Technology Explained

It is fair to say, that the fighting in the Persian Gulf and recent disasters in the North Sea, graphically illustrate the vulnerability of onshore and offshore oil/gas installations to Anti-Shipping Missile (ASM) attack. The Barrow Island area and Withnell Bay facilities and the North Rankin Platform, are thus lucrative targets for a serious opponent. It is not unreasonable to surmise, that the threat alone of such attack (potentially stopping 30% of our national natural gas production capacity) could serve to tie many of the RAN’s area defence SAM firing vessels to air defence picket duty covering these sites, thus effectively reducing RAN resources available for offensive and other defensive operations. This situation will be exacerbated if the Timor Sea oil/gas wells are developed for production. To these targets we must add the expanding RAAF and Army infrastructure in the Northern Territory and North of WA and of course Cape York. Were the proposed spaceport to go ahead, it would represent a target of considerable propaganda value.

To defend the North and North-West the RAAF is expanding a chain of airfields, some of which are established and several of which are new, including the hub of Northern operations, Tindal near Katherine in the NT. To the West Learmonth, Port Hedland and Derby, to the East Gove, Weipa and Cairns, these airfields would support detachments of F-I aircraft from the squadron home based at Tindal. These aircraft would receive inflight refuelling support from tankers operating or staging from Darwin/ Tindal and thus, could carry out intercepts several hundred nautical miles off the coast if necessary, alternately Combat Air Patrol endurance could be stretched considerably. Limitations in numbers of aircrew and support personnel would however dictate ground alert rather than standing CAP which will impose a need tor good early warning of inbound hostiles.

While the basing of interceptors close to targets is an important aspect of air defence, it is of limited value without extensive low level radar coverage, command posts and associated C3 facilities. Long range early warning of inbound threats will be provided by the Jindalee Over The Horizon Radar (OTHA). OTHA is invaluable as it can detect and track low flying aircraft and ships at ranges beyond 1500nm. It has limitations though, as its accuracy in range and azimuth locate a target only within an area of several nautical miles with no height finding capability,. with performance fluctuating subject to ionospheric conditions. OTHA will thus provide an indication of an inbound threat and its location with an accuracy that may or may not provide for a successful intercept. As it lacks the ability to identify an aircraft from IFF/ESM/flight profile, its usefulness for the close control of interceptors is limited, more so since an extensive network of communications relays would be required to control air defence aircraft (a HF datalink is another alternative, penalised in performance however by ionospheric conditions).

These gaps in capability are filled with an AEW aircraft, which carries ESM, IFF and a centralised C3 network with it, regardless of the state of the ground based infrastructure it is defending. The capabilities of AEW and OTHR are thus clearly complementary, with OTHA providing up to several hours of warning, AEW aircraft and interceptors can be positioned to provide the best possible coverage of targets accessible by the inbound hostile(s). The AEW aircraft would then identify the threat and control intercepts taking advantage of its on board systems.

It must be stated that proponents of either system who reject the alternative have not understood the difficulties involved in covering the vast area of the North and North-West with a handful of fighter aircraft. It is expected that the AEW aircraft wouldbe covering the two most sensitive areas in the North and North West, operating from Learmonth and Tindal, with other deployments possibly made to support operations in other areas if necessary.

The air defence of the North and North West is uniquely characterised by a low density of possibly very sophisticated threats operating over land and sea, distances imposing the need for considerable range/endurance and an undisputable requirement for extensive C3 tied into a larger national air defence system. These C3 systems should have the ability to feed OTHA target track data to AEW aircraft for association with ESM, IFF and radar tracks while providing for the transfer of near realtime tactical situation data into the national air defence system. The RAAF’s eventual choice of AEW aircraft will thus have to not only account for airframe and radar/lFF/ESM performance, but also consider the capacity of the airframe and system hardware and software, to accommodate the hardware and software required for a tie in to what should eventually become the integrated National Air Defence and Airspace Control System.

REFERENCES:  (I) Schlesinger RJ, ‘Principles of Electronic Warfare’, Peninsula Publishing, 1979.

(2) ‘Airborne Early Warning Overview’, GEC Avionics, paper prepared for Air Power in the Defence of Australia. ANU July, 1986.

(3) Evans SD, AM, ‘Air Operations in Northern Australia’, SDSC Working Paper No101, ANU, 1986.

(4) Sinnot DH, ‘The Jindalee Over-The-Horizon Radar System’

paper prepared tor Air Power in the Defence of Australia, SDSC ANU July, 1986.

Readers with an interest in phased array radar principles are directed to the following (very good) tutorial: Brookner E, ‘Phased Array Radars’, Scientific American, February 1985.