New Era in Electronic Warfare

Sept. 1, 1981
Soviet air defenses keep on growing at a prolific rate; their density, numbers, complexity, and reliance on C3 (command control and communications) are mushrooming. Conversely, the importance of defense suppression to USAF’s tactical airpower keeps growing by leaps and bounds. This fall, the Air Force’s ability to suppress hostile air defenses—in the form of vastly improved tactical electronic warfare (EW) capabilities—will take a major step forward with the entry of the first EF-111A into the operational inventory. This unique EW system serves to negate Soviet and other hostile early warning, ground control intercept, and acquisition radars.

As Lt. Gen. Lawrence A. Skantze, Commander of the Air Force Systems Command’s Aeronautical Systems Division, put it at the rollout of the first production EF-111A at Grumman Aerospace Corp.’s Calverton, N. Y., plant on June 19: “The EF-111A is born of a great necessity—the need to modernize and improve our capabilities in electronic warfare.”

EW is as vital as bombs on targets and enemy aircraft killed, yet far less palpable and, thus, less understood and appreciated. Those who understand EW best refer to it as a force multiplier that maximizes the effectiveness of all combat elements by boosting aircraft survival and the ability to get through to the target area to carry out assigned tasks. In the last analysis, it is a cat and mouse game with an enemy who uses his missiles, antiaircraft artillery, and interceptors to decimate the other side’s tactical airpower.

As General Skantze put it: “Without the ability to neutralize an enemy’s radar system, we lose—we lose costly aircraft and their even more valuable crews. If we are not able to strike our targets, we lose the air battle. If we lose the air battle, we lose the war—it’s painfully simple.”

The relatively recent emphasis by the Soviets on fielding tactical and strategic air defense systems—surface-to-air missiles (SAMs), antiaircraft artillery (AAA), and airborne interceptors—that exhibit roughly the same degree of mobility as the tactical forces they accompany and protect necessitates that US defense suppression match this trait.

The active components of the Air Force’s defense suppression system already incorporate a high degree of mobility in the F-4G Wild Weasel as well as the Highspeed Antiradiation Missile (HARM) and the expendable tactical drone, or Locust, which are under development. The latter is equipped with a seeker-warhead payload and can be ground-launched in large numbers to fly to areas where enemy radars are thought to be operating. Once in the target area, the Locust drone will acquire, home on, and destroy target radars with a fragmentation warhead.

On the EW side of defense suppression, two new systems meet the criterion of mobility. One is the Compass Call system designed to counter the steadily improving Soviet command control and communications (C3) network. This system, a special EC-130H aircraft, disrupts selected portions of the Soviet force management system through standoff jamming, thus causing loss of control over Soviet tactical airpower. The other is the supersonic EF-111A. This new system results from the integration of two thoroughly battle-tested weapons: the F-111A, a veteran of the Vietnam War, supersonic, maneuverable, and one of the most capable fighter bombers in the Air Force; and the ALQ-99 jamming system of the equally combat-proven Grumman EA-6B Prowler.

There is, General Skantze said at the recent rollout ceremony, “no known equivalent to the EF-111A Tactical Jamming System in terms of electronic warfare sophistication and sheer radiated power. The high-performance EF-111A airframe, coupled with the smartest and most powerful jamming system, makes it the most versatile electronic warfare weapon system anywhere.”

What’s more, he added, the EF-111A includes a considerable growth potential to meet increasing threats “well into the next century.”

One of the early and costly lessons of the Southeast Asian war was that Soviet-built long-range radars detected USAF aircraft almost from the moment of “gear up” and that the obsolete EB-57s and EB-66s were incapable of effectively jamming their radars. The situation in Europe is worse, with the thick curtain of air defense and surveillance radars getting more lethal every year. There the defensive thicket of SAMs keeps growing, with the Soviets adding one new model about every two years.

What’s more, the steady addition of new systems—the latest being the SA-12—has not caused the Warsaw Pact forces to retire any of the older ones—except the antiquated SA-1—from active service. The result is a profusion of thousands of ground-to-air weapons providing overlapping coverage in terms of altitude and range, leaving no flight profile safe from attack. These SAM belts operate in concert with a multitude of redundant radars, including early warning ground-controlled intercept and height-finder systems that can pick up and track NATO aircraft on takeoff, SAM control radars that guide Soviet SAMs against these aircraft, and radars that accurately aim AAA against them.

These radars, in turn, feed control centers that decide when and which targets are to be engaged by interceptors, SAMs, and AAA, thus maximizing the effectiveness of this defense system. Capping this lethal curtain is a fleet of Soviet and Warsaw Pact fighters that is being modernized at a rapid rate. Additionally, in the not too distant future, a Soviet version of USAF’s AWACS, the SU-AWACS, can be expected to augment the radar network along the Warsaw Pact’s western perimeter.

