Plain English Meaning

A short saying in aviation that states a basic truth pilots rely on. The classic one about pressure and temperature reminds you that when you fly into lower pressure or colder air, your real height above the ground is less than what your altimeter shows.

Full Definition

A short, accepted truth or rule of thumb in aviation that captures a fundamental principle pilots are expected to know and apply. In the context of pressure and temperature, the well-known axiom is: 'From high to low, look out below,' which warns that flying from an area of high pressure or temperature into an area of low pressure or temperature causes the aircraft's true altitude to be lower than the altimeter indicates.

Context Anchor

Seen in aircraft performance discussions, especially when how and temperature affect and .