LOP

Now convert this magnetic bearing to true bearing by adding or subtracting variation (add easterly and subtract westerly).
Now plot this line with your plotter on the NDB and you have a line of position (LOP).

so that the station is abeam and then measuring the degrees traversed against time. This is a form of running fix in that two bearings are taken, at an interval, from one source and the aircraft's position is the distance along the second LOP from ...