Connect Points (Plot Course Lines)

T-6A NAVIGATION

CHAPTER TWO

204.

CONNECT POINTS (PLOT COURSE LINES)

A course line is the actual path over the ground the aircraft will follow when flying the low-level

route. For T-6A operations, each leg of the course is simply a straight line from one turnpoint to

the next (Figure 2-2).

205.

MEASURE AND RECORD COURSES AND DISTANCES

With circles and lines drawn on the chart, measurements can be made for course and distance.

Using a plotter, measure the True Course of each leg by comparing the course line to a longitude

line (Figure 2-3). Because TPCs use Lambert Conformal projection, each longitude line is

aligned to true North, and provides a reference for all course line measurements. The measured

course is the True Course (TC). To get the Magnetic Course (MC), apply the average magnetic

variation for that leg. Lines of equal magnetic variation appear on TPC scale charts as blue

dashed lines with variation shown in degrees East or West. MC is equal to the TC minus East

variation or plus West variation. In Figure 2-3, a combat plotter shows the course from point A

to point B to be 065. If magnetic variation is 2 E, then the magnetic course is 063. In North

West Florida, magnetic variation is small, but your aviation career may take you places where

variation exceeds 40 or 60! Obviously, not applying or incorrectly applying variation can have

severe mission impact in these situations!

MC = TC (- East Magnetic Variation) or (+ West Magnetic Variation)

Tolerance for course measurement is + 2 and errors are easily made. Some common errors are:

Reading a reciprocal heading off the combat plotter, such as 245 for the example in Figure 2-3.

Not aligning the plotter with the course, or not aligning the center of the plotter over a longitude

line.

Incorrectly applying magnetic variation to the true course to compute magnetic course.

LOW-LEVEL CHART PREPARATION

2-3