Punctured pressure cabin.

There has been a bit of a furore over here concerning the new US
requirement to airlines to supply air marshals when requested. The
concern is mainly over the possible puncture of a pressure cabin.
What do readers think is the result of decompression via a bullet hole?

Mike
--
M.J.Powell

In article ,
"M. J. Powell" wrote:

There has been a bit of a furore over here concerning the new US
requirement to airlines to supply air marshals when requested. The
concern is mainly over the possible puncture of a pressure cabin.
What do readers think is the result of decompression via a bullet hole?

Unnoticeable is almost all cases. A mild annoyance in the remainder, as
long as we're discussing smallarm-caliber rounds.

"M. J. Powell" wrote in message
...

There has been a bit of a furore over here concerning the new US
requirement to airlines to supply air marshals when requested. The
concern is mainly over the possible puncture of a pressure cabin.
What do readers think is the result of decompression via a bullet hole?


There won't be decompression via a bullet-sized hole. There are already a
variety of leaks in the pressure vessel. There are simply some things which
must penetrate the vessel. They're sealed reasonably well, but there's
still some unavoidable leakage. The pressure is maintained by controlling
the outflow of pressurized air. Another small hole will simply cause the
control valve to close a bit to compensate.

What do readers think is the result of decompression via a bullet hole?

Whose bullet? The American sky marshals (and presumably others) use
frangible bullets, which wouldn't make a hole.

The Brit argument is that the terrorist would use their guns in a
"shoot-out" caused (of course!) by the sky marshal's gun. Okay, we've
postulated that the terrorist has successfully smuggled a gun on
board. Why is that? So he can crash the plane into a target? Could be,
huh?

So are you worse off risking explosive decompression, or of crashing
into Times Square at midnight?

As to the possibility of explosive decompression, as I understand the
matter, it could happen if a bullet fractured a window (though not if
it went through the skin). That's a mere possibility, as opposed to
the certainty of a suicide dive, absent the sky marshal.

A normal bullet hole would be no problem. There's already a much
larger vent to the outside, which stabilizes cabin pressure against
the fresh & heated air being pumped in from the engines. People
smarter than I say that this hole is about three inches in diameter.


all the best -- Dan Ford
email:

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

Cub Driver wrote in
:


What do readers think is the result of decompression via a bullet hole?

Whose bullet? The American sky marshals (and presumably others) use
frangible bullets, which wouldn't make a hole.

To the best of my knowledge,that's wrong;US Sky Marshals use .40 cal JHP
(jacketed hollowpoint) ammo(premium,the good stuff),as they might need to
penetrate some barrier that a hijacker hid behind.

Frangible ammo can be defeated by some forms of clothing,or a
shield.(briefcase?)

--
Jim Yanik
jyanik-at-kua.net

From: Cub Driver

snip

As to the possibility of explosive decompression, as I understand the
matter, it could happen if a bullet fractured a window

It would still be only annoying. A few ear aches and a lot of noise along with
oxygen masks dropping. The person sitting next to the window might lose his
reading material or dinner.

This has been discussed here before and a Google search would turn up a lot of
information.

Dan, U. S. Air Force, retired

"B2431" wrote in message
...
From: Cub Driver

snip

As to the possibility of explosive decompression, as I understand the
matter, it could happen if a bullet fractured a window

It would still be only annoying. A few ear aches and a lot of noise along
with
oxygen masks dropping. The person sitting next to the window might lose
his
reading material or dinner.

This has been discussed here before and a Google search would turn up a
lot of
information.

Dan, you are forgetting that there was indeed documented evidence of a
passenger being sucked out of a blown window brought out during that
discussion--a TAM Fokker F28 turboprop somwhere over Brazil (see:
www.crashdatabase.com/cgi-bin/
webdata_crashdatabase.cgi?cgifunction=Search&Airli ne=%5ETAM%24 ). There was
also a fatality during a 1989 Piedmont Airlines 737 rapid decompression
(www.canard.com/ntsb/ATL/89A099.htm ). As to the non-fatal effexcts, the
experience of an Aer Lingus 737 tends to point to some rather significant
injuries during a 1999 depressurization accident, with lots of ruptured
eardrums and severe nosebleeds, etc. I would not disagree that these
potential problems are far outweighed by the threat of some whacko with a
knife/bomb/etc., said whacko being dispatched by an air marshal, even with
the remote potential of causing a rapid decompression being preferrable to
the alternative. But the effect of such a decompression is likely going to a
bit worse than cleaning your tray table off and causing a few earaches.

Brooks



Dan, U. S. Air Force, retired

From: "Kevin Brooks"
Date: 1/1/2004 1:01 AM Central Standard Time
Message-id:


"B2431" wrote in message
...
From: Cub Driver

snip

As to the possibility of explosive decompression, as I understand the
matter, it could happen if a bullet fractured a window

It would still be only annoying. A few ear aches and a lot of noise along
with
oxygen masks dropping. The person sitting next to the window might lose
his
reading material or dinner.

This has been discussed here before and a Google search would turn up a
lot of
information.