As early as 1971, the Air Force recognized the need for a dedicated airborne tactical jamming system, the primary reason being that strike aircraft no longer can carry enough electronic countermeasures—or the required electrical power—to jam the growing number of sophisticated hostile radars. A range of options was considered by the Air Force, including an “Improved Tactical Electronic Warfare System” (which turned out to be too costly) as well as use of the US Navy’s EA-6B Electronic Warfare aircraft (which on closer examination was found wanting in speed and range for he Air Force mission).

The solution meeting the cost and operational requirements best and with the least risk turned out to be the grafting of the EA-6B’s ALQ-99 jamming system on existing F-111A airframes. Following competitive design studies, Grumman Aerospace Corp. was selected late in 1974 by the Air Force as the prime contractor of the EF-111A program, involving, initially, full-scale development of two preproduction systems. During 1977 and 1978 the preproduction aircraft underwent exhaustive initial Operational Test and Evaluation at Eglin AFB, Fla., and Mountain Home AFB, Idaho, that established their ability to cope with all mission requirements, included were tests against the E-3A AWACS, the outcome of which was not disclosed for reasons of security beyond the bland assertion that the EF-111A “did well.”

In March 1979, the Defense Systems Acquisition Review Council (DSARC) ordered the EF-111A into full production, concurrent with completion of the Operational Test and Evaluation program. The production program provides for the conversion of forty-two aircraft to the EF-111A configuration at a cost—exclusive of the airframes—of about $1. 2 billion, or about $21 million per aircraft. While these forty-two aircraft are coming out of the Tactical Air Command’s active inventory, the boost in overall tactical air capability produced by the EF-111A is expected to more than offset this reduction.

By the same token, the economic benefit of using airframes that are already paid for is major, especially in light of the relatively low total of flying hours piled up by the F-111As involved. These aircraft, the Air Force believes, are good for at least 10,000 hours of flying time, yet to date have averaged only about 2,000 hours. At presently envisaged usage rates, the EF-111As should thus have a lifespan of twenty to thirty years.

The EF-111A is to achieve IOC (initial operational capability) in November 1983 and full operational capability, with delivery of the forty-second production aircraft, late in 1985. For the time being, there is no indication that the US government plans to make the aircraft available for foreign military sales.

The EF-111A’s Intrinsic Pluses

The Air Force chose the F-111A as the air vehicle of the tactical jamming system for a number of reasons. Paramount were the aircraft’s availability from the inventory on a “sunk-cost” basis and the fact that it offers fighter performance combined with great endurance on station. The latter two traits make the EF-111A compatible with all airborne elements of the strike force in terms of structural strength, maneuverability, and performance—including the ability to penetrate enemy airspace and escape at supersonic speed.

Equally crucial is the EF-111A’s ability to loiter for up to four and three quarter hours without refueling—in part a result of its variable sweepwing design. Because of its great endurance and a mission radius of up to 1,000 miles, the EF-111A can provide jamming protection for many strike aircraft sorties on a single mission. The aircraft’s operating range extends from speeds in excess of Mach 2.1 at altitudes up to 50,000 feet to the low supersonic regime on the deck. Even though the EF-111A accommodates three tons of sophisticated electronic equipment, including antennas, computers, and display devices, the aircraft retains high maneuverability—including a seven “G” plus turning capability—to assure a high degree of survivability in hostile environments.

Exterior modifications include a narrow, canoe-shaped radome, sixteen feet in length, on the underside of the fuselage, that houses the antennas for the high-powered jamming transmitters; and a pod mounted on the vertical stabilizer for the receiving antennas and ancillary equipment, including a processor to detect hostile radar emissions.

Other significant modifications to the F-111A airframe include the incorporation of a higher capacity air-conditioning system and the addition of a liquid cooling system to handle the heat load of the jamming equipment, the installation of ninety-kw generators (vs. sixty) to provide the jammer electrical power, and numerous areas of structural modification. Also included is the installation of all new electrical wiring, some 25,000 cables, and more than 100 antennas of various types.

The Tactical Jamming System is comprised of three major subsystems. The ALQ-99 jamming subsystem consists of sensitive receivers that detect threat radars at long range, and computers, displays, and controls that locate and identify threat signals and automatically assign exciters and jamming transmitters, which provide optimum modulations amplified to high power levels to destroy the threat radar’s detection capability. The Terminal Threat Warning Subsystem, common to the entire F-111 force, detects emissions of selected, weapon-associated threat radars, processes the data, and provides immediate warning information to the crew of impending attack by SAMs, AAA, or interceptors. The active-protection system automatically provides specialized jamming signals to degrade the accuracy of SAM, AAA, and interceptor target tracking systems.

Improvements of the ALQ-99 multipurpose electronic countermeasure system that tailor it to USAF requirements lead to more rapid detection and identification of enemy transmissions; greater automation and less reliance on human involvement and manual operations; expanded computer functions to provide more sophisticated and flexible jamming options; and more independent jamming signals over a wider range of frequencies. The Airborne Instruments Laboratory ALQ99E jammer is a fourth-generation system that appears capable of defeating the vast majority of known Soviet radars.

