INTERCEPT PROCEDURES TEXTBOOK
Leading Turns / Accounting for Drift in Turns
The second consideration, drift control, is easily handled by remembering that drift is a
function of slant range and degrees off collision bearing. Also remember that the number of
degrees off of collision bearing will double as the range halves. The number of degrees the
fighter has to turn to collision course (attack heading with goal TA achieved) will also have an
effect on the drift. The main concern, however, should be the number of degrees of turn from cut
heading to attack heading or directly to lead for a F-1 shot. This distance varies from one
situation to another, and is accommodated by what will be referred to as "leading the turn."
Leading the turn takes into account the fact that drift is a function of SR and the bogey's
degrees off of CB. If the fighter were to wait to achieve the exact goal TA before turning to
attack heading (the heading required to put the goal TA on collision), the bogey would continue
to drift past the goal while the fighter was in the turn. This drift is due to the fighter's turn radius
as the fighter cannot instantaneously change heading and establish itself on a collision course.
The tighter the turn rate, the less effect the turn will have on TA drift.
Understanding this, the turn to AH or lead must be made prior to reaching the goal TA. The
further the turn, the more lead required. Similarly, more lead is required for shorter slant ranges
because the bogey is drifting faster. As a result, a basic rule-of-thumb to calculate lead points for
the various cuts is determined by assuming 1° of drift for every 20° of turn to AH (or directly to
lead). Slant range is taken into account by starting with a standard rate turn to AH outside of
20nm, a hard turn from 20-16 nm, and a hard-as-possible turn to AH or lead) inside of 16 nm.
Additionally, the hard as possible turn should be used for instances where the fighter is late to
commence the turn. This rule-of-thumb for calculating how much to lead turns must be
tempered with headwork; because the rate at which a bogey drifts is a function of both range and
degrees off of collision bearing (CB), the fighter must understand when and why particular turn
rates will be better in some situations over others.
Reconversions are defined as actions that change the intercept as required by changing TA
after the fighter has steadied up on its initial cut. Reconversions are mandatory if the fighter is
more than 1 degree off of the desired goal, and are required as dictated by the changing TA and
LS during the intercept. Reconversions cease at 14 nm.
If on a cut into or a 0 cut with less than goal LS, use a cut away large enough to achieve
the goal, but not so much as to place the contact off the scope.
If on a cut away and having achieved goal LS, turn to a 0° cut.
If new GCI calls or radar contact on the scope puts the fighter in a different spatial
category (I, II, III or IV) with respect to bogey's nose and/or flight path, change the cut
as required by the new area problem. If on a cut larger than required by the new
information, the current cut can be maintained.