Phalanx CIWS Upgrades: How the U.S. Navy Secures Last-Line Ship Defense Through 2029
The United States Navy has embarked on a long-term program to sustain, modernize, and overhaul the Phalanx Close-In Weapon System (CIWS) across its surface fleet through 2029. This initiative reflects the Navy’s recognition that the Phalanx remains a critical last line of defense against modern threats such as cruise missiles and unmanned aerial vehicles. By committing to a multi-year plan, the Navy ensures that the system remains reliable, effective, and fully integrated into the fleet’s layered defense strategy.
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| Phalanx CIWS. Photo: gdots.com |
Rationale Behind the Multi-Year Plan
The Navy’s decision to adopt a multi-year approach is driven by several practical and strategic considerations. First, it guarantees that the Phalanx systems are available and operational before ships are deployed, preventing dangerous capability gaps. Second, it allows maintenance schedules to be synchronized with shipyard availabilities, reducing downtime and maximizing fleet readiness.
Another important factor is the stability of the supply chain for ammunition, spare parts, and trained personnel. By planning years in advance, the Navy can avoid shortages that might otherwise compromise operational effectiveness. This approach also ensures that crews remain proficient in operating and maintaining the system, which is essential given the complexity of the technology.
The Role of the Phalanx CIWS
The Phalanx CIWS is designed as the final protective barrier against incoming threats that have penetrated other layers of a ship’s defenses. Its rapid-fire 20 mm Gatling gun, combined with advanced radar and electro-optical sensors, allows it to detect, track, and destroy targets at extremely close range. Although its effective range is relatively short compared to modern anti-ship missiles, its speed and precision make it indispensable.
The system is capable of engaging a wide variety of threats, including supersonic missiles, low-flying aircraft, drones, and even small surface vessels. Its automated nature allows it to function with minimal input from the ship, ensuring that it can continue to operate even if other systems are damaged. This independence makes it one of the most reliable defensive assets in the Navy’s arsenal.
Technical Specifications
The Phalanx CIWS weighs approximately 12,400 to 13,600 lb (5,600 to 6,169 kg) and stands 15.5 feet (4.7 meters) tall. It is armed with a six-barrel M61A1 Vulcan Gatling gun chambered in 20×102 mm ammunition, the system achieves a muzzle velocity of 3,600 feet per second (1,100 meters per second), giving it the ability to intercept fast-moving targets. The Phalanx CIWS demonstrates remarkable firepower with its dual fire rate of 3,000 or 4,500 rounds per minute, ensuring flexibility in ammunition expenditure. This capability allows operators to balance between conserving rounds and delivering maximum firepower when facing high-speed threats.
Combined with its 1,550-round enhanced lethality cartridge magazine, the system is always prepared for sustained engagements. The weapon’s effective firing range is about 1,625 yards (1,486 meters), with a maximum range of 6,000 yards (5,500 meters). Its elevation and traverse capabilities allow it to engage targets across a wide arc, with Block 1B variants capable of elevating from −25° to +85°. These specifications highlight the system’s ability to respond quickly and accurately to threats approaching from multiple directions.
Power and Drive Systems
The system operates on a three-phase 440V, 60 Hz electric power supply, consuming 18 kW during search operations and up to 70 kW while tracking. Its gun drive is pneumatic, while the mount drive is electric, providing both reliability and precision in movement. These features ensure the weapon can respond instantly to rapidly approaching targets.
Advanced Radar and Sensor Integration
Equipped with a Ku-band digital Moving Target Indicator (MTI) search radar and a Ku-band pulse Doppler monopulse tracking radar, the Phalanx achieves exceptional detection accuracy. These radars work in tandem with a forward-looking infrared (FLIR) imaging system and an automatic acquisition tracker. This integration allows the system to identify, track, and engage threats even in low-visibility or electronic warfare environments.
Cooling and Operational Reliability
To maintain peak performance, the Phalanx CIWS relies on seawater cooling at 20 gallons per minute and 30 psig pressure. This cooling system ensures that the electronics and gun components remain stable during intense firing sequences. By preventing overheating, the system maintains continuous readiness in prolonged combat scenarios.
Evolution of the Phalanx System
Since its introduction, the Phalanx has undergone several major upgrades to keep pace with evolving threats. The original Block 0 configuration featured first-generation solid-state electronics and limited capability against surface targets. In 1988, the Block 1 upgrade improved radar, ammunition, computing power, and rate of fire, while also increasing the maximum engagement elevation.
The Block 1A introduced a new computer system to counter more maneuverable targets, reflecting the growing sophistication of anti-ship missiles. By 1999, the Block 1B added a forward-looking infrared (FLIR) sensor, enabling the system to engage small surface vessels and low-flying aircraft. This upgrade also allowed operators to visually identify and target threats, expanding the system’s versatility.
Block 1B and Baseline 2 Enhancements
The Block 1B variant, which has been standard across the fleet since 2015, incorporates several significant improvements. These include an automatic acquisition video tracker, optimized gun barrels, and Enhanced Lethality Cartridges (ELC). The Mk 244 ELC round, with its heavier tungsten penetrator and aluminum nose piece, is specifically designed to defeat modern anti-ship missiles.
