Search results
Results From The WOW.Com Content Network
An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. [1] The measurement of altitude is called altimetry , which is related to the term bathymetry , the measurement of depth under water.
The greater the altitude, the lower the pressure. When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is a type of altimeter called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, and skydivers use wrist-mounted versions for similar ...
Old altimeters were typically limited to displaying the altitude when set between 950 mb and 1030 mb. Standard pressure, the baseline used universally, is 1013.25 hectopascals (hPa), which is equivalent to 1013.25 mb or 29.92 inches of mercury (inHg). This setting is equivalent to the atmospheric pressure at mean sea level (MSL) in
QFE - is the barometric altimeter setting that causes an altimeter to read zero when at the reference datum of a particular airfield (in practice, the reference datum is either an airfield center or a runway threshold). In ISA temperature conditions the altimeter will read the height above the airfield/runway in the vicinity of the airfield.
The rule affected only those aircraft operating under IFR when in level flight above 3,000 ft above mean sea level, or above the appropriate transition altitude, whichever is the higher, and when below FL195 (19,500 ft above the 1013.2 hPa datum in the UK, or with the altimeter set according to the system published by the competent authority in ...
Aircraft altimeters measure the relative pressure difference between the lower ambient pressure at altitude and a calibrated reading on the ground. In the United States, Canada [2] and Japan, these altimeter readings are provided in inches of mercury, but most other nations use hectopascals. Ground readings vary with weather and along the route ...
The altimeter, which is usually a barometer calibrated in units of distance instead of atmospheric pressure, can therefore be set in such a way as to indicate the height of the aircraft above ground. This is done by communicating with the control tower of the airport (to get the current surface pressure) and setting the altimeter so as to read ...
Experiments in 1659 by Robert Boyle of the Royal Society were made using a barometer underwater, and led to Boyle's law. [1] The French physicist, mathematician and inventor Denis Papin published Recuiel de diverses Pieces touchant quelques novelles Machines in 1695, where he proposed a depth gauge for a submarine. [2]