Patriot uses an advanced aerial interceptor missile and high performance radar systems. Patriot was developed at the Redstone Arsenal in Huntsville, Alabama, which had previously developed the Safeguard ABM system and its component Spartan and Sprint missiles.
The name "Patriot" is an acronym of Phased Array Tracking Radar to Intercept Of Target. A more fanciful acronym was Protection Against Threats, Real, Imagined, Or Theorized. The symbol for Patriot is a drawing of a Revolutionary War-era Minuteman.
Patriot systems have been sold to the Republic of China (Taiwan), Egypt, Germany, Greece, Israel, Japan, Kuwait, the Netherlands, Saudi Arabia, and Spain. The Republic of Korea is also in the process of purchasing several second-hand Patriot systems after North Korea test-launched several ballistic missiles to the Sea of Japan and went ahead with underground nuclear testing in 2006. In August of 2008, the United States and Poland signed an agreement to temporarily station a US Patriot battalion to help deter attacks from rogue states and to guard the US missile defense complex in Poland.
The Patriot system is modular and highly mobile. A battery sized element can emplace in less than one hour. All components consisting of fire control section (radar set, engagement control section, antenna mast group, electric power plant) and launchers are truck or trailer mounted. The radar set and launchers (with missiles) are mounted on an M860 Semi-Trailer which is towed by an M983 HEMTT. Missile reload is done using an M985E1 truck with a crane on the back. This crane is bigger than the standard crane found on most HEMTTs. Called a "Guided Missile Transporter" or GMT, this crane removes spent "cans" (empty missile canisters) off of the launcher. It then replaces them with fresh missiles. Because the crane nearly doubles the height of the HEMMT when not stowed, crews informally refer to it as the "scorpion tail". A standard M983 with a regular sized crane is referred to as the LRPT (Large Repair Parts Transporter).
The heart of the Patriot battery is the fire control section and associated launchers, consisting of the AN/MPQ-53 or -65 Radar Set, the AN/MSQ-104 Engagement Control Station (usually referred to as the "ECS" or more commonly as "the van"), the OE-349 Antenna Mast Group, and the EPP-III Electric Power Plant. The system's missiles are transported on and fired from the M901 Launching Station, which can carry up to four PAC-2 missiles or up to sixteen PAC-3 missiles. A Patriot battalion is also equipped with the Information Coordination Central, or ICC, a modified ECS which is designed to coordinate the fires of a battalion and uplink Patriot on to the JTIDS network.
The AN/MPQ-53 Radar Set equips PAC-2 and older units, and the AN/MPQ-65 Radar Set equips PAC-3 units. The main difference between these two radars is the addition of a second traveling wave tube (TWT), which gives the -65 radar increased search, detection, and tracking capability. The radar's antenna array consists of over 5,000 elements which "flash" the radar's beam many times per second. Additionally, the radar's antenna array contains an IFF interrogator subsystem, a track-via-missile array, and at least one "sidelobe canceller" (SLC), a small array designed to decrease interference that might affect the radar. Patriot's radar is somewhat unique in that it is a "detection-to-kill" system, meaning that a single unit performs all search, identification, track, and engagement functions. This is in contrast to most SAM systems, where several different radars are necessary to perform all functions necessary to detect and engage targets.
The beam created by the Patriot's flat phased array radar is comparatively narrow and highly agile compared to a moving dish. This gives the radar an unmatched ability to detect small, fast targets like ballistic missiles, or low radar cross section targets such as stealth aircraft or cruise missiles. Additionally, the power and agility of Patriot's radar is highly resistant to countermeasures, including electronic countermeasures (ECM) radar jamming and radar warning receiver (RWR) equipment. Patriot is capable of quickly jumping between frequencies to resist jamming.
The Patriot Radar costs $38 million.
The AN/MSQ-104 Engagement Control Station (ECS) is the nerve center of the Patriot firing battery. The ECS consists of a shelter which is mounted on the bed of an M927 5-Ton Cargo Truck or on the bed of a Light Medium Tactical Vehicle (LMTV) Cargo Truck. The main sub-components of the ECS are the Weapons Control Computer (WCC), the Data Link Terminal (DLT), the UHF communications array, the Routing Logic Radio Interface Unit (RLRIU) and the two "manstations" that is the system's man-machine interface. The ECS is air conditioned, pressurized (to resist chemical/biological attack), and shielded against Electromagnetic pulse (EMP) or other such electromagnetic interference. The ECS also contains several SINCGARS radios to facilitate voice communications.
