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Old 10-21-2013, 03:12 PM
Huvudtvätt is offline
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Can you really access the cargo hold from the cabin on commercial aircraft?


You see this in movies all of the time. Someone has hidden a bomb, or snakes or terrorists or something in the cargo hold and the hero opens a hatch and climbs down to take care of it. Sometimes there is even an elevator you can take to get there.

Yet you never see these hatches in real life, at least not in my experience. And it would seem like a great security risk to have easy access to all the stuff that they wouldn't let you carry on as cabin luggage.
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Old 10-21-2013, 03:21 PM
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Are airplane cargo holds even pressurized? IIRC that they aren't - in which case, even if such a hatch existed, it'd require superhuman strength to open it.
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Old 10-21-2013, 03:23 PM
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Related, can you depressurize the cabin?
Say there were snakes on your plane- couldn't you depressurize, chill them into torpor, and stuff them in the overhead luggage compartments?
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Old 10-21-2013, 03:23 PM
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We have a couple of airline pilots on the board who will no doubt weigh in, but I think it's safe to say that in general, no, you can't.

Sometimes a part of the cargo space is used for crew rest bunks or lavatories, those of course would be accessible. The luggage, however, is not.
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Old 10-21-2013, 03:37 PM
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Part would have to be pressurized and heated for pets.
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Old 10-21-2013, 03:41 PM
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Quote:
Originally Posted by Smapti View Post
Are airplane cargo holds even pressurized? IIRC that they aren't - in which case, even if such a hatch existed, it'd require superhuman strength to open it.
Yes, they are pressurised.
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Old 10-21-2013, 03:46 PM
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Not in a DC-9-30 which I worked on back in the day. I believe that's true for the updated MD-80 series of the same aircraft.

The cargo hold in the DC-9 is pressurized, but doesn't have direct airflow into them. There are little valves between the roof of the cargo compartments and just under the floor of the cabin to allow pressure to equalize, but the air could get stale in the cargo bays. It's not directly heated either and can get cold in them.

There is a panel in the cockpit that allows someone to go down into the E&E (electronics and environmental) compartment. This compartment is on the save level and just forward of the cargo compartment, but there's no way to get from the E&E into cargo compartment.
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Old 10-21-2013, 04:30 PM
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I would think they are pressurized - they put dogs there. I will await a more learned member of the board here to confirm.
  #9  
Old 10-21-2013, 06:28 PM
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They are definitely pressurised. It would be difficult not to pressurise the cargo hold as it would place a lot of stress on the floor between the cabin and the hold. It is much better to use the entire structure of the fuselage as the pressure hull.

As for getting down there, you definitely can't in the BAe146, and I would be very surprised if you could in other small-medium airliners. As for B747, A380, and similar, I doubt you'd be able to but I don't know. You can get in to the cargo bay in the Dash 8 as it is behind a bulkhead at the rear of the passenger cabin and the bulkhead has a door.

Quote:
Originally Posted by aNewLeaf
Related, can you depressurize the cabin?
Say there were snakes on your plane- couldn't you depressurize, chill them into torpor, and stuff them in the overhead luggage compartments?
Yes you can depressurise the cabin. You wouldn't do it to chill the snakes though, you'd do it to starve them of oxygen.

Last edited by Richard Pearse; 10-21-2013 at 06:29 PM.
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Old 10-21-2013, 07:11 PM
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Originally Posted by aNewLeaf View Post
Related, can you depressurize the cabin?
Say there were snakes on your plane- couldn't you depressurize, chill them into torpor, and stuff them in the overhead luggage compartments?
Wouldn't it be better to turn off the cabin heat? It would slow down the snakes, but the passengers wouldn't need oxygen masks.
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Old 10-21-2013, 07:14 PM
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Originally Posted by aNewLeaf View Post
Related, can you depressurize the cabin?
Certainly; at the very least you could use something to punch a hole in the skin of the plane or break a window. The real question is can you do so in a controlled fashion that lets you re-pressurize the plane afterwards.
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Old 10-21-2013, 09:15 PM
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Quote:
Originally Posted by aNewLeaf View Post
Related, can you depressurize the cabin?
Say there were snakes on your plane- couldn't you depressurize, chill them into torpor, and stuff them in the overhead luggage compartments?
You can but they will seek warmth by climbing up your pant legs.

There are a number of planes like the 747 that have hatches which allow entry/exit of the plane without using the normal side door. usually through the nose wheel/avionics bay.
  #13  
Old 10-21-2013, 10:26 PM
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Originally Posted by Der Trihs View Post
Certainly; at the very least you could use something to punch a hole in the skin of the plane or break a window. The real question is can you do so in a controlled fashion that lets you re-pressurize the plane afterwards.
Yes you can. You can set the pressurisation to manual mode and open the outflow valves which are valves in the fuselage that control how much air is let out of the cabin. You can control the rate at which the cabin depressurises so that ears and sinuses aren't traumatised. Once the snakes are unconscious and restrained you can put the pressurisation back to auto and the cabin will "descend" back to where it should be.
  #14  
Old 10-21-2013, 10:41 PM
Richard Pearse is offline
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Quote:
Originally Posted by Magiver

There are a number of planes like the 747 that have hatches which allow entry/exit of the plane without using the normal side door. usually through the nose wheel/avionics bay.
The avionics bay on the 146 is accessible from a hatch in the flight deck and a hatch on the right side of the nose. It also has the benefit of sitting low to the ground so you don't need a ladder to get to the avionics bay.

