Source : The Indian Defence Review, © 1995 by Lancer Publishers & Distributors.
The coalition forces' use of airborne early warning and control (AWACS) aircraft made the most important contribution to the prevention of widespread air losses during the air war over Iraq in 1991. While these aircraft had their origins in handling the doctrine of massed "wave" air attacks to counter the then Soviet air doctrines in Central Europe, the AWACS aircraft has proved a vital component in modem air warfare and C3I. Therefore, a survey of current programmes and aircraft should be of interest at a time when new technologies - the planar array radar - are entering the competition against first-generation rotating airborne radars.
The interim and final reports to the US Congress on the "Conduct of the Persian Gulf Conflict" may give little details of the successful use of AWACS aircraft, the reports do note "Air Force (Boeing) E-3 (Sentry) airborne warning and control aircraft and Navy E-2C (Hawkeye) early warning aircraft operated round-the-clock to guard against attacks by Iraq's remaining air force and to provide airborne command and control." It understates the success of Coalition Forces' aircraft in shooting down 35 Iraqi fixed-wing aircraft in air-to-air combat, without friendly losses. The US Air Force Sentry aircraft served jointly with Saudi Arabian Air Force 18 Squadron's five E-3 Peace Seninel aircraft, and in conjunction with US Navy carrier-based E-2C aircraft.
Asian air forces are increasingly taking note of the importance of AWACS and less sophisticated airborne early-warning (AEW) aircraft. Taiwan has now taken delivery on four E-2Ts (basically E2B version) aircraft and Australia has an outstanding requirement for a new AWACS aircraft in support of Northern Territory defence objectives. Further afield, Brazil became the first customer for the Ericsson Erieye AEW platform last September, when Brazil ordered six Erieye-equipped Saab 340 aircraft.
For the most sophisticated demands, aircraft with volume are required. Past conversion of Boeing 707 airframes are showing limits in meeting volume intensive needs, resulting in offering the newer Boeing 767 for a number of clients. Earlier proposals with strong prospects for future sales include the venerable P-3 Orion or C-130 Hercules, the latter using either nose-and-tail (APY-920) configuration or rotodome (APS-145) fittings. Also proposed to China were GEC-Marconi APY-920 radars onboard a Yun-8 (AN-12), while Israeli Aircraft Industries (IAI) Elta division has fitted one aircraft as a prototype for a combined airborne-maritime surveillance Yun8 version, for use over the South China Sea. China is reported to have ordered Beriev A-50 Mainstay AWACS, which would be integrated with airborne control of PLAAF MiG-31 Foxhound, Su27 Flanker and F-7 Airguard interceptors.
Smaller, lower-cost and lower-endurance AEW aircraft are being proposed, mostly using twin engined commercial airframes. These include:
In the rotary-wing category, the Royal Navy acquired eight specially modified Westland Sea KingAEW.2 helicopters fitted with Thorn EMI Searchwater radar; with similar outfitting of some Spanish Navy Sea King SH-3Hs. In December 1992, the Japanese Diet approved purchase of the first two Boeing 767 ASWACS aircraft, on behalf of the Japanese Air Self-Defence Force (JASDF). A second pair was ordered on 28 October last year, with the first two E-76727C aircraft (IOC in early 1998).
Thus, the market offers prospective customers a significant number of platforms to choose from, whether fitted with conventional rotating radars in rotodomes or with planar (Elta EUM-2032) or phased array (Elta Phalcon) radars. The following survey is intended to provide an overview of alternative platforms for Asian clients.
"Strategic" AWACS
These are three "strategic" AWACS in widespread services: Boeing E-3 Sentry; Beriev A-50 Mainstay, and Tupolev Tu-126 Moss aircraft. In early 1998, the Boeing E-767 will enter service in the JASDF (supplementing 13 E-2C Hawkeyes). In Asia, India and Australia are both candidates for these platforms, while China is likely to more widely adopt the A-50 Mainstay in this decade (if other conversions prove technically inadequate or excessively expensive). More recently, NATO and American E3Cs, augmented by British E-3D and French E3Fs are operating in the South European theatre monitoring air activity over former Yugoslavia (Operation Deny Flight).