The WCC is the main computer within the Patriot system. It is a 24-bit parallel militarized computer with fixed and floating point capability. It is organized in a multiprocessor configuration which operates at a maximum clock rate of 6 megahertz. This computer runs the operator interface, calculates missile intercept algorithms, and provides limited fault diagnostics. Compared to modern personal computers it has somewhat limited processing power, although it has been upgraded several times during Patriot's service life.
The DLT (Data Link Terminal) is the system which connects the ECS to Patriot's Launching Stations. It uses either a SINCGARS radio or fiber optic cables to transmit encrypted data between the ECS and the launchers. Through the DLT, the system operators can remotely emplace, slew or stow launchers, perform diagnostics on launchers or missiles, and fire missiles.
The UHF communications array consists of three UHF radio "stacks" and their associated patching and encrypting equipment. These radios are connected to the antennas of the OE-349 Antenna Mast Group, which are used to create UHF "shots" between sister Patriot batteries and their associated ICC. This creates a secure, real-time data network (known as PADIL, Patriot Data Information Link) which allows for the ICC to centralize control of its subordinate firing batteries.
The Routing Logic Radio Interface Unit (RLRIU) functions as the primary router for all data coming into the ECS. The RLRIU gives a firing battery an address on the battalion data network, and sends/receives data from across the battalion. It also "translates" data coming from the WCC to the DLT, facilitating communication with the launchers.
Patriot's crew stations are referred to as Manstation 1 and 3 (MS1 and MS3). These are the stations where Patriot operators interface with the system. The manstations consist of a monochrome (green and black) screen surrounded by various Switch Indicators. Each Manstation also has a traditional QWERTY keyboard and "isometric stick", a tiny joystick that functions much like the mouse of a PC. It is through these switch indicators and the Patriot user interface software (organized into dozens of separate pages known as "tabs") that the system is operated.
The ECS costs in excess of $5 million.
The OE-349 Antenna Mast Group (AMG) is mounted on an M927 5-Ton Cargo Truck. It includes four 4 kW antennas in two pairs on remotely controlled masts. The antennas can be controlled in azimuth, and the masts can be elevated up to 100 feet 11 inches above ground level. Mounted at the base of each pair of antennas are two high-power amplifiers associated with the antennas and the radios in the collocated shelter. It is through these antennas that the ECS and ICC send their respective UHF "shots" in order to create the PADIL network.
Integral leveling equipment permits emplacement on slopes of up to 10 degrees. Each launcher is trainable in azimuth and elevates to a fixed, elevated, launch position. Precise aiming of the launcher before launch is not necessary, thus no extra lags are introduced into system reaction time. Each Launcher is also capable of providing detailed diagnostics to the ECS via the data link.
The LS contains four major equipment subsystems: The launcher generator set, the launcher electronics module (LEM), the launcher mechanics assembly (LMA), and the launcher interconnection group (LIG). The generator set consists of a 15 kW, 400 Hz generator which powers the launcher. The LEM is used for the real-time implementation of launcher operations requested via data link from the ECS. The LMA physically erects and rotates the launcher's platform and its missiles. The LIG connects the missiles themselves to the launcher via the LMRD, or Launcher Missile Round Distributor.
The first fielded variant was the round MIM-104A, "Standard". It was optimized solely for engagements against aircraft and had very limited capability against ballistic missiles. It had a range of 70 km (44 miles), and a speed in excess of Mach 3. The MIM-104B "ASOJ" or "anti standoff jammer" is a missile designed to seek out and destroy ECM emitters. The MIM-104C PAC-2 missile was the first Patriot missile which was optimized for ballistic missile engagements. The GEM series of missiles (MIM-104D/E) are further refinements of the PAC-2 missile. The PAC-3 missile is a totally new interceptor, featuring a Ka band active radar seeker, employing 'hit-to-kill' interception (in contrast to previous interceptors' method of exploding in the vicinity of the target, destroying it with shrapnel), and several other enhancements which dramatically increase its lethality against ballistic missiles. It has a substantially lower range of 15 km. The specific information for these different kinds of missiles are discussed in the "Upgrades" section.
