altimeter


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Related to altimeter: Aircraft Altimeter

altimeter

(ăltĭm`ĭtər, ăl`tĭmē'tər), device for measuring altitude. The most common type is an aneroid barometerbarometer
, instrument for measuring atmospheric pressure. It was invented in 1643 by the Italian scientist Evangelista Torricelli, who used a column of water in a tube 34 ft (10.4 m) long.
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 calibrated to show the drop in atmospheric pressure in terms of linear elevation as an airplane, balloon, or mountain climber rises. It shows height above sea level, but not above such land features as hills, mountains, and valleys. The radio altimeter, or terrain-clearance indicator, is an absolute altimeter; it indicates the actual altitude over water or over terrain, however uneven. It operates by first sending either continuous or pulse radio signals from a transmitter in an aircraft to the earth's surface. A receiver in the aircraft then picks up the reflection of the signals from the surface. The time it takes for the signals to travel to the earth and back is converted automatically into absolute altitude that can then be read from a calibrated indicator. The radio altimeter is used in the automatic landing systems of aerospace vehicles; systems developed from radio altimeters can automatically control military aircraft flying at high speeds and low altitudes.

altimeter

[al′tim·əd·ər]
(engineering)
An instrument which determines the altitude of an object with respect to a fixed level, such as sea level; there are two common types: the aneroid altimeter and the radio altimeter.

altimeter

altimeter
Altimeter indicator dial.
altimeter
Construction of a simple altimeter.
An instrument to indicate the height of an aircraft above a predetermined datum, normally sea level. Specifically, an instrument similar to an aneroid barometer that utilizes the change of atmospheric pressure with altitude to indicate the approximate elevation above a given point or plane used as a reference. A simple pressure altimeter is an airtight metal case, the interior of which is kept at atmospheric pressure by a tube connecting it to the static tube of the ASI (airspeed indicator). Inside the instrument case, a partially evacuated aneroid capsule is secured at the center of one of its faces to a base rigidly fixed to the casing. A leaf spring prevents the collapse of the capsule. The capsule expands as aircraft gains height. The expansion of the capsule is converted into height through a system of gears. A pressure altimeter suffers from barometric, temperature, instrument, and lag errors. Radio or radar altimeters indicate heights above ground level.

altimeter

an instrument that indicates height above sea level, esp one based on an aneroid barometer and fitted to an aircraft
References in periodicals archive ?
Therefore, pilots could become desensitized to the necessity of managing their altimeter setting in the aircraft because (up to) half of their instrument training each year is in a flight simulator.
The regulation requires an independent secondary mechanical altimeter, airspeed indicator, attitude instrument and a magnetic heading instrument (a compass will suffice).
The lack of snow in this part of Antarctica means that radar signals emitted by CryoSat's altimeter bounce straight off the glistening ice and back to the satellite.
The car compass and the car altimeter both are world-class products that need no electricity to run, are easy to install and need little to no maintenance.
The new digital low range altimeter (DLRA) LRA-2100 uses digital signal processing to gauge the aircraft's height above terrain.
THY said the automatic throttle control system of the plane, which controlled the speed of the aircraft, got the relevant height information from the left altimeter and considered the wrong data as an indicator of landing at the ground.
The standby altimeter measures air pressure to let you know how far your bird is above sea level.
Mr Roberts, who heads for Scotland tomorrow, added: "It sounds sophisticated but we will have to hunt around for the altimeter which will fall to earth and only then can we check if the rocket went high enough to beat the record.
Turkish Airlines 737-800 that crashed last week on approach to Amsterdam reduced power prematurely due to a malfunctioning altimeter, and by the time the pilots reacted it was "too late to recover the flight," Dutch Safety Board Chairman Pieter van Vollenhoven said yesterday.
Pieter van Vollenhoven, the chief investigator, said at 700m "the left altimeter suddenly showed a change in altitude, which it transmitted
A lot of pilots don't fully understand how their barometric altimeter works.