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Altitude: Difference between revisions
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To use a barometer as a tool to measure the altitude, the [[altimeter]], means it must be corrected for weather influences. For that the airfield has an accurate barometer and they know the height of the airfield above [[Mean Sea Level]]. From those two they will calculate the barometric pressure at [[Mean Sea Level]], the QNH. It will transmit the QNH and with that the altimeter in the aircraft can be corrected for weather influences and will display the [[#True height]]. This way the [[#Indicated altitude]] will be accurate for a certain area around the airfield as long as the weather remains stable. | To use a barometer as a tool to measure the altitude, the [[altimeter]], means it must be corrected for weather influences. For that the airfield has an accurate barometer and they know the height of the airfield above [[Mean Sea Level]]. From those two they will calculate the barometric pressure at [[Mean Sea Level]], the QNH. It will transmit the QNH and with that the altimeter in the aircraft can be corrected for weather influences and will display the [[#True height]]. This way the [[#Indicated altitude]] will be accurate for a certain area around the airfield as long as the weather remains stable. | ||
QNH is a vital tool to use a height map of an area, hence it is vital during approach of an airfield. | QNH is a vital tool to use a height map of an area, hence it is vital during approach of an airfield. There have been dramatic accidents where pilots were flying using [[#Pressure altitude]] (during descend) while they should have used the [[#True altitude]] making the height map of the area useless. In bad visibility mountains have not been noticed and the ground was higher as expected. | ||
==Additional information== | ==Additional information== | ||
<!-- Repository for less relevant information related to altitude --> | <!-- Repository for less relevant information related to altitude --> | ||