In summary: You assume that the target is stationary(ish) and you know, say, that it is to your front/left.

You fly straight and note when the other plane comes into radio range (i1), and when it goes out of radio range again (o1).

Now you turn 90 degrees left and note when it goes into range (i2) and out of range again (o2).

Now you connect i1 and o1 with a segment S1, and draw a perpendicular to it, P1, through its midpoint (the "Line segment bisector"). Similar, with 1 replaced by 2.

The intersection of P1 and P2 is where the target is.

This works because the edge of the radio range is (basically) a circle that you're intersecting with your segments, and the perpendicular bisectors go through the centre of the circle.

Cool technique. It doesn't even depend on your turn being exactly 90 degrees. It does depend on the pilot on the other radio jabbering on non-stop, and you knowing where you are - without GPS etc.

Frankly, the navigators of early last century, before GPS and inertial navigation system - respect. They knew how to reckon. (Here, the guys in the jet had INS, apparently, but still, hats off!)