The Baseline 2 radar upgrade further enhances detection performance, reliability, and maintainability. It also introduces a surface mode that improves the system’s ability to track and destroy threats close to the waterline, such as fast-attack craft. Together, these enhancements ensure that the Phalanx remains effective against both traditional and asymmetric threats.
Integration with Other Systems
The Phalanx CIWS is not an isolated system but part of a broader defensive network. Its FLIR sensor can be linked with the RIM-116 Rolling Airframe Missile (RAM) system, extending engagement range and improving accuracy. This integration allows ships to employ a layered defense strategy, with the Phalanx serving as the final safeguard.
By combining radar, electro-optical sensors, and missile systems, the Navy creates a multi-dimensional shield against incoming threats. The Phalanx’s ability to operate autonomously ensures that even if other systems fail, the ship retains a last line of defense. This redundancy is critical in modern naval warfare, where saturation attacks are increasingly common.
Operational Considerations
The Phalanx requires only minimal inputs from the ship to function, relying primarily on electrical power and cooling water. For full operation, it also uses compass heading data and the WinPASS subsystem, which allows technicians to conduct diagnostics and store engagement data. This design ensures that the system can remain operational even under battle damage conditions.
Training is another key factor in maintaining operational readiness. It typically takes six to eight months to train a technician to operate, maintain, and repair the CIWS. This investment in human capital underscores the complexity of the system and the importance of skilled personnel in ensuring its effectiveness.
Ammunition and Engagement Process
The Phalanx uses 20 mm armor-piercing discarding sabot (APDS) rounds or high-explosive incendiary tracer (HEI-T) rounds. Each round costs approximately $30, and the system typically fires 100 or more rounds when engaging a target. The ammunition handling system includes two conveyor belts, one feeding rounds to the gun and the other returning empty shells to the magazine.
The engagement process begins with the search radar detecting potential targets and passing data to the system’s computer. Once a target is identified as a threat, the mount turns to face it and hands tracking over to the precision radar. The system then fires automatically or recommends firing to the operator, walking rounds onto the target until it is destroyed.
Limitations and Challenges
Despite its effectiveness, the Phalanx has limitations that must be acknowledged. Its short effective range means that it can only engage threats that have already penetrated other defensive layers. Additionally, the system does not incorporate identification friend or foe (IFF), relying solely on real-time radar data to determine whether to engage.
Another challenge is the increasing speed and maneuverability of modern anti-ship missiles. While the Phalanx has been upgraded to counter many of these threats, the margin for error remains small. This reality underscores the importance of integrating the system with other defensive measures to create a comprehensive shield.
Centurion C-RAM
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| Centurion C-RAM. Photo: U.S. Army |
Ammunition Adaptation
One of the most important modifications for the land-based Centurion was the change in ammunition. Naval Phalanx systems typically use tungsten armor-piercing rounds, which are effective at sea but pose significant risks in populated areas. To address this, the Centurion employed 20 mm High-Explosive Incendiary Tracer, Self-Destruct (HEIT-SD) rounds.
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| Photo: U.S. Army |
These rounds were originally developed for the M163 Vulcan Air Defense System and were specifically chosen to minimize collateral damage. If a round failed to hit its target, it would self-destruct upon tracer burnout, preventing unexploded ordnance from falling into civilian areas. This adaptation made the Centurion far more suitable for urban environments like Baghdad, where civilian safety was a constant concern.
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| Photo: U.S. Army |
Comparison with Other Defense Systems
While the Centurion proved effective in Iraq, it was not universally adopted by all U.S. allies. Israel, for example, tested a single system but ultimately pursued its own Iron Dome defense system. The Iron Dome offered a broader engagement envelope and was optimized for intercepting rockets at longer ranges, making it more suitable for Israel’s unique security environment.
Nevertheless, the Centurion filled a critical gap for the U.S. Army during a period of intense insurgent activity. Its rapid development and deployment demonstrated the ability of the military-industrial complex to adapt naval technology for land warfare. The system’s success also highlighted the importance of layered defense strategies in modern conflicts.
Legacy and Continued Relevance
The Centurion’s legacy lies in its role as a bridge between traditional close-in defense systems and modern counter-rocket technologies. It provided immediate protection at a time when no other system was available to counter the persistent threat of indirect fire. Its effectiveness in Iraq validated the concept of adapting naval CIWS technology for terrestrial use.
Although newer systems and technologies have since emerged, the Centurion remains a symbol of rapid innovation under combat pressure. Its combination of mobility, precision, and reduced collateral damage set a precedent for future land-based defense systems. The lessons learned from its deployment continue to influence the development of counter-projectile solutions worldwide.
Future Developments
The Navy and Raytheon continue to explore improvements to the Phalanx system. In 2017, a new electric gun design was tested, replacing the pneumatic motor and reducing system weight by 180 pounds (82 kilograms). This innovation also allows the system to fire at variable rates, conserving ammunition while maintaining effectiveness.
Future upgrades are likely to focus on improving sensor performance, ammunition lethality, and system integration. As threats evolve, the Phalanx must continue to adapt to remain relevant. The Navy’s multi-year plan ensures that these developments can be implemented systematically and without disruption to fleet operations.
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