[RESOLVED] B1825.15 Ballistic Missile Intercept Calculations Failing

[4Emprah]

The calculations for trying to intercept incoming ballistic missiles does not seem to work for the GBI batteries. As seen in the attached scenario, the launchers will not even attempt an intercept (Fort Greely) or attempt to lead the target so far ahead that the GBI missiles will guarantee a miss (Vandenburg SFB).

ABM Testing.zip

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[Nikel]

I have tested in previous builds.

The interceptors from Vanderberg did this turn to impact the incoming RV in B1662.

I had to change the db to v512.

w1662.gif (705.22 KiB) Viewed 372 times

[4Emprah]

I'm thinking it might be an altitude issue, with how high the ICBM apogee is and what the interceptors say they can reach. The missile is up around 2,800 km at the area I imagine the Fort Greely interceptors would be used:

Screenshot 2026-04-05 185250.png (15.94 KiB) Viewed 346 times

The GBI [CE-II Blk, GMD] has a listed engagement altitude of 2,000 km:

Screenshot 2026-04-05 185448.png (3.54 KiB) Viewed 346 times

At a glance it seems like the ICBM is climbing too high, but I am not an expert on ballistic mechanics.

[blu3s]

This is an issue with the GBI propulsion elements from the DB. IIRC, this is fixed for next DB update, DB516

[Nikel]

Tested in B1852 with db v516, the GBI interceptors will turn now to impact the incoming missile. So it is fixed.

Tested also in the new build, without updating the db of the scenario, and the turn may happen or not.

v516.gif (2.51 MiB) Viewed 237 times

[Mark352]

Tested in B1852 with db v516, the GBI interceptors will turn now to impact the incoming missile. So it is fixed.

Tested also in the new build, without updating the db of the scenario, and the turn may happen or not.

I don't think this is fixed. The site in Alaska should be engaging that ICBM. That appears to be a problem with something, I just know what. It's good see that GBI from the Vandenburg site can successfully intercept the ICBM but, I still feel like the Alaska site should be trying a first shot at it.

[Mark352]

Tested in B1852 with db v516, the GBI interceptors will turn now to impact the incoming missile. So it is fixed.

Tested also in the new build, without updating the db of the scenario, and the turn may happen or not.

I don't think this is fixed. The site in Alaska should be engaging that ICBM. That appears to be a problem with something, I just know what. It's good see that GBI from the Vandenburg site can successfully intercept the ICBM but, I still feel like the Alaska site should be trying a first shot at it.

I apologize. Upon further review this is working in Build 1852 as per Nikel's previous post. My bad. The Alaska site does engage and LRDR is seeing the missiles. Thanks!

[Nikel]

I apologize. Upon further review this is working in Build 1852 as per Nikel's previous post. My bad. The Alaska site does engage and LRDR is seeing the missiles. Thanks!

No need to apologize Mark


Edit: I forgot to update the database to v516.

In this scenario the Alaskan GBI will also fire if the second one is removed.

What makes sense, the GBI unit is the same for both scenarios in the db, number 3710.

What are different are the Californians.


ABM Test

Alaska 3710

California 3711


Nuclear War test

Alaska 3710

California 2467

GBI 2.gif (1.69 MiB) Viewed 166 times