I know a lot about airplanes, but I've always wondered the vents deal with air pressure in the sky

  • $\begingroup$ The answers to this question explain that in quite a bit of detail. $\endgroup$
    – reirab
    Aug 6, 2015 at 20:23

1 Answer 1


Came across this diagram that sums it up pretty nicely:

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  • You get 'bleed' air from the engine compressor stage. On 'bleedless' aircraft, such as the B787, this is done by electric compressors instead.

  • Air temperature and pressure is adjusted as necessary in the conditioning packs since it heated up a lot when it was compressed.

  • Air is then distributed to the different 'zones'. A bit of the cabin air is recirculated.

  • Some areas, such as the cockpit, generally receive air directly from the packs without recirculating at a slightly higher pressure, to blow possible smoke away from the interior and to prevent smoke being recirculated into the cockpit. For the same reason, you try create a flow out through the baggage hold.

Here is a more complicated diagram from avsoft's website for a CRJ200:



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