Point to point vor/tacan nav. Hmmmm, how to explain that with out a picture......
Imagine your RMI is a map. The scale is defined as the outer circle is either your dme, or the dme of the point that you are aiming for, whichever is the greater.
eg if you were hdg 090 and were on the 180r/100d, trying to get to a point 135/50d. the scale is 100nm and you imagine yourself on the circumference of your instrument at the 3 oclock position (180R, relative to hdg 090 which will be at the top, 12o'clock position))
now imagine your next point on the "map" in this case, it would be 45deg clockwise from the top, and half way between the centre and the circumference. (for goodness sake get a circular thing to look at while you imagine this!)
Now draw a line from your ppos to your next point and then "translate" it so that it runs through the middle. Read off the hdg and voila!
Alternatively turn so that the imaginary line from ppos to next point is vertically upwards and you will be pointing the right way! give or take the drift, of course.
Hope this hasn't given you a headache
