The Real Truth Behind The Radar Notch | How Beyond Visual Range Combat Works

There are a lot of myths floating around the Internet about the radar "notch" phenomenon. It is a real phenomenon but it's not a magic get-out-of-jail free card for fighter pilots. So how does it work? And what are it's limitations? We'll answer these questions in this video.
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Obligatory disclaimers:
The presence of DOD Visual Information in this video does not constitute endorsement by the DOD or any of its departments. Any views expressed by the presenter are those of the presenter and do not represent the views of the DOD or any of its components.

[@TheOpsCenterByMikeSolyom]

During the making of this video there were a couple patches to DCS that moved the notch window a few degrees to the side. This happened twice with one of them hitting right as I recorded the radar screen videos. So it is slightly off from the diagrams I used later on (by about 5 degrees). However, in all cases the notch window was about 20 degrees wide. Other than that everything else should be accurate. Apologies for that discrepancy.

[@mortlet5180]

7:27 Unfortunately, ED has unrealistically nerfed ARH missiles so that this isn't true in-game. You can be caught completely unaware that you're in an enemy's WEZ and (even if he has held a good, clean, high update rate radar track on you for the entire missile flight duration) the missile will *always* give its target an early enough warning so that a simple, instinctive beaming split-S is guaranteed to save you if it was launched at a BVR distance. ED's justification is that the missile requires 8-10 seconds of active radar illumination to home in on the target, however this doesn't match what is publically said about American ARH missiles (that the target has less than a second of warning) when they are launched at unsuspecting targets. Even when you actually go and calculate the linear approximation for the downrange and crossrange uncertainty of the mothership's radar, illuminating a 1m^2 non-maneuvering target at a conservative F-Pole of 25nm, assuming a standard X-Band radar with a 2GHz bandwidth and a 2.5 degree main lobe FWHM; then assuming the missile has an endgame velocity of Mach 1.5 and the ability to turn at ~15g, versus a target velocity of Mach 1.0, the minimum amount of active terminal maneuvering time required to compensate varies with target aspect (closure velocity varies between roughly Mach 0.5~2.5), but is almost always less than 1 second (a beaming target maximizes the uncertainty and requires ~1.31s at 15G, but only ~0.76s at 30g). 1:20 This also doesn't make any sense as implemented in DCS, since even the very first fighters with analog Pulse Doppler radars used gates to isolate sections of the radar data cube (for example, in addition to the cross-range or azimuth gate, there would be a down-range gate, a velocity gate, an altitude or elevation gate, etc.), the *only* IRL circumstances where the ground clutter returns would even get to the notch filter together with the real target return, would be when the target is close enough to the ground so that the clutter extends into the same RDC element. Even worse is how DCS makes notching just as effective over large bodies of water, as if the water produces anywhere near the same magnitude of clutter (just look at satellite ISAR images of airports or airfields near the ocean; the contrast between aircraft landing/taking off and the inky black water makes them easy to pick out).

[@ethanmckinney203]

Second-time-around returns. It's a thing.

[@mortlet5180]

@@ethanmckinney203 What, specifically, are you referring to? Creeping wave returns to the illuminating radar? Multipath effects when over a flat ground plane?

[@SDsc0rch]

top notch content as usual

[@KentLavisMW]

Is that a pun?😂😂

[@TheOpsCenterByMikeSolyom]

Okay that was a good pun.

[@staubsauger2305]

Great content, thanks Mike. At the 4:00 mark there is the comment that when the motor burns out the missile cannot generate more *kinetic* energy. Physicist here so I'd like to point out that the missile cannot generate more *total* energy (ignoring tailwinds which are not a factor in this discussion), but the missile can exchange potential energy (increased by higher altitude) for increased kinetic energy. Lofting missiles diving down can do this at least until air density really has an effect on drag. The point you are making is perfectly valid, most missiles in DCS have short burn motors and this can be used to defeat them. I'm just being precise with the physics terminology. Please keep these videos coming, they are great.

[@TheOpsCenterByMikeSolyom]

That's a great point. Thanks for sharing.

