Here’s What Would Happen If Airplanes Weren’t Pressurized

Without pressurization, traveling by plane would be uncomfortable and perhaps even deadly. Here's why.

When you’re miles high in the sky, you might occasionally wonder about the amazing invention of flying. How does it all work—really? And how do we safely go from one place to another in this big hunk of metal? But then the flight attendant brings you your drink and the thought likely flies out of your head. Well, one of those amazing things that allow for safe air travel is pressurization, and you might want to raise your glass to it. It’s generally something most of us don’t give much thought, but it’s what allows us to fly way up in the sky without passing out from a lack of oxygen. Don’t miss more airplane trivia facts you never knew about, too.

Thin air can cause issues

The higher you get above sea level, the thinner the air gets—meaning you get less oxygen from each breath than you would at lower altitudes. If you’ve ever gone from sea level up into the mountains in a short time span, you’ve likely noticed the effects of the thinner air, at least until your body has a chance to acclimate to the different oxygen level. Ever taken a fast elevator ride up to the top of a tall building and have your ears pop? Same principle. Now think about suddenly zooming thousands of feet in the air, without anything protecting you from that thin air. The effects would be severe.

Plus, obviously, humans need oxygen to survive. At high altitudes, the air is too thin to provide enough oxygen to sustain the human body. As National Geographic notes, “at very high altitudes, atmospheric pressure and available oxygen get so low that people can become sick and even die.”

Believe it or not, high altitudes are also the reason you’re more likely to cry on planes.

Solving a potentially deadly problem

From the time when people first discovered ways to take flight, there was a constant push to go increasingly higher. To aim for the clouds and even above them. But that soon presented a problem. Once modern man constructed planes capable of reaching significant heights, it didn’t take long for people to realize that the air up there was too thin for us to safely breathe. In the beginning, existing planes were retrofitted with a makeshift, and often rudimentary, pressure-stabilizing setup. According to Air & Space, the U.S. Army Air Corps first flew an airplane built with a pressurized cabin in 1937.

What pressurization does

California Aeronautical University explains that today’s commercial jets typically fly at altitudes of between 30,000 and 43,000 feet above sea level. This range is the “sweet spot,” where the plane can travel at optimum speed while avoiding much of the lower-altitude turbulence and burning less fuel. The downside: The air at that height doesn’t have enough oxygen for people to breathe safely.

To solve that problem, passenger planes have a built-in pressurization system that keeps the air pressure inside the plane steady at a level that’s safe and comfortable for the people traveling on the plane. This is done through a carefully designed system that constantly circulates compressed air through a specific heating and cooling process that regulates air pressure levels. This pressurization consistently keeps the air pressure inside the plane’s cabin at a level roughly equivalent to what it would be like at around 8,000 feet above sea level.

Check out these other hidden airplane features you didn’t know were there.

What happens when a plane loses air pressure

If you’ve ever flown, you’ve no doubt seen flight attendants demonstrate how to use the oxygen masks, which are designed to drop from panels above the seats if the plane loses air pressure. In case of emergency, it’s important to grab your mask and put it in place over your face quickly, to avoid the issues that can be caused by the decreased oxygen levels.

Passengers on a plane that has lost air pressure can suffer physical symptoms that can be painful and possibly life-threatening. In one instance where the flight crew apparently didn’t correctly complete the pressurization process, passengers almost immediately experienced severe pain in their ears, nosebleeds, and other issues. Fortunately, incidents of that type are rare, as planes are equipped with an alert system that warns the crew if there’s a problem with the pressurization system.

Next, read about some of the scariest moments pilots have experienced on the job.

Bobbi Dempsey
Bobbi Dempsey is a freelance writer, editor and content specialist whose credits include NY Times, Forbes, Family Circle, Good Housekeeping and many others. She has written both consumer-facing and B2B content for numerous companies in the technology, healthcare, education, and personal finance industries.