I hope others noted the significance of the slightly less than 4 minute time taken to reload the Phalanx gun. That's the window of opportunity the enemy has to get in. The only other thing you need to know is how long the gun can fire before it needs reloading. Given the rate of fire (4,500 rounds per minute), that can't be very long. Basically, an enemy just needs to launch cheap decoys at the ship for a minute or two then send in the real thing while the defenders are reloading.

We had a few of these on my ship. Man, it was so cool watching these go off. When you think about the number of guns and rounds per second, it's like the sky would be full of projectiles. Nothing can penetrate that space.

Our unit once repelled from some UH1H at Bowman Field in Louisville KY but we were forbidden to fire blanks to represent a hot LZ because the EPA did not want the noise. Our officer said later, the first casualty in the next conflict would be the EPA. There are times the keepers of the keys in the Washington Distribution Center have been educated beyond their ability to think.

The Army had this system years ago and called it Vulcan. We had the guns mounted on an APC carriage and a towed version. I had four of the mounted guns in my platoon in Germany in 77-78, a great weapons system.