Dan, you are forgetting that there was indeed documented evidence of a
passenger being sucked out of a blown window brought out during that
discussion--a TAM Fokker F28 turboprop somwhere over Brazil (see:
www.crashdatabase.com/cgi-bin/
webdata_crashdatabase.cgi?cgifunction=Search&Airl ine=%5ETAM%24 ). There was
also a fatality during a 1989 Piedmont Airlines 737 rapid decompression
(www.canard.com/ntsb/ATL/89A099.htm ). As to the non-fatal effexcts, the
experience of an Aer Lingus 737 tends to point to some rather significant
injuries during a 1999 depressurization accident, with lots of ruptured
eardrums and severe nosebleeds, etc. I would not disagree that these
potential problems are far outweighed by the threat of some whacko with a
knife/bomb/etc., said whacko being dispatched by an air marshal, even with
the remote potential of causing a rapid decompression being preferrable to
the alternative. But the effect of such a decompression is likely going to a
bit worse than cleaning your tray table off and causing a few earaches.

Brooks



Dan, U. S. Air Force, retired

I was referring to the blown out window. The passenger you refer to was blown
out a six foot hole according to your cite.

I agree a big chunk of skin suddenly departing the aircraft can cause major
damage and fatalities like the Hawaii Air stewardess deplaning prematurely.
There was also a case in the 1970s of a DC-10(?) where the aft cargo hatch blew
and took a row or two of seats with it.

On the other hand in the late 1980s a C-141B departed Eglin AFB and a hatch
over the cargo compartment blew. One of my men was standing directly below it
at the time. He noticed sudden day light, very loud noise and a bit of pain. I
believe the aircraft was at approximately 30 kilofeet at the time. It returned
to Eglin, made a safe landing and everyone sent to the base hospital for
evaluation.

Dan, U. S. Air Force, retired

B2431 wrote:

: I agree a big chunk of skin suddenly departing the aircraft can cause major
: damage and fatalities like the Hawaii Air stewardess deplaning prematurely.
: There was also a case in the 1970s of a DC-10(?) where the aft cargo hatch blew
: and took a row or two of seats with it.

IIRC there have been incidents with the cargo hatches of DC-10s,
but not limited to the loss of a number of seats; the entire
aircraft was lost --- depressurisation of the cargo bay
caused the cabin floor to collapse, destroying the control
runs.

As a result, modern aircraft were designed to have vents around
the cabin floor.

Emmanuel Gustin

"B2431" wrote in message
...
From: "Kevin Brooks"
Date: 1/1/2004 1:01 AM Central Standard Time
Message-id:


"B2431" wrote in message
...
From: Cub Driver

snip

As to the possibility of explosive decompression, as I understand the
matter, it could happen if a bullet fractured a window

It would still be only annoying. A few ear aches and a lot of noise
along
with
oxygen masks dropping. The person sitting next to the window might lose
his
reading material or dinner.

This has been discussed here before and a Google search would turn up a
lot of
information.

Dan, you are forgetting that there was indeed documented evidence of a
passenger being sucked out of a blown window brought out during that
discussion--a TAM Fokker F28 turboprop somwhere over Brazil (see:
www.crashdatabase.com/cgi-bin/
webdata_crashdatabase.cgi?cgifunction=Search&Airl ine=%5ETAM%24 ). There
was
also a fatality during a 1989 Piedmont Airlines 737 rapid decompression
(www.canard.com/ntsb/ATL/89A099.htm ). As to the non-fatal effexcts, the
experience of an Aer Lingus 737 tends to point to some rather significant
injuries during a 1999 depressurization accident, with lots of ruptured
eardrums and severe nosebleeds, etc. I would not disagree that these
potential problems are far outweighed by the threat of some whacko with a
knife/bomb/etc., said whacko being dispatched by an air marshal, even
with
the remote potential of causing a rapid decompression being preferrable
to
the alternative. But the effect of such a decompression is likely going
to a
bit worse than cleaning your tray table off and causing a few earaches.

Brooks



Dan, U. S. Air Force, retired

I was referring to the blown out window. The passenger you refer to was
blown
out a six foot hole according to your cite.

Heh? "Pressurization was lost at an altitude of 33,000 feet when the right
engine disintegrated, causing pieces of the engine to break two cabin
windows." That does not a six foot hole equal.


I agree a big chunk of skin suddenly departing the aircraft can cause
major
damage and fatalities like the Hawaii Air stewardess deplaning
prematurely.
There was also a case in the 1970s of a DC-10(?) where the aft cargo hatch
blew
and took a row or two of seats with it.

Two windows is not a big chunk of skin. Neither was the Piedmont accident a
"big chunk of skin", and a passenger still died.


On the other hand in the late 1980s a C-141B departed Eglin AFB and a
hatch
over the cargo compartment blew. One of my men was standing directly below
it
at the time. He noticed sudden day light, very loud noise and a bit of
pain. I
believe the aircraft was at approximately 30 kilofeet at the time. It
returned
to Eglin, made a safe landing and everyone sent to the base hospital for
evaluation.

A cargo hatch blew out of a DC-10 in 1974, and it took a big chunk of the
cabin floor above, with passengers, out of the aircraft--the rest of the
aircraft then augered in. Face it, rapid decompression *can* (does not mean
*will be*) be a very bad thing, even when it may just involve a window.

Brooks


Dan, U. S. Air Force, retired