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Last Updated: Mon Jan 27 11:18:09 UTC 2014

Support Jamming and Force Structures
Journal of Electronic Defense, May 2002
by Dr Carlo Kopp

In December 2001 the DoD released the Joint Airborne Electronic Attack Analysis of Alternatives (AEA AoA) document, which distills the findings of a team comprisising more than 180 specialists across the armed services, DoD and industry.

The unclassified summary document (refer JED March '02 p26) underscores the difficulty in reconciling the EA role against a complex multiservice force structure. In this month's feature JED will explore some of the deeper strategic and technological challenges the US faces in providing the vital EA capability.

EA, Platforms and Paradigms

Until the 1998 retirement of the USAF's EF-111A Raven fleet, support jamming was a specialised capability in the land based USAF and CV based Navy/USMC force structure. While the core Tactical Jamming System (TJS), the Eaton/AIL AN/ALQ-99 was substantially common, its mode of deployment into combat was unique to its respective users, with the Navy operating its dedicated EA-6B Prowler fleet.

How the two services came to operate variants of one TJS on very different platforms is a reflection of the trend well established by the 1970s, of taking the core theatre strike asset then in use and adapting it to carry the jamming payload. The USAF's EB-66 and Navy operated EKA-3 support jammers were land and CV based variants of the one airframe. By the early 1970s the last vestiges of commonality in platforms vanished as the Navy deployed the EA-6A and then substantially re-engineered 4 seat EA-6B, while the USAF rebuilt over 40 F-111A bombers into the superlative EF-111A Raven.

The parallel model of EA capabilities was a good fit to the environment of the latter Cold War period. The EA-6B was well matched in performance to the A-6E, the Navy's core strike asset, while the EF-111A fit very closely with the USAF's F-111E/F wings based in the UK and very much the backbone of the NATO strike force.

This fit worked well both in logistical terms due to substantial commonalities in support infrastructure, but also in tactical terms as closely matched climb, cruise and penetration performance and capabilities facilitated escort jamming as well as standoff jamming. Economies of scale implicit in the operation of jammer variants of the mainstream tactical bomb truck alleviated the total cost of operating the respective jammer fleets.

This model began to unravel over the last decade, with the massive force structure downsizing following the collapse of the Soviet Bear. The Navy's A-12 foundered and died, leaving the Navy without a medium bomber type as the increasingly less survivable A-6E was phased out. The USAF, threatened with repeated F-22 cancellations and the concurrent pressure to accept new build F-15Es and F-16Cs to keep the industrial base alive, progressively retired all four F-111 strike variants - even though the F-111's other user, Australia, plans to operate them to 2020 or beyond.

The retirement of the A-6E and F-111A/D/E/F changed the whole context of the EA/SJ capability in the evolving force structure model. Neither the USAF nor the USN/USMC now operates a medium bomber type - the role having been subsumed with varying degrees of success by multirole fighters, ie the F-15E Beagles, F-16C Lawn Darts, F/A-18C/D Bugs and F-14B/D Bombcats. The EF-111A and the EA-6B became specialised platforms without the economic advantages of a large base of bombers using common basic airframes, bomb-nav systems, propulsion, electrical, hydraulics and defensive EW equipment.

The disappearance of the medium bomber class is significant, since this category of aircraft carried sufficient internal fuel to provide very good in theatre loiter performance, vital for persistent suppression of hostile emitters, yet was also survivable enough to operate at the boundaries or indeed inside a hostile integrated air defence system. The inverse square law of the J/S equation is operative here, since the closer a jammer of a given power rating is to the target emitter, they better the J/S ratio.

While the emergence of low observable or stealth capabilities remains the most important single development in defence penetration capabilities since the advent of radar, stealth is not a Romulan invisibility cloak and even stealthy types benefit from support jamming, especially against low band radars which may be capable of some measure of detection performance where shorter wavelength radars are impotent. Therefore the EA role remains useful, and with large fleets of non-stealthy legacy teen series fighters and heavy bombers in service until 2040, will be critical to force survivability until an all stealth combat aircraft fleet is fielded.

An EA platform carrying a TJS package should be highly survivable in contested air space, since the value of such an asset in monetary and tactical terms is very high - it is a priority target for any IADS operator.

The challenge of providing an EA capability after the retirement of the EA-6B fleet remains daunting. Fighter airframes are not optimised for persistent loiter in the manner of an EA-6B or EF-111A, with high aspect ratio 26-27 degree swept wing. This is an important design optimisation for an aircraft intended to loiter with many thousand pounds of jamming payload.

The need for good loiter performance in an EA platform has not diminished with time, the opposite has occurred. With the EA-6B tasked in Aghanistan with the jamming of hostile battlefield communications using modified ALQ-99 pods, the demise of an opposing IADS only sees the EA asset swung into another vital information superiority role.

If we take a long term perspective view of the EA role, the platform becomes a generic Multirole Electronic Attack asset which uses its powerful digitally programmable emitter package to cripple any asset an opponent uses which relies upon RF free space transmissions, while concurrently using its capable emitter locating package to find, classify if not fingerprint hostile emitters.

