When is a HARM in range?

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Hedgehog
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When is a HARM in range?

Post by Hedgehog » Mon Jun 08, 2020 7:17 pm

There are several important principles related to effective employment of HARM missiles.

a) HARMs do not receive information from the RWR in TOO or PB modes.* Sometimes the RWR will 'see' an emitter that the HARM doesn't, or vice versa. HARMs have their own sensors. The HARM has to see the target to get a lock.

b) Neither the HARM nor the RWR have any means of determining distance to a threat emitter. It can only tell what direction it's coming from.

c) You can set the HARM to display only hostile (HOS) emitters to minimize the chance of launching on friendly emitters.

We nearly always use HARMs in TOO mode. So now you have a good HARM target and an itchy pickle thumb. When can you launch?? How do you know when the HARM is in range? Since it has no way of knowing the distance to the emitter, you will never get any sort of 'in range' cue from a HARM.

The AGM-88 HARM has a stated range of 80 nm, though 30-35 nm is probably more realistic in the sim based on testing.

There are 3 principles you can employ to determine if you are in range for a HARM launch.

1. Distance to emitters in known. Say your strike target is an airfield at WP5. Intel says it is protected by SA-2 SAMs. You're approaching WP5 and you see SA-2 on your HARM page. If your HUD says you are 28 nm from WP5, guess how far away the SAMs are... yup. More than likely 28 nm. Not rocket science.

2. 5 Degree Rule. If the HARM target box is below the -5 degree line on your HUD pitch ladder, it's probably in range. "But that range will vary depending on altitude!" True, but the HARM's range also varies with altitude, so the rule is pretty much valid at any altitude.

3. Hedgehog's Rule. If it's shooting at you, it's in range.


* Self-Protect mode (SP) is a different ballgame. In SP mode, the HARM does not need to 'see' the emitter. It simply flies toward where the RWR says the emitter is and starts looking there.
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Re: When is a HARM in range?

Post by Hedgehog » Mon Jun 21, 2021 8:23 pm

Pre-Briefed (PB) mode is obviously now implemented in the Hornet. That's a whole different animal. In PB, the HARM is commanded to fly to a pre-determined location (typically a waypoint) and then start looking for a specific emitter that is identified by a DED code which must be entered before the weapon is launched.
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