The first seven of these are in the larger PAC-2 configuration of a single missile per can, four of which can be placed on a launcher. PAC-3 missile canisters contain four missiles, and as such sixteen rounds in total can be placed on a launcher. All Patriot missiles consist of a missile (or missiles) mounted within a canister that looks like a long box that is both the shipping and storage container and the launch tube. Patriot missiles are referred to as "certified rounds" as they leave the factory, and no additional maintenance is necessary on the missile prior to its being fired.
The PAC-2 missile is 5.8 meters long, weighs about 900 kg and is propelled by a solid-fueled rocket motor at speeds in excess of Mach 5.0.
The radome is made of slip cast fused silica approximately 16.5 millimeters (0.64 inch) thick, with nickel alloy tip, and a composite base attachment ring bonded to the slip cast fused silica and protected by a molded silicone rubber ring. The radome provides an aerodynamic shape for the missile and microwave window and thermal protection for the RF seeker and electronic components.
The Patriot guidance section consists primarily of the modular digital airborne guidance system (MDAGS). The MDAGS consists of a modular midcourse package which performs all of the required guidance functions from launch through midcourse and a terminal guidance section. The track-via-missile seeker is mounted on the guidance section, extending into the radome. The seeker consists of an antenna mounted on an inertial platform, antenna control electronics, a receiver, and a transmitter. The Modular Midcourse Package (MMP), which is located in the forward portion of the warhead section, consists of the navigational electronics and a missile borne computer which computes the guidance and autopilot algorithms and provides steering commands according to a resident computer program.
The warhead section, just aft of the guidance section, contains the proximity fused warhead, safety-and-arming device, fuzing circuits and antennas, link antenna switching circuits, auxiliary electronics, inertial sensor assembly, and signal data converter.
The propulsion section consists of the rocket motor, external heat shield, and two external conduits. The rocket motor includes the case, nozzle assembly, propellant, liner and insulation, pyrogen igniter, and propulsion arming and firing unit. The casing of the motor is an integral structural element of the missile airframe. It contains a conventional, casebonded solid rocket propellant.
The Control Actuator Section (CAS) is at the aft end of the missile. It receives commands from the missile autopilot and positions the fins. The missile fins steer and stabilize the missile in flight. A fin servo system positions the fins. The fin servo system consists of hydraulic actuators and valves and an electrohydraulic power supply. The electrohydraulic power consists of battery, motor pump, oil reservoir, gas pressure bottle, and accumulator.
Patriot was first introduced with a single missile type: the MIM-104A. This was the initial "Standard" missile (still known as "Standard" today). In these early days the system was used exclusively as an anti-aircraft weapon, and this initial variant had no capability against ballistic missiles. This was remedied in the late 1980s, when Patriot received its first major system overhaul with the introduction of the Patriot Advanced Capability missile and concurrent system upgrades.
Through the 1980s, Patriot saw a number of smaller upgrades, mostly to its software. Most significant of these was a special upgrade to discriminate and intercept artillery rockets in the vein of the Multiple Launch Rocket System, which was seen as a significant threat to South Korea. This feature has not been used in combat and has since been deleted from United States Army Patriot systems, though it remains in South Korean systems. Another upgrade the system saw was the introduction of another missile type, designated MIM-104B and called "ASOJ" or "anti stand-off jammer" by the Army. This variant is designed to help Patriot engage and destroy ECM aircraft at standoff ranges. It works similar to an anti-radiation missile in that it flies a highly lofted trajectory and then locates, homes in on, and destroys the most significant emitter in an area designated by the operator.
