Good Move

by Michael Puttré
May. 1, 2001

The Maginot Line in France prior to WWII seemed like a pretty good idea at the time. Its layered belts of fortifications and obstacles were an optimal mix to defeat a frontal assault by a modern force: mines, wire, and traps to fix enemy units; howitzers and machine guns to kill infantry; and rifled anti-tank guns to stop contemporary armor in its tracks. Hardened against aerial attack and artillery bombardment, the chain of interlocking positions with underground lines of communication, storage, and barracks facilities was the apex of the trench-warfare system. Too bad the Germans went around it.

Traditionally, air-defense networks have resembled a series of interlocking concentric circles: low-band volume search radars, mid-band target-acquisition radars, high-band fire-control systems; organized tree-like with local operation centers (LOC) reporting to sector operations centers (SOC), which in turn report to regional operations centers (ROC). This, like the Maginot Line, is the system-centric and site-centric approach to defense design. At its height the US HAWK and Nike Hercules, later Patriot, "belts" in Central Europe were the best example of this approach. "That defense design was developed when we faced a known enemy and a clearly defined border between friend and foe," said COL Peter W. Thomson, director of combat developments at the US Army Air and Missile Defense (AMD) School (Ft. Bliss, TX). "In a future non-contiguous battlefield we will not have the luxury of those fixed boundaries."

Certainly, the KARI integrated air-defense system of Iraq, designed and built by what was then Thomson-CSF of France, was one such hierarchical implementation that suffered from fixed boundaries. In the KARI system, Iraq was divided into four sectors, each controlled by a SOC that reported directly to the national air-defense operations center (ADOC) in Baghdad, which by extension controlled about 500 radars located at approximately 100 sites. Each SOC transmitted data back to intercept operations centers (IOC), which in turn controlled surface-to-air-missile (SAM) batteries and fighter aircraft at air bases. There were a number of IOCs across the four sectors in Iraq feeding data to individual SOCs. Each IOC was optimized to direct either SAMs or fighter aircraft against incoming enemy aircraft.

Each IOC was connected to observer and early-warning area-reporting posts. A 1997 US Government Accounting Office report evaluating the Desert Storm air campaign noted that despite the numerous components of KARI, its actual operating capabilities were quite limited. The system was designed to counter comparatively limited threats from Israel and Iran, with each SOC capable of tracking a maximum of 120 aircraft. While sufficient against an attack from either regional opponent, the system was inadequate to cope with a force of hundreds of aircraft and unmanned aerial decoys. Since part of the effectiveness of KARI depended on its ability to vector intercepting fighters to attacking aircraft, the threat was severely reduced with a substantial portion of the Iraqi air force destroyed, inactive, or fleeing to Iran early in the campaign.

The Need for SEAD

The allied air campaign over Iraq popularized suppression of enemy air defenses (SEAD) in the lexicon of military planers and analysts. The need to fight the enemy's air defenses in a dedicated and methodical way arose during the Viet Nam War, where US airmen faced batteries of radar-directed SAMs linked to a countrywide command and control network. The "Wild Weasel" aircraft that undertook SEAD missions in Southeast Asia – F-100Fs, F-105F/Gs, and F-4Cs – in general were aircraft modified to carry electronics and weapons to attack SAM and radar sites. These progenitors led directly to the F-4G Wild Weasel, which was built specifically for the SEAD role. The success of these aging aircraft in the Gulf War did little to postpone their retirement, along with the EF-111 Raven planes with the broader mission of electronic-countermeasures (ECM) support.

That the US Air Force denuded itself of its dedicated SEAD and electronic-attack (EA) platforms has been the subject of prolonged and increasingly contentious debate. Another aspect of the debate might be whether the same sorts of dedicated SEAD/EA platforms are best suited to the task of defeating modern air defenses, imbued with new technologies and new thinking. Moreover, the vast majority of the world's air forces are never likely to consider dedicated aircraft for such specialist roles, due to limitations in resources, technology, or personnel. And yet they also may find themselves flying into the teeth of a new order of air defenses.

An icon of integrated air defense such as Iraq's KARI does not take the shellacking it did without others taking notice. Certainly, the Iraqis themselves have made efforts to update their air-defense communications in an effort to make the system more flexible in the face of an enemy that can strike indifferently from north, south, or the sea. Such flexibility may be seen in the performance of the Yugoslav air- defense system during the NATO air campaign of 1999. With much the same equipment, Yugoslav forces were able to fire an average of three times as many missiles at NATO aircrews than the Iraqis launched at Coalition aircraft during Desert Storm, albeit to little effect. One explanation of the discrepancy in launches versus hits is that NATO aircraft over Yugoslavia tended to fly too high for man-portable air-defense systems (MANPADS) to have an impact, as they did over Iraq.

