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В авиации высота, на которой движется летательный аппарат, называется Высотой полёта.
In aviation the height the aircraft is flying in is called the altitude. It is expressed in feet. The international foot is defined as exactly 0.3048 metres. In aircrafts the altitude is measured with the altimeter. The basis of the altimeter is the same as a aneroid barometer, an airtight drum that will change shape depending on the pressure of the surrounding air. The higher the aircraft the larger the drum. The altimeter is very sensitive and the air pressure caused by the weather has great influence on it.
In contrast to altimeters, ground radar is perfect for measuring directly the altitude above the ground without being influenced by the weather. It is used for ground warning systems.
In communication with ATC two types of altitude are being used:
- The altimeter reading.
The altimeter can be set to three possible references
- to QNH, resulting in the indicated altitude "matching" the true altitude (see below).
- to the Standard pressure (29.92" Hg or 1013.25 hPa) making the altimeter show the pressure altitude. This configuration should only be used in high altitudes.
- to the height above the airfield. While on the runway the indicated altitude would read zero. Near the airfield the indicated altitude would be the absolute altitude (above ground level).
What you have to use depends on the local flight rules.