The hydraulic bay and cargo bays on the other hand are only accessible from the outside.

Last edited by Richard Pearse; 10-21-2013 at 10:42 PM.
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Old 10-21-2013, 10:48 PM
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Quote:
Originally Posted by Richard Pearse View Post
The avionics bay on the 146 is accessible from a hatch in the flight deck and a hatch on the right side of the nose. It also has the benefit of sitting low to the ground so you don't need a ladder to get to the avionics bay.

The hydraulic bay and cargo bays on the other hand are only accessible from the outside.
Yes but if you're a snake don't you want the comfortable glow of electronics versus the cold cold cargo in back?
  #16  
Old 10-21-2013, 11:38 PM
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That's where I'd be if I was a snake.
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Old 10-22-2013, 12:10 AM
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I was in the very back row of a DC-10 & the pilot came back, went through a door / hatch that looked like a door and I could what appeared to be the outer skin. Wind noise also became much more intense. Was in there about 5 minutes, came out & talked to the stewards, gave my attentive look a "Do not say a word to anybody." & went back up front.

( We had an inflight situation that the crew in the back & I in the last row knew was not normal. We heard it go [not normal] )

Went on to the next destination and we changed planes. Not sure if we were supposed to or if it was because of what they found. They did not let me be in the loop.
  #18  
Old 10-22-2013, 01:31 AM
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For most modern airliners, no. For the 747, yes, you can get access to the forward cargo hold, but wouldn't be able to do much there since it is jammed full of LD-3 containers.
  #19  
Old 10-22-2013, 06:36 AM
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The 777 has an access hatches to both the forward and aft cargos. The forward hatch is just aft of the flight deck door, the aft access is between doors 3R and 3L. The 737, the plane I have worked on the most in my 30 years at Boeing only has an emergency access panel to the forward cargo. The gain access, the carpets would need to be pulled up and possibly a seat moved to gain access. It is something that would be difficult, if not impossible, to do while the plane is in the air.
  #20  
Old 10-22-2013, 06:44 AM
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Quote:
Originally Posted by Richard Pearse View Post
They are definitely pressurised. It would be difficult not to pressurise the cargo hold as it would place a lot of stress on the floor between the cabin and the hold. It is much better to use the entire structure of the fuselage as the pressure hull.
This. A large flat surface (like the floor of a 747's passenger deck) that's resisting a pressure differential is subjected to bending loads and must be built rather thick and rigid (and therefore heavy). A curved surface (like the skin of a 747's fuselage) that's resisting a pressure differential is subjected to simple tension and can do the job with a lot less material/weight. ISTR the cabin is kept at a "pressure altitude" of about 5,000 feet, i.e. the internal pressure is about 11 psi. At 35,000 psi the ambient presssure is just 3.5 psi, so the inside/outside pressure differential at cruise is about 7.5 psi. Assuming a 747 fuselage is ~20 feet wide, a full-width strip of fuselage floor measuring 1 foot from front to rear would be subjected to 21,600 pounds of force (in addition to the weight of passengers and seats) if the cargo area were not pressurized. Think "seven Honda Civics." The floor ain't that robust.
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Old 10-22-2013, 07:01 AM
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A Heathrow airplane loader was very happy some 10-15 years ago that he was able to reach the cabin from the cargo hold of a plane bound for the West Indies when his colleagues didn't notice that he was still in there and closed the door. His employer wasn't as happy, though, when they were presented with an invoice from British Airways for a round ticket to Trinidad (or wherever the plane was headed).
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Old 10-22-2013, 08:20 AM
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Of course snakes are cold-blooded. A main reason we need oxygen is to burn the calories that keep us warm, which is why we eat a lot - while snakes eat a lot less often. So I assume they also use a lot less oxygen and would take longer to feel the effects of low oxygen... So I assume, as others pointed out, the snakes will slow down due to cold. Meanwhile, they will seek out warm... you.
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Old 10-22-2013, 10:25 AM
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I would think they are pressurized - they put dogs there. I will await a more learned member of the board here to confirm.
Legendarily, the cargo compartment temperature control in the cockpit is called the Dead Dog Switch.

I would be sorely disappointed to learn that the scene in The High and the Mighty where John Wayne goes into the belly of the crippled DC-4 to get luggage to throw overboard couldn't really have happened.
  #24  
Old 10-22-2013, 01:35 PM
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The really fun "secret" route on the 777 is the escape hatch from the aft overhead crew rest area (bunks and private area for the crew). One of the stowage bins above the passenger seats is a dummy (locked on the outside) that is really an emergency escape from the crew rest. An attendant could, from inside the crew rest, open the stowbin door, flip out a little ladder, and climb down right into the lap of a passenger "Don't mind me. sir, I'm just a carry-on"
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