Phalanx CIWS
The Raytheon Phalanx Close-In Weapon System, a radar-guided 20mm Gatling gun system used for ship self-defense, with demonstrated capability against UAS and small boat threats.
System Overview
What It Is
Phalanx CIWS (Close-In Weapon System) is the US Navy's last-ditch automated defense system, using a radar-guided 20mm Gatling gun to destroy incoming anti-ship missiles, aircraft, and increasingly UAS targets. The land-based C-RAM variant has been used for counter-rocket and counter-UAS defense at forward operating bases.
How It Works
Phalanx uses its own search and track radars to autonomously detect, evaluate, track, and engage incoming threats without requiring external input. The system's closed-loop fire control radar tracks both the incoming target and the outgoing stream of 20mm rounds, automatically adjusting aim to bring fire onto target. Against UAS, Phalanx can engage small drone targets in its close-in defense zone.
Primary Capability
Autonomous close-in defense against anti-ship missiles, UAS, and surface threats using radar-guided 20mm cannon.
Combat Record / Operational History
Extensively deployed worldwide on US and allied naval vessels. Land-based C-RAM variant deployed to Iraq and Afghanistan for base defense, engaging rockets, mortars, and UAS threats.
Overview
The Phalanx Close-In Weapon System (CIWS) is one of the most iconic and widely deployed weapon systems in the world, serving as the last line of automated defense on US Navy and allied warships for over four decades. While originally designed to defeat anti-ship cruise missiles, the system's radar-guided 20mm Gatling gun has proven effective against UAS targets, and its land-based C-RAM variant has been used for counter-drone defense at forward operating bases.
Development History
Phalanx was developed by General Dynamics (now Raytheon) in the 1970s and entered service with the US Navy in 1980. The system was the world's first autonomous close-in weapon system, designed to engage incoming missiles that penetrated all other defensive layers. Over its four-decade service life, Phalanx has been continuously upgraded, with the Block 1B variant adding electro-optical and infrared sensors for improved capability against surface targets, helicopters, and small UAS.
Operational Concept
Phalanx operates autonomously, using its own search radar to scan for threats and its tracking radar to engage them. When a threat enters the engagement zone, the system automatically evaluates it, tracks it, and opens fire with its M61A1 20mm Gatling gun at 4,500 rounds per minute. The fire control system tracks both the target and the bullet stream, making real-time adjustments to walk the rounds onto the target. Against UAS, Phalanx Block 1B uses its EO/IR sensor to complement radar tracking for improved engagement of small, slow-moving drone targets.
Future Development
Raytheon continues to upgrade Phalanx with improved processing, new engagement algorithms optimized for UAS targets, and enhanced sensor integration. The system is expected to remain in service for decades to come, complementing newer directed energy and missile-based defenses. The land-based C-RAM variant continues to evolve for the base defense and counter-UAS mission.
Technical Specifications
- Weapon: M61A1 20mm Gatling gun
- Rate of fire: 4,500 rounds/minute
- Tracking radar: Ku-band
- Search radar: digital
- Effective range: 1.5 km
- Fully autonomous engagement capable
Range
~5 km
~1.5 km
Compatible Platforms
Deployed By
Key Features
- Fully autonomous engagement capability
- Self-contained sensor and weapon
- Extremely high rate of fire
- Combat-proven over four decades
- Continuous upgrades (Block 1B with EO/IR)
Advantages
- Decades of combat-proven reliability
- Fully autonomous last-ditch defense
- Effective against multiple threat types
- Widely fielded with global logistics support
Limitations
- Short effective range
- Limited magazine capacity
- Falling debris hazard over populated areas
- 20mm round may be excessive for small drones