AA727
Topic Author
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Exits During Flight

Thu May 08, 2003 7:47 am

My dad just came in the door, just got back from flying AA from Orlando. He told me that he was wondering, what the hell prevents someone from opening an emergency exit during flight? Although I thought it was a weird question, it got me thinking. I couldn't come up with an answer except that I'm sure if someone tried to open the door, a crowd of people would jump on him pretty quick. But, I'm sure that the airlines have SOME other way of preventing this!

Sean
 
OPNLguy
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RE: Exits During Flight

Thu May 08, 2003 7:56 am

The doors and exits are what they call "plug" doors, and are bigger than the openings (via internal mechanical stuff) when closed. As such, the pressurized cabin pushes the door against it's frame, and it won't open.

Now, in the movies, that show this happening all the time..... Not in real life...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
m717
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RE: Exits During Flight

Thu May 08, 2003 8:00 am

If you look closely, you'll notice the exits (both door and window) are "plug" type exits. In other words, they seat against the fuselage structure. They must all first be opened inward before moving outward. The aircraft pressure differential (in most cases around 8 psi at typical cruise altitudes) would prevent the opening of these exits in flight. Think of the number of square inches in any exit, multiply times 7 or 8, and this would be the force in pounds that you would have to overcome to open this exit.
 
ScooterTrash
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RE: Exits During Flight

Thu May 08, 2003 8:00 am

The air pressure inside the cabin is greater than the air pressure outside. This pushes the emergency exit door (from this inside) up against the fuselage very tightly. Since you have to pull the exit inward to open it, the exit cannot be opened in flight because you would not be strong enough to overcome the pressure differential. This is why the exits are called "plug" type doors.

The main cabin doors are the same way. Watch someone open one sometime and you will see they must first move inward in order to be opened.
 
m717
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RE: Exits During Flight

Thu May 08, 2003 8:02 am

OPNLguy,

I see you beat me by a couple of minutes. I guess you were posting as I was typing.  Smile/happy/getting dizzy
 
m717
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RE: Exits During Flight

Thu May 08, 2003 8:11 am

This discussion reminds me of my favorite "media aviation expert" story. It was during coverage of 9/11. One of the network's "experts" was talking about UAL 93 with it's flight path being shown via a flight tracker in the background. He made this statement: "If I wanted to prevent an airliner from reaching it's destination, I would open an emergency exit and cause a rapid decompression. There's no way that aircraft would reach it's destination."

I thought, "What an idiot. And the network pays this guy to be an 'aviation expert' ".
 
OPNLguy
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RE: Exits During Flight

Thu May 08, 2003 9:37 am

>>>He made this statement: "If I wanted to prevent an airliner from reaching it's destination, I would open an emergency exit and cause a rapid decompression. There's no way that aircraft would reach it's destination."

I wish I had a buck for every dumb comment like this from a media person--I'd be rich, retired, and living at an undisclosed location.

It sounds like he'd watched "Die Hard 2" or some other cinematic masterpeice once too often...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
aa61hvy
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RE: Exits During Flight

Thu May 08, 2003 10:30 am

I think the doors weigh like 40lbs, so a frail lady could not do it.
Go big or go home
 
AA727
Topic Author
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RE: Exits During Flight

Thu May 08, 2003 11:17 am

Bit of an obvious answer I overlooked Smile/happy/getting dizzy. Thanks

Sean
 
m717
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RE: Exits During Flight

Thu May 08, 2003 11:24 am

" I think the doors weigh like 40lbs, so a frail lady could not do it."

That's what they (window exits) weigh by themselves. Put 7+ psi pressure differential against them, and they weigh considerably more. So much more that not even the strongest could "do it".
 
cdfmxtech
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RE: Exits During Flight

Thu May 08, 2003 11:48 am

In addition to that, airplanes such as the B737 Next gens have flightlock solenoids that prevent the emergency exit door handles from even being moved to the open position.

 
ScooterTrash
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RE: Exits During Flight

Thu May 08, 2003 12:20 pm

OPNL and M717:

Okay, that was strange.... Less than a minute separation between our posts! That's a first for me!
 
