This question already has an answer here:

I'm reading a Citation M2's Pilot Training Manual, and it says:

...When the throttles are advanced for takeoff, the bleed air turns on (if not already on for heating), and the pressurization controller starts closing the outflow valves to pressurize the airplane. The cabin altitude may descend by as much as 200 feet during this pre-pressutization prior to lift off.

What's the purpose of the pre-pressurization prior to lift off?


marked as duplicate by Sanchises, Pondlife, mins, fooot, kevin Nov 14 '17 at 19:10

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.