Figure 5 - P-8250079

INTERCEPT PROCEDURES TEXTBOOK

Analyzing the Drift

Certain factors must be considered when analyzing the drift in the counterturn.

(a)

Turn drift is countering the intercept drift

(b)

When scope drift = 0, then

fighter's turn rate = intercept drift rate

As an example, Figure 5 shows the fighter in a right turn, with AO at 10R. As long as the

fighter can keep the bogey at 10R AO, the turn drift is equal to the intercept drift.

Figure 5

Notice that as the slant range decreases, the amount of turn required to hold the bogey at the

same angle off increases. This is because, as slant range decreases, the number of degrees off

collision bearing increases. Therefore, the intercept drift rate will also increase, necessitating a

faster turn rate from the fighter.

Maximum Drift Rates

The aircrew can utilize this knowledge of intercept drift to predict when intercept drift will

be at a maximum. At this maximum point, the turn rate of the fighter must also be at a maximum

to counter this drift.

Since intercept drift is a function of degrees off CB, the maximum intercept drift will occur

when the bogey is the furthest away from CB. This happens at the pure beam position, which is

90DTG, or 90 Heading Crossing Angle, with the bogey on the nose. Figure 6 illustrates this

concept.

At 90 DTG, cut = 90 (cut = 180 - DTG)

CB = cut = 45

Bogey is 45 off CB at the beam