Air defence weapon systems - the next step
The ADF's current short range air defence (SHORAD) weapon systems provide a credible but limited capability in support of the land force. Under Joint Project 117 Defence is working up a requirement for a ground-based air defence weapon system (GBADWS) to defend both operational forces and strategic assets against new and emerging threats.
According to the Defence Capability Plan JP117 seeks to acquire a ground based air defence weapon system (GBADWS) to provide an effective capability to defend operational forces and strategic assets from the current and developing air threat, including a capacity to engage stand-off weapons. This translates as a modern air transportable (C-130) system that is capable of protecting strategic military and civil assets, contained within a land area nominally measuring 15km x 15km, from airborne attack by current and emerging airborne threats, including stand-off weapons. Ty
At this stage an all-important statement of the threats has not been provided and the system is not specified to be as mobile as, for example, a tracked vehicle. In light of system developments overseas where mobility is becoming increasingly important the ADF may look again at this aspect.
Our view is that JP 117 is probably focussed on a system with the capability to defeat low-to-medium altitude, probably transonic, aircraft at medium range and stand-off weapons, such as Harpoon and cruise missiles, that are launched at a considerable distance from the defended area. The system may not be required to intercept extended range guided artillery munitions fired from a ship standing off shore. The threat density will probably be defined to be modest and the operational environment to be benign, particularly the EW (ECM and ECCM) environment, although for coastal defence, stand-off jamming by accompanying aircraft should not be precluded. Consideration of this sort of environment will reduce the initial complexity and expense of a GBADWS without compromising its growth to handle a more complex environment if the foundations of the system are adequate.
Other important factors to be considered in the selection process include mobility in the field, the crew size including the number of operators, time to set up and test the system, and break it down, reliability, maintainability and availability, system growth potential to defeat new threats and countermeasures as they emerge and, of great importance, who else uses the system. Such data will undoubtedly be provided in the future.
The introduction of a modern GBADWS will add to the demands for enhanced intellectual skills and expertise in the ADF, Defence and Australian Industry, with the latter likely to provide through-life support of the system. The only resident expertise in the ADF in such systems is being developed in the RAN, where the adoption of the ESSM and its integration with ships' tactical data and fire control systems is a close parallel capability. From an industry capability perspective the Australian companies that are involved in the ESSM program for the Anzac ship and the FFG are likely to be well-placed to participate in this new challenge, as are those companies with a detailed knowledge of the ADF's C4ISR objectives and operating rationale.
Air defence weapon systems cover the spectrum of long range, very high altitude, theatre air defence systems, designed to intercept ballistic missiles at long ranges before they penetrate the theatre being protected, through area to point defence systems, with the latter providing defence of a very limited area, such as a ship or a headquarters complex. But their effectiveness depends on early warning, tracking and declaration of threats, without which they are unlikely to succeed against high-speed 'pop-up' threats. The GBADWS sought under JP117 will not include a capability against ballistic missiles and will fit into the small area defence category.
In the Australian context, the weapon system will be an integral component of the ADF's open-architecture, layered Australian Air Defence System, AADS. AADS is being progressively evolved to provide the ADF with air surveillance, command, control and communications covering a regional theatre that extends many hundreds of kilometres off mainland Australia and over an arc that covers most of Australia's north and that includes air defence of ADF and strategic civil assets.
Air surveillance is currently provided by JORN, ground-based air defence radars, selected military ATC radars and, when available, air defence-capable ships. By the end of the decade the AADS's surveillance capabilities undoubtedly will be augmented by high altitude surveillance aircraft such as the unmanned Global Hawk and Wedgetail and perhaps later by the US-owned surveillance satellite IR system, SBIRS.
It is evident, therefore, that to maximise its effectiveness a GBADWS needs to be capable of being fully integrated with the AADS structure so that it can be provided with early warning real-time data about threats, their composition and apparent intentions well before threats are detectable by the system itself. It is equally important that the system has all other data about the engagement of the threats by other response assets and about the asset(s) being protected, through its connection, for example, to HQ NORCOM. The provision of situation awareness data to the GBADWS is crucial to the implementation of battlefield management in its area of operation.
However, the integration of GBADWS with systems such as AADS will not diminish its capability to be employed in an essentially stand-alone mode as the single defensive system for a high value asset. This mode of employment will use the long endurance capability of the system to provide a high readiness state and rapid response against threats, leaving other assets such as fighters to perform other missions.