For the system, the PAC-2 upgrade was similar to the PAC-1 upgrade. Radar search algorithms were further optimized, and the beam protocol while in "TBM search" was further modified. PAC-2 also saw Patriot's first major missile upgrade, with the introduction of the MIM-104C, or PAC-2 missile. This missile was optimized for ballistic missile engagements. Major changes to the PAC-2 missile were the size of the projectiles in its blast-fragmentation warhead (changed from around 2 grams to around 45 grams), and the timing of the pulse-doppler fuse, which was optimized for high-speed engagements (though it retained its old algorithm for aircraft engagements if necessary). Engagement procedures were also optimized, changing the method of fire the system used to engage ballistic missiles. Instead of firing two missiles in an almost simultaneous salvo, a brief delay (between 3 and 4 second) was added in order to allow the second missile fired to discriminate a ballistic missile warhead in the aftermath of the explosion of the first.
PAC-2 was first tested in 1987 and reached Army units in 1990, just in time for deployment to the Middle East for the Persian Gulf War. Although no evidence of actual hits was ever recorded, it was here that Patriot started to be regarded as a successful ABM system and a proof that ballistic missile defense was indeed possible. The complete study on its effectiveness remains classified.
There have been many more upgrades to PAC-2 systems throughout the 1990s and into the 21st century, again mostly centering on software. However, the PAC-2 missiles have been modified significantly, into four separate variants known collectively as "GEM" or "guidance enhanced" missiles.
The chief upgrade to the original GEM missile was a new, much faster proximity fused warhead. Tests had indicated that the fuse on the original PAC-2 missiles were detonating their warheads too late when engaging ballistic missiles with an extremely steep ingress, and as such it was necessary to shorten this fuse delay. The GEM missile was also given a new "low noise" seeker head designed to reduce interference in front of the missiles radar seeker, and a higher performance seeker designed to better detect low radar cross section targets, such as stealth aircraft. The GEM was used extensively in Operation Iraqi Freedom, with a perfect success rate.
Just prior to OIF, it was decided to further upgrade the GEM and PAC-2 missiles. This upgrade program produced missiles known as the GEM/T and the GEM/C, the "T" designator referring to "TBM", and the "C" designator referring to cruise missiles. These missiles were both given a totally new nose section, which was designed specifically to be more effective against low altitude, low RCS targets like cruise missiles. Additionally, the GEM/T was given a new fuse which was further optimized against ballistic missiles. The GEM/C is the upgraded version of the GEM, and the GEM/T is the upgraded version of the PAC-2. The GEM+ entered service in 2002, and the Army is currently having all of its PAC-2 and GEM missiles upgraded to the GEM/C or GEM/T standard.
The PAC-3 upgrade is the most significant upgrade Patriot has received thus far, and is one of the most comprehensive upgrade programs ever undertaken on an American weapon system. Nearly every aspect of the system received a significant upgrade. The PAC-3 upgrade took place in three stages, and units were designated Configuration 1, 2, or 3 based on the stage of upgrade they were in.
The system itself saw another upgrade of its WCC and its software, and the communication setup was given a complete overhaul. Thanks to this upgrade, PAC-3 operators can now see tracks on the Joint Tactical Information Distribution System (JTIDS), which greatly increases the situational awareness of Patriot crews. The software can now conduct a "tailored TBM search", optimizing radar resources for search in a particular sector known to have ballistic missile activity, and can also support a "keepout altitude" to ensure ballistic missiles with chemical warheads or ERS ("early release submunitions") are destroyed at a certain altitude. For Configuration 3 units, the Patriot Radar was completely redesigned, adding an additional TWT (traveling wave tube) which increased the radar's search, detection, tracking, and discrimination abilities to previously unheard of levels. In fact, the PAC-3 radar is capable, among other things, of discriminating whether or not an aircraft is manned and which of multiple reentering ballistic objects are carrying ordnance.
The PAC-3 upgrade carried with it a new missile design, nominally known as MIM-104F and called PAC-3 by the Army. The PAC-3 missile dedicated almost entirely to the anti-ballistic missile mission. Miniaturization has made the PAC-3 missile much smaller than the previous Patriot missiles; a single "can" (canister)now holds four missiles where one was once held. The PAC-3 missile is also much more maneuverable than previous variants, thanks to dozens of tiny rocket motors mounted in the forebody of the missile (called ACMs, or Attitude Control Motors). However, the most significant upgrade to the PAC-3 missile is the addition of a Ka band active radar seeker. This allows the missile to drop its uplink to the system and acquire its target itself in the terminal phase of its intercept, which improves the reaction time of the missile against a fast-moving ballistic missile target; the PAC-3 missile is, in fact, accurate enough to select, target, and home in on the warhead portion of an inbound ballistic missile. The active radar also gives the warhead a "hit-to-kill" capability that completely removes the need for a traditional proximity-fused warhead. This greatly increases the lethality against ballistic missiles of all types.
