FCOM Pressurisation
Greetings everyone,
I have a question which I feel only this website can answer.
I was going through the A320 FCOM and was in the pressurisation chapter.
As I was reading about its pre-pressurisation function, the FCOM went on to say that the system on the take off roll pressurises the cabin at a rate of -400 fpm.
Is there someone who could help me out to understand why that happens. If the system maintains cabin rate of -400 fpm, the pressure differential would increase and make the job of the pressurisation system harder and make it more uncomfortable for the passengers.
As always, thank you.