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Patriot Advanced Capability-3 (PAC-3)

Patriot Advanced Capability-3 (PAC-3) is a high/medium advanced surface-to-air guided missile air defense system. BMDO planned to select either (1) the Extended Range Interceptor (ERINT), which was designed to destroy missiles by colliding with them; or (2) the Patriot Multimode Interceptor, which incorporated a multimode seeker and an improved explosive warhead. BMDO planned to make its selection before the PAM program enters engineering and manufacturing development in early 1994.

In FY94 the Army selected ERINT to be the PAC-3 missile. This small, agile missile combined several state-of-the-art technologies to provide hit-to-kill lethality and increased fire power in an asset defense role against both TBMs and air breathing threats. PAC-3 is a major upgrade to the Patriot system. The PAC-3 Operational Requirements Document (ORD) represents the Army Air Defense need to buy back required battlespace lost against the current and evolving tactical missile and air breathing threat. PAC-3 is needed to ounter/defeat/destroy the 2008 threat and to extend Patriot's capabilities to accomplish new/revised missions. The PAC-3 missile has a lethality enhancer and uses hit-to-kill technology to destroy ballistic missile targets. In tandem with the upgraded radar and ground control station, PAC-3 interceptors can protect an area about seven times greater than the original Patriot system. Lockheed Martin Vought Systems and Raytheon are the prime contractors for the PAC-3.

The PAC-3 Program consists of two interrelated acquisition programs - The PAC-3 Growth Program and the PAC-3 Missile Program. The Growth program consists of integrated, complementary improvements that will be implemented by a series of phased, incrementally fielded material changes. The PAC-3 Missile program is a key component of the overall improvements of the Patriot system, it will provide essential increases in battlespace, accuracy, and kill potential.

PAC-3 is a much more capable derivative of the PAC-2/GEM system in terms of both coverage and lethality. The PAC-3 has a new interceptor missile with a different kill mechanism -- rather than having an exploding warhead, it is a hit-to-kill system. The PAC-3 missile is a smaller and highly efficient missile. The canister is approximately the same size as a PAC-2 canister but contains four missiles and tubes instead of a single round. Selected Patriot launching stations will be modified to accept PAC-3 canisters.

The PAC-3 Missile uses a solid propellant rocket motor, aerodynamic controls, attitude control motors (ACMs) and inertial guidance to navigate. The missile flies to an intercept point specified prior to launch by its ground-based fire solution computer, which is embedded in the engagement control station. Target trajectory data can be updated during missile flyout by means of a radio frequency uplink/downlink. Shortly before arrival at the intercept point, the PAC-3 Missile's on board Ka band seeker acquires the target, selects the optimal aim point and terminal guidance is initiated. The ACMs, which are small, short duration solid propellant rocket motors located in the missile forebody, fire explosively to refine the missile's course to assure body-to-body impact.

Initially the Army did not consider changing the PAC-3 range requirement to give it more of an overlap with THAAD's lower boundary of 40 kilometers. In 1999 Hans Mark, the Pentagon's director of defense research and engineering, suggested that BMDO should consider raising the THAAD intercept requirement from 40 kilometers to 60 or 80 kilometers to simplify the problem of guiding the missile and make operation of the seekers easier to manage.

The Battalion Tactical Operations Center (BTOC) is an M900 series 5-ton expandable van that has been modified by the addition of data processing and display equipment, and utilized by the battalion staff to command and control the Patriot battalion. The BTOC allows the staff to perform automated tactical planning, communications link planning, and to display situational awareness information.

In 1995 PAC-3 Configuration 1 added a new pulse Doppler processor that significantly improved radar performance. Engagement Control Station (ECS) and Information Coordination Central (ICC) upgrades improved weapons control, computer throughput, memory and reliability. ECS and ICC upgrades also added an optical disk and embedded data-recording equipment to decrease computer access times, improve reliability and provide a tactical data-recording capability.

In 1996 PAC-3 Configuration 2 improved the communications processor and added the Joint Tactical Information Distribution System to improve communications and interfaces with joint forces. Fielded Post Deployment build (PDB) 4 software improved multifunction radar performance, detected small radar cross section targets and improved system detection, identification and engagement of anti-radiation missiles and aircraft carrying those missiles. The PEO Missile Defense approved full-rate production for the PAC-3 Configuration 2 Communication Enhancement Phase I (CE-1) in October 1995. This contained the bulk of the hardware modifications for Configuration 2. The last major upgrade prior to the fielding of the full PAC-3 capability, Configuration 2 included improved radar performances, a self defense capability against anti-radiation missiles, and the ability to receive and process information from external intelligence sources.

In 2000 PAC-3 Configuration 3 Ground Equipment added dual travelling wave tube units and a new radio frequency exciter to the radar to further improve radar multifunction performance and detection of small targets in cluttered environments. A Classification, Discrimination, Identification Phase III program significantly improved radar range performance to discriminate and identify a tactical ballistic missile warhead from other target debris or objects. Post Deployment Build 5 software improved radar multifunction performance, determined tactical ballistic missile impact and launch points, and provided interfaces with the Terminal High Altitude Area Defense System. Remote launch improvements increased the location of launchers from the ECS from a distance of 10 kilometers to 30 kilometers. This dramatically increased Patriot's defended area.

The PAC-3 Missile has been selected as the primary interceptor for the multi-national MEADS program. Managed by the NATO MEADS Management Agency (NAMEADSMA), MEADS is a transatlantic development program focused on the next generation of air and missile defense. MEADS will focus on risk reduction, application of key technologies and validation of a system design incorporating the PAC-3 Missile as the prime interceptor.

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