All told, the PAC-3 upgrade has effectively quintupled the "footprint" that a Patriot unit can defend against ballistic missiles of all types, and has considerably increased the system's lethality and effectiveness against ballistic missiles. It has also increased the scope of ballistic missiles that Patriot can engage, which now includes several intermediate range. However, despite its increases in ballistic missile defence capabilities, the PAC-3 missile is a less capable interceptor of atmospheric aircraft and air-to-surface missiles. It is slower, has a shorter range, and has a smaller explosive warhead compared to older Patriot missiles (although it generally relies on its kinetic "hit to kill" warhead).
Patriot's PAC-3 interceptor will be the primary interceptor for the new MEADS system, which is scheduled to enter service alongside Patriot in 2012.
Lockheed Martin Missiles and Fire Control, Dallas, Texas, is the prime contractor on the PAC-3 Missile Segment upgrade to the Patriot air defense system. The PAC-3 Missile Segment upgrade consists of the PAC-3 Missile, a highly agile hit-to-kill interceptor, the PAC-3 Missile canisters (in four packs), a fire solution computer and an Enhanced Launcher Electronics System (ELES). These elements are integrated into the Patriot system, a high to medium altitude, long-range air defense missile system providing air defense of ground combat forces and high-value assets.
The PAC-3 missile is currently undergoing testing for a significant new upgrade, currently referred to as "MSE" or "Missile Segment Enhancement". The upgrade includes a new fin design and a new, more powerful rocket engine. The modification is alleged to increase the operational capability of the current PAC-3 missile up to 50% and is scheduled to be added to all existing PAC-3 missile stores by 2008.
Further upgrades to the dual-TWT radar set, the JTIDS uplink, and the system's processors and memory are scheduled to take place in the next few years.
Once emplaced, the system requires a crew of only three individuals to operate. The Tactical Control Officer (TCO), usually a lieutenant, is responsible for the operation of the system. The TCO is assisted by the Tactical Control Assistant (TCA). Communications are handled by the third crewmember, the communications system specialist. A 'Hot-crew' composed of an NCOIC (usually a Sergeant) and 1 or more additional launcher crew members is on-hand to repair/refuel launching stations, and a reload crew is on standby to replace spent canisters after missiles are fired. The ICC crew is similar to the ECS crew at the battery level, except its operators are designated as the Tactical Director (TD) and the Tactical Director Assistant (TDA).
Patriot battalions prefer to operate in a centralized fashion, with the ICC controlling the fires of all of its subordinate firing batteries through the secure UHF PADIL communications network.
The US Army operates several Patriot battalions:
Following is the process a PAC-3 firing battery uses to engage a single tactical ballistic missile with two PAC-3 missiles:
Prior to the Persian Gulf War, ballistic missile defense was an unproven concept in war. During Operation Desert Storm, in addition to its anti-aircraft mission, Patriot was assigned to shoot down incoming Iraqi Scud or Al Hussein short range ballistic missiles launched at Israel and Saudi Arabia. The first combat use of Patriot occurred 18 January 1991 when it engaged what was later found to be a computer glitch. There were actually no Scuds fired at Saudi Arabia on 18 January This incident was widely misreported as the first successful interception of an enemy ballistic missile in history.
Throughout the war, Patriot missiles attempted engagement of over 40 hostile ballistic missiles. The success of these engagements, and in particular how many of them were real targets is still controversial. Post war video analysis of presumed interceptions suggests that no Scud was actually hit.
A government investigation revealed that the failed intercept at Dhahran had been caused by a software error in the system's clock. The Patriot missile battery at Dhahran had been in operation for 100 hours, by which time the system's internal clock had drifted by one third of a second. For a target moving as fast as an inbound TBM, this was equivalent to a position error of 600 meters.
