Altimeters are important navigation instruments for aircraft and spacecraft pilots who monitor their height above the Earth's surface. Skydivers and mountaineers also use altimeters to pinpoint their location in the sky or on the ground. The most common types of altimeters are barometric.

What is barometer used for?

A barometer is a scientific instrument used to measure atmospheric pressure, also called barometric pressure. The atmosphere is the layers of air wrapped around the Earth. That air has a weight and presses against everything it touches as gravity pulls it to Earth.

What are the two most common types of altimeter used?

The two main types are the pressure altimeter, or aneroid barometer, which approximates altitude above sea level by measuring atmospheric pressure, and the radio altimeter, which measures absolute altitude (distance above land or water) based on the time required for a radio wave signal to travel from an airplane, a ...