Guest

RE: Exits During Flight

Fri May 09, 2003 12:25 am

I was answering flight attendant questions in a classroom not too long ago, in one of these sessions where "a pilot" is scheduled to present the point of view of flight crews vs. cabin crews... etc...
xxx
With some 8 psi cabin pressure differential, we computed the total pressure which "plugs" an exit door of a 747 against the fuselage structure frame... if I remember well, we computed it to be 16,000 kg... 35,000 lbs or so...
xxx
So if you need to go outside the plane in-flight, to go and puff a cigarette sitting on the wing, be ready to use muscles...  Smile
xxx
Happy contrails
(s) Skipper
 
dc10hound
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RE: Exits During Flight

Sat May 10, 2003 3:08 am

I know it's a "horse of different color" (aft cargo door/ramp), but check this:

Passengers sucked out of plane
Friday, May 9, 2003 Posted: 1:17 PM EDT (1717 GMT)

KINSHASA, Congo -- Several passengers were sucked out of a Russian-made cargo plane when the aircraft's rear door flew open during a flight over the Democratic Republic of Congo.


http://www.cnn.com/2003/WORLD/africa/05/09/plane.deaths/index.html
"Eagles soar. But weasels never get sucked into jet intakes.."
 
shaun3000
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RE: Exits During Flight

Sun May 11, 2003 3:24 pm

Skipper:

How'd you get 35,000 lbs? 35,000 (lbs) /8(lbs/in^2) = 4735 in^2 / 12 in^2 = 365 ft^2. That's a damn big door.
 
Checkerboard
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RE: Exits During Flight

Sun May 11, 2003 9:57 pm

How about the cargo bay doors? Are they also "pluge" type?
Thanks a lot!
 
L-188
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RE: Exits During Flight

Sun May 11, 2003 11:37 pm

Actually Shaun3000 the calculation is....

35000/8

4735/144 which equals out to roughly 33 square feet.

Which sounds about right.

You have to divide by 144 since there are 12 inches in a foot, so 12 inches on a side times 12 inches on a side would equal 144 inches square in a square foot.

[Edited 2003-05-11 16:40:30]
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EssentialPowr
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RE: Exits During Flight

Mon May 12, 2003 1:15 am

"With some 8 psi cabin pressure differential, we computed the total pressure which "plugs" an exit door of a 747 against the fuselage structure frame... if I remember well, we computed it to be 16,000 kg... 35,000 lbs or so..."

From the above ex, the "total" pressure is 8 psi, the resultant force is 35000 lbs. Force is a different concept than pressure...
 
airplay
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RE: Exits During Flight

Mon May 12, 2003 1:47 am

Everyone except one has ignored the pressure and speed locks installed in some aircraft.

What would stop someone from opening an emergency exit while the airplane is taking off? Many aircraft utilize speed (above 80 KTS or so) and/or pressure locks that inhibit the opening mechanism at inappropriate times.

Strangely enough, not all emergency exists are "plug" types either. There are a few instances of exits held in by claws. Much like the cargo door that blew open in one of the examples above.

By the way, the main doors are protectd by speed and/or pressure locks that inhibit the opening mechanism too.

 
avioniker
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RE: Exits During Flight

Tue May 13, 2003 2:04 am

On the 737NG, once the throttles are pushed up for takeoff with the doors closed, the lock solenoids drop into position and the plane is pressurized to a level slightly below the ambient field pressure (.125 diff). Since the emergency exits are plug doors it'd be hard to get them open. You have to pull the handle hard enough to overcome the solenoid pins plus be able to overcome about 90lbs of force pushing the door outward.
The Cargo bin doors are plug type doors also.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
EssentialPowr
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RE: Exits During Flight

Tue May 13, 2003 2:51 am

It's rather implicit from the calculation preformed above that, once the cabin shows a psid, opening a plug type door becomes almost impossible.

"By the way, the main doors are protectd by speed and/or pressure locks that inhibit the opening mechanism too."

Which aircraft?
 
cdfmxtech
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RE: Exits During Flight

Tue May 13, 2003 3:27 am

The B777 is the only aircraft that I know of which has Main Door Flightlocks and they rely on airspeed. Above 80 kts, door are locked
 
qwerty
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RE: Exits During Flight

Tue May 13, 2003 4:17 am

my brother was on a flight (way before 9/11) where someone in the exit row freaked out and pulled the handles on an over wing exit after rotation.

Of course, nothing tragic happened, but the captain did quickly return and plane waited on the ground for hours for mech.s to reset the exit.

And, of course, the guy who freaked out got his mouth bloodied first and then his ass kicked before landing. Turns out he was diabetic and had some kind of blood sugar/rage/fear issue. Don't know whether he was charged or not, but these days, I HOPE he would be.
 
EssentialPowr
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RE: Exits During Flight

Tue May 13, 2003 3:32 pm

cdfmxtech-

Thanks for the input. It appears Airplay has made a mistake in his blanket assumption of "speed/and or pressure locks"...other than the 777, no Boeing I'm aware of has a "speed" input lock. I'm not sure on Airbus products, but I don't think so there either...
 
MxCtrlr
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RE: Exits During Flight

Tue May 13, 2003 7:09 pm

A perfect example of this was when I was with the original Pan Am. We had two serious-injury incidents back-to-back - one at MIA and one at JFK - involving personnel injuries while opening the A300 passenger doors. It seems that with as little as .5 differential PSI, it is still possible to open the A300 door however, at that differential PSI, the door opens with a force of over 845 pounds! The poor operator of the door who is unfortunate enough to open it with .5 differential PSI, is launched like a toy airplane!