Boeing E-3 Sentry
Boeing has built 68 E-3 Sentry aircraft, in service With the US Air Force (34), Britain (seven), France (four), Saudi Arabia (five), and 18 procured for NATO multinational use. Production of the basic Boeing 707-320B airframe was long ago discontinued, as have now airframe conversions. The origins of the programme were growing US/NATO concerns over the growing threat of low-flying strike aircraft Posed by the then Warsaw Pact air forces. Sentry's in the USAF are expected to remain in service until at least year 2025, while other countries are likely to keep them active for another ten years - with the requirement for continued updating in the intervening years.
The European environment required several modifications to standard E-3A configuration, which resulted in an agreed "standard" configuration. This new configuration was an improvement over the first 24 E-3As, referred to as "Core E-3s", which had a basic capability of detecting both high- and low-f lying aircraft at ranges exceeding 400 kilometres with the E-3A at 9,000 metres. These aircraft had a 17-man crew, were powered by four P&W TF-33 turbofans and had a Westinghouse APY- 1 surveillance radar in the 9.1-Metre diameter rotodome.
The first "Standard" configuration delivered as USAF E-3 No. 27 in 1981 (through No. 35) and all subsequent NATO-owned aircraft. The aircraft have higher data rate processing IBM CC-2 computers, added high frequency radios, ECM equipment, enhanced ECM resistant voice coms, JTIDS, and provision for self-defence systems. The last NATO aircraft was handed over on 25 April 1985. Major system suppliers included Westinghouse and AEG Telefunken (radar), Eaton Corp, (IFF), Standard Eiektrik Lorenz AG and IBM (data processors), Hazeltine Corp. and Siemens AG (data displays), Elektronik-System-Gessellschaft (software), and a group handling communications (E-Systems, Rockwell Intern. Collins, General Atronics Corp., AEG Telefunken, Hughes Aircraft and Sperry Marine Systems), with installation and final check-out functions done by Donier Reparaturwerft GmbH; plus other companies involved in the complex multinational programme on behalf - on the alliance.
In mid-1987, Boeing Defense was given a $241.5 million contract to provide various upgrades, including full-scale development (FSD) contract on systems development and system integration of Boeing/UTL AN/AYR-1 ESM system for all American and NATO E-3s. The AYR-1 is designed to detect hostile and friendly emitter signals to determine aircraft category - "hostile or friendly". The APY radar operated within the rotodome rotates at a normal rate of 6 rpm, giving a scan rate of ever 10 seconds. Operation frequency is in the 10 centimetres wavelength, with seven operating modes: including a pulse Doppler elevation scan (PDES), pulse Doppler non-elevated scan, beyond-the-horizon (BTH) mode, a short-pulsed maritime mode, passive, and a test/ maintenance and standby modes.
In mid-1990, a NATO aircraft modernization programme was approved, with the first Mod. Block 1 upgrade contract placed in June 1993. The upgrade provides for Link 16 (JTIDS) data links, new monitoring consoles and Have Quick secure voice coms. All 18 NATO aircraft are now to be upgraded, with 16 being undertaken by DADA (Germany). The NATO E-3 acquisition represented the largest, commonly funded acquisition programme undertaken by the alliance.
USAF E-3s have undergone a series of upgrades, including E-3B standard involving two prototypes and 22 "Core 3" airframes. New equipment included upgraded VHF coms, CC-2 computers, five further consoles (CDCs), improved jam-resistant radio coms, added UHF radios, maritime surveillance capability into the AN/APY-1 radar, and Have Quick anti-jam countermeasures. The first E-3B was delivered in July 1984, with modification kits provided by the Boeing Defense & Space Group. Included were colour displays from Hazeltine, under a $16 million contract. The last 10 USAF airframes were upgraded under "Block 25 Mod." programme - providing for five more CDCS, five further UHF radio and Have Quick - to become E-3Cs.
The United Kingdom became the second customer, ordering six E-3D Sentry AEW.1s. These were the first CFM56 powered aircraft, with first delivery in July 1989, with first aircraft hand-over to the RAF Sentry Training Squadron in June 1990. No. 8 Squadron assumed E-3 operations to replace antiquated Shakelton AEW.2s, with final IE-3D delivered on 12 May 1992. RAF aircraft are unique in also having Loral 1017 Yellow Gate ESM systems installed on wingtips, added stiffeners outboard for the CGM56 engines, and a refuelling probe offset to starboard. France ordered three E-3F SDA aircraft in February 1987, with follow-on single aircraft orders in August (two planned further aircraft orders were not taken up). The French aircraft also have the prominent upper-deck refuelling probe and CFM56 turbofans. UTA Industries conducted final fitting-out on the aircraft, with the first aircraft flown on 27 June 1990 and delivered in October. Final aircraft on the order was handed over in February 1992. All aircrafts are in service with Escadre de Detection Aeroportee 36 (EDA 36) at Avord AB, with two subordinate sections (EDA 1/36 and EDA 2/36).
