Closure and Collision: TID “Hot” and “Cold” Sides

Following the introduction of basic concepts such as Lateral Separation, Drift and Closure Rate, this is a more in-depth look at the relation between TA, SR and the information provided by the TID in Aircraft Stabilized mode.

The Hot and the Cold

P-825, 6-17, defines the “Hot” and the “Cold” sides of the attack display:

  • The hot side of the display is the portion of the attack display where the fighter should place the contact to increase the rate at which LS is being removed. This represents a turn toward bandit flight path.
  • The cold side is the direction the fighter should turn to place the contact to slow down, stop or reverse the removal of LS. In other words, this is a turn away from bandit flight path.

A non-marginal apostille is the fact that the line that divides the Hot and the Cold sides is the collision bearing.
This subdivision allows the RIO to immediately understand how the TA will evolve if the status quo is maintained, and to plan ahead or act immediately if necessary.

On modern attack display, it looks like this (I rarely use images taken from other documents to avoid any possible issue with copyright et similia. © in this case goes to US Navy, I guess):

wvr-1b-attack-display-hot-cold
“Hot” and “Cold” on a modern Attack Display (CNATRA P-825, 6-17. ©US Navy)

The question, as usual, is how we can apply these concepts to the avionics of the F-14A and B.

Tactical Information Display

Using the TID in AS, we know that a contact’s vector is generated relatively to the headings and velocities of the F-14 and the contact.
Let’s consider the usual scenario seen in the previous article. For simplicity’s sake, we consider the two protagonists as co-speed and co-altitude. On the left, TID GS, on the right TID AS. The two aircraft are, at the moment, on a Collision course.

wvr-1b-scenario1

I am now trying to replicate the sides’ definition of Attack Display of the T-45 onto the TID: the green area is the WVR limit (10nm), the golden dotted and dashed line is the Collision Bearing. The question is, which part is Hot and which part is Cold?

wvr-1b-scenario1-coloured

In order to make the situation more clear, I extended BFP, FFP and added markings to track the position of the aircraft as time passes.

wvr-1b-scenario1-exp2

The scenario on the left sees the F-14 and the contact on a Collision Course, as FFP and BFP intersect at the same moment.
On the right, the top contact is flying in the area between the Collision Bearing and the FFP, the bottom contact if flying between the side of the TID and the Collision Bearing.

The changes in the TA and ATA are visible, but to further highlight them, I connected the different positions in space and time with grey lines increasingly darkening.

wvr-1b-scenario1-exp3

It is now immediately clear how placing the target between the FFP and the Collision increases the TA and therefore reduces the loss of LS. Viceversa, the bottom scenario sees the TA decreasing, further accelerating the drop of LS.

Practical Example

I put together a short video showing a similar scenario by means of the TID and Tacview.

Three contacts are flying at different distances and following different courses. The one in the middle is flying on a Collision Course. I recorded the changes in the various parameters as the SR decreased (these values are calculated from TacView).
The complete set of data is available here.

wvr-1b-scenario2-contact-south

The Southern contact flies past the F-14 at some point so the TA is initially decreasing, reaching zero and then increasing again, but in the opposite direction.

The speed at which the TA changes depends on Vc and it is inversely proportional to the SR. This means that the lower the SR, the quicker the TA changes: this is intuitive and the extreme case is the merge, where the TA can turn from hot to cold and viceversa in a fraction of a second.

wvr-1b-scenario2-contact-chart

Note: the lack of “smoothness” is caused by the fact that TacView reports TA as integer, whereas ATA is a float value.

wvr-1b-scenario2-contact-chart-ATA

The Middle target is on Collision, in fact the TA does not change at all until the SR is very low (we did not actually hit the other aircraft, just flew in his wake). The Northern contact shows how the TA increases whilst the ATA decreases. This means that the target flew in front of the F-14.
The Southern contact behaves in the opposite way: the F-14 flew in front of the contact (which is something that should be avoided) so the aspect moved from a side to the other.

This video shows the whole scenario from the point of view of the RIO. I overlaid the TacView track to provide an additional perspective.

Conclusions

Understanding the information provided by the TID is fundamental to increase SA and rapidly plan the course of actions required to achieve the intended objective.

This is relevant when discussing the Intercept Geometry, but also in almost any phase of the air combat: for instance, understanding the aspect of the target can improve the performance of a missile and knowing how to manipulate the LS at a glance can help the RIO to position the aircraft in an advantageous position.

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