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 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 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 coloured lights that indicate a safe channel