Phalank CISW : The Ultimate Defense Shield

Developed as the final line of defense (terminal defense or point defense) against anti-ship missiles (AShMs), including high-g and maneuvering sea-skimmers, the first system was offered to the U.S. Navy for evaluation on USS King in 1973. It was accepted and production started in 1978, the first ship fully fitted out was USS Coral Sea in 1980. The Navy began placing CIWS systems on noncombatant vessels in 1984.

The basis of the system is a 20 mm M61 Vulcan Gatling gun autocannon linked to a radar system for acquiring and tracking targets. The gun fires at a variable 3000/4500 rounds per minute depending on the Block, or version of the system. It is mounted in a self-contained turret along with an automated fire control system. The system automatically searches, detects, tracks, engages and confirms kills using its computer-controlled radar system. Because it is self-contained, Phalanx is ideal for support ships which lack integrated targeting systems and generally have limited sensors. The entire unit weighs between 5500 kg and 6100 kg (12,400 to 13,500 lb).

Developed as the final line of defense (terminal defense or point defense) against anti-ship missiles (AShMs), including high-g and maneuvering sea-skimmers, the first system was offered to the U.S. Navy for evaluation on USS King in 1973. It was accepted and production started in 1978, the first ship fully fitted out was USS Coral Sea in 1980. The Navy began placing CIWS systems on noncombatant vessels in 1984.

The basis of the system is a 20 mm M61 Vulcan Gatling gun autocannon linked to a radar system for acquiring and tracking targets. The gun fires at a variable 3000/4500 rounds per minute depending on the Block, or version of the system. It is mounted in a self-contained turret along with an automated fire control system. The system automatically searches, detects, tracks, engages and confirms kills using its computer-controlled radar system. Because it is self-contained, Phalanx is ideal for support ships which lack integrated targeting systems and generally have limited sensors. The entire unit weighs between 5500 kg and 6100 kg (12,400 to 13,500 lb).

Phalanx has been developed through a number of different configurations. The basic style is the Block 0. The Block 1 (1988) offers various improvements in radar, ammunition, rate of fire, increasing engagement elevation to +70 degrees, and computing. These improvements were intended to increase the system's capability against emerging Soviet supersonic anti-ship missiles. Block 1A introduced a new computer system to counter more maneuverable targets. The Block 1B PSuM (Phalanx Surface Mode, 1999) adds a forward looking infrared (FLIR) sensor to allow the weapon to be used against surface targets. This addition was developed to provide ship defense against small vessel threats and other "floaters" in littoral waters and to improve the weapon's performance against slower low-flying aircraft. The FLIR's capability is also of use against low-observability missiles and can be linked with the Rolling Airframe Missile system to increase RAM engagement range and accuracy. The Block 1B also allows for an operator to identify and target threats.

The U.S. and Canada are in the process of upgrading all their Phalanx systems to the Block 1B configuration. The Block 1B is also used by other navies such as Japan, Egypt, Bahrain and the Royal Navy^[2]

Operation

The CIWS is designed to be the last line of defense against anti-ship missiles. Due to its design criteria its effective range is very short relative to the range of modern ASMs, from 1 to 5 nautical miles (9 km). The gun mount moves at a very high speed and with great precision. The system takes minimal inputs from the ship making it capable of functioning despite potential damage to the ship. The only inputs required for operation are 440 V AC at 60 Hz and water for electronics cooling. For full operation including some non-essential functions, it also has inputs for true compass ships heading and 115 V AC for the PASS and tape drive subsystems.

Radar subsystems

The CIWS has two radars that work together to engage targets. The first radar is the search radar, located inside the radome on the weapon control group (top of the white painted portion). The search subsystem provides bearing, range, velocity, heading, and altitude information of potential targets to the CIWS computer. This information is analyzed to determine whether the detected object should be engaged by the CIWS system. Once the computer identifies a valid target (see details below), the mount moves to face the target and then hands the target over to the track radar. The track radar is an "orange peel"-style radar that is more precise, but can only view a much smaller area. The track radar observes the target until the computer determines that the probability of a successful hit is maximized and then, depending on the operator conditions, the system will either fire automatically or will recommend fire to the operator. While firing, the system tracks outgoing rounds and 'walks' them onto the target.

