to get their masks on and get the plane down below
25,000' as rapidly as it can possibly be done.

A couple links to the sad story of Payne Stewart a few years ago. I was
working in Minnesota and there was great consternation as the plane autopiloted
its way across a corner of the state and the military wondered if it would be
necessary to shoot it down. Had it come much closer to a big city, they would
have had to make that decision.

http://www.newsmax.com/articles/?a=1999/10/25/164032

http://www.cnn.com/US/9910/26/shootdown/

The NTSB report:
http://www.ntsb.gov/publictn/2000/AAB0001.htm

I'd always assumed, as many did, that something catastrophic happened shortly
after takeoff, like a window failing, and the pilots didn't even have time to
get oxygen masks on. A friend suggests it never pressurized, which makes one
wonder whether they could become anoxic to the point they were helpless even
without a catastrophe, if they didn't realize the cabin was never
pressurizing...but lots of folks have told me about the foolishness that comes
with lack of oxygen. The full report makes fascinating reading...accident
investigation includes lots and lots of stuff.

On Tue, 30 Dec 2003 19:43:55 -0800, "G.R. Patterson III"
wrote:

Aviation wrote:

On the one hand, passengers need to get denser air to breathe
but large aircraft have oxygen masks that drop down.

[snip]

As for your ears, they're already toast. The pressure just dropped
from the pressure at 8,000' to that at cruise altitude in a few seconds.

Based on what others have written about chamber simulations, it would
appear that irreversible ear damage (which is what I would infer as
being "toast") is not an inevitable consequence, although. I've no
doubt that the sensation from any reversible consequences is not
always pleasant .

Basically, the pilots need to get their masks on and get the plane down below
25,000' as rapidly as it can possibly be done. The descent to 10,000' can be made
a little more leisurely, but not much - there's always someone in the cattle
section who panicked and isn't wearing a mask.

One aspect that I have not seen addressed in this thread is the fact
that most oxygen systems can provide supplemental oxygen for a few
minutes only (I dimly recall figures like 3-5 minutes, but that may be
inaccurate). The pilots also need to get down to 10,000 feet within
that time before everyone's oxygen generators run out.

Regards,

George
************************************************** ********************
Dr. George O. Bizzigotti Telephone: (703) 610-2115
Mitretek Systems, Inc. Fax: (703) 610-1558
3150 Fairview Park Drive South E-Mail:
Falls Church, Virginia, 22042-4519
************************************************** ********************

Dr. George O. Bizzigotti wrote:

"G.R. Patterson III" wrote:

Basically, the pilots need to get their masks on and get the plane down below
25,000' as rapidly as it can possibly be done. The descent to 10,000' can be made
a little more leisurely, but not much - there's always someone in the cattle
section who panicked and isn't wearing a mask.

One aspect that I have not seen addressed in this thread is the fact
that most oxygen systems can provide supplemental oxygen for a few
minutes only (I dimly recall figures like 3-5 minutes, but that may be
inaccurate). The pilots also need to get down to 10,000 feet within
that time before everyone's oxygen generators run out.

How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

Easily. My MU-2 can descend 10,000fpm. Any jet can easily do it.

Mike
MU-2


"Scott M. Kozel" wrote in message
...
Dr. George O. Bizzigotti wrote:

"G.R. Patterson III" wrote:

Basically, the pilots need to get their masks on and get the plane down
below
25,000' as rapidly as it can possibly be done. The descent to 10,000'
can be made
a little more leisurely, but not much - there's always someone in the
cattle
section who panicked and isn't wearing a mask.

One aspect that I have not seen addressed in this thread is the fact
that most oxygen systems can provide supplemental oxygen for a few
minutes only (I dimly recall figures like 3-5 minutes, but that may be
inaccurate). The pilots also need to get down to 10,000 feet within
that time before everyone's oxygen generators run out.

How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

"Scott M. Kozel" wrote in message

How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

I'd guess about 3-4 minutes from FL600 to 10K. Just my guess, never read up
on the craft. But 12-15 K ft/m would not be unusual in an emergency
descent.


Regards,

John Gaquin
B727, B747

"Scott M. Kozel" wrote in message ...

How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

Push the yoke forward :-)

On Wed, 31 Dec 2003 at 11:53:49 in message
, Scott M. Kozel wrote:

How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

I believe with the two inboard engines on reverse thrust the outer two
on idle. On my only Concorde flight (a test with volunteer passengers)
we descended from cruise height with two engines on reverse thrust. All
I remember was that the clouds below seemed to come up very fast!
--
David CL Francis

"Scott M. Kozel" wrote in message
...
How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

Easy, it's called an Emergency Descent. Power to idle, spoilers/speedbrakes
deployed, maybe gear extended (depends on aircraft), then dive at redline
speed. The airplane I fly (Lear 60) it takes an initial deck angle of ~ 20
degrees nose down to obtain redline, then ~ 10-12 degrees to hold it there.

We practice it every time we have a simulator check. Never takes more than
3 mins to get from FL450 to 10,000 ft.

Mish

Mish

Do you have enough bleed air with throttles at idle?

Thrust curve is not linear with throttle position so some rpm above
idle might be required in some birds???

Change in time down to 18K or so would not be much different. I used a
figure of 18K as a target alt to get on the safe side in a emergency
descent.

USAF set 34K (cockpit altitude) as the point to go to pressure
breathing. Easy to suck in and fill lungs and hard to breath out (open
exhaust valve). This assisted the lungs to get enough oxy. Took a
while to accustom to blowing out with each breath against valve but
soon became routine.

Big John
Pilot ROCAF


On Mon, 05 Jan 2004 18:38:52 GMT, "Gary Mishler"
wrote:


"Scott M. Kozel" wrote in message
...
How could an SST like the Concorde get from cruising altitude down to
10,000 feet in 3-5 minutes?

Easy, it's called an Emergency Descent. Power to idle, spoilers/speedbrakes
deployed, maybe gear extended (depends on aircraft), then dive at redline
speed. The airplane I fly (Lear 60) it takes an initial deck angle of ~ 20
degrees nose down to obtain redline, then ~ 10-12 degrees to hold it there.

We practice it every time we have a simulator check. Never takes more than
3 mins to get from FL450 to 10,000 ft.

Mish