[@JonBrase]

8:08 The target disappearing from the attacker's scope does not necessarily defeat the missile. If the attacker continues illuminating and somehow manages to keep the target in-beam without seeing it (or by seeing it with a different sensor), the missile will still get reflections, and the doppler shift it sees will be dependent on its own intercept geometry, not the attacker's.

[@TheOpsCenterByMikeSolyom]

You are correct that theoretically it is possible. However, we're talking about semi-active radar homing missiles at that point of the video. Those missiles require a narrow beam of energy to illuminate the target. Wide beams run the risk of illuminating something else in the air and sending the missile off course. With that requirement you need the launching aircraft to maintain a good lock. How do you maintain a lock on the target if the target has faded? You don't. So the launching aircraft can't accurately guide a semi-active missile that it can't see. But I suppose if you want to go to an extreme you can say that some random radar waves could hit the target and that would be enough. However, I've never heard of this happening in DCS or from any of the real life fighter pilots I've worked with.

[@BMD8]

The problem in DCS is with fox3 missile guidance on terminal phase, if you can get into a 2.5deg notch near the ground (under 100f agl), that missile will miss you 90% of the time, reliably and repeatably. it's not kinematic defence when the missile flies over your canopy or tail plane

[@freakmusicaddict]

You can do it 100% of the time. Just gotta practice also pretty sure you can do it a little higher too.

[@BMD8]

@@freakmusicaddict nothing is ever 100%, especially inside ed code

[@freakmusicaddict]

@@BMD8 Na that is just a skill issue, at close range it is just a very small time window. The only thing that could happen is you get a desynced missile but that is online only.

[@wmouse]

I think you've highlighted an interesting difference between people playing a game and real world combat pilots: a 10% chance to die is a terrifyingly high chance of dying. The F-105 suffered such high losses in Vietnam that it was phased out in favor of the F-4. What was that attrition rate? Less than 2%.

[@freakmusicaddict]

@@wmouse yea in DCS you can practice notching with the same parameters every time unlike in the real world where the parameters are not necessarily known or can be simulated close enough.

[@iantron9417]

The MLC filter window (notch) is not caused by a zero radial velocity condition. That is the zero doppler condition. Furthermore if the author modifies his test to have aircraft flying roughly perpendicular to the radar, they will stay in the notch regardless of antenna train angle. There is no limited forward cone for the notch.

[@Mobius118]

Excellent video, thank you for these!

[@S3NTRY]

Great stuff! Thanks again, Mike!

[@KentLavisMW]

Impressive video as always! Love it.

[@jackhaffenhoff1365]

Love these videos.

[@alexandrebelinge8996]

I enjoy your video a lot !!

[@auqanova]

when i try to notch in fox 3 combat, i generally try to notch the missile itself, rather than the launching emitter. that should work just fine in that case yes? of course i know this makes it easier for the opponent to make follow up shots, but i should able to save myself from a missile in otherwise kinematically lethal ranges like this i think.

[@schmitty5461]

Notching a fox 3 before it goes pitbull/active would be kind pointless I would think.

[@surt2083]

In dcs it's incredibly easy to notch a fox 3 missile and that's what you should be doing. There is specific type of bvr fight called notch fighting. Since notching in dcs is is a 100% tactic(if the miasile is in the notch window it will 100% get notched) the ranges of the fight can get up to 2-3 miles close if both fighters are experienced.

[@TheDarkman222]

That was my exact thinking. If I put a fox3 on my 9 o clock and not the firing jet I should be able to notch it. Of course the closer the missile the harder to get the right notching angle? Can someone clarify?

[@TheOpsCenterByMikeSolyom]

Yeah absolutely. It can work. But it can also fail. So you always take a risk when trying a notch. I've always viewed a notch defense as something you would use when there's no other choice. My preference is to follow the guidance I've talked about in the rest of the BVR series and work a plan that keeps you outside the enemy's effective range.