Royal Saudi Air Force (RSAF) E-3A Peace Sentinel were approved for sale in 1981, with five aircraft purchases and augmented in the support role by eight KE-3A in-flight refuelling tankers and logistic support aircraft, similar to the E-3s but without radar and surveillance equipment. AWACS E-3 aircraft were delivered between June 1986 and September 1987, and are operated by No. 18 Squadron at Riyadh Military City Airport. Saudi aircraft has a flight crew of four, with upto 13 mission specialists and have the CFM56-2A-2 turbofan engines, but lack JTIDS and Have Quick systems. The aircraft were active during the Gulf War of 1991 monitoring Northern Persian Gulf air activity and were directly responsible for tracking and C2 function that resulted in shoot-down of two Iraqi Mirages over the Gulf. Two aircraft on station can therefore cover the Red Sea and Persian Gulf simultaneously, while a third can provide overlap coverage while orienting its sector scan coverage towards the Israeli and the Jordan borders. The accompanying graphic of two E-3s stationed over Sea of Japan waters provides an idea of highland low-altitude coverage capability.
In May 1987, a new, long-range multi-stage improvement programme for the E-3 was initiated under a USAF award for the ICON (Integration Contract) to Boeing Defense. ICON will provide both US and NATO aircraft with an electronic support measures (ESM) passive surveillance capability, and offer future block enhancements.
Under the Radar System Improvement Programme (RSIP), in 1989, Westinghouse won a development contract ($223 million) for upgrading APY-1 and APY-2 radars to improve surveillance capability, with new CDC processors and pulsed compressed waveform for improved sensitivity against small airborne targets (i.e., cruise missiles). The new radar gives the airborne commander real-time surveillance coverage of 3 million cubic miles of airspace. With over 600,000 components, the APY2 is among the most complex airborne radar ever developed, with company reports indicating availability rates of 95 per cent. Other upgrades included modifying the radar control and maintenance consoles. In 1993, Boeing delivered production-quality, upgraded IBM CC2 computer systems to NATO as part for the. Memory Upgrade Programme to the CC2E model. In the same year, other major NATO contracts were let to Boeing, including a $294.5 million contract as part of Mod. Block 1 phase of modernization; plus a $35.5 million to install and test hardware. Last year, two other US and NATO ESM upgrade contracts were let to Boeing Defense, with NATO retrofits to be done by Daimler Benz Aerospace.
With the end of the Cold War, mission activity has been lessened and airframe lifetime is likely to be significantly longer than originally projected. Therefore, future emphasis will be on upgrading the E-3's hardware and software systems under the Extend Sentry programme, with some 130 upgrade projects under study by the Electronic Systems Command through year 2001. New cockpits, navigations aids with INS-GPS technologies, IFF upgrades, enhanced communications and radio systems, and defensive countermeasure systems are likely improvements in coming years.
Beriev A-50 mainstay
Successor to the Tu-126 (NATO: Moss) in the then Voyska PVO. The Beriev OKB A-50 is an airframe design conversion of the successful IL76 transport. The Russian Air Force has about 25 operational of the aircraft, designated Sistiem Dainovo Radiolokacyo-mnovo Obanrushenya (SDRLO - Long-Range Detection System). Beriev work began in the late 1970s, first prototype may have flown in 1981. Production averaged two per year from 1982 and then rose to five per year by the mid1980s. "Tests, and evaluation were continuing in 1985, by which time at least four Mainstays had been completed, with production expected to continue at the rate of five a year" (Mason and Taylor). This production rate was held until 1990(two delivered). Some estimates as high as 40 airframes were prepared, but delays in electronics have resulted in a much smaller inventory than would otherwise be obvious (Sources: Soviet Military Power, various editions; Soviet Air Force (A. V. M. Mason and J. R. W. Taylor).
