Also referred to as 'radar height' or feet/metres above ground level (AGL). :вЂЉii It can be measured using a radar altimeter (or 'absolute altimeter').

Absolute altitude is the vertical distance of the aircraft above the terrain over which it is flying.

In UK aviation radiotelephony usage, the vertical distance of a level, a point or an object considered as a point, measured from mean sea level this is referred to over the radio as altitude.(see QNH)

Indicated altitude is the reading on the altimeter when it is set to the local barometric pressure at mean sea level.

There are several types of altitude in aviation: On the flight deck, the definitive instrument for measuring altitude is the pressure altimeter, which is an aneroid barometer with a front face indicating distance (feet or metres) instead of atmospheric pressure. When flying at a flight level, the altimeter is always set to standard pressure (29.92 inHg or 1013.25 hPa). So when the altimeter reads the country-specific flight level on the standard pressure setting the aircraft is said to be at 'Flight level XXX/100' (where XXX is the transition altitude). Pressure altitude divided by 100 feet (30В m) is the flight level, and is used above the transition altitude (18,000 feet (5,500В m) in the US, but may be as low as 3,000 feet (910В m) in other jurisdictions).

ДЄviation altitude is measured using either mean sea level (MSL) or local ground level (above ground level, or AGL) as the reference datum. Parties exchanging altitude information must be clear which definition is being used. 'true altitude'), or implicitly through the context of the communication. In aviation, the term altitude can have several meanings, and is always qualified by explicitly adding a modifier (e.g.

Definition of a altitude geometry