[@JonBrase]

It's the missile's ability to see the target that's relevant to a kill, so yes, notching the missile is what you need to do for a pitbull Fox 3. It should also work for a Fox 1 or a non-terminal Fox 3, but since a Fox 1 isn't emitting anything itself, you'd have to identify the missile visually to notch it, so notching the illuminator is the better bet in general. In principle, the illuminating radar could be steered by another sensor, though. In this case, the illuminating radar itself wouldn't see you, but as long as the other sensor kept it pointed to illuminate the target, the missile would still pick up the reflections, and they'd have a different doppler shift than the ground clutter if you didn't have the missile notched, so you'd have to notch the missile. I'm not sure if any aircraft (especially those likely to be limited to Fox 1's) have this capability, however.

[@thunderace4588]

Thank you Mike.

[@chihirobelmoable]

DCS tactic : notch to defeat missiles by visually tallying them as DCS renders a missile at least a single dot whatever distance it is at. BMS tactic : Skate / Short Skate / Banzai.

[@freakmusicaddict]

@@chihirobelmoable I bet you could also defeat missile reliable in BMS with notching but because only extreme larpers play that game they don't do it.

[@briantoplessbar4685]

@@freakmusicaddictI play BMS because DCS is hot dogshit

[@chihirobelmoable]

@@freakmusicaddict you can but still not like in DCS...in BMS I remember I could notch defeat ARH if you completely make relative closure velocity almost 0 like making the plane stall vertically.

[@silience4095]

Great video! I just have a small nitpick at 4:23. The lift vector is always perpendicular to the incoming air, it's defined as such. Therefore, it does not affect the speed of the missile at all. Only drag can affect the speed, which is defined to be pointing in the direction of relative airflow.

[@cmptohocah]

Lift that is pointing backwards, relative to the direction of flight, IS one of the components of drag. Angle of attack for example causes it to tilt backwards.

[@silience4095]

@@cmptohocah The backwards component of the total reaction is drag, and the other is lift. Lift and drag are perpendicular, but yes the total reaction is pointing slightly backwards. Lift and Drag are defined like this, because Lift becomes unable to add/remove energy (does not affect your speed), while Drag can only slow you down, it can't make you change direction like lift does. Now this means that stuff like the Lift/Drag ratio equal your glide ratio, among other very useful things. Look at the wikipedia page for Lift-to-drag ratio, and the image on the right side.

[@cmptohocah]

@@silience4095 I am not 100% sure what you are trying to say here, but all I wanted to point out to you is that when the lift vector, produced by the lift surface(s), is tilted the component of the lift that is acting in the same direction as the drag, becomes a part of the drag. That is one of the reasons you need to add power in a level turn, 'cause extra lift you need to produce in order to stay level is also increasing the total drag force.

[@silience4095]

@@cmptohocah It's just a terminology thing. Lift is always perpendicular to the relative airflow at infinity. Drag is always parallel to the relative airflow at infinity. Lift doesn't tilt back, because it's defined that way, it's more useful if it doesn't. What does tilt back is the total reaction, or total aerodynamic force.

[@palleh.jensen4648]

Thanks Mike.

[@TURKWING]

Thanks for video. Against AESA Radar, notch is not effective cause AESA emits simultaneously beams both CW and pulse.

[@roebuckpayne]

To me, a large portion of notching is kinematically draining the missile

[@TheOpsCenterByMikeSolyom]

This is it exactly.

[@swenic]

So notching doppler radar is/was possible because there is no detectable velocity difference to distinguish the target from the background?

[@MattH-wg7ou]

Essentially, thats the basic idea.

[@Nevan_Nedall]

Perhaps I'm misunderstanding but I feel the assertion that you can only notch in a specific range of angles off of the attackers nose is inaccurate. Theoretically, theres no reason you couldnt notch from anywhere within the entire radar arc, so long as you fly 90 degrees relative to the radar pointing at you. If an attacker has their radar deflected 50 degrees, and you fly 90 degrees relative to the radar (40 / 130 degrees relative to their nose), you should still be notcbing just fine, no?