The radar system had successfully detected the Scud and predicted where to look for it next, but because of the time error, looked in the wrong part of the sky and found no missile. With no missile, the initial detection was assumed to be a spurious track and the missile was removed from the system. No interception was attempted, and the missile impacted on a barracks killing 28 soldiers.
At the time, the Israelis had already identified the problem and informed the US Army and the PATRIOT Project Office (the software manufacturer) on February 11, 1991, but no upgrade was present at the time. As a stopgap measure, the Israelis recommended rebooting the system's computers regularly, however, Army officials did not understand how often they needed to do so. The manufacturer supplied updated software to the Army on February 26, the day after the Scud struck the Army barracks.
Preceding failures in the MIM-104 system were failures at Joint Defense Facility Nurrungar in Australia, which was charged with processing signals from satellite-based early launch detection systems.
On April 7, 1992 Theodore Postol of the Massachusetts Institute of Technology, and Reuven Pedatzur of Tel Aviv University testified before a House Committee stating that, according to their independent analyses, the Patriot system had a success rate of below 10%, and perhaps even a zero success rate. In response to this testimony and other evidence, the staff of the House Government Operations Subcommittee on Legislation and National Security reported, "The Patriot missile system was not the spectacular success in the Persian Gulf War that the American public was led to believe. There is little evidence to prove that the Patriot hit more than a few Scud missiles launched by Iraq during the Gulf War, and there are some doubts about even these engagements. The public and the United States Congress were misled by definitive statements of success issued by administration and Raytheon representatives during and after the war.
Also on April 7, 1992 Charles A. Zraket of the Kennedy School of Government, Harvard University and Peter D. Zimmerman of the Center for Strategic and International Studies testified about the calculation of success rates and accuracy in Israel and Saudi Arabia and discounted many of the statements and methodologies in Postol's report.
It is important to note the difference in terms when analyzing the performance of the system during the war.
According to Zimmerman, in accordance with the standard firing doctrine on average four Patriots were launched at each incoming Scud – in Saudi Arabia an average of three Patriots were fired. If every Scud were deflected or destroyed the success rate would be 100% but the Accuracy would only be 25% and 33% respectively.
Both testimonies state that part of the problems stem from its original design as an anti-aircraft system. PATRIOT was designed with proximity fused warheads, which are designed to explode immediately prior to hitting a target spraying shrapnel out in a fan in front of the missile, either destroying or disabling the target. These missiles were fired at the target's center of mass. With aircraft this was fine, but considering the much higher speeds of TBMs, as well as the location of the warhead (usually in the nose), PATRIOT would most often hit closer to the tail of the Scud due to the delay present in the proximity fused warhead, thus not destroying the TBM's warhead and allowing it to fall to earth.
The Iraqi redesign of the Scuds also played a role. Iraq had redesigned its Soviet-style Scuds to be faster and longer ranged, but the changes weakened the missile and it was more likely to break up upon re-entering the atmosphere. This presented a larger number of targets as it was unclear which piece contained the warhead.
What all these factors mean, according to Zimmerman, is that the calculation of "Kills" becomes more difficult. Is a kill the hitting of a warhead or the hitting of a missile? If the warhead falls into the desert because a PATRIOT hit its Scud, is it a success? What if it hits a populated suburb? What if all four of the engaging PATRIOT missiles hit, but the warhead falls anyway because the Scud broke up?
According to the Zraket testimony there was a lack of high quality photographic equipment necessary to record the interceptions of targets. Therefore, PATRIOT crews recorded each launch on videotape, and damage assessment teams recorded the Scud debris that was found on the ground. Crater analysis was then used to determine if the warhead was destroyed before the debris crashed or not. Furthermore, part of the reason for the 30% improvement in success rate in Saudi Arabia compared to Israel is that the PATRIOT merely had to push the incoming Scud missiles away from military targets in the desert or disable the Scud's warhead in order to avoid casualties, while in Israel the Scuds were aimed directly at cities and civilian populations. The Saudi Government also censored any reporting of Scud damage by the Saudi press. The Israeli Government did not institute the same type of censorship. Furthermore, PATRIOT's success rate in Israel was examined by the IDF (Israel Defense Forces) who did not have a political reason to play up PATRIOT's success rate. The IDF counted any Scud that exploded on the ground (regardless of whether or not it was diverted) as a failure for the Patriot. Meanwhile, the U.S. Army who had many reasons to support a high success rate for PATRIOT, examined the performance of PATRIOT in Saudi Arabia.
