Seeing the AWG-9: Why TWS is a “BAD” Radar Mode

To reinforce one of the points I raised about radar modes during my recent livestream, I decided to quickly put together a simple animation and use it in my next livestream, which is now postponed with no ETA.
I would like to share such an animation anyway, as it can be interesting to old and ab initio F-14 Tomcat players alike.
Once again, these animations were not planned, so I used the models of the AWG-10’s antenna and the F-4 Phantom II. Just pretend it is a Tomcat with its AWG-9!

TWS the “Bad”: Raison d’Être

The raison d’être behind this discussion is the incorrect but unfortunately common habit of letting the AWG-9 stir in Track-While-Scan rather than being proactive, thus changing modes, azimuth, and elevation. The best way to convey the message is to see the volume of airspace covered by the radar itself.

Let’s start with something simple. The rectangular white pyramids, which I will refer to as “cones” going forward, as it is simpler and closer to the shape of the main lobe, represent the two possible combinations of Track-While-Scan: one taller and the second wider. We will see the details later.
Having two combinations of bars and azimuth is great, as the radar can be better employed depending on how the contacts are arranged. On the other hand, “Twiz” has to complete a refresh every circa 2 seconds, which limits the available options.
Track-While-Scan has other limitations and drawbacks but, for the purpose of this article, let’s focus on the point just mentioned.

The green cone represents a variety of radar modes free from the constraints that affect TWS: Pulse Search, Pulse Doppler Search, and Range-While-Search. Note the nomenclature commonality: these are “search” radar modes, whereas Track-While-Scan allows “tracking” multiple targets whilst “scanning” the airspace, something that Single-Target Tracking modes do not allow doing. So, quick tip: if you remember these similarities, then you will be able to promptly determine which radar mode does what.
As you can see, Search modes are both wider and taller than Track-While-Scan, and by a considerable margin.

Bars, Azimuth, and their Cost

I mentioned the 2-second refresh of Track While Scan. In terms of scan bars and azimuth, this leaves the WCS or the user, depending on which Twiz mode you are using, with two options:

1. 40°, 4 bars, equivalent to 6.3°, so taller and narrower;
2. 80°, 2 bars (3.6°), wider and shorter.

Search modes can use any combination of bars and azimuth, reaching the incredible setting of 130° and up to 8 bars, ergo 11.5°. Note that the number of bars is not directly proportional to the height of the cone, as a narrow overlap exists.
The elephant in the room is that a fully open Search mode takes a lot of time to complete a full pattern. This image is from the animation you can watch in the video above (which is accurate timing-wise), and shows the huge difference between the various modes, along with the approximated movement of the radar antenna.

Why TWS is a “bad” mode

The next animation should further reinforce the point: range, in fact, affects the amount of airspace covered by the radar cone. Note that the F-14 Phantom is located at an altitude of circa 29500ft, or circa 9km. I have activated the shadows and the terrain, so you should be able to perceive volumes and depth better.

• At 10nm, the difference is not particularly meaningful compared with the previous examples.
  

  

• At 25nm, Search modes start to appear much bigger, especially in terms of azimuth.
  

  

• It is at 50nm that we have the first drastic change, as the Search modes intersect the ground in a couple of spots where the terrain is not perfectly flat. This is relevant, as leakers and potential threats can sneak underneath our aircraft and attack the Tomcat unseen. Such a tactic was used in real life against Iranian Tomcats. Twiz instead starts to really show its limitations in both dimensions.
  It is important to note how, no matter the radar used, a gap will always exist under any aircraft’s belly. This is where working as a Section becomes essential, as radars can be mated and stacked to maximise radar coverage and improve safety. If you are interested, I can make a similar animation to explain the process.
  

  

• At 80nm, the tallest TWS setting finally reaches the ground, but the cost is the tiny azimuth covered.
  The Search modes instead plunge through the terrain. This might sound like a waste, but it all comes down to the specific situation, expected threat, terrain, et cetera, and the radar should be adjusted to maximise Situational Awareness, safety, and efficiency.
  

  

• Lastly, I decided to show what happens at 120nm, which is circa the range at which most aircraft, besides smaller fighters, are detected in Pulse Doppler Search. As you can see, the cone is absolutely huge, and takes full advantage of the power of the AWG-9. However, Track-While-Scan is absent. Range-While-Search should be absent as well, and the reason is rather simple: these modes are less “raw” and provide targets’ range information as well. The cost of determining such parameter is the maximum range, which sits at circa 80nm – 90nm for most fighters.
  

  

Conclusions

I hope these impromptu animations have helped you to understand why sitting on Track-While-Scan all the time is usually detrimental. Such a mode creates more issues than benefits for the crews, as they do not take advantage of the power of the AWG-9.
To reiterate the point, if used correctly, TWS is an excellent radar mode. It is its suboptimal usage that makes it “bad”.

I hope you have found this brief discussion useful. Please don’t hesitate to share feedback and questions.

Leave comments and feedback in the Discussion Forum thread.