How High Do Airplanes Fly Into The Atmosphere?

Many travelers take it for granted, but flight is one of the most thrilling scientific advances of all time. If you’ve ever been sky-high over your favorite city, you know how impactful travel can be, not just via the experiences you have and people you meet, but also the reminder that humans are tiny, and the world is huge. Although that can come with some anxiety — remember that your plane is highly unlikely to crash! — it’s also really cool to learn about how flight works and why.

Recalling elementary-level science, you probably remember that the Earth is surrounded by various layers of atmosphere. Some of those areas are traversable by airplane, while others require something a bit more powerful — like a space shuttle. Here’s what to know about how high airplanes fly into the atmosphere!

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Earth Has Many Levels Of Atmosphere, And Planes Can Only Travel In Two

View from 47,000 feet above Kazakhstan

The Earth has many layers of atmosphere surrounding it, but airplanes can only go as high as the second layer, the stratosphere. Even then, passenger planes don’t often go that high, generally staying at lower elevations in the troposphere.

Passenger Planes Generally Stay in the Troposphere

View of clouds and a city from 30,000 feet

Earth’s troposphere is the bottom layer of the atmosphere, the part where humans live and breathe. It’s around 7.5 miles high all around the Earth, except it does dip lower at the poles and higher at the equator.

• Most of the water cycle happens in the troposphere; 99% of water vapor and aerosols stay here.

Passenger planes tend to fly at heights of around 30,000 and 42,000 feet, which is around 5.6 to 7.95 miles. Different aircraft have flight ceilings, however, so some planes can go higher than others. Regulations also specify how high a certain plane can fly.

• How high can commercial airplanes fly? A maximum of 42,000 feet

According to SimpleFlying, flying lower is generally safer, because of potential impacts on the plane’s engines as well as risks should the airplane’s cabin become depressurized. Given that most planes go down due to factors like user error, lack of plane maintenance, and weather conditions, it makes sense to stick closer to the ground than the stars.

Some planes can fly as high as the stratosphere, however, which ranges between 7.1 and 31 miles above the Earth. The stratosphere is where the ozone layer is, and the higher you go, the warmer it gets. The same concerns that make flying higher in the atmosphere a challenge for planes also make flying in the stratosphere anywhere from risky to impossible.

Aircraft that can fly in the stratosphere, according to specs:

• Boeing 737; flight ceiling of 41,000 feet (7.76 miles)
• Concorde supersonic jet; 60,000 feet (11.36 miles)
• MiG-29 Fulcrum; fighter aircraft with a 13.7-mile maximum altitude

High air is super thin, which SimpleFlying explained can wreak havoc on an aircraft’s engines, wings, and its ability to re-start should a failure occur. It’s also harder to breathe at higher altitudes, and passengers and crew have less time to put on oxygen masks the higher they fly, because those elevations mean mere seconds of consciousness without the pressurized cabin.

Often, turbulance is also higher the higher you fly into the atmosphere. Your flight might have more turbulance than usual anyway, but flying lower can help with that.

Why Can’t Airplanes Fly Higher Into The Atmosphere?

Satellite in orbit

Some planes can fly higher into the atmosphere — namely the supersonic jet from Concorde — but the main reason airplanes can’t fly higher is because of the strain it puts on not only the planes themselves, but the humans on board.

For example, the mesosphere ranges from 31 to 50 miles above the surface of the Earth, and it’s freezing there, getting colder the higher you go. NASA says the mesosphere is the coldest place anywhere within Earth’s system.

The thermosphere, which lies about 50 to 440 miles above Earth, has no clouds and no water vapor. At the bottom of the thermosphere is the ionosphere, but it’s often lumped in with the thermosphere.

• The International Space Station orbits in the thermosphere.

Beyond the area where most humans can travel, the exosphere is between 440 miles and 6,200 miles above Earth’s surface. It’s the highest layer of the atmosphere, and it’s the closest to space; NASA notes that particles began to “escape into space” because the layer doesn’t act like gas.

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So where does space begin? NASA says that’s around 62 miles above Earth’s surface, at something called the Karman line. Most of Earth’s atmosphere is below that, but there is a limit to how much scientists can explore the layers, and parts of Earth’s atmosphere could be as far as 391,000 miles from the surface.

Your next flight definitely won’t venture anywhere near there, unless you’re headed to space!

References: NASA, SimpleFlying, BBC