The Phalanx CIWS is a close-in weapon system for defence against anti-ship missiles. It
was designed and manufactured by the General Dynamics Corporation, Pomona Division. Consisting
of a radar-guided 20 mm Gatling gun mounted on a swiveling base, the Phalanx is used by
multiple Navies around the world, notably the Royal Navy and the United States Navy
on every class of surface combat ship, by the United States Coast Guard aboard its Hamilton-class
and Legend-class cutters and the navies of 16 allied nations.
A land based variant, known as C-RAM, has recently been deployed in a short range missile
defense role, to counter incoming rockets and artillery fire.
Because of their distinctive barrel-shaped radome and their automated nature of operation,
Phalanx CIWS units are sometimes nicknamed "R2-D2" after the famous droid from Star Wars.
History The Phalanx Close-In Weapons System was developed
as the last line of automated weapons defense against anti-ship missiles, including high-g
and maneuvering sea-skimmers. The first prototype system was offered to the U.S. Navy for evaluation
on USS King in 1973 and it was determined that additional improvements were required
to improve performance and reliability. Subsequently, the Phalanx Operational Suitability Model
successfully completed Operational Test and Evaluation onboard USS Bigelow in 1977. OSM
exceeded operational maintenance, reliability, and availability specifications. DSARC-III
followed OPEVAL which was followed by approval for production in 1978. Phalanx production
started with orders for 23 USN and 14 Foreign Military Sales systems. The first ship fully
fitted out was the USS Coral Sea in 1980. The Navy began placing CIWS systems on non-combatant
vessels in 1984. Design
The basis of the system is the 20 mm M61 Vulcan Gatling gun autocannon, used since the 1960s
by the United States military in nearly all fighter aircraft, linked to a Ku-band radar
system for acquiring and tracking targets. This proven system was combined with a purpose-made
mounting, capable of fast elevation and traverse speeds, to track incoming targets. An entirely
self-contained unit, the mounting houses the gun, an automated fire control system and
all other major components, enabling it to automatically search for, detect, track, engage,
and confirm kills using its computer-controlled radar system. Due to this self-contained nature,
Phalanx is ideal for support ships, which lack integrated targeting systems and generally
have limited sensors. The entire unit has a mass between 5,500 and 6,100 kg.
Upgrades
Due to the continuing evolution of both threats and computer technology, the Phalanx system
has, like most military systems, been developed through a number of different configurations.
The basic style is the Block 0, equipped with first generation solid state electronics and
with marginal capability against surface targets. The Block 1 upgrade offered various improvements
in radar, ammunition, computing power, rate of fire, and an increase in maximum engagement
elevation to +70 degrees. These improvements were intended to increase the system's capability
against emerging Russian supersonic anti-ship missiles. Block 1A introduced a new computer
system to counter more maneuverable targets. The Block 1B PSuM adds a forward looking infrared
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 RIM-116 Rolling
Airframe Missile system to increase RAM engagement range and accuracy. The Block 1B also allows
for an operator to visually identify and target threats.
The U.S. is in the process of upgrading all their Phalanx systems to the Block 1B configuration.
All Phalanx systems in use by the U.S. Navy are scheduled to be upgraded to Block 1B by
FY 2015. The Block 1B incorporates a stabilized Forward-Looking Infra-Red sensor, an automatic
acquisition video tracker, optimized gun barrels, and Enhanced Lethality Cartridges for additional
capabilities against asymmetric threats such as small maneuvering surface craft, slow-flying
fixed and rotary-winged aircraft, and unmanned aerial vehicles. The FLIR sensor improves
performance against anti-ship cruise missiles, while the OGB and ELC provide tighter dispersion
and increased first hit range; the Mk 244 ELC is specifically designed to penetrate
anti-ship missiles with a 44 percent heavier tungsten penetrator and an aluminum nose piece.
