altimeter


altimeter

Instrument that measures the altitude of the land surface or of any object, such as an airplane. The mechanical pressure altimeter measures atmospheric pressure relative to sea level through a series of bellows, gears, and springs, which move pointers on a dial. Radio altimeters measure the distance of an aircraft above the ground rather than above sea level by indicating the time a pulse of radio energy takes to travel from the aircraft to the ground and back; they are used in automatic navigation and blind-landing systems.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on altimeter, visit Britannica.com.

Seen & Heard

What made you look up altimeter? Please tell us what you were reading, watching or discussing that led you here.

Get Our Free Apps
Voice Search, Favorites,
Word of the Day, and More
Join Us on FB & Twitter
Get the Word of the Day and More