A US Department of Defense report published last year entitled "Kosovo/Operation Allied Force: An After-Action Report" described the Yugoslav air defenses as extremely capable, but not state of the art: "Much more capable air defense systems are currently available for sale on the international arms market. The [DOD] needs to prepare for the possibility that, in the years ahead, the United States may face an adversary armed with state-of-the-art air defense systems."

Where the Yugoslavian forces excelled was in husbanding their radars and missiles to offer a determined threat throughout the 78-day air campaign. Various sources say the Yugoslav air-defense forces used camouflage, good timing, and prudence in operating their radars. In total, the whole system was more flexible and survivable. If they had not been dealing with the foremost practitioner of SEAD on the planet, the Yugoslav air-defense forces likely would have had the kills to match their skills.

"The longer you sit in one place and transmit, the more apt you are to swallow a missile," said Charles Pickar, manager of air and missile defense business development, Lockheed Martin (Syracuse, NY). This basic fact is a key motivator of the networking concept as applied to air defense. "I have a number of assets on the battlefield. As one shuts down, I can transfer in real time responsibilities for coverage to another asset, keeping the force protected as it moves. It's not just as an asset moves; it may, in fact be destroyed or go down for some reason. Such a transfer is something that would be, hopefully, almost automatic."

Defense in Motion

"The hierarchical approach to air and missile defense is changing," said the US Army's Thomson. "We are developing the capability to employ exactly the right mix of capabilities at the right place and time in the battlespace." With the objective Air and Missile Defense Planning and Control System (AMDPCS) as the backbone for battle management, command, control, computers, and intelligence (BMC4 I), US forces are developing the ability to connect any combination of sensors or missile-launch platforms and tailor the air- and missile-defense package to protect a specific force and defeat the full range of expected threats. Thomson said that with this approach, the BMC4I will move away from the layered approach of the past. While there will still be the theater authority that will be in overall control, within Army AMD the BMC4 I will work on where the threat is detected and will then select the best missile on the best launcher anywhere in the network to defeat that threat. Given that the threat meets theater-specific hostile criteria, the network will issue the fire command, rather than the traditional "theater to brigade to battalion to fire unit" command sequence.

The old hierarchical structure is also changing in the way that target information is distributed. In the past, targets were typically passed to the next higher echelon, correlated, and then sent up to the next echelon. Similarly, targets reported by a higher-echelon sensor were reported down, node by node. With secure data-broadcast technology, such as the Joint Tactical Information Distribution System (JTIDS), which is the communications component of Link-16, all elements on the net are supposed to receive target information at the same time. The JTIDS family of terminals (Class 2 and 2H for the Air Force, Navy and Marine Corps; and 2M for Army) are intended to permit rapid and secure exchange of essential command control and status information with all terminals in the tactical theater, regardless of service. The future concept is what the Army likes to call, "plug and fight," with reference to the plug-and-play concept of modern computer networks. As Thomson describes it, the old way of doing business was much like the old way of hooking up computer peripherals, via a serial or parallel port. It was often time consuming and complex and usually required a computer reboot.

The future concept is like the Universal Serial Bus concept. Plug in the new peripheral, it "shakes hands" with the computer that already has the appropriate software, and you are up and running in seconds.

"Today we move entire Patriot batteries to adjust our defenses," Thomson said. "This requires march order, movement, and emplacement – all time-consuming events that take all of that battery's capabilities out of the fight. In the future, we will move individual launchers and sensors to adjust the defense design." When a sensor moves, for example, it will "unplug" from the network. The network will automatically detect that change and adjust sectors for the remaining sensors to compensate. In areas where it cannot compensate, the network will alert the commander of increased risk. When the moving sensor returns and "plugs back in" to the network, the capability is restored at the new location and the capability of the network adjusted accordingly. The same would occur if a sensor or launcher was battle damaged or had a maintenance fault. Thus, the amount of combat power lost to movement or casualty effects is significantly reduced. In the long term, armies need the capability to "sense on the move," much as navies do with ships at sea.

The Next Wave

"The wave of the future as we see it what we're calling 'sensor-centric networking' or 'network-centric warfare,'" said Lockheed Martin's Pickar. "If you are networking sensors, you are giving them – almost by definition – built-in survivability, because you don't have any one critical node that can be knocked out [that will bring down the system]. You have sort of a broadcast of all sensor information and the appropriate headquarters of the appropriate agencies that are going to take action in an air-defense role are getting that information through various channels."

