[RESOLVED] Questions Regarding LRDR, SBX-1 and GBI's

[Mark352]

I've been experimenting with the scenario from the book Nuclear War: A Scenario. Interesting book that came out in 2024. The scenario depicted in House of Dynamite is similar to the book but, it was not based on the book. I'm using v1.08 build 1706

Based on the attached test scenario I have the following questions.
-Is the SBX-1 successfully tracking an ICBM required for a successful engagement by the GBI's?
-Is the SBX-1 WAD or is something amiss?
-Why does LRDR not track the ICBM inthis scenario? It doesn't seem to be WAD.
-Is it plausibly realistic for an Arleigh Burke DDG to successfully shoot down an incoming RV from an ICBM?

In my tests the DPRK ICBM is targeted on the Pentagon, Washington DC (like the book) and is setup to launch when the scenario starts. It's detected at 26 seconds in by SIBIRS and/or Checkmate satellites. I believe I have all the appropriate radar stations setup that could be in play.

AN/TPY-2 - JASDF Shariki
AN/TPY-2 - JASDF Kyougamisaki
AN/FPS-108 Cobra Dane - Shemya, Alaska
SBX-1 - Bering Sea near Adak, Alaska
LRDR - Clear SFS, Alaska
AN/FPS-115 - Beale AFB, California
AN/FPQ-16 (PARCS) - Cavalier SFS, North Dakota

I typically have the SBX-1 deployed to one of six random deployment locations in my tests; for the purposes of this test scenario I place it in the Bering Sea just north of Adak. It seems to work best there.

During play the DPRK ICBM is tracked by the AN/TPY-2 as the ICBM climbs. The SBX-1 sees the missile as it comes over Siberia but, no longer tracks as it comes over the Arctic. The LRDR in Alaska does not track the missile at all and the Alaska based GBI's do not fire. When attempting a manual attack the Weapon Allocation window indicates Automatic fire NOT possible, Unable to intercept target. The missile continues on and is tracked by the AN/FPQ-16 (PARCS) in North Dakota and GBI's are launched from the Vandenburg AFB site that have absolutely no chance of intercepting the RV. I've probably run through this over 100 times and the GBI from Vandenburg never come close. As the RV approaches the target it's launched on by a BMD equipped Arleigh Burke DDG of the east coast. It often takes out the RV (not in the book).

Sixteen minutes into the scenario a DPRK SSB about 300 to 350 nm of the off the California coast launches an SLBM towards Diablo Canyon NPP. The majority of the time the SLBM is easily shot down by the Vandenburg GBI. The satellites and Pave Paws at Beale AFB detect and track that missile. (No mention of any attempt to engage the SLBM in the book)

So the GBI's seem to work real well against the SLBM but, not at all against the ICBM. I don't understand why the LRDR doesn't detect the ICBM (maybe a bug?) or why the GBI's in Alaska can't intercept the ICBM.

I can't rule out that I may be doing something wrong with this scenario. Thanks for taking a look see.

[blu3s]

Thanks for the detailed report

Some of the things you mention may be a bug, we will look into it and come back to you.

[thewood1]

I had thought GBIs weren't designed for ICBM interception, but IRBM and the like.

[tylerblakebrandon]

I had thought GBIs weren't designed for ICBM interception, but IRBM and the like.

Wiki entry cites designed for ICBM intercept as well as test interceptions.

https://en.wikipedia.org/wiki/Ground-Ba ... se_Defense

Now THAAD is designed specifically for short, medium, and intermediate range ballistic missiles.

[Mark352]

Thanks for the detailed report

Some of the things you mention may be a bug, we will look into it and come back to you.

I have uploaded a corrected version of the test scenario in my original post. The SLBM mission was not executing. My mistake. It should be working now. Sorry about that.

Thanks again!

[blu3s]

No problem, in fact I did two scenarios, one with just the SLBM and then other with a few ICBMs against different points of CONUS.

Thanks!

[blu3s]

The SBX is working fine,

The GBI and LRDR are a DB issue that will need to be addressed in a future DB update

[Mark352]

Got it. Thanks for looking into this.

[thewood1]

This is a great chart that Dimitris shared on discord.

Screenshot 2026-01-16 095506.jpg (145.26 KiB) Viewed 539 times

Gives a good reference to what system to use where and on what. This is the most concise graphic I have seen on US BMD.

[Nikel]

Testing Mark352's scenario in B1852.

The NK missile impacts on the Cobra Dane radar in the Aleutian islands, instead of the Pentagon that is the target in the mission, a new bug?

[Mark352]

The NK missile impacts on the Cobra Dane radar in the Aleutian islands, instead of the Pentagon that is the target in the mission, a new bug?

That's weird. I downloaded the version posted here to the forum and played it in v1.09 Build 1825.15 and the NK missile goes for the Pentagon not the Cobra Dane.

The GBI in Alaska still don't launch. Issue with the GBI and LRDR stills exists.

[Nikel]

That's weird. I downloaded the version posted here to the forum and played it in v1.09 Build 1825.15 and the NK missile goes for the Pentagon not the Cobra Dane.

Hi Mark.

Note that I am talking about B1852, the last beta.

https://forums.matrixgames.com/viewtopic.php?t=416771

[blu3s]

Could be there was a change in behavior in the Opp Scrambling setting for the Strike Mission. If you change it to prioritize mission targets, it fires to the designated target.

[Nikel]

Could be there was a change in behavior in the Opp Scrambling setting for the Strike Mission. If you change it to prioritize mission targets, it fires to the designated target.

You are right.

Do you not consider it a bug then?

[Nikel]

The GBI in Alaska still don't launch. Issue with the GBI and LRDR stills exists.

I noticed that it will fire if you remove the second GBI unit.

It is more effective though in the last build and with the updated db. There is a final sprint to impact the missile

GBI.gif (2.78 MiB) Viewed 278 times

[Mark352]

Hi Mark.

Note that I am talking about B1852, the last beta.

https://forums.matrixgames.com/viewtopic.php?t=416771

My bad. I see that now. Thanks!

[Mark352]

The GBI in Alaska still don't launch. Issue with the GBI and LRDR stills exists.

I noticed that it will fire if you remove the second GBI unit.

It is more effective though in the last build and with the updated db. There is a final sprint to impact the missile

That's interesting. Wonder why the Alaska based GBI will engage if the California based GBI is removed. I need to check out the latest beta. Thanks for the info.

[Dimitris]

So this is resolved ?

[Mark352]

So this is resolved ?

No. I don't believe it's resolved. It is my understanding that the GBI based in Alaska should be able to engage the incoming ICBM. The manual launch panel just indicates unable to intercept without a reason. The California based GBI can intercept the ICBM but, seems to me the Alaska site should be engaging the ICBM. Am I wrong?

I don't understand why the Alaska site will engage the SLBM when the California GBI site is removed.

The SBX-1 tracks the ICBM, the LRDR does not.

[Nikel]

The red text should give more information.

Could it be that CMO decides which GBI interceptor has more possibilities?

Regarding the LRDR, i have seen it working if you update the db to v516.

LRDR.png (92.46 KiB) Viewed 233 times