Since Boeing designs their plug-type doors differently from Airbus, the same situation does not occur. Instead, with Boeing aircraft, if you leave the air conditioning packs running and everything else closed up, you may not be able to exit the aircraft or, if you've left it powered down and closed up, with the ground air conditioning attached and running, you may not be able to get back into the aircraft later! (I've seen this happen a few times and it is embarassing having to wait until the pressure bleeds off so that you can get into the aircraft!

MxCtrlr  Smile/happy/getting dizzy
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dc10hound
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RE: Exits During Flight

Tue May 13, 2003 8:44 pm

We had two serious-injury incidents back-to-back - one at MIA and one at JFK - involving personnel injuries while opening the A300 passenger doors.

And the A300 is still doing it....

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001212X22314&key=1
"Eagles soar. But weasels never get sucked into jet intakes.."
 
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Bruce
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RE: Exits During Flight

Wed May 14, 2003 1:07 am

Flight Attendant to passenger: "sir if you really feel the need to have a cigarette on this flight then feel free to go outside and have a seat on the wing. Its just a little windy out there and chilly."
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
dc10hound
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RE: Exits During Flight

Wed May 14, 2003 1:40 am

with Boeing aircraft, if you leave the air conditioning packs running and everything else closed up, you may not be able to exit the aircraft or, if you've left it powered down and closed up, with the ground air conditioning attached and running, you may not be able to get back into the aircraft later!

Only if you've managed to get the pressurization outflow valve closed, inadvertently or on purpose...
"Eagles soar. But weasels never get sucked into jet intakes.."
 
MxCtrlr
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RE: Exits During Flight

Wed May 14, 2003 2:44 pm

Well, closing the outflow valve would fall under the inclusion of "everything else". I have had cases on the 727 where, when power was removed from the aircraft or the aircraft was put on the ground service buss, the outflow valve closed. In that case, if no other doors were open, the cabin would pressurize from the ground air conditioning unit.

As to the A300 "exploding door syndrome", we also had one incident like this at Carnival in JFK. One of the caterers was either seriously injured or outright killed when he opened the door while the aircraft was pressurized. As I recall, that aircraft was out of service for some time as, when the door slammed against the open stop, it cracked the door frame extensively.

MxCtrlr  Smile/happy/getting dizzy
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DAMN! This SUCKS! I just had to go to the next higher age bracket in my profile! :-(
 
AJ
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RE: Exits During Flight

Wed May 14, 2003 3:02 pm

There is something very reassuring about the simplicity of the 767/DC-10/L-1011 style doors which remain inside the aircraft at all times, few moving pieces and very secure:

The only exception is the swing out (once called Jetescape on DC-8s) exits used on some 767s, however as they are not used as regular exits and are manned (or womanned) by F/As at critical times their security seems sound:

However the main cargo doors are a different matter, however lessons learned in blood on the DC-10 and 747 seem to have made the large, outward swinging cargo doors very safe:

 
OPNLguy
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RE: Exits During Flight

Wed May 14, 2003 10:04 pm

>>>However the main cargo doors are a different matter, however lessons learned in blood on the DC-10 and 747 seem to have made the large, outward swinging cargo doors very safe:

There was a book out after the 1974 THY DC-10 crash near Paris entitled "Destination Disaster" and there's quite an informative section on the virtues/pitfalls of "plug" doors and "C-latch" doors, as well as their actuation and latching. Of particular note for its foresight is a copy of a memo that a Convair (DC-10 fuselage sub-contractor) engineer (Dan Applegate) wrote about his concerns about DC-10 cargo door and floor problems and future failure modes. Great reading.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
EssentialPowr
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RE: Exits During Flight

Thu May 15, 2003 5:41 am

Airplay,

"Everyone except one has ignored the pressure and speed locks installed in some aircraft."

CDfmxtech mentioned the speed input on the 777...so to what other a/c are you referring?

 
AJ
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RE: Exits During Flight

Thu May 15, 2003 9:19 am

OPNLguy, I've read many books that cover the THY crash in 1974, but none so readable and understandable as Air Disaster by Macarthur Job. He covers the 'Windsor Incident' as well as THY, with excellent diagrams for the not so understanding. The involvement of the FAA and ignored findings from Windsor are interesting to say the least.
Air Disaster also covers United's door loss out of Honolulu in the same detail.
 
aer lingus
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RE: Exits During Flight

Sat May 24, 2003 3:19 am

The simplest answer is the pressure acting on the doors Big grin  Big grin  Smile
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