altimeter

American  

[al-tim-i-ter, al-tuh-mee-ter] / ælˈtɪm ɪ tər, ˈæl təˌmi tər /

noun

1. a sensitive aneroid barometer that is graduated and calibrated, used chiefly in aircraft for finding distance above sea level, terrain, or some other reference point by a comparison of air pressures.

2. any device used for the same purpose that operates by some other means, as by radio waves.

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altimeter British  

/ ælˈtɪmɪtə, ˈæltɪˌmiːtə /

noun

1. an instrument that indicates height above sea level, esp one based on an aneroid barometer and fitted to an aircraft

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altimeter Scientific  

/ ăl-tĭm′ĭ-tər /

1. An instrument that measures and indicates the height above sea level at which an object, such as an airplane, is located.

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Etymology

Origin of altimeter

First recorded in 1820–30; alti- + -meter

Explanation

An altimeter measures how far above ground something is. You wouldn't want to fly a plane without an altimeter! The two halves of altimeter should give you a clue to its meaning: altitude is height above ground, and meters are used to measure distance. An altimeter measures altitude. This is an extremely important device in the field of aviation. When flying an airplane, pilots needs to know exactly what their altitude is: the altimeter tells them. Pilots flying helicopters, blimps, and other flying vehicles use altimeters too. A plane without a working altimeter isn't safe to fly.

Example Sentences

This is done using a specific type of satellite called an altimeter, which sends down radar pulses to very precisely measure the height of the ice surface.

From BBC • Feb. 26, 2024

“Instead the microwave altimeter’s wider footprint allowed Chandrayaan-3 to better tolerate abrupt changes in altitude,” explains Priyanka Mehrotra of SAC, who is lead system designer of Chandrayaan-3’s Ka-Band microwave altimeter.

From Scientific American • Aug. 23, 2023

The Federal Communications Commission granted them licenses for the C-Band spectrum and dismissed any risk of interference, saying there was ample buffer between C-Band and altimeter frequencies.

From Seattle Times • Jun. 30, 2023

At the time, pilots used the altimeter, which measures altitude, terrain charts and visual cues to avoid accidents.

From New York Times • Jun. 2, 2023

The compass was still gyrating loosely, but the altimeter was functioning accurately, as far as he could judge, and showed them to be floating about a thousand feet above the seashore and parallel with it.

From "The Subtle Knife" by Philip Pullman