# Pressure within a commercial jet's cargo area? **URL:** \ **Category:** Factual Questions\ **Created:** [April 5, 2001, 1:28pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915 "2001-04-05T13:28:45Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![choosybeggar](https://avatars.discourse-cdn.com/v4/letter/c/8c91f0/32.png) [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)\ **Post date:** [April 5, 2001, 1:28pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/1 "2001-04-05T13:28:45Z")
Is the cargo area pressurized like the passenger compartment? Is is simply left at ambient? ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [April 5, 2001, 1:37pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/2 "2001-04-05T13:37:55Z")
It is kept pressurized, although not at full sea level pressure. Many times pets in carriers are down there. Also, some things that passengers have packed may be affected if they weren’t kept at pressure. ---
**Author:** ![choosybeggar](https://avatars.discourse-cdn.com/v4/letter/c/8c91f0/32.png) [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)\ **Post date:** [April 5, 2001, 1:50pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/3 "2001-04-05T13:50:15Z")
> [@](#): > > \*Originally posted by AWB \* > **It is kept pressurized, although not at full sea level pressure.** To clarify the OP, is the cargo are pressurized to the same extent as the passenger area? And is the done simply to keep pets alive and shampoo bottles from messing up my underwear? ---
**Author:** ![Threadkiller](https://avatars.discourse-cdn.com/v4/letter/t/aca169/32.png) [@Threadkiller](https://boards.straightdope.com/u/Threadkiller)\ **Post date:** [April 5, 2001, 3:02pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/4 "2001-04-05T15:02:45Z")
> [@](#): > > \*Originally posted by choosybeggar \* > Is the cargo area pressurized like the passenger compartment? Is is simply left at ambient? The ambient bit has been answered. Here is a mailbag answer that comes close to the topic: [Why do my ears hurt when I fly in a pressurized jet?](http://www.straightdope.com/mailbag/mpressur.html) My SWAG would be that the cabin and the cargo area would be pressurized to the same degree. Reasons: [ul] - Much easier to build a permeable cabin floor than to make it a pressure boundary - The round shape of the hull is much easier to reinforce as a pressure boundary than an extended semicircle. - Much easier to have to keep one area at a set pressure than two. [/ul] ---
**Author:** ![manhattan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manhattan/32/7_2.png) [@manhattan](https://boards.straightdope.com/u/manhattan)\ **Post date:** [April 5, 2001, 3:35pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/5 "2001-04-05T15:35:19Z")
Cargo compartments on commercial aircraft come in four types: Class A: Pressurized, not compartmentalized and within easy reach of cabin attendants. Think closets, galley storage, etc. Class B: Pressurized, reachable by crew, but compartmentalized. Fluffy rides here. Class C: Pressurized or not, compartmentalized, has a fire suppression system. Passenger luggage is usually placed in a non-pressurized class C compartment. Class D: Not pressurized, compartmentalized, generally do not have fire suppression systems (except for the lack of air at altitude). This is where the mail goes, along with most other paying cargo, spare parts the airline is lugging back and forth, etc. Not all aircraft have all four types of cargo areas, but most decent sized jets will have a B and a C. I can’t make the link work directly to the FAA regs on this subject, but it’s in 14 CFR 25.857 and available at their website. ---
**Author:** ![Kamandi](https://avatars.discourse-cdn.com/v4/letter/k/5daacb/32.png) [@Kamandi](https://boards.straightdope.com/u/Kamandi)\ **Post date:** [April 5, 2001, 4:02pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/6 "2001-04-05T16:02:38Z")
Manhattan has it technically, but for the layman: Cargo under the passenger floor is pressurized (can’t think of an example where it’s not) to the same pressure as the cabin. The trouble is, _it’s not often heated_. Fluffy won’t suffocate, she’ll freeze. Some cargo areas behind the last row of seats in the cabin (behind the aft pressure bulkhead) are neither pressurized nor heated. Some unheated cargo areas (pressurized or non-pressurized) may have passive heat (the cabin air may vent there), but that doesn’t guarantee a comfy ride for Fluffy. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [April 5, 2001, 4:25pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/7 "2001-04-05T16:25:57Z")
> [@](#): > > Pressurized or not, compartmentalized, has a fire suppression system. Passenger luggage is usually placed in a non-pressurized class C compartment. I’ve always been curious about this. Suppose I had some luggage that I did not want placed in a depressurized area, for whatever reason. Can I request that it ride in fluffy’s section? Do I have to pay extra for that? What do I ask for? What I thought really amusing when I took somebody and their pet to the airport was that the pet got issued a complete ticket, not just a baggage claim of some sort. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [April 5, 2001, 4:52pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/8 "2001-04-05T16:52:36Z")
Somewhat related to the OP: A Turkish Airlines DC-10 crashed in Paris in 1974 for reasons related to pressurizing the cargo hold. After takeoff, at 11,000 feet the aft left cargo door blew open. The pressure difference between the upper and lower compartments caused the passenger floor to collapse. Unfortunately, the control cables for the tail ran through the floor and were broken. It’s been a long time since I read about this, but I seem to remember some criticism that there should have been better venting between the passenger deck and cargo hold. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [April 5, 2001, 11:54pm UTC](https://boards.straightdope.com/t/pressure-within-a-commercial-jets-cargo-area/60915/9 "2001-04-05T23:54:33Z")
> [@](#): > > \*Originally posted by yabob \* > \*\* > > > [@](#): > > > > Pressurized or not, compartmentalized, has a fire suppression system. Passenger luggage is usually placed in a non-pressurized class C compartment. > > I’ve always been curious about this. Suppose I had some luggage that I did not want placed in a depressurized area, for whatever reason. Can I request that it ride in fluffy’s section? Do I have to pay extra for that? What do I ask for?\*\* Well… depends on what it is. If you go to an airline and say “I want this baggage to ride in a pressurized area, can you make sure of that?” I imagine the next few steps would involve unzipping said baggage so the airline can examine the contents to make absolutely sure that whatever it is poses no hazards. Whether they charge you extra or not may depend on the airline. But certainly, if you want it to be comfy and pressurized I’m sure they will accomodate your wishes. Or, if it’s small enough, you could just put it in a carry-on and it can ride with you. Certain types of cargos do have restrictions. If you look at a FedEx form there’s a spot on it to indicate cargo that shouldn’t be put on passenger planes - presumably potentially harzardous stuff.