While the deployment of capable ESM systems on future assets such as the F-22A, smart tankers or MC2A platforms, and derivative non-kinetic tasked UCAV airframes, may prove to be an excellent means of finding hostile emitters, the fundamental need to engage them in the electromagnetic domain will remain. No missile or guided bomb can travel at the speed of light, imposing a response time limitation on all kinetic means of engaging a hostile emitter. While High Power Microwave (HPM) weapons remain a promising means of genuinely lethal (to Silicon) electromagnetic attack, they too are bounded the inverse square law imposing the same kinematic limitations of a guided weapon - the HPM delivery platform has to get close enough to kill the emitter.

If we are to draw long term conclusions about the Electronic Attack role and its importance, one conclusion is that the evolution into a more generic Multirole Electronic Attack role is already in progress (the term Information Attack would better describe this role but it has already been usurped by the cyberwar community!), while another is that we can expect to see Moore's Law enabling an increasing effort by opponents to fuse data - especially from low band radars or networked emitters in an attempt to counter evolving stealth capabilities. Therefore the ability to carry a powerful programmable jamming package into contested airspace will remain important, if not critical for many combat scenarios.

The Future Force Structure Problem

How should this be reconciled against the planned future force structures?

The AEA AOA analysis explores a wide range of alternatives including UAVs, bizjets, EA-6B, F-15E, F/A-18F, JSF, F-22, B-737, B-767, B-1B and B-52H derivatives. Yet the public and not-so-public debate following the release of this analysis does not show highly decisive preferences. The most likely successor to the Navy's EA-6B will probably be the EF-18 (F/A-18G) simply as it will be the standard CV fighter asset, at least until the JSF arrives on a carrier deck. This aircraft will not provide the kind of survivable deep penetration capability we will see in the F-22, but is likely to be adequate for the littoral combat environment central to Navy air operations.

From a land based air power perspective, the EF-18 is not particularly competitive against the USAF F-22 which has the ability to go deep, perform the mission repeatedly and survive no matter how good the IADS might be - stealth and supersonic cruise are hard to beat. While a JSF based solution might be viable in terms of subsonic persistence, it will not have the survivability of an F-22 airframe. If the intent is to carry an expensive jamming package deep into heavily defended airspace then an F-22 based solution may be the only viable choice, especially since the aircraft's kinematic and observables performance makes it a difficult target for the best S-300/400 series SAMs - even if cued to the jammer emissions.

The alternative of stand-off jamming using a large airframe or high flying UAV runs into two key obstacles - the inverse square law pushes up the size, weight and cost of the jamming package, while the limited survivability of the platforms constrains their effective footprint to less than the radio/radar horizon. Mobile S-300/400 style long range SAMs could push the operating orbits of such EA platforms well back from the FEBA, further exacerbating the inverse square law constraints.

The Global Strike Task Force (GSTF) model envisages the use of a combined force of F-22As and B-2A penetrating deep inside hostile airspace, with the F-22 elements sanitising airspace to permit 24 hour operations by the B-2A element. The GSTF is the centre-piece of USAF strategic planning and could become in the long term the force structure paradigm for an AEF, should the USAF acquire additional F-22 and B-2C aircraft. In this context an F-22 derived EA capability is a good force structure fit, even if it does represent a more expensive basic platform.

The difficulty with any F-22 derived solution will be persistence. Experience in Aghanistan with 'persistent bombardment' by B-52H and B-1B heavy bombers [Ed: now termed killbox interdiction] clearly illustrates that the engagement of dispersed and highly mobile ground targets such as ballistic missile launchers and SAM systems will require the ability to loiter in contested airspace. This is an easy task for a B-2 to perform, but will be challenging even for the large F-22 which is optimised for supercruise and agility - and arguably puts the smaller JSF out of the game altogether.

An F-22 derivative with more internal fuel and a variable cycle engine would fit this role better than the baseline design does, as it would better fit the GSTF strike roles. However, such a derivative will incur development costs which in turn exacerbates the existing political arguments over the aircraft. If the USAF were to acquire the 750 or so F-22s originally planned, this argument might be wholly academic - in such a build volume the incremental costs of modest design alternations would not be decisive.

The force structure issues implicit in providing a credible and survivable EA capability with the longevity which makes for a good investment of taxpayer's funding are not trivial problems. The very limited range of production types in the post 2010 period complicate this problem very significantly.

The genuine risk is that by adopting expedient or indeed affordable solutions the US will find itself with a large investment in assets with poor survivability and thus limited operational flexibility in the long term, forcing in turn yet another replacement cycle. The intellectual effort expended in the AEA AOA study illustrates that this is a problem which is not easily or cheaply solved.

The central question is that of what value should be placed upon the EA capability, over the longer term. With dominance in the information domain becoming an increasingly central feature of the global warfighting paradigm, the argument that Multirole Electronic Attack capabilities will progressively increase in value has much merit. Gazing into the strategic crystal ball is never easy, but this is one prediction which is unlikely to fail. The challenge will lie in articulating this reality in terms understood by parties other than the EW/IW community.

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