Why do commercial planes fly at 35,000 feet?

Question

Why do commercial planes fly at 35,000 feet?

In: 13

Answer 1

The higher you go, the thinner the air is, and that gives a few advantages. Assuming you fly at an altitude where your engines can create enough power:

Thin air causes less drag.

Less drag means you can fly faster for a similar amount of fuel.

Less fuel costs less money.

Faster speed means happy customers and more flights you can fly during a given time period.

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The jetliner that does 550mph over the ground at say 30,000 feet, can’t fly nearly that fast at say 5,000 feet, even if it uses way more power trying to do so. So higher= faster and less expensive.

Answer 2

The higher you go, the thinner the air is, and that gives a few advantages. Assuming you fly at an altitude where your engines can create enough power:

Thin air causes less drag.

Less drag means you can fly faster for a similar amount of fuel.

Less fuel costs less money.

Faster speed means happy customers and more flights you can fly during a given time period.

​

The jetliner that does 550mph over the ground at say 30,000 feet, can’t fly nearly that fast at say 5,000 feet, even if it uses way more power trying to do so. So higher= faster and less expensive.