INTERCEPT PROCEDURES TEXTBOOK
outward, TA is smaller than the current estimate. During last ditch, do not make secondary
corrections. However, TA can be adjusted based on drift observed. During last ditch over 4 nm
of downrange travel, for every 1º of drift, add or subtract 5º of TA in the appropriate direction.
A bogey bears 30º left of the fighter's nose with the weapons officer assuming a 60ºL cut and
30ºR TA. The bogey drifts inward 2º over 4 nm (inside 15 nm). The fighter does not make a
correction, but instead adds 10º to the TA estimate. The fighter then turns for the proper lead
AO for 40ºR TA. Prior to lead, the weapons officer can update the bogey heading using the new
cut if time and SA allow it (30ºL AO & 40ºR TA = 70ºL cut). However, the primary focus
should be leading the bogey at the proper range. Realize that, for low TA, proper last ditch
analysis will take the intercept to 11 nm (4 nm of analysis). A late turn to lead is acceptable.
Due to this, it is important not to allow this to "snowball" and get behind for the rest of the
intercept. Once inward or outward drift is initially recognized in last ditch, the fighter should
understand whether TA is increasing or decreasing instead of waiting until 11 nm to decide to
add or subtract the change noted.
Preventing Change in Direction of Pass
Using last ditch procedures, outward drift indicates that TA is decreasing. Low TA and
outward drift indicates a possible change in the direction of pass, and a risk of flying across the
bogey's flight path.
Direction of pass is the most important variable to determine (and preserve) in an unknown
intercept. Therefore, last ditch procedures with low TA are different than those discussed earlier.
If inside 20 nm and outward drift is observed with 20º AO or less, the bogey will immediately
be brought to the nose because the fighter is in danger of flying across the bogey's nose
(changing DOP). This turn to put the bogey on the fighter's nose may preserve the existing DOP.
Furthermore, checking DOP can be broken into two separate phases: 20-15nm, and last ditch,
starting at 15nm. From 20-15 nm and after bringing the bogey to the nose, if the drift indicates a
change of DOP, turn in the direction of the drift to put the bogey at 20 AO ("out by 20") and
assume a 40 cut. If the drift does not indicate a change in DOP, then turn in the direction of the
drift and put the bogey at 10 AO and assume a 20 cut with 10 TA.
Once last ditch has started, with < 20 AO and outward drift is noted, bring the bogey to the nose.
Then quantify degrees of drift to make a TA assessment. For example, a contact is 20°R AO at
14nm with outward drift. The fighter turns to bring the bogey to the nose. Once the contact is
established on the nose, start last ditch analysis, in this case at 13nm. With 2° of right drift over
2nm you should call the TA 20°R (interpolate that 2° of drift over 2nm equals a 1/1 ratio). If you
have 1° of left drift over 2nm there was no change of direction of pass and you should call the
TA 10°L (interpolate a 0.5/1 ratio).
Upon noting outward drift with 20º AO or less (inside 20nm),
immediately turn to place the bogey on the fighter's nose to check DOP.