Gun and ammunition handling system

The Block 0 CIWS mounts (hydraulic driven) fired at a rate of 3,000 rounds per minute and they could only hold 989 rounds in the magazine drum. The Block 1 CIWS mounts (hydraulic) also fired at 3,000 rounds per minute with an extended magazine drum holding 1550 rounds. The Block 1A and newer (pneumatic driven) CIWS mounts fire at a variable rate of 3,000/4,500 rounds per minute and also had the larger 1550 round magazine. The velocity of the rounds once fired is approximately 3,600 feet per second (1,100 m/s). The rounds are armor piercing tungsten penetrator rounds with discarding sabots. The kinetic projectiles are designed to pierce and explode an incoming missile's warhead. Use of otherwise more effective high explosive shells would risk destroying the missile airframe while allowing the warhead to continue a ballistic trajectory into the ship. The ammo handling system uses 2 conveyor belt systems. One of the systems takes the rounds out of the magazine drum and takes them to the gun. The second conveyor system takes either the empty shells or non-fired rounds and routes them back to the opposite end of the drum.

CIWS contact target identification

The CIWS does not recognize identification friend or foe, also known as IFF. The CIWS has only the data it collects in real time from the radars to decide if the target is a threat and to engage it. A contact has to meet multiple criteria for it to be considered a target; some of the criteria are listed below.

1) Is the range of the target increasing or decreasing in relation to the ship? The CIWS search radar will see contacts that are out-bound and discard them. The CIWS will only engage a target if it is approaching the ship.

2) Is the contact capable of making a maneuver to hit the ship? If a contact is not heading directly at the ship, the CIWS looks at its heading in relation to the ship and its velocity. It then decides if the contact can perform a maneuver to still hit the ship.

3) Is the contact traveling between the minimum and maximum velocities? The CIWS has the ability to engage targets that travel in a wide range of speeds; however it is not an infinitely wide range. The system has a target maximum velocity limit; if a target exceeds this velocity, the CIWS will not engage it. It also has a minimum target velocity, meaning any contact going below that velocity will not be engaged by the CIWS. The operator also has the option to adjust the minimum and maximum limits within the limits of the system.

What is described above are the basics of how the CIWS works. There are many other subsystems that run in the background to ensure proper operation, such as environmental control, transmitter, mount movement control, power control and distribution and so on. It takes 6 to 8 months to train a technician to maintain, operate, and repair the CIWS.

Phalanx in combat

The Phalanx system has never been credited with shooting down any enemy missiles or aircraft.^{[citation needed]}

On February 25, 1991, during the first Gulf War, the Phalanx-equipped USS Jarrett was a few miles from the USS Missouri and the British destroyer HMS Gloucester. A Sea Dart missile launched from Gloucester destroyed an Iraqi Silkworm missile (often referred to as the 'Seersucker'), at which Missouri also fired its SRBOC chaff. The Phalanx system on Jarrett, operating in the automatic target-acquisition mode, fixed upon Missouri's chaff and fired a burst of rounds. From this burst, four rounds hit Missouri which was two to three miles (about 5 km) from Jarrett at the time. There were no injuries.^[3] Incidentally, this is the first validated, successful engagement of a missile by a missile, during combat at sea.

June 4, 1996, a Japanese Phalanx accidentally shot down a US A-6 Intruder. The US plane was towing a radar target during gunnery exercises. A Phalanx aboard the Asagiri class destroyer Yūgiri locked onto the Intruder instead of the target. Both pilots ejected safely.^[4] A post accident investigation concluded that the Yūgiri's gunnery officer gave the order to fire before the A-6 was out of the CIWS engagement envelope.^[5]

Land based version

The U.S. Army's version of the Navy's CIWS Phalanx anti-missile system is called the C-RAM, part of the US Army's Counter-Rocket, Artillery, Mortar initiative. The land-based Phalanx was deployed in Iraq in the summer of 2005. It protects the forward operating bases and other high-value sites in and around Baghdad and is deployed by the British in the south of the country. Israel is considering buying the system to counter rocket attacks and defending point military installations. Each system uses a 20 mm M61A1 Gatling gun firing 3,000 or 4,500 M-246 or M-940 rounds per minute.^[6][7]

Whereas naval Phalanx systems fire tungsten armor-piercing rounds, the C-RAM uses the HEIT-SD (High-Explosive Incendiary Tracer, Self-Destruct) ammunition originally developed for the M163 Vulcan air-defense system. These rounds explode on impact with the target, or upon tracer burnout.

Similar systems

• AK-630, Russian CIWS
• Kashtan, Russian CIWS
• Goalkeeper CIWS, Dutch CIWS
• Meroka CIWS, Spanish navy
• SeaRAM, U.S. missile-based CIWS
• Type 730 CIWS, Chinese CIWS