In Figure 13, the aircraft is still heading 340°; however, the head of the needle has fallen.
The aircraft is now on the 070°R. When the head of the needle is at the 3 or 9 o'clock position,
the aircraft is at its closest point to the station. The head of the needle will continue to fall and
the DME will increase again.
In Figure 14, the head of the needle has fallen 20° and we now find ourselves on the 060°
radial, and at a DME of 15.5. Our flight path has caused us to cross the arc, go inside of it and
then outside of it to 15.5 DME. The simultaneous occurrence of the needle's falling 10° below
the wingtip and the DME's increase to figure greater than that of the arc signals us to turn the
aircraft once again. (Figures 15, 16, 17)
4-10 TACAN ARCING