Fighter Combat - Tactics and Maneuvering

348 TACTICAL INTERCEPTS
Figure 10-1. Intercept Terminology
case the interceptor is said to be on "collision heading." The angle between
the interceptor's nose (heading) and the target LOS is known as the antenna-train
angle (ATA), the target relative bearing, or the lead angle (lag
angle if the interceptor is pointed behind the target). When the interceptor
is on collision heading, the lead angle and target bearing remain constant
and target range decreases. This constant target bearing is called "collision
bearing," and the lead angle (or ATA) approximates target aspect when
fighter and interceptor are roughly co-speed. As long as the interceptor
maintains collision heading, target bearing/ ATA, and target aspect will
remain constant. If the interceptor turns a few degrees to the right in this
case, and then flies straight, ATA will continue to increase and target
aspect will decrease until the interceptor crosses in front of the target.
Conversely, if the interceptor turns a few degrees to the left of collision
heading (toward the target), and then flies straight, the target will appear to
continue to "drift" toward the interceptor's nose (lead angle will decrease)
until the target crosses in front of the interceptor. All the while target
aspect will be increasing. A radical left turn by the interceptor placing it on
a reciprocal course to that of the target, parallel to the target's course,
maintains constant lateral separation, while both ATA and target aspect
increase.
Forward Quarter
Description
As the name implies, the forward-quarter (FQ) intercept is one in which
the interceptor approaches from the target's forward quarter. A special case
of the FQ intercept is the head-on approach, where the interceptor reduces
displacement to zero and the two aircraft converge "beak-to-beak." Figure
10-2 illustrates the more general case.