INTERCEPT PROCEDURES TEXTBOOK
Changing Target Aspect
We have established that if the bogey is not on collision bearing, or angle off does not equal
collision bearing (or CATA), then drift will occur. For every degree the bogey drifts in angle
off, there will be an equal amount of change in target aspect.
For example, in Figure 5 note the change in TA in a 160 DTG, R-L situation where the
collision bearing is 10°R (20°R cut) with the bogey at 20°R AO and the TA 0°. The bogey is
10° right of collision bearing and will, therefore, drift to the right. After 10° of drift the bogey
will be 30°R and, since the set-up is the same, the TA will have changed by an amount equal to
the amount of drift. Consequently, the TA would be 10°R. Ten degrees of drift changed the TA
Proof with a 180 DTG Set-up
The previous rule can be proven most easily in the special case of a set-up with 180 DTG, as
in Figure 6 and 7. Assume 180 DTG with 10°R AO at 20 miles. (Note: with 180 DTG,
AO = TA in both amount and direction). The lateral displacement is 20,000 feet, and will remain
constant since the FFP (fighter flight path) is parallel to the BFP (bogey flight path).