A position line or line of position (LOP) is a line (or, on the surface of the Earth, a

curve In mathematics, a curve (also called a curved line in older texts) is an object similar to a line, but that does not have to be straight. Intuitively, a curve may be thought of as the trace left by a moving point. This is the definition that ...

) that can be both identified on a chart (

nautical chart A nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or river bank, banks. Depending on the scale (map), scale of the chart, it may show depths of water (bathymetry) and heights of ...

aeronautical chart An aeronautical chart is a map designed to assist in the navigation of aircraft, much as nautical charts do for watercraft, or a roadmap does for drivers. Using these charts and other tools, pilots are able to determine their position, safe alt ...

) and translated to the surface of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. The intersection of a minimum of two position lines is a fix that is used in position fixing to identify a navigator's location. There are several types of position line: *

Compass A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with No ...

bearing – the

angle In Euclidean geometry, an angle can refer to a number of concepts relating to the intersection of two straight Line (geometry), lines at a Point (geometry), point. Formally, an angle is a figure lying in a Euclidean plane, plane formed by two R ...

between

north North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and the line passing through the compass and the point of interest *

Transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1980 film), a 1980 Israeli film * ''Transit'' (1986 film), a Canadian short film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countrie ...

– a line passing through the observer and two other reference points * Leading line – the line passing through two marks indicating a safe channel *

Leading lights Leading lights, also known as range lights in the United States, are a pair of light beacons used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At nigh ...

– the line passing through two beacons indicating a safe channel * Sector lights – the lines created by masked colored lights that indicate a safe channel

See also