Figure 4.6-15 Tacan Point to Point 4

Now that the two points are plotted, and the computer is correctly oriented (with the black

"TAS" and "TC" circles at the top), the direct course between the two fixes can be

computed. To do this, first connect the two dots with a straight line. It's a good idea to mark

the destination dot with a circle. This will help to avoid reading reciprocal courses.

The next step is to rotate the circular grid until the line connecting the two dots is vertical

(parallel to the vertical grid lines). (Figure 4.6-15). Additionally, the dot representing the

destination must be above the dot representing the present position (the arrow points up).

Figure 4.6-15 Tacan Point to Point 4

To find the direct course (no wind), read the number that is directly above the "TC" symbol

at the top of the computer. That number (157) is the MAGNETIC course to the desired

destination.

In effect, what was drawn is a point on a chart (green, circular grid) showing the present

location and another point showing the destination. Then, a line was drawn connecting

those two points; and the direction between the two points (the magnetic course) was

determined.

To determine the distance between the two points, utilize the Headwind/Tailwind scale as

displayed on the CR-3. Read the appropriate displayed range using the same scale

numbers used for plotting DME. The distance between the two points can now be found. In

this case the distance is 75NM (7.5 squares at 10NM each). Therefore, if the aircrew flies a

magnetic COURSE of 157 degrees for 24NM, they should arrive at the desired destination.

4.6-138