The Phalanx Close-In Weapon System (CIWS) is the only system that is more reassuring than any other one when defending a warship against sea-skimming missiles, speed-record attack boats, or cannon rounds that seem to come from nowhere. That radar-guided Gatling gun has made itself at home on U.S. Navy ships and many others, the last resort between the ship and disaster.
Phalanx was developed in the 1960s and 1970s, during which anti-ship missiles were being introduced and changing naval warfare. These low-altitude, high-speed weapons made underfunded adversaries threats to billion-dollar ships.
The Navy reacted in two ways: improve in-service missile defense and design a gun system with sufficient rounds to be fired rapidly enough to reach the threat quickly enough to destroy it singly at close ranges. The Phalanx was the gun, which was built around the M61A1 Vulcan 20mm rotary gun with the capacity for 4,500 rounds per minute firing.
Most incredible about the system is that all these abilities are integrated. Search and track radars, complex fire-control computers, and the Vulcan six-barreled gun are all included in one package. Engaged and up, it can find, chase, and kill attacking targets automatically—a task that was done before using a number of different systems and a team of men.
The M61A1 Vulcan that makes up the bulk of the system is not a standard weapon. It has electrically heated barrels that allow it to achieve highly elevated rates of fire needed to shoot at fast-flying missiles or mortar shells. Spreading the firing burden out among six barrels keeps them from overheating during short bursts of high-energy firing. It uses tungsten armor-piercing ammunition against naval targets or self-destructing rounds in its land-based C-RAM mode to reduce damage to non-combatants.
Enhanced in a series of blocks after its first deployment aboard the USS Coral Sea in 1980, Phalanx improved radar sensitivity and included added ammunition capacity in Block 1. Block 1A added processing capability, and the system could engage three targets at once. Its most notable upgrade came in the form of Block 1B, which came with a forward-looking infrared sensor and operator control stations for use in manual targeting to strengthen its ability to intercept missiles, helicopters, small boats, and unmanned aerial vehicles.
The system has consistently demonstrated itself on the battlefield. During the Gulf War, it successfully intercepted dozens of incoming missiles. In ground operations, the C-RAM variant also defended bases from rocket and mortar attacks, with success rates as high as 70 to 80 percent. Its ability to act seconds after detecting saved thousands of lives and defended irreplaceable equipment.
Incorporation into greater combat systems only enhances its functionality. Phalanx is designed to operate either independently or in concert with the combined defense of the ship, cooperating with other systems like Rolling Airframe Missile. Layered defense is needed in today’s conflict, where any single system would be incapable of defending against all threats. Directed-energy gear continues to evolve, but the Phalanx is a necessary prompt-response guardian.
There are, of course, weaknesses in the system. It has a short range, effectively a “last line of defense.” Ammo is rapidly depleted during battle, and regular maintenance needs to be performed to maintain it in combat condition. Its small size and self-contained design, however, make it easy to install, a big reason why it is still so popular.
Cost is another reason that Phalanx has persisted. Even after it’s become more costly to produce year by year, the system’s still much cheaper per encounter than missiles. It’s costing around 300 rounds at around $8,000 to conduct an average intercept—a fraction of the cost of even the cheapest guided missile, but very probably as good at stopping close-in threats.
With new missile technology and new tactics, the Phalanx CIWS is still an elephant gun. Automation, rate of fire, and flexibility make it a reliable defender of the fleet—a tribute to fine balancing between sea attack and defense.