A close-in weapon system is a point-defense weapon system for detecting and destroying short-range incoming missiles and enemy aircraft which have penetrated the outer defenses, typically mounted shipboard in a naval capacity. Nearly all classes of larger modern warships are equipped with some kind of CIWS device. There are two types of CIWS systems. A gun-based CIWS usually consists of a combination of radars, computers, and rapid-firing multiple-barrelrotary cannons placed on a rotating turret. Missile-based CIWSs use infra-red, passive radar/ESM or semi-active radarterminal guidance to guide missiles to the targeted enemy aircraft or other threats. In some cases, CIWS are used on land to protect military bases. In this case, the CIWS can also protect the base from shell and rocket fire.
Gun systems
A gun-based CIWS usually consists of a combination of radars, computers and rotary or revolver cannon placed on a rotating, automatically-aimed gun mount. Examples of gun-based CIWS products in operation are:
Short range: the maximum effective range of gun systems is about ; systems with lighter projectiles have even shorter range. The expected real-world kill-distance of an incoming anti-ship missile is about or less, still close enough to cause damage to the ship's sensor or communication arrays, or to wound or kill exposed personnel. Thus some CIWS are augmented by installing the close range SAMs on the same mount for increased tactical flexibility.
Limited kill probability: even if the missile is hit and damaged, this may not be enough to destroy it entirely or to alter its course enough to prevent the missile, or fragments from it, from hitting its intended target, particularly as the interception distance is short. This is especially true if the gun fires kinetic-energy-only projectiles.
CIWS are also used on land in the form of C-RAM. On a smaller scale, active protection systems are used in some tanks, and several are in development. The Drozd system was deployed on Soviet Naval Infantry tanks in the early 1980s, but later replaced by explosive reactive armour. Other systems that are available or under development are the Russian, Israeli, American and the South African-Swedish.
