A position line is a line that can be identified both on a nautical chart or aeronautical chart and by observation out on the surface of the earth. The intersection of two position lines is a fix that is used in position fixing to identify the navigator's location.
There are several types of position line:
- Compass bearing - the angle between north and the line passing through the compass and the point of interset
- Transit - a line passing through the observer and to other reference points
- Leading line - the line passing through to marks indicating a safe channel
- Leading lights - the line passing through to beacons indicating a safe channel
- Sector lights – the lines created by masked coloured lights that indicate a safe channel