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Comment by jhartwig | Hacker News Reader

I had thought it had been used during the gulf war in a friendly fire event.

The Missouri got raked with it from its escort ship - not pleasant for anyone concerned I'd say.

http://billgx.com/2019/10/autonomous-friendly-fire/

tldr: the Missouri fired a chaff and the other ships CIWS was all “not in my airspace” and started shooting at it even though the Missouri was behind the target. Interesting, I wonder if the whole battlegroup has synced systems now to avoid such things, e.g. 1) I’m going to launch something, everyone else disregard it as a threat and 2) if a threat has a friendly behind it, don’t shoot it.

Maybe 2) is more of a judgement call since a few bullet holes is probably preferential to the alternative.

IFF in any capacity on Phalanx seems like a poor match.

At ranges that close... you really want a "deconstruct anything in the air" device, not a "consider what you're about to hit" device.

Which I'd imagine has been designer pushback on complicating it and going that route.

Safety through deciding what mode to set it in; not through leaving it alone and forgetting about it.

I don’t disagree, but I’m sure they had to come up with some mitigation after this. If each ship is shooting down the other ships primary/secondary/whatever countermeasure then in a worst case scenario you and your sister ships are only left with your CIWS. And they might still be busy shooting at your sister ships chaffs to deal with the real threat. I don’t know much about it, I just found it interesting.

Seems a bit like Star Trek - “Their shields go down for a split second when they fire”. Maybe the system goes dark for a second to avoid shooting down outgoing items? Syncing the shields might make this better (or expose other weaknesses?)

The issue is time.

Say it's a YJ-83 clone, so around mach 1.4 terminal velocity (476 m/s).

Phalanx tracks at 10km, engages at around 4km.

So it has ~8.4 seconds of engagement time to try to destroy the incoming missile.

... And that's a relatively slow modern target. A P-800 gets up to mach 2.4. BrahMos is mach 3?

I'd guess the Navy would generally rather keep CIWSs on a hair trigger, and just space their ships further apart in combat situations.

And afaik, most of the CIWSs have been removed in favor of RAM, since the gun-limited engagement ranges don't make much sense anymore.

Yep that's the one

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