Ever wondered why pretty much every flight you've ever taken cruises at 36,000 feet? There are actually a number of reasons.

Have you ever looked up in the sky and seen an airplane flying miles above your head, leaving a trail behind it? Chances are that aircraft is an incredible 36,000 feet in the air. If you have taken a flight, you might have even heard your pilot refer to that specific height. His or her voice coming over the tannoy and announcing the plane has reached its cruising altitude of 36,000 feet.


But why is that the optimum altitude for commercial flights? We're here to explain with a little help from Travel + Leisure. There are actually a number of reasons. The first is the thinner air. Since 36,000 feet is a further 7000 feet higher than the peak of Mount Everest, the air up there is pretty thin. That allows the aircraft to travel faster while using less fuel.

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Flying at this height also lessens the chance of a plane coming into contact with something else. Birds and drones mainly, but also other aircraft. Planes flying east are required to fly at an odd altitude (so 35,000 feet) while planes flying west fly at even numbers. That is obviously to prevent them from colliding with each other should their flight paths cross.

Weather is a big factor too. Since planes fly so high, they're actually above the part of Earth's atmosphere called the troposphere. That's the area in which the weather happens. That's why it can be pouring down with rain outside your plane window one minute, and sunny the next. The higher altitude also reduces the chance of turbulence, although it can and does still happen, as some of you will know.

Last but not least is what might happen in the case of an emergency. Should something go wrong, the plane being so high above the Earth gives the pilot a lot more time to try to fix an issue or find a safe place to land. All in all, the 36,000 figure is not one which has been randomly picked out of the air. There's method to planes cruising at that altitude, and all of the above reasons add up to why flight is such a popular way to travel.

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