One of the questions the postmortem tries to answer simple: “Intercept Geometry: is it worth studying it?”
The intercept geometry discussion was long and went too deep to be applied to DCS out of the box (or in a real situation, for the matter). The topics are, in fact, “school” notions, as Victory205 (SME for Heatblur) defined them. However, it provides a set of bedrock concepts that have concrete and immediate benefits.
A concrete example
Tactical Pascale recently (at the moment of writing) release a video about a simple GCI-driven intercept. In case you have not seen it yet, this is the link.
It is very well-made, simple to understand and provides a beautiful first look at a simple intercept.
So, why not take the occasion to a have a chat about what the “school stuff” allows you to understand?
The new-pilot’s point of view
Let’s say a new pilot watches the video and take notes (TP = Tactical Pascale):
- TP assessed the bearing, if it does not change, there is collision heading;
- TP realizes the bearing is not changing;
- TP plans the manoeuvre to create space;
- TP, once the bearing has changed enough, turned towards the target again, creating a triangle, with the angles adjacent the hypotenuse quite similar (20°);
- TP turns to the reciprocal;
- TP, at a certain angle, starts the turn into the bandit.
It is a lot to digest for a new player, but there are valuable information here: for instance, the importance of a controller (especially a good one, and the AWACS in DCS is not one of them), on top of the ability of viewing the scenario from a different perspective, and to plan ahead using the information the pilot has.
Moreover, the video clearly shows how the mechanic of the intercept is quite simple when the target is cooperative: understand the situation, create space, use the created space to manoeuvre and gain a concrete advantage (FOX-2 from the RQ).
The “school stuff” point of view
After studying the “school stuff”, we have a much, much better understanding of what Tactical Pascale is doing.
In primis, we understand the ultimate objective: a stern conversion turn into the bandit’s rear quarter, enabling both Visual Identification (VID) and FOX-2 employment versus a cooperative target.
We can immediately imagine the gameplan: we need a certain amount of lateral separation to make the turn, so we need to gain it (Cut-Away), lose it (Cut Into) or maintain it (Zero Cut). However, we do not have information about the Target Aspect, but this is easily solved by using the drift (which, at range, can take a bit of time – this is another limitation of the dreadful DCS AWACS).
Once we have the TA, the range comes from the BRA call, so we can determine the LS. At that point, we can implement the original gameplan, obtain a satisfactory amount of LS, then turn to Zero-Cut to lock it. Then, either the Counterturn tables (or other means), we can execute the conversion.
Now let’s break down the process and have a look at the modus operandi.
“TP assessed the bearing”
“TP realizes the bearing is not changing”
Even worse, he will never build Lateral Separation because flying towards the Bandit Reciprocal “locks” the Lateral Separation because the relation between the Target Aspect and the Range will be always constant.
“TP plans the manoeuvre to create space”
He does it by adding a ±50° offset (Cut Away). However, when deciding the angles, you should consider if the amount of offset is enough (or too much!). This is a good question: Tactical Pascale aims for an LS of 7-8 nm before the conversion, so approximately between 40,000ft – 50,000ft, and at the moment the target aspect is zero. It takes time to build it up. However, we know that the relations between the angles change faster as the slant range decreases (the triangle, whichever is built, has sides directly affected by the range). Since the target is still about 70 nm away, there is time. Nevertheless, just to be on the safe side, Tactical Pascale hit the burners, so the angles build up quicker.
Back to the video, since TP knows the BR and the bearing, his objective is introducing a bearing of 330. At that point, the Target Aspect will be: TA = BR → BB = 310 – 330 = 20 Right.
“TP turns to collision”
In the video, Tactical Pascale builds an isosceles triangle with the angles at the base of 20° each. Those angles are the Target Aspect and the Antenna Train Angle, and this scenario occurs very often in the basic documentation. However, be careful with the speed: the “CC → TA=ATA, but opposite is sign” relation works only when the aircraft are co-speed. The relations still kind of holds if delta speed is low enough, but the greater it is (imagine an F-14A gating whilst intercepting a Tu-95), the angles can be incredibly different (Refer to this study to have an idea of the magnitude of the possible error if the heading of the fighter is not constantly corrected).
Back to the scenario, if the angles are maintained, the F-5 will physically impact the target. This is not the goal of the Stern Conversion intercept so, at some point, something has to change.
The formula TP used is one of the basic CCC (Collision Course Correction) formulas discussed in the CNATRA P-825/02 and on the website in the Intercept Geometry Study Part 7 (and the book as well): BR → BB → CC.
“TP turns to the reciprocal”
- in primis the LS is locked: the range decreases, but the TA increases;
- in secundis, the ratio at which the angles change is knows: the angles double as the range is halved. This allows us to predict what is going to happen in the future, and at what range (or angle) we should start the Counterturn (CT).
In the video, TP turns to reciprocal at about 25 nm. Assuming the TA calculated before is still more or less correct, the resulting Lateral Separation is: LS = 25 * 20 * 100 = 50,000ft. Spot on!
“TP, at a certain angle, starts the turn into the bandit”
Unfortunately, he burned a bit of separation when his heading was slightly too hot, but eventually the manoeuvre was again spot on.
If it is not apparent yet, there’s a flippin’ metric ton of stuff going on even in an intercept as simple as the one showed by Tactical Pascale, to such an extent that we can tell already that spending some time studying the basics of the intercept geometry really provide a different view on any virtual combat scenario. Most importantly, it allows to quickly react to changes in the gameplan (e.g. if the target is jinking), and to understand the consequences that those changes have on the intercept.
So, to answer the question, is it worth it? Well, you tell me. The mechanical application of procedures such as the one described in Tactical Pascale’s excellent video do not require any background knowledge, so it is entirely up to the player whether