Another system upgrade is the Phalanx 1B Baseline 2 radar to improve detection performance,
increase reliability, and reduce maintenance. It also has a surface mode to track, detect,
and destroy threats closer to the water's surface, increasing the ability to defend
against fast-attack boats and low-flying missiles; the Baseline 2 radar upgrade is to be installed
on all U.S. Navy Phalanx systems by FY 2019. The Block 1B is also used by other navies,
such as Canada, Portugal, Japan, Egypt, Bahrain, and the UK.
In May 2009, the US Navy awarded a $260 million contract to Raytheon Missile Systems to perform
upgrades and other work on the Phalanx. Comparison with other CIWS
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. 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 three-phase at 60 Hz and water
for electronics cooling. For full operation, including some non-essential functions, it
also has inputs for true compass ship's heading and 115 V AC for the PASS subsystem.
Radar subsystems The CIWS has two antennas that work together
to engage targets. The first antenna, for searching, is located inside the radome on
the weapon control group. 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, the mount moves to face the target and then
hands the target over to the track antenna. The track antenna is extremely precise, but
views a much smaller area. The tracking subsystem 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 fired at a rate of
3,000 rounds per minute and held 989 rounds in the magazine drum. The Block 1 CIWS mounts
also fired at 3,000 rounds per minute with an extended magazine drum holding 1,550 rounds.
The Block 1A and newer CIWS mounts fire at a rate of 4,500 rounds per minute with a 1,550
round magazine. The velocity of the rounds fired is approximately 3,600 feet per second.
The rounds are armor-piercing tungsten penetrator rounds or depleted uranium with discarding
sabots. The Phalanx CIWS 20MM rounds are designed to destroy a missile's airframe and make it
unaerodynamic, thus keeping shrapnel from the exploding projectile to a minimum, effectively
keeping collateral damage to a minimum. The ammunition handling system has two conveyor
belt systems. The first takes the rounds out of the magazine drum to the gun; the second
takes empty shells or non-fired rounds 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 only has 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:
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. Is the contact capable of maneuvering 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 still perform
a maneuver to hit the ship. 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 limit. Any contact 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. There are many other subsystems that together
ensure proper operation, such as environmental control, transmitter, mount movement control,
power control and distribution, and so on. It takes six to eight months to train a technician
to maintain, operate, and repair the CIWS. Incidents
Drone exercise catastrophic accidents On February 10, 1983, the USS Antrim was
conducting a live fire exercise off the east coast of the United States using the Phalanx
against a target drone. Although the drone was successfully engaged at close range, the
target debris bounced off the sea surface and struck the ship. This caused significant
damage and fire from the drone's residual fuel, which also killed a civilian instructor
aboard this ship. On October 11, 1989, the USS El Paso was
conducting a live fire exercise off the east coast of the United States using the Phalanx
against a target drone. The drone was successfully engaged, but as the drone fell to the sea,
the CIWS re-engaged it as a continued threat to the El Paso. Rounds from the Phalanx struck
the bridge of the USS Iwo Jima, killing one officer and injuring a petty officer.
Iraqi missile attack in 1991 Gulf War On February 25, 1991, during the first Gulf
War, the Phalanx-equipped frigate USS Jarrett was a few miles from the US battleship USS Missouri
and the British destroyer HMS Gloucester. The ships were attacked by an Iraqi Silkworm
missile, at which time the Missouri fired its SRBOC chaff. The Phalanx system on Jarrett,
operating in the automatic target-acquisition mode, fixed on Missouri's chaff, releasing
a burst of rounds. From this burst, four rounds hit Missouri which was two to three miles
from Jarrett at the time. There were no injuries. A Sea Dart missile was then launched from
Gloucester in a 'tail end' engagement; destroying the Iraqi missile as it passed between Gloucester
and Missouri, achieving the first successful engagement of a missile by a missile during
combat at sea.
