Air Pressure
Pressurisation System
The engines are just big air pumps, squishing air into the cabin at a higher pressure than outside the plane. In just the same way that the weight of the atmosphere above squashes the air at ground level, the pressurisation system makes the air pressure inside the cabin high enough for us to breathe.
It would be possible to keep the air pressure the same as on the ground, but the aeroplane would need to be heavier (as strong and heavy as a submarine!) and the engines would have to be bigger (using more fuel). So, to keep the price of your air ticket down to an affordable level the cabin is only partly pressurised.
This means that as the plane climbs the air pressure in the cabin reduces, but not as much as outside, and not to such a low pressure that you cannot breathe comfortably. The air pressure inside the cabin is roughly the same as if you were standing on top of an 8000 foot (2500 metre) tall mountain.
I don’t believe you… I want some proof!
