HARM tracking when enableEmission false, setOnOff false, or Alarm State green after HAS launch

[MartinCo]

Hi ED,

With the most recent patch HARMs are pin point accurate even when the radars are set to enableEmission false, setOnOff false, or the alarm state green after a launch.

I have rolled back to DCS 2.9.17.12034 and this behavior was not present.

I believe this is true in the 18 as well (based on earlier thread) and a general HARM issue.

DCS Version: DCS 2.9.18.12722

Reproduction:

* Set up HAS for BB, SD, P, HK
* Launch one harm at each target at > 30nm
* setEmission Off via F10 menu
* Note that RWR indications are removed as they are off
* HARMs continue and precisely hit all 4 targets

It seems the HARMs have the precise coordinates immediately and INS rather than radar homing

Video: 

Please find mission/track:
 

Mission: harms.miz

Track File: harm-emission-off-tracking.trk

 

Thanks,
MartinCo

 

Edited 9 hours ago by MartinCo
added info on rollback not showing this issue

[EricJ]

I don't fly the F-16 but the HARM is designed to remember the location of the emitting radar if it goes off. That was a feature added to real world HARMs due to experience with the Vietnam War when SAM radar operators turned off their radars due to a Shrike or Standard ARM attack and confuse the missile. If I'm reading right then that's intended behavior.

[MartinCo]

It was the AGM-88D that got upgraded to have GPS and ability to engage targets after turning off their radar - not our AGM-88C (which to my knowledge only used radar homing)

Just tested in POS/EOM just toggle launch too - ripple them all within a few seconds and then turn off the emitters - still precise hits from 35+nm

This does make all IADS systems / Skynet etc. a bit pointless (since if the harm will hit anyhow, no point going silent) - and didn't used to be the case (else these projects wouldn't have existed!)

Edited 12 hours ago by MartinCo

[EricJ]

I just googled it and it says the C can still engage if the radar is shut off, and isn't as accurate, The D model is more accurate though, through the GPS/INS and so on.

Edited 12 hours ago by EricJ

[MartinCo]

Right - but this is pin point accurate after turning them off immediately after launch from more than 30nm without much time to evaluate and refine the target and reduce the CEP

I just downgraded to the previous patch (DCS 2.9.17.12034) and they all missed, both in HAS, POS/EOM etc. which is very different to the current patch

 

Edited 9 hours ago by MartinCo

[DSplayer]

This month's patch included some changes to the HARM that were not included in the changelog. Now, a HARM upon target loss will attempt to hit the last known INS position of the target while attempting to search for the signal. The HARM is not laser pinpoint accurate in INS, but can still get close enough to kill the targets as is in your case. I will note that if you were to make the radars stop emitting even earlier in flight, the miss area would increase further.

In previous patches (like the June patch), the HARM after target loss basically didn't fallback to its INS and continued the last command it had before target loss. That behavior was not correct.

There are also some other HARM changes like I said, but they're slightly unrelated to this specific case.