A position line or line of position (LOP) is a
line (or, on the surface of the Earth, a
curve) that can be both identified on a chart (
nautical chart or
aeronautical chart) and translated to the surface of the
Earth. 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:
Compassbearing – the
angle between
north and the line passing through the compass and the point of interest
Transit – 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 – the line passing through two beacons indicating a safe channel
Sector lights – the lines created by masked colored lights that indicate a safe channel