How is cabin pressure maintained in an aircraft

As airplanes ascend higher into the sky, they pump air into the cabin space to pressurize it. All commercial airplanes have pressurized cabins such as this. Rather, cabin pressurization is an important safety feature. So, how does cabin pressurization work, and why is it important for airplanes? Airplanes pressurize their cabins by pumping air into them.

Once the cabin achieves an ideal pressure level, the airplane will maintain it. Most airplanes control their cabin pressure via an outflow valve. In the open position, excess air will bleed out. The cabin pressure will then drop to an appropriate level, resulting in the outflow valve closing. Some airplanes use other methods to regulate cabin pressure, but most modern-day commercial airplanes rely on an outflow valve for this purpose.

Cabin pressurization is important because of the nuances between low- and high-altitude air density. Air is less dense at high altitudes than low altitudes. You can reach Swayne at swayne boldmethod.

To: Separate email addresses with commas. Now What? All Videos. Planes Careers. This story was made in partnership with Republic Airways. Check out the full series here. Ready to apply for a pilot slot? Submit your application here. Live from the Flight Deck. John Pozadzides.

Bryan Burke. Ken Mist. Sign Up. Swayne Martin Swayne is an editor at Boldmethod, certified flight instructor, and an Embraer First Officer for a regional airline. Recommended Stories. Would You Go? How DME Works. Air is pressurized by the engines. Turbofan engines compress intake air with a series of vaned rotors right behind the fan. At each stage of compression, the air gets hotter, and at the point where the heat and pressure are highest, some air is diverted.

Some of the hot, high-pressure air, called bleed air , is sent to de-ice wings and other surfaces, some goes to systems operated by air pressure, and some starts its journey to the cabin.

The cabin-bound air has to be cooled first in an intercooler , a device like a car radiator that sheds the heat to the ambient air scooped aboard for that purpose.

The air packs compress the incoming air to heat it before sending it to another intercooler to dump the heat to the outside. The air then expands through an expansion turbine, which cools it the way blowing with your lips pursed results in a cool flow of air.

Now the air is ready to mix with air from the cabin in a mixer, or manifold , that adds the new air to the recirculating cabin air, which is moved by fans. To maintain a comfortable temperature for the passengers, automatic systems regulate the mixture of heat from the engines and cold from the air packs.

To maintain the pressure in the cabin equal to that at low altitude, even while the airplane is at 30, feet, the incoming air is held within the cabin by opening and closing an outflow valve , which releases the incoming air at a rate regulated by pressure sensors. Think of a pressurized cabin as a balloon that has a leak but is being inflated continuously.

On the ground, the airplane is unpressurized and the outflow valve is wide open. During preflight, the pilot sets the cruise altitude on a cabin pressure controller. As soon as the weight is off the main wheels at takeoff, the outflow valve begins to close and the cabin starts to pressurize. Your ears may pop, but the effect is mild because the climb rate is only feet per minute. When the airplane descends, the pilot sets the system controller to the altitude of the destination airport, and the process works in reverse.