Where does this come from, and can I check it?

Air bled from the engines enters a sealed fuselage while a valve meters it out to set the cabin pressure. The figure is taken from Federal Aviation Administration, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a technology fact?

Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

An outflow valve holds the cabin at hill altitude

Air bled from the engines enters a sealed fuselage while a valve meters it out to set the cabin pressure Cabin pressure is controlled by the rate at which air leaves, not by making the hull airtight. At cruise an airliner holds a cabin altitude of roughly 1,800 to 2,400 metres, about the pressure of a hill town. The valve opens wider during descent so the pressure matches the airport before the doors are opened. It sits in Mondo's technology collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Federal Aviation Administration

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Tags: aviation, pressure, cabins

An outflow valve holds the cabin at hill altitude: the short answers

Where does this come from, and can I check it?: Air bled from the engines enters a sealed fuselage while a valve meters it out to set the cabin pressure. The figure is taken from Federal Aviation Administration, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a technology fact?: Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.