A Fifth Estate documentary, quotes the former Israeli Defense Minister as saying the Israeli government was so dissatisfied with the performance of the missile defense, that they were preparing their own military retaliation on Iraq regardless of US objections. That response was cancelled only with the cease fire with Iraq.
Israel was concerned over the use of biological or chemical agents in the Scuds. The Patriot gave the Israeli government a way to calm their people in the early days of the war.
Patriot batteries had at least eight independently confirmed TBM kills during the campaign, and Patriot batteries themselves reported successfully shooting down all eleven Iraqi TBMs that threatened coalition assets, including one TBM that would have struck the headquarters of the 101st Airborne Division and another that would have struck the Combined Land Forces Command Center, the highest echelon command location in Iraq at the time. This Scud missile was shot down by C Battery 2-1 ADA on 1 April 2003 at 0923hrs Local Time. Echo Battery, 2nd Battalion, 43rd Air Defense Artillery fired and successfully engaged with the first PAC-3 missiles in combat. Patriot also provided radar surveillance for coalition assets who lacked a clear picture over much of Iraq.
Patriot PAC-3, GEM, and GEM+ missiles both had a very high success rate intercepting Al Samoud-2 and Ababil-100 tactical ballistic missiles. However, no longer-range ballistic missiles were fired during that conflict.
Operation Iraqi Freedom marked the first use of Patriot to maneuver with and cover the forward combat elements in a large operation - previously, it had been thought that the system was too large to be quickly redeployed, and its use was restricted to defending primarily stationary assets - but during Operation Iraqi Freedom, several Patriot batteries successfully "leapfrogged" forward to protect the airspace above the units driving towards Baghdad in the first weeks of the war. Maneuvering of the Patriot batteries did, however, make establishing communications between Patriot units highly difficult, which contributed to at least one friendly fire incident, mentioned below.
B Battery, 6-52 ADA (Ansbach, Germany: First forward deployed patriot unit in history), which was assigned to the 31st ADA Brigade, was the first PATRIOT unit in Baghdad.
PATRIOT had two fratricides in Iraq, one against a British RAF Tornado GR4A, the other against an F/A-18 Hornet. The Tornado was engaged because the system mistakenly classified it as an anti-radiation missile (ARM). This was a result of mistakes on many different levels. First, the Tornado was inbound for landing at the time of the incident, which took it directly over the PATRIOT firing battery. Second, RAYTHEON PATRIOT planners had made the parameters by which the system classifies ARMs too wide, which allowed for a track appearing like the Tornado to be classified as an ARM by the system. Third, and probably most significantly, the Tornado did not have its IFF transponder on, which could have been an instant indication of the misclassification.
The other fratricide, on an F/A-18 Hornet, was a PATRIOT system error resulting from a misclassified TBM. The system engaged the Hornet automatically after the software, in conjunction with the PATRIOT radar, incorrectly classified the aircraft as a TBM. The PATRIOT system software classified the F/A-18 Hornet as a TBM, and its flight path showed it inbound to the Karbala Gap region. The aircraft was engaged by the PAC-III PATRIOT missile shortly after the launching stations were brought into operation. The aircraft that was flying with the F/A-18 Hornet was almost engaged by a rear PATRIOT unit as well, until the order was given to disregard.
A third Blue-on-blue incident occurred when a USAF F-16 Falcon incorrectly identified a PATRIOT battery as an SA-2 battery, after the battery's radar signature was detected by the F-16. At the time, the PATRIOT battery was protecting the 101st Airborne Division's Headquarters near the Forward Line of Troops (FLOT). The F-16 fired an AGM-88 HARM missile, which struck directly in front of the PATRIOT Radar Set, rendering it non-mission capable. The affected PATRIOT unit was forced to swap its radar set with another unit's in the immediate area; it must be noted that the replacement radar set had not fully undergone a testing period after receiving its PAC-3 upgrade/enhancements. The same battery was later responsible for the fratricide of the F/A-18 mentioned above.