Air Navigation
Before the advent of modern aids dead reckoning was widely used in air navigation, taking into account displacement of position caused by wind as far as possible, often using a tool called a wind triangle. As a rule dead reckoning (DR) positions were calculated at least once every 300 miles and when making combined turns totaling more than 30 degrees from the initial heading out of the last DR position.
Simple dead reckoning fell out of use for air navigation, but is used by inertial navigation systems (INSes), which are nearly universal on more advanced aircraft. The INS is used in combination with other navigation aids, such as GPS, in order to provide reliable navigation capability under virtually any conditions, without the need for external navigation references.
However, simple dead reckoning is still widely used by civil aircraft not equipped with GPS or radio navigation aids. The pilot periodically establishes a location fix from visual sighting of landmarks with reference to a map, allowing errors in dead reckoned course to be corrected. Pilots of advanced aircraft are trained in dead reckoning, which remains usable in case of failure of advanced navigational systems.
Read more about this topic: Dead Reckoning
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