If you were exposed directly to that environment, you would lose consciousness in seconds.
To make flight possible, airplanes are pressurized. Air is pumped into the cabin to simulate the pressure you’d experience at around 6,000–8,000 feet above sea level. This allows passengers to breathe normally and remain comfortable.
But pressurization creates an enormous engineering challenge.
The air inside the plane is pushing outward on the fuselage with tremendous force—every second of the flight.
At cruising altitude, the pressure difference between the inside and outside of the aircraft can exceed 8 pounds per square inch (psi). That might not sound like much, but spread across the entire surface of the plane, it translates into tens of thousands of pounds of force trying to tear the aircraft apart.
