Doors--------------can they?

[atom290]

I’m having an argument with my flat mate.

She says that an aircraft door cannot be opened mid flight. In her defence she is an air hostie, although having just done a night flight she is a grumpy one, so says she knows best.

Now I think they can:

1. Hollywood films show it’s possible!
2. The air pressure is less on the outside so therefore it would help the opening of the door?

So the only thing stopping it is:

do the doors open inwards?
Am I wrong?

[Mr E]

I think there's an awful lot of saftey gear on a passanger jet to prevent a door being opened with a pressure imbalance.....

[atom290]

But if a person wanted to could it be done?

She isnt talking to me now and doors are being slammed...told you she was grumpy!

[Mr E]

One would assume there's a way to bypass the safeties should they fail.

I haven't got a clue though.

[atom290]

Can Hollywood be wrong?

Whenever a gun is fired in a plane a little hole turns into a big hole, usually because the token fat person got sucked through it.

Funny how no nuns get sucked out?

so surely if you unlocked the mechanism the door would open itself?

[pbrett]

You can. All doors on a plane are emergency doors. They'd be a bit crap if you couldn't open them in all circumstances wouldn't they?

[atom290]

This is true but once you are on the ground, be it land or sea, then yes that would make sense. But as they dont come standard with parachutes 30,000 feet might be a reason to stop the door from opening.

Its a question I need answering so I can go and wake her up and tell her shes wrong!

[swilly]

Is your air-hostess friend fit.

Any photo's

WHo gives a shite about aircraft doors.

Where are those photos.

[atom290]

Its obviously true blokes do wake up with a stiffy!

[deltaf]

Nope! You cant open the door in mid flight..
The reason being that the door opens INWARDS to start with, so the higher air pressure inside the plane will keep it closed, (applies at higher altitudes).

Calculate the surface area of the door inside(includes portholes) then apply normal atmospheric to it, and then add to that the pressure difference OUTSIDE, say 5 psi.
Youd end up with 20 psi per sq in holding it shut, which youd never overcome, us humans being weedy an all........

[atom290]

That was one of my thoughts

What about the ones over the wings, I thought they open outwards?

[forever_driving]

If you're ever on a plane with her say "Right, I'm going to show you that these doors DO open and run over to a door". If she runs after you screaming "NOOOOOO", then in her heart she knows that the doors can be opened. If she stays where she is and remains, you're wrong. Of course, if the door does actually open, you'll be sucked out the plane and at least while you fall back to earth, you can be at peace with yourself because you were right all along

[vixpy1]

swilly said:

Is your air-hostess friend fit. Any photo's WHo gives a shite about aircraft doors. Where are those photos.

Too bloody right, we want photots

[wedg1e]

So why do I keep hearing the cockpit instruction 'Door selectors to automatic (or manual)' issued over the PA to the cabin crew? The doors are always opened manually (ie not hydraulically); if the cockpit can override this then presumably that could only apply if they knew the cabin crew weren't able to open them; in that case why do they need an override, since the cabin crew tell those sat next to the emergency exits how the doors work?

More fuel for the debate...

Ian

[Size Nine Elm]

deltaf said:

Nope! You cant open the door in mid flight.. The reason being that the door opens INWARDS to start with, so the higher air pressure inside the plane will keep it closed, (applies at higher altitudes). Calculate the surface area of the door inside(includes portholes) then apply normal atmospheric to it, and then add to that the pressure difference OUTSIDE, say 5 psi. Youd end up with 20 psi per sq in holding it shut, which youd never overcome, us humans being weedy an all........

Not quite...

Even pressurised aircraft don't maintain sea level pressure at altitude - half that maybe, hence ear problems on descent as the plane repressurises.

At 30,000 ft air pressure outside is about 1psi, and inside would be about 8 psi, so about a 7 psi difference. Still tricky to open the door against.

And to revert back to topic, you just get Michael Caine in to blow the bloody doors off.

[simpo two]

Common sense says that doors cannot be opened during flight - at least not without releasing some kind of lock. Otherwise, and pressure permitting, anyone with a bad attack of claustrophobia etc and having a panic attack would simply be able to open it to get out. A bad idea.

[blueyes]

wedg1e said:

So why do I keep hearing the cockpit instruction 'Door selectors to automatic (or manual)' issued over the PA to the cabin crew? The doors are always opened manually (ie not hydraulically); if the cockpit can override this then presumably that could only apply if they knew the cabin crew weren't able to open them; in that case why do they need an override, since the cabin crew tell those sat next to the emergency exits how the doors work? More fuel for the debate... Ian

I think the manual and automatic refer to the deployment of the bouncy-castle chutes. Automatic just before take off so that they bounce out if you open the door in an emergency and manual, when you land so that they don't.

Could be wrong though.

[Leadfoot]

1 - orginal Q:
No the doors can't be opened in flight. As has been pointed out by deltaf, the higher pressure inside the cabin forces the doors shut. It might just be possible to move the door slightly at low altitude when the pressure differential inside to outside is smaller but you wouldn't get it fully open.
They are known as 'plug' type doors as the door is bigger than the opening (if you look at the door on any Boeing <767 being opened, you'll see it swing inwards first then go thru' the frame at an angle for clearance. Other types/manufacturers use different methods but to the same end) - hence they plug the gap.

2 - Wedg1e:
"doors to automatic" is the instruction given to the cabin crew to arm the escape slides. When they are in "automatic" (this is just the term used for the announcement, correctly it should be "armed" - but that's not the sort of phrase you'd want to hear over the p.a.) the escape slide will deploy automatically whenever the door is opened.
"doors to manual" is the instruction to disarm the slide on arrival.

3 - overwing doors:
Open inwards. See plug doors above.
This is changing on newer aircraft types (latest 737's AFAIK) so that the door goes up into the ceiling, but still inside, as the normal types have to be removed into the cabin & then thrown out of the hole. As they are quite heavy they can get stuck in the cabin & impede passenger egress (Airtours 737 fire at Manchester being case in point).

HTH

[MarkK]

blueyes said:

wedg1e said: So why do I keep hearing the cockpit instruction 'Door selectors to automatic (or manual)' issued over the PA to the cabin crew? The doors are always opened manually (ie not hydraulically); if the cockpit can override this then presumably that could only apply if they knew the cabin crew weren't able to open them; in that case why do they need an override, since the cabin crew tell those sat next to the emergency exits how the doors work? More fuel for the debate... Ian I think the manual and automatic refer to the deployment of the bouncy-castle chutes. Automatic just before take off so that they bounce out if you open the door in an emergency and manual, when you land so that they don't. Could be wrong though.

Spot on actually.

I'm pretty sure that it would be technically possible to open the doors in flight. There would be safety interlocks to prevent accidental operation but there is no way they would hard wire the doors shut as there would always be the chance that it would interfere with their operation in a real emergency.

In reality I think a combination of air pressure would make them difficult to open and the aircrew would have ways of enabling or disabling their operation.

[Leadfoot]

MarkK said:

There would be safety interlocks to prevent accidental operation

This only applies where the doors are normally unlocked & opened electricaly (B767, DC10 & L1011 all use motors to raise the doors upwards into the ceiling - still opening inwards tho'). The electrical circuit is disabled whenever the plane is in the air.
They all still have emergency sytems to open the doors, which would work in flight if it were not for the pressure difference acting on the door.