In selecting the ALQ-99, the Air Force capitalized on some $250 million the US Navy had already invested in this system and, because of its technically mature status, sharply reduced developmental risks. The ‘”E” version of the ALQ-99 shares some seventy percent of all parts with the original design used on the EA-6A and EA-6B aircraft.

The reason the Air Force opted for a new system rather than adapt the Navy’s EA-6B is that the latter aircraft was not designed for the high-density ground environment prevalent in Europe and also lacks both the endurance and flexible performance of the F-111A. Further, by designing a high degree of automaticity into the EF-111A, the Air Force aircraft’s crew was reduced to two—a pilot and an electronic warfare officer.

The ALQ-99E ECM unit can be “grown” significantly in terms of capacity to meet changes in the threat. Information about new threats, not in the memory of the IBM 4 Pi computer, can be fed into the system either through entries on the electronic warfare officer’s keyboard in the cockpit or by changing the computer software. Updating the latter takes only about five minutes. The EW officer can test the information and, if necessary, override it by entering proper commands with the keyboard and display unit in the cockpit.

Preflight insertion into the computer memory of topical intelligence information enables the EW officer to concentrate en unpredicted threats during the flight. Compared to the tactical jamming system of the EA-6B, the EF-111A’s system offers greater speed and capacity in locating and identifying uncharted hostile radars and in defeating them. The growth margin in the tactical jamming system’s computer is half again the presently used level.

A Variety of Jamming Modes

Exhaustive, USAF-supervised testing established clearly that the EF-111A is capable of meeting the gamut of combat requirements for radar jamming. The new system radiates many hundred kilowatts of radio frequency power in a directional, half-omni, or full-omni mode, and in a way that adapts to prevailing, specific radar threats with the help of on-board computers. Additionally, the system could be modified, if necessary, through the use of higher gain antennas to increase its effectiveness against such “targets” as Soviet AWACS aircraft, but in the process probably would have to skink its jamming beam width to a degree that might reduce its effectiveness against other essential targets beyond the optimal level. The EF-111A’s jamming capability, at this time, appears sufficiently powerful and flexible to cope with electronically agile radar, or EAR, if the Soviets ever deploy such a system.

Barrier/standoff jamming is one of the three missions of the EF-111A Tactical Jamming System. The aircraft performs this task while operating on the friendly side of the FEBA (forward edge of the battle area), out of range of the adversary’s ground-based weapons. Several orbiting EF-111As would use their vast jamming power to create an electronic barrier to mask the movement of friendly strike aircraft from hostile radar detectors. By denying the adversary the ability to monitor NATO airspace, the friendly forces can refuel, join up, and begin their strikes—all undetected by the searching eyes of the enemy radar nets.

In the penetration/escort mission, the EF-111A can accompany tactical strike aircraft to targets deep behind enemy lines to augment the force’s own ECM, EW drones, and other countermeasure techniques. Because of the EF-111A’s high performance and great endurance, it can keep up with or stay ahead of the strike force during penetration to hold up an electronic shield that causes confusion, delays, and loss of effectiveness for the enemy’s air defense system.

In the close air support role, the EF-111A will operate along the FEBA to suppress the enemy’s antiaircraft artillery and surface-to-air missile (SAM) systems while the strike force delivers its weapons and recovers.

While the Air Force, as yet, has not assigned any reconnaissance tasks to the “Electronic Fox,” the system is intrinsically capable of feeding radar threat information into a common network. This will be doubly true when the EF-111A is retrofitted with a JTIDS (Joint Tactical Information Distribution System) terminal. Eventually the EF-111A will probably be linked with USAF’s E-3A AWACS by JTIDS. The Electronic Fox not only can be controlled by and feed information to the E-3A, but is also well suited for protecting the AWACS from hostile interceptors by shielding it through barrier jamming, thus providing the large aircraft with a high degree of electronic “invisibility.”

The EF-111As will be operated by the Tactical Air Command’s 388th Electronic Combat Squadron at Mountain Home AFB, Idaho.

There is a possibility that heavily modified F-111Es—incorporating a high degree of commonality with some EF-111A technology—might serve as PAVE MOVER aircraft several years from now. PAVE MOVER, scheduled for DSARC II (full program go-ahead) sometime next year. The system combines advanced technologies in the areas of side-looking moving target indicator radars, digital signal and data processing, and weapons guidance capabilities, and integrates these technologies for real-time target acquisition and strike capabilities.

PAVE MOVER, a pivotal element of Assault Breaker (a combination of programs meant to cope with the vast number of armored ground targets associated with the Warsaw Pact in the second echelon), is being developed by AFSC’s Electronic Systems Division and the Rome Air Development Center to provide real-time standoff surveillance and cooperative strike capabilities for both Air Force and Army weapon systems.

Grumman, as well as Hughes Aircraft, is involved in this evaluation program, which involves the launching of GBU-8 (HOBO) glide bombs and T-16 and T-22 guided missiles against a variety of moving and stationary targets. The current program phase is an advanced technology effort slated for completion in July 1982. The Air Force, as yet, has made no firm decisions on which aircraft will serve as the PAVE MOVER platform.