Fighter Combat - Tactics and Maneuvering

BASIC FIGHTER MANEUVERS 63
Lead Pursuit
A lead-pursuit path is followed by positioning the aircraft's nose ahead of
the target, or "bogey," fighter. As discussed in the gun-employment section,
the practical maximum lead when the attacker is maneuvering near
the target's plane of turn is often limited by the attacker's over-the-nose
visibility and the requirement that he maintain sight of the bogey. "Blind"
lead turns may be appropriate under some circumstances, but they are
inherently dangerous, both because of the possibility of a collision and
because of the potential for losing sight of the bogey and allowing it to gain
a more threatening position or to escape. Larger amounts of lead can often
be generated by turning in a parallel plane with the target, so that sight
may be maintained over the side of the attacker's nose.
The purpose of lead pursuit is primarily to increase closure on the target
by use of geometry. The ideal lead angle for greatest closure depends on
relative aircraft positions, relative speeds, and target maneuver. As with
missiles, a proportional-navigation course usually maximizes closure, and
can be estimated visually as the lead angle that causes the target to appear
to remain stationary against the distant horizon. If the target's drift appears
to be toward the attacker's nose, more lead is called for, and vice versa.
The lead-collision or lead-pursuit curve may even allow an attacker to
close on a much faster target, particularly if that target turns toward the
attacker at a rate that places the attacker at a large AOT.
Figure 2-1 depicts a fighter using lead pursuit to close on a faster target
from a rear-hemisphere position. Note that in this example the target
aircraft is turning toward the attacker, inscribing a rather large arc in the
sky, while the attacker keeps his nose in front of the target's position and
turns inside its flight path to close the range. The attacking fighter is not
maintaining a perfect proportional-navigation (lead-collision) track in this
case, since the LOS to the target is rotating throughout the maneuver, but
Figure 2-1. Effects of Arcing and Lead Pursuit