Accidental downing of US aircraft by the Japanese destroyer Yūgiri
On June 4, 1996, a Japanese Phalanx accidentally shot down a US A-6 Intruder from the USS Independence
that was towing a radar target during gunnery exercises about 1,500 miles west of the main
Hawaiian island of Oahu. A Phalanx aboard the Asagiri class destroyer Yūgiri locked
onto the Intruder instead of the target. Both pilots ejected safely. 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. 21st century
Centurion C-RAM
Seeking a solution to constant rocket and mortar attacks on bases in Iraq, the United
States Army requested a quick-to-field anti-projectile system in May 2004, as part of its Counter-Rocket,
Artillery, Mortar initiative. The end result of this program was 'Centurion'. For all intents
and purposes a terrestrial version of the Navy's CIWS, the Centurion was rapidly developed,
with a proof of concept test in November that same year. It began deployment to Iraq in
2005, where it was set up to protect forward operating bases and other high-value sites
in and around the capital, Baghdad. Israel has purchased a single system for testing
purposes, and was reported to have considered buying the system to counter rocket attacks
and defend point military installations. However, the swift and effective development and performance
of Israel's indigenous Iron dome system has ruled out any purchase and deployment of Centurion.
Each system consists of a modified Phalanx 1B CIWS, powered by an attached generator
and mounted on a trailer for mobility. Armed with a 20 mm M61A1 Gatling gun, the unit is
capable of firing 4,500 20MM rounds per minute. In 2008, there were more than twenty CIWS
systems protecting bases in the U.S. Central Command area of operations. A Raytheon spokesman
told Navy Times that 105 attacks were defeated by the systems, most of those involved mortars.
Based on the success of Centurion, 23 additional systems were ordered in September 2008.
Like the naval version, Centurion uses Ku-band radar and FLIR to detect and track incoming
projectiles, and is also capable of engaging surface targets, with the system able to reach
a −25 degree elevation. The Centurion is reportedly capable of defending a 1.2 km
square area. One major difference between the land and sea based variants is the choice
of ammunition. Whereas naval Phalanx systems fire tungsten armor-piercing rounds, the C-RAM
uses the 20MM HEIT-SD ammunition, originally developed for the M163 Vulcan Air Defense
System. These rounds explode on impact with the target, or on tracer burnout, thereby
greatly reducing the risk of collateral damage should any rounds fail to hit their target.
SeaRam Utilizing the armament of the RIM-116 Rolling
Airframe Missile, and based on the mounting and targeting systems of the Phalanx, SeaRAM
was developed in response to concerns about the performance of gun-based systems against
modern, super-sonic sea-skimming anti-ship missiles. Designed as a companion self-defense
system to Phalanx, the SeaRAM is equipped with an 11 cell RAM launcher, and provides
defense at a longer range. Due to the common mounting, SeaRAM inherits the relatively easy
installation characteristics of its gun-based sibling, with Raytheon stating that "[SeaRAM]
fits the exact shipboard installation footprint of the Phalanx, uses the same power and requires
minimal shipboard modification." Currently in the trial stages, SeaRAM is fitted to the
Independence Class Littoral Combat Ship. Operators
Specifications
Gun: 1× 20 mm M61 Vulcan 6-barreled Gatling cannon
Height: 4.7 m Weight: 12,500 lb, later models 13,600 lb
Elevation −25° to +85° Muzzle velocity: 1,100 m/s
Rate of fire: 4,500 rounds/minute Maximum burst size: 1000 rounds
Ammunition capacity: 1,550 rounds Radar: Ku band
100% Kill distance: Classified Cost: $35 million
Similar systems AK-630, Russian CIWS
Kashtan CIWS, Russian Gun-Missile CIWS Goalkeeper CIWS, Dutch CIWS
Meroka CIWS, Spanish navy Barak 1, Israel. missile-based
RIM-116 Rolling Airframe Missile, U.S. missile-based Type 730 CIWS, Chinese CIWS
References Notes
External links Official United States Navy Warfighters Encyclopedia
CIWS page GlobalSecurity.org fact file
Raytheon Company Phalanx CIWS product page