ALR-46 RWR - Why unable to detect launches from SA-5, SA-11, MiG-23, etc?

[Istari6]

Having learned to fly the F-4, I'm now moving into learning the weapons and defensive systems before diving into Reflected's "MiG Killers" campaign.  Just diving into the ALR-46 and how it operates, and was surprised to see the wide array of threats where the ALR-46 cannot detect a launch.

In particular, I was struck at the tables in the Heatblur manual that listed the following threats as providing no warning on launch:

* SA-5

* SA-11

* MiG-23

* F-4

Wouldn't all these systems work by SARH?  Why wouldn't a mid-1970s RWR be able to detect the CW signal of weapon guidance and alert the pilot?  It seems like fighting the MiG-23 in particular will be more challenging without knowing we've had an Apex launched at us.  

(BTW - I know that there's no warning for IR-guided systems like SA-13, that's understandable)

Edited Thursday at 05:34 PM by Istari6

[d0ppler]

At least for the MiG-23 (and MiG-21), their radar frequency is outside the bands of the RWR. Even the Viper won't see them on it's RWR. In fact I don't think any plane (in DCS) will detect them on their RWR.

[Istari6]

That's very strange.  On the inability to detect the MiG-23s CW signal, I'm 95% sure I've heard MiG-23 launch alerts when I was flying the Tomcat.  But it also seems strange that the USAF fitted RWR antennas that weren't tuned to cover the threat band of the F-4s greatest air-to-air threat in the 1970s.  I trust Heatblur has done the research and this is how the real F-4E-45MC worked.  Just trying to understand why the USAF would possibly implement such a system?  

[d0ppler]

Disregard what I said. I just saw MiG-23 on the RWR in the Viper just now.
Maybe I've dreamt, but I'm 47% sure they weren't visible couple of years back.

[Istari6]

The Viper has had a lot of Early Access issues.  My group experienced major issues with CCIP accuracy and GPS-guided weapons missing due to winds aloft.  I even logged a bug report with ED showing methodically through a controlled test how inaccurate JDAM, JSOW and WCMD were with any winds aloft.  They never replied beyond "we're looking into it", but I did notice that they listed a fix in a recent update, a year later.  So I wouldn't be surprised if the Viper just had a bugged RWR earlier.  

[Ivandrov]

On 10/16/2025 at 1:33 PM, Istari6 said:

Having learned to fly the F-4, I'm now moving into learning the weapons and defensive systems before diving into Reflected's "MiG Killers" campaign.  Just diving into the ALR-46 and how it operates, and was surprised to see the wide array of threats where the ALR-46 cannot detect a launch.

In particular, I was struck at the tables in the Heatblur manual that listed the following threats as providing no warning on launch:

* SA-5

* SA-11

* MiG-23

* F-4

Wouldn't all these systems work by SARH?  Why wouldn't a mid-1970s RWR be able to detect the CW signal of weapon guidance and alert the pilot?  It seems like fighting the MiG-23 in particular will be more challenging without knowing we've had an Apex launched at us.  

(BTW - I know that there's no warning for IR-guided systems like SA-13, that's understandable)

My understanding is that the circuitry responsible for sounding off launch warnings is specifically reserved for the guidance commands of certain C/D band SAM systems. These have very distinct signals.

 

The RWR will however sound off anytime it detects a PRF change from a present emitter. So, you'll be able to hear a MIG-23 change from search to track for instance by listening to the new guy audio tones.

 

It's an entirely different beast of RWR from anything else we've had before especially simulation wise.

 

At the time these were installed, the MIG-23 really wasn't the primary air threat, they were only in service a few years at that point, and it is unlikely that the US intelligence community at that point had the proper ELINT data to be able to feed to RWRs in the first place.

 

Also keep in mind that we're still really less than a decade (like 6 or 7 years) from when these types of RWR systems were geting fitted in these aircraft in the first place, and their primary focus in these first iterations were for SAM threats. Which is why air threats in the threat library get the short end of the stick as far as identification.

 

I guess as a TL:DR, the primary radar threat that these first RWR's were looking for was the SA-2 and the other systems employed by Vietnam. Everything else is extra.

