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Planes fly high in the air, we all know that. But there has to be a reason that they all seem to fly in the same place. So where do planes fly in the sky?

Commercial planes fly at an altitude of around 36,000 feet in the layer of the atmosphere called the stratosphere. Planes fly in the stratosphere to increase fuel efficiency, lessen the risk of issues due to air traffic, avoid weather events, and to have time to deal with emergencies.

If you pay attention to what the pilot says while flying, you’ve probably heard many of them say that you’ve reached the cruising altitude of 35,000 or 36,000 feet. But why do planes always seem to fly at the same altitude? In this article, we’ll take a look at where planes fly in the sky and why that layer of the atmosphere is better than other altitudes.

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Where Do Planes Fly In The Atmosphere?

If you’ve ever flown in a plane, or if you’re a pilot yourself, then you know one thing for certain — planes fly high in the air. Like really high. From your vantage point in the sky, you might see nothing but the tops of the clouds you’re flying over. And if you can see the ground, you won’t be able to make out anything except the planet’s surface itself. And from down here from where I’m sitting, the plane would just look like a tiny speck in the sky.

But where do planes fly in the sky and why do they fly at those heights?

Planes fly in the middle layer of the atmosphere known as the stratosphere. Without getting too far into the nitty-gritty details of the composition of the atmosphere, it’s mainly made up of five layers. These include the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. For the sake of this article, we’ll focus on the stratosphere and the two adjacent layers.

What Is The Stratosphere?

The troposphere is where we live, down here on the surface of the planet. As you probably know from middle school science classes, this is the only layer of the atmosphere that is naturally conducive to human life. The air is just thick enough to where we can breathe, the temperature is livable, and the weather events (usually) aren’t too drastic.

And while planes certainly can fly in the troposphere — smaller aircraft and helicopters typically do — the stratosphere is where most commercial planes are operating at their best. The second layer of the atmosphere, the stratosphere, is around 30,000 to 160,000 feet. This will vary in different spots of the globe, with it being higher near the equator and lower at the poles. But in most places, planes fly at the heights they do because it falls right within the stratosphere.

In this layer of the atmosphere, air is thinner than down here on earth, which is why pressurized aircraft cabins are a necessity. The temperatures in the stratosphere are far colder than down here on earth, but the way that the temperatures change is a bit strange. The temperature is stratified — hence the name of the layer — meaning that it gets warmer as altitude increases; this is opposite of what happens in all other layers of the atmosphere!

But enough about what the stratosphere is, let’s get into why it’s so beneficial for planes to fly there.

Why Do Planes Fly In The Stratosphere?

Now that you know that planes fly in the stratosphere and you have an idea of what it is, let’s take a look at why planes fly in the stratosphere. After all, planes and pilots wouldn’t waste the energy and time needed to reach those altitudes if it wasn’t for good reason!

Increased Fuel Efficiency

The main reason that planes fly in the stratosphere is to make the most out of fuel consumption. The fuel that planes run on is very different from the gasoline that you and I fill up our cars with to drive around town. It’s not cheap and airlines want to get the best fuel efficiency possible out of it. And since the air is much thinner in the stratosphere than it is in the troposphere, planes are able to get much better fuel efficiency.

The reason for this mainly comes down to how planes fly in the first place. Not only is lift necessary for a plane to stay in the air, it also needs to be able to overcome drag and friction in the atmosphere so it can keep flying forward. The jet engines on planes are designed to operate at optimal efficiency in the thin air of the stratosphere. More power and less drag leads to better fuel efficiency and faster airspeeds.

Less Air Traffic

Another reason why most types of planes try to fly in the stratosphere is to avoid the air traffic down here in the troposphere. Even though if you look up into the sky it seems like there is just endless space, it can get pretty crowded up there all things considered. Most smaller airplanes, helicopters, drones, etc. fly at lower altitudes and remain in the troposphere, so it can get congested.

To avoid all of this, commercial airplanes like to fly in the stratosphere between 30,000 and 43,000 feet. This way, they can stay above the traffic generated from the smaller aircraft. And once they’re up in the stratosphere, planes are actually required to turn on autopilot so that it keeps them within 1,000 feet of a set altitude. This also helps to control air traffic and keep everyone flying as safely as possible.

Avoiding Weather Events

Sure, sometimes when you’re flying you might go through a thunderstorm or get battered about by winds and rain. But most of the time, this happens before you actually reach cruising altitude. This is because most of the weather events that we experience down here on earth happen in the troposphere. So if planes fly in the next layer of the atmosphere, they can avoid severe weather events as much as possible.

After all, if you’ve ever been on an airplane and looked out the window after you’ve reached cruising altitude, then you probably see the clouds below you. Most of the weather that we experience down here on earth is generated in the clouds, so flying in the stratosphere helps to avoid this as much as possible.

Dealing With Emergencies

One final reason that planes fly so high in the air is so that pilots have ample time to deal with emergencies. Although this is something that we don’t really like to think about as either pilot or passenger, it is still a reality and is one that must be taken seriously. Planes (and pilots) can experience a multitude of problems while flying that could potentially cause a plane to go down.

By flying at such extreme heights, pilots have more time to react to these issues and emergencies so that they can do everything in their power to safely land the aircraft. You never want to hear a pilot come over the radio and say there is an issue with the airplane, but it’s something that everyone involved needs to be prepared for. And having ample time to figure out a solution could easily be the difference between life and death.