Why do aeroplanes have pressurised cabins

Read More. Call Us: Skip to content. How Cabins Are Pressurized Airplane cabins are pressurized by forcing air into the cabin. Why Pressurized Cabins Are Necessary Cabins are pressurized to create a safe and comfortable environment for pilots, crew and passengers.

More Popular Posts. How is Aluminum Metal Anodized? November 11, Products. 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.

The structural strength of the airplane determines how much differential pressure the cabin can tolerate—a typical figure is eight pounds per square inch—and the fuselages of new airplane designs are pressurized and depressurized many thousands of times during testing to ensure their integrity.

The higher the maximum differential pressure, the closer to sea level the system can maintain the cabin. Federal Aviation Regulations say that without pressurization, pilots begin to need oxygen when they fly above 12, feet for more than 30 minutes, and passengers have to use it continuously above 15, If the door blew off a jet at altitude, all the air in the cabin would depart very quickly and a momentary thick fog would envelope the cabin as the water vapor in the air condensed instantly.

Loose articles would fly around and foam rubber would burst as the tiny air bubbles within it expanded. Of the passengers on board, 30 experienced symptoms, and five were sent to the hospital to get their ears, noses, and throats evaluated.

A Ryanair flight from Croatia to Dublin encountered the same situation in July and had to make an emergency landing after deploying oxygen masks one flyer even tweeted out a photo of his bloodied mask. And, of course, there was the tragic incident this April of the woman who died after being partially sucked out of a Southwest Airlines plane window that was broken by an engine explosion.

Stories like these perpetuate the fear we all have when stepping into a steel behemoth whizzing through the sky at 36, feet: that something completely out of our control will go wrong, causing our brains to ooze out of our ears.

All airplane cabins are pressurized to simulate the amount of pressure felt at 8, feet. Pressurization happens via the engines, which compress incoming air, heat it up, and then divert some of that hot compressed air to the cabin.

Finally, the cooled air is combined with air already in the cabin using a mixer, or manifold. If planes were pressurized at ground level, they would have to be made with heavier materials and use more fuel. Just like the human body can only survive in a certain range of temperatures, it can only survive in a certain range of pressures.

When a plane is ascending and descending, atmospheric pressure changes, and our bodies try to equalize the internal pressure to match the outside environment. The equalizing process is usually assisted by an air crew ensuring that the cabin is pressurized, but even with that help, many people still feel effects of altitude change through things like ears popping, which happens because your middle ear is trying to equalize pressure with the surrounding atmosphere.

If a cabin crew does not remember to pressurize the cabin, as with the Jet Airways flight, the gases in your body will expand beyond what they are supposed to, rupturing tissues and causing bleeding. 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.