Edited Saturday at 07:22 AM by Ivandrov

[okopanja]

SA-5: no change in signal on launch compared to tracking. At longer distance the missile seekerdoes not even point to the target. This occurs later once it turns on the target from above.

In short you can not know if this little chunk of meta attached to a much larger chunk of metal carrying large amount of explosive is traveling into your direction:

 

Edited Saturday at 08:05 AM by okopanja

[Muchocracker]

On 10/16/2025 at 12:45 PM, d0ppler said:

Even the Viper won't see them on it's RWR. In fact I don't think any plane (in DCS) will detect them on their RWR.

Demonstrably false. Sapfir's operate well within X band range. 

[Istari6]

OK thanks for the answers so far.

Sounds like there are several hypotheses:

1. Our F-4E ALR-46 might represent a mid-1970s model, which didn't have the ELINT data yet to properly convey a MiG-23 CW lock.  
2. RWRs of the ALR-46 era were focused strongly on ground threats, particularly the new SAM threat (SA-2, SA-3).  So lacking warnings for radar locks from aerial threats is typical for the period.
3. The SA-5 uses a different guidance method than the more typical SA-2 and SA-3 systems.  It seems to be a form of radio command guidance, not creating the characteristic CW tracking signal of other SAM systems.  Thus it's not detected by the ALR-46?  This is particularly weird, given that the ALR-46 seems to have been installed in B-52s, and you'd think they'd want warnings against SA-5s.  Perhaps the B-52s had other ways of detecting an SA-5 launch against them, given they were primary targets for that system?

As Ivandrov says, "It's an entirely different beast of RWR from anything else we've had before especially simulation wise".

What seems odd is that the per the Heatblur manual, our ALR-46 has a library capable of identifying and showing the following threats:

* SA-10 ("10")
* SA-11 ("11")
* SA-19 ("19")
* Patriot ("P")
* Rapier ("R")

It's also capable of detecting Launch from the following threats: 

* R-77 (MiG-29, Su-27)
* AIM-120
* SA-15 

So the library has clearly been updated at some point to represent post-1980 threats.  Anyway, thanks again for the info, helps make some sense of the unique behavior of this RWR system compared to others I've seen.  

 

[okopanja]

52 minutes ago, Istari6 said:

3. The SA-5 uses a different guidance method than the more typical SA-2 and SA-3 systems.  It seems to be a form of radio command guidance, not creating the characteristic CW tracking signal of other SAM systems.  Thus it's not detected by the ALR-46?  This is particularly weird, given that the ALR-46 seems to have been installed in B-52s, and you'd think they'd want warnings against SA-5s.  Perhaps the B-52s had other ways of detecting an SA-5 launch against them, given they were primary targets for that system?

At this stage your statement is a hypothesis. I am curious to see if you bring something fresh on this matter.

Note also that Syrian S-200 downed Israeli F-16 in 2008. Given the range of this SAM, if the RWR was giving the launch warning I would have expected that F-16 would have easily outmaneuvered the missile. Please note that very little technical information is known about this incident. Basically what was reported by IDF.

However, here is the video you can watch to learn more about S-200:

 

52 minutes ago, Istari6 said:

It's also capable of detecting Launch from the following threats: 

* R-77 (MiG-29, Su-27)
* AIM-120
* SA-15 

You do not make proper distinction here: there are 2 warnings here. One when the missile leaves the rail, the second when the missile itself becomes active with it's own radar.

In DCS launch warning is given for R-77 and is based on assumed presence of DL signal. We know this since original 29s radar has to undergo the installation of this additional channel. ED assumes that this signal is well known hence in most of the airplanes in DCS you will get launch warning even if the missile was launched from "TWS2" mode. AIM-120 does not give launch warning, it is assumed that DL updates are "silent" (no documentation available for obvious reasons), so the only indication you will have is either STT/search pass or missile becoming active on you once close enough. 

If you were worried about R-77 vs AIM-120, the later one has multiple advantages over the former in DCS.

Also SA-15 uses different kind of guidance than the other 2. 

Edited 16 hours ago by okopanja