Technological advances have enabled a significant reduction in size of equipment, increased capability and precision, reduced logistics burden, and higher reliability. Technology has also taken us from the analog world to predominantly a digital world. The digital world provides the capability to make significant improvements in capability, and, to a lesser degree, through software-only changes. This technology extends beyond common computers to radar-signal processing and missile seekers. A software-only change gave Patriot its initial, although limited, capability to counter tactical ballistic missiles (TBM) during Desert Storm.

"A good example of how you update existing technology is in the TPS-59 program with the Marine Corps," said Paul Goulette, director of air and missile defense radar programs, Lockheed Martin. "It was the first solid-state, phased-array radar that was fielded. The radar was software-programmable, and in 1998 we completed the TBM upgrade of that radar when we changed the surveillance templates. Essentially, we changed the software in that radar and gave it a TBM capability. The TPS-59 was able to shoot down tactical ballistic missiles with the HAWK system. Also, we did some experiments with Patriot. So that's an example of a modern radar that is programmable that has been upgraded to provide an increased capability."

The next stage of development is represented by the radars for the Medium Extended Air Defense System (MEADS), a cooperative effort between Lockheed Martin (Orlando, FL), EADS (Munich, Germany), and Alenia Marconi Systems (Rome,Italy) to develop an air- and missile-defense system capable of countering tactical ballistic missiles and air-breathing threats, including cruise missiles, that is tactically mobile and transportable. It will be employed either in combination with other systems as part of an integrated air defense, or individually in stand-alone operations. "Our new system requirements define very sophisticated ECM threats," Goulette said, "and we've come up with radar-system architectures and overall air-defense architectures that can defeat those threats. One of the enabling technologies is digital beam forming. The MEADS radars are fully digital adaptive beam forming. From an electronic warfare perspective, that provides us tremendous capability for the radar to counter active ECM."

According to Goulette, all presently fielded radar systems form beams through analog beam formers, where return signals from each element are combined using analog combiners; some beams are formed with difference beams so the receiver can determine exactly where the target is within the beam. If you want to do advanced operations, like sidelobe cancellation, you would have cancel loops that would take the interference signals and mix them in with the primary ones and come up with adaptive null. It takes lots of hardware and very precise matching of components to pull this together. With digital beam-forming systems, depending on the architecture, what you are doing is taking the signals at every element of the antenna and going through a receiver right into an analog-to-digital converter. Now you have element-level digital data, and with today's processing you can form beams any which way you want.

"You can do very sophisticated adaptive processing where you can even put deep nulls in your main beams," Goulette said. "You can null-out main-beam jammers that are trying to screen targets. You can handle many, many jammers and provide very deep nulls on those types of ECM threats. Once you go to digital beam forming you can really do so much more with the radar."

The MEADS architecture has a multifunction radar for early-entry applications. It can perform the surveillance function, fire-control function, and also does the missile communications. "It would have reduced capability, because it doesn't have the long legs of a dedicated surveillance asset to give it a good cue, but the point is that if you are coming in for early entry you can defend a port or an airport while you're trying to bring in additional equipment," Goulette said.

This is possible because the radar is software programmable for many modes of operation. The different modes could be looking for air-breathing targets or tactical ballistic missiles. The radar may be operating in a rotating 360-degree surveillance mode in one situation and in a sectorized, longer-range mode in another if the goal is to get high-range resolution data on a target.

Crows or Ducks?

The tactical ballistic missile is the driving requirement on future air-defense systems for the US and its allies. This requirement results in radars that have very long-range detection capabilities. It requires that interceptors, such as the Patriot Advanced Capability PAC-3 and the Standard-3, be very fast, kinematically very agile, and very lethal. "Basically, it makes air-breathing threats sitting ducks," Goulette said.

If true, this will likely have some impact on how SEAD is performed in the future. A relative handful of dedicated SEAD aircraft with jammer pods and anti-radiation missiles will be less effective against an air-defense system that can create null zones around jamming sources while reconfiguring itself when individual assets are threatened or knocked out. In fact, these valuable aircraft themselves may fall victim to new-breed interceptor missiles. Moreover, improved air-defense communications make it possible to closely integrate more mobile short- and medium-range air-defense systems, such as the Stinger-firing Avenger, into the networks, making them even more effective. Mobile, short-range systems tied into the network can deal with "low-value" aerial threats, such as UAVs and decoys, while leaving high-value threats to the super-interceptors.

The more mobile the air-defense network becomes, the less success would-be attackers will have in suppressing it. Current SEAD platforms and tactics were developed to defeat site-centric air-defense systems. Operations of modern air-defense networks are acquiring the good sense not to stay put. It remains to be seen how SEAD will evolve to counter these moves.