Figure 1 - P-8010101

INSTRUMENT NAVIGATION

Figure 1

If you mentally estimated a heading of 060 for 56 NM, you are well on your way to a good

understanding of point-to-point navigation. The diagram should help those who have trouble

with the mental picture. To interpret the diagram, you must estimate the direction of the dotted

line. You have references to work with, however. Notice that the dotted line is canted somewhat

(about 30) north of the 090 radial. If that is the case, then the line must represent a course of

060. As for distance, notice the length of the segment connecting the TACAN with 090/50. It

is obviously 50 NM. If that line is 50 NM, then the dotted line is certainly longer (about 5 NM

longer) than 50 NM. These rough estimations will help prevent your making erroneous

decisions concerning your point-to-point navigation, and they will help you build confidence in

your navigation abilities.

Computer Method

So that the principles of point-to-point navigation might be more clearly understood, it is

convenient for us to use the CR-2 navigation computer; specifically, the wind side. When using

the CR-2, the center or grommet on the wind side is equated to the location of the TACAN

station, common to both your present location and the point to which you wish to proceed.

To plot your position on the computer, utilize the methods you have learned for plotting

winds, i.e., substituting TACAN radials for wind directions and TACAN DME for wind velocity.

It is very important that you distinguish between your position and the point to which you are

proceeding. One method is to use a triangle (or target) as your desired destination and a circle as

your own position.

Figure 2 illustrates an aircraft presently on the 360R/40 DME. Your desired position is in

the 270 R/30 DME. Note the plotting of the two positions.

TACAN POINT-TO-POINT 5-3