Intercept Geometry – Part XIII: In-Depth Timeline (continuation: FOX 3/1/2)

Geometry: Assessment

Cranking is a “Cut-away” manoeuvre, and hence it generates lateral separation even if the slant range is decreasing by increasing the Target Aspect. However, if left unchecked, the Target Aspect can drastically increase, creating less than optimal conditions for the following FOX-1 employment.
Since the plan is converging again towards the target to fire another missile, the Target Aspect should not increase past 45° – 50°, otherwise the manoeuvre to recover the TA may drag the contact out of the radar volume.
Whatever the case, the fist Cut should be aggressive, to immediately correct the geometry: reducing the Cut later is simpler than trying to predict the correct turn from the Crank.

Situational Awareness Assessment

On top of controlling the intercept and act by commanding the appropriate manoeuvres, the RIO must also ensure that his level of Situational Awareness is high. In particular, the target may jink or the fighter maybe under potential threat. If that’s the case, the Section may have to answer in an appropriate fashion.
If the conditions to press are not present, the Section can Abort. The suggested abort criteria were discussed in the previous parts.
The single most important criterium is being “Spiked” or “Naked”: if the fighters are spiked, then the threat probably have sensors awareness and may be engaging the Section (if it has not already with an ARH missile).

Notching

Crank is the first step of the mechanism that serves both the purpose of maintaining SA, guiding the missile and preventively defend from hostile actions.
“Notching” is a manoeuvre that aims to place the threat on the beam and also involves an altitude loss: beaming places the fighter in the MLC filter and the altitude loss prevents the threat to disable the filter and introduces ground clutter.

Abort

Abort is the maximum G manoeuvre, with full afterburner, to stay outside the WEZ the threat. The goal is creating maximum separation.
Crank, Notching and Abort are somewhat connected as they can happen one after the other.

Geometry: Controlling the Target Aspect

The AIM-7 Sparrow does not share the powerful rocket motor of the AIM-54, so its employment requires shorter ranges and a more accurate control of the intercept and the angles.

A Sizeable Range Problem

When the AIM-54 reaches the A-Pole, it is activated by the WCS. The distance at which the missile is activated is defined by the Target Size switch located in the DDD:

• Small: 6 nm;
• Norm: 10 nm;
• Large: 13 nm.

If the switch is set to small, the RIO has less time to work the geometry to reduce the TA before the missile is activated by the WCS and vice versa for Large.

Example

A simple test shows that an AIM-54A Mk47 launched on timeline at M1.0 at 20,000ft, followed by a crank is activated by the WCS at ~23nm from the target. Setting the Target to Small or Large change the A-Pole by ±2 nm circa.
Such range is usually sufficient to Cut into aggressively to decrease the TA to < 20°.

Saving the Day

If the RIO is late for whatever reason, he can:

• Cut more aggressively, commanding Buster;
• Skip the FOX-1 employment and prepare for a DT / CT for a FOX-2 employment, either from the FQ or the RQ post CT.

FOX-1 Employment [10 – 12 nm]

When the Target Aspect is satisfying, the RIO commands a turn to Lead Collision and employs.
The AIM-7 Sparrow can be launched in different modes, using a CW antenna via PSTT or using PD STT mode.
Before locking, the Section should re-sanitize the area using Search mode. The operation also allow the RIO to quickly lock from the DDD, an operation much more reliable than switching from TWS to STT directly.

STT ASE Circle

Both Single-Target-Tracking modes display the ASE circle when a lock is established (Figure 265). The visual indications allow employing the AIM-7 Sparrow in the optimal way by allowing the pilot to manoeuvre to place the indicator in the middle of the ASE circle.
Alternatively, the RIO can approximate the Lead Collision by calculating the value of the Lead ATA.

Displacement Turn [8 – 10 nm]

Post FOX-1 employment, it is time to assess the geometry again. To properly set up a FOX-2 shot from the RQ, in fact, the fighter needs to increment the Lateral Separation removed during the FOX-1 setup. This is done by executing a Displacement Turn between 6nm and 8nm depending on the Target Aspect.

The Displacement Turn was extensively discussed in the previous parts. It consists, fundamentally, in a Cut whose side depends on the amount of Lateral Separation available at that moment.
Failing to create enough room may hinder the RQ FOX-2 employment, but can also start a merge with the fighter in a non-advantageous position.

Counterturn and FOX-2 Employment

The Counterturn (CT) consists in a hook-like manoeuvre to place the fighter behind the target, using the space created by the Displacement Turn.
The flow of the manoeuvre depends heavily on the Target aspect, but it should terminate nevertheless within ½ nm and 1½ nm from the bandit.

Forward-Quarter FOX-2 Employment

The AIM-9 Sidewinder, depending on the version, can be launched from the Forward-Quarter. This technique is more dangerous than a conversion, as it exposes the fighter much more to the target. However, it is a valid option to keep in mind if DT and CT fail to position the aircraft to a more advantageous position.
Suggested parameters for proper employment:

• check the TA and the LAR (max TA is usually ~80);
• target locked in STT, AIM-9 selected, dot in the ASE circle;
• target range between 1.5 nm and 5nm.

Another occasion where the FQ FOX-2 can prove useful is versus a non-cooperative target which tries to place the fighters in pure pursuit or nose-on.

Rear-Quarter FOX-2 Employment

Launching the AIM-9 Sidewinder from the rear of the target increases its performance (or enables the missile usage, depending on the version).
Suggested parameters for proper employment:

• target locked in STT, AIM-9 selected, dot inside the ASE circle (pitch and azimuth ±8°);
• target range between ½ nm and 1½n m;
• closure between 0 and 100 kts, no opening;
• hard turn or less;
• drift stabilized (slight inward drift is acceptable).