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>From a performance viewpoint the effectiveness of a GBADWS is determined by several factors. One is that accurate and real-time data about approaching threats is imperative so that the system can be cued in advance of their detection, tracking and identification capabilities. Another is that the overall performance of the GBADWS must be inherently superior to that of any anticipated threats. A third is that the performance of the system must not be inhibited by the environment and fourth, the system must be inherently flexible to allow it to be deployed advantageously and its configuration changed to cope with different geographic environments and different configurations of the assets the system is required to defend.
A hostile force will almost certainly carry out aerial surveillance of ADF strategic assets and the GBADWS protecting them. If the GBADWS is in a fixed configuration the ability of the system to protect the asset may be significantly reduced, leading to a pre-emptive attack to disable it. In the jargon of air-land warfare the Suppression of Enemy Air Defences (SEAD) may occur. So, it seems that in addition to air transportability an imperative will be that a GBADWS will also be mobile, but not to the extent that it can fight while moving.
Most GBADWS use missiles to attack threats, but one Italian system uses high rate-of-fire automatic guns and munitions that are almost certainly proximity fuzed. GBADWS that are missile-based use various guidance techniques including beam riding, command guidance, semi-active radar, fully active radar and infrared homing. Missiles using both radar and infrared homing techniques are also emerging.
Beam riding and command guidance techniques allow the use of a relatively simple missile because all of the homing computations are carried out on the ground and transmitted as guidance commands to the missile using a low power data link. Hence the missile does not require a seeker; but continuous tracking of a threat that is necessary with such a system exposes the radar to radar countermeasures generated by a manned threat, such as SEAD mentioned above. SEAD is presently invested in manned aircraft but the use of UAVs will undoubtedly appear on the scene over this decade. Patriot and the earlier Hawk are successful examples of command-guided missiles.
A semi-active radar homing missile requires continuous illumination of a threat by a target illumination transmitter that is usually integrated with the tracking radar, with the missile detecting the reflections from the threat and homing on them. Semi-active homing systems do not operate well if the threats are low-flying due to the possibility of terrain masking and radar clutter from the land. But the method is widely used in air-to-air and ship-launched missile systems.
The naval SM-1/2 area defence and Evolved Sea Sparrow Missile (ESSM) short range air defence missiles use this technique, with SM-2 having command-guided as well as fully active radar and IR homing regimes of use. A disadvantage of this system regardless of its application is that continuous target illumination, albeit at fairly low power levels, is required and offers the probability of radar countermeasures being implemented against the GBADWS' radar.
The above problems favour a fully active homing missile because it contains an autonomous radar to illuminate a threat and a receiver to detect the reflections from it. The overwhelming advantages of a fully active radar homing system is that it is a 'fire and forget' system that does not rely on a ground radar system but the missile is still capable of being jammed.
The USAF's widely used fully active homing AMRAAM is employed in a surface launched mode in the Norwegian ADSAMS (Air Defence Surface-Air Missile System) and is being procured by the RAAF for its air-launched BVR missile for the F/A-18s. Passive IR homing missiles are also in the fire and forget category. The naval ESSM is configured to use radar or IR homing in its terminal phase.
Despite the variety of missile homing systems available, if the threat is manned it will undoubtedly generate RF and IR countermeasures (CM) to confuse or jam the system it is attacking and the success of CM significantly impacts the Probability of Kill of the whole GBAD system.
If the threat is unmanned, such as a missile launched from a stand-off aircraft, there are other issues to consider such as the size of the threat which may not generate a usable radar reflection for semi- or fully-active homers or an adequate thermal signature, and its speed. In such cases, the command-guided system, such as that used for SM-2, may be the optimal solution as a ground-based radar can generate very high power to illuminate a small threat to ensure that it generates usable reflections.
The spectrum of GBADW systems is very broad. At the top end of capability Patriot is probably the best current example of a GBADWS, but its performance and price, and size that impacts rapid transportability, almost certainly places it outside the ADF's requirement. In the middle of the spectrum there is a large number of European systems including the Alenia Difesa Spada 2000, Boeing Avenger (a mobile Stinger system whose range may be inadequate), Saab BAMSE, Euromissile Roland M3S, Eurosam SAMP/T, Kentron SAHV, Matra-BAES Rapier FSC/Jernas, Oerlikon Aerospace ADATS, Raytheon Land AMRAAM, Thales Crotale (new generation) and a number of Russian systems. All these systems are tailored to meet a specific operational environment and in many cases specific threats.
By Fred Haddock & Tom Muir, Canberra