[@Generic_Name_1-1]

I don't think so, because both aircraft are moving with their own velocities. So the target is still moving relative to what the radar sees as the ground, thus allowing it to see the notching aircraft. It works nose on because your relative velocity to the radar is the same as the grounds velocity to the radar. Any difference between those two figures will make you visible

[@Nevan_Nedall]

@@Generic_Name_1-1 The radar isnt looking for movement relative to the enviroment, it's looking for the dopler effect. The whole reason notching works is because you trick the radar into filtering you out because your relative speed is low enough that it thinks you're the ground.

[@Generic_Name_1-1]

@@Nevan_Nedall that's literally what I said. And yes, in effect it is looking for relative velocity to the ground. Because the doppler gate is calibrated to the ground so it can filter the return out. If you aren't presenting the same relative velocity to the radar as the ground you will be visible to the radar

[@cmptohocah]

@@Generic_Name_1-1 From what I understand there is a theoretical notch circle where your relative velocity to the radar will be minimal. Mike just had the targets fly in a straight line, hence why they entered-exited the notch.

[@Generic_Name_1-1]

@@cmptohocah that would work if you were stationary, but since the target aircraft is also moving even if the radar signal is on the 3-9 line because you're off axis to the nose of the radar aircraft, the radar will still see you. Like I said both aircraft still have velocities, unless you're flying cold with the radar notched you're neither the same velocity to the ground or the same velocity as the radar itself.

[@Im_TheSaint]

i can literally notch 5nm fox3 missiles with almost 100% reliability in fights i fight on mp servers, let alone in a sterile environment it gets a bit harder under 5nm but its doable down to like 2 nm, at which point there isn't really enough time to turn from hot or cold into the notch, even if you turn at peak instantaneous rate. so, my only response is, get good

[@joe92]

Is the 20 degrees centered on radar's pointing direction? It seems offset to one side in the graphics.

[@TheOpsCenterByMikeSolyom]

Yeah, I mentioned this in the pinned comment. During the making of the video there were some patches that shifted the window slightly. I'd already changed things twice and it was minor enough that I felt a comment would cover it. Hopefully that helps.

[@markthegamer5304]

I wonder how much the METEOR will throw off people who count on the WEZ being easily made smaller

[@TheOpsCenterByMikeSolyom]

We do have some longer range missiles represented in DCS. The F-14's Phoenix and the MiG-31's R-33/AA-9. Real world those both have extreme ranges. So those might be good to train against if you want to see what it might be like.

[@PrezDCS]

I don't like how much this video undersells the efficacy of the notch. There's some key points that I think are missing if the idea is to present accurate information as to how notching works specifically in DCS. I think this is great otherwise for a general information type video.

[@TheOpsCenterByMikeSolyom]

I'd be glad to hear some of the points if you don't mind sharing. Also, I do hear a lot of people share some wild stories about notching. But I only wanted to cover the things that I could personally recreate. And I fired a ton of missiles to make sure none of those were a fluke. But if you have more to share I definitely want to hear it.

[@PrezDCS]

@@TheOpsCenterByMikeSolyom I genuinely think there's a lot to learn from this and your other videos. They are very good for introductory knowledge as that is the aim. I just think there are some elements, that many others also never mention, such as taking into account how repeatable things are in DCS since it's a game. How things are programmed very binary at time. Notching is extremely easy, almost comically so. Things can obviously change, and I prefer your method of attempting to make a more or less timeless piece. I just thought the title of this video in particular struck me the wrong way with the information you provided.

[@mygoodsir539]

well its not actually only at 20 degrees thats just cause thoes planes only entered the notch for the amount of time it took to travel 20 degrees. if the planes held the notch they shouldnt show up on radar as they reach the sides

[@kizvy]

this also works in wt btw

[@TheOpsCenterByMikeSolyom]

Awesome. I have never tried it. But glad to hear it works there too.

[@swenic]

Would going vertical also notch?

[@TheOpsCenterByMikeSolyom]

Yes actually. Flying straight down at the ground will do it. However, you can only do that for so long. 😃

[@swenic]

Good to know :) Is a vertical notch followed by either cover if there is any or by a low level horizontal notch going cold a sound strategy or is simply a long U-turn preferable?

[@ericschoonover7350]

@TheOpsCenterByMikeSolyom I would like to connect with you about sponsoring the production of more videos.