Designed as a last-ditch defense against incoming threats, the close-in weapons system (CIWS) mounts a radar, 20mm gun and control system. And the Navy has to test them somehow.
The above video shows an advanced Phalanx Mod 1B mount, gratefully for the Marine aviator involved, free but unloaded.
It is one of two such mounts on the amphibious dock landing ship USS Germantown (LSD 42) and you’ll see it lock on then train on an AV-8B Harrier during a routine operational test (OPTEST), firing when the attack plane is in range.
If you note, the CIWS (“sea-whiz” like cheese whiz but a whole lot more deadly) is programmed to stop firing once its arc of heavy 20mm round would intercept part of the ships itself, and does not follow the Harrier once it is leaving as it is no longer a threat.
As the mount only holds 1,550 rounds, and the 6-barreled M61 Vulcan gatling gun has a theoretical rate of fire of some 4,500 rounds per minute, the CIWS would have dumped about a third of its magazine on the hapless Harrier in the seven second burst had it been loaded.
Germantown is part of the Bonhomme Richard Amphibious Ready Group and is participating in amphibious integration training and a certification exercise with the embarked 31st Marine Expeditionary Unit.
And if you want to see what a live-fire burst with ammo but sans Harrier looks like, check this out below.