A-50 has demonstrated a capability to detect low-fliers ("look-down, shoot-down") detection capability in assisting MiG-31, MiG-29 and other aircraft in making effective intercepts on hostile aircraft and cruise missiles, according to US DoD. The 9-metre (29 feet 6 inches) rotodome has a much improved radar compared to the Tu-126, which lacked effective tracking capability over land and low-altitude targets. During the Gulf War, A-50s were observed flying sorties to monitor Coalition Forces' air operations from Turkey and Northern Iraq, while operating over the Southern Black Sea and Caucasus area. Air patrol operations are reported as normally conducted at 10,000 metres flying figure eight flight patterns, with upto 100 kilometres between orbit centres. The aircraft has significant detection and C2 improvement over the original Flap Jack radar onboard the Tu-126s and must be regarded as an effective platform for the mission under most electronic environments. While the Russian Air Force is currently the only operator, some foreign air forces may still desire to acquire the A-50, including India, Pakistan and two or three air forces in the Middle East.
Boeing E-767
The most recent large AWACS in production is the Boeing E-767, part of a company effort to find a successor to the successful -707 airframe conversion. First revealed in December 1991, the aircraft became one of a number of contenders for a (then) Japanese Air Self-Defence Force (JASDF) strategic AWACS aircraft. With a mission designed to provide airborne surveillance over the Japanese homeland and maritime regions North-East of the Japanese peninsula, endurance and range: - plus airfield suitability - were major factors in the Boeing bid. With in-flight refuelling, the -767 was capable of missions upto 22 hours long, with an unrefuelled range of 8,335-9,260 kilometres (4,500-5,000 nautical miles), while more practical mission to cover the Japanese maritime "1,000-Mile Defence Zone" coverage allows for missions of 7 hours endurance, plus offering a ceiling upto 12,700 metres. In December 1992, the Japanese Defence Agency (JDA) announced the aircraft selection, with a pending order for four aircraft. Parliamentary approval followed in early 1993, with a two-aircraft order placed in November and a further two under the next fiscal year budget (in October 1994).
The aircraft has volume that is not readily available in the -707 conversion, being based on the civil Boeing 776-27C version. Initial airframe is being flown at Boeing Defence & Space Group facility at Wichita, with the first two aircraft due for hand-over to the JASDF in early 1998. Aircraft contract is valued at $840 million. The aircraft are strengthened versions of the 767-200, due to rotodome weight support needs and offer 50 per cent more floor space than the earlier -707 (E3). Avionics are essentially those of the 'Standard" US-NATO model, including Westinghouse APY-2 (E-band) radar, supported by IBM CC-2 computers, Hazeitine CDCS, Teletronics APX-103 IFF/TADIL-C array, passive Loral 1017 and UTL Corp. AYR1 sensors, and with four-abreast consoles, placed back-to-back in the aircraft interior. The flight crew now consists of two pilots and a mission crew of 18, including seven surveillance operators. The new aircraft offers potential clients current technologies in avionics and flight controls, two General Electric CF6-80C2 turbofan engines (61,500 lbs st.), and similar electronics to existing US-NATO E-3s, plus compatibility with many foreign operator civil air fleets, while retaining the overall characteristics of a first-rate long-range AWACS, category aircraft. The first JASDF aircraft was being fitted with 99-inch radius crown beams and steel struts to support the 12,500-lb rotodome at Boeing's Wichita in March this year.
The aircraft has the potential of attracting further orders in coming years and will be a strong contender to fulfill the Australian AEW&C requirement. Other NATO members may still order large AWACS aircraft, both in support of NATO missions and to serve national interests, including Italy, Turkey, Spain, South Korea (ROK) (though none have defined a requirement as yet). As such, out of an understood market for 45-55 near-term new AWACS and AEW&C aircraft worldwide, the Boeing E-767 could capture about half the existing market by the end of the decade.
Alternative retrofits
Israel has been marketing IAI's subsidiary Elta "Phalcon" EU2075 D-band paired phased-array antenna conversion for a number of years, with sales already recorded in China and Chile. One People's Liberation Army/Air Force (PLAAF) Shaanxi Yun-8 (Y-8; Cub) conversion was undertaken in the late 1980s, while Israel has adopted a Boeing 707 conversion as demonstrated at the 1993 Paris Air Show. The full system requires a fairly large aircraft and thus does not meet the requirements of many potential Asian operators. The AWACS market in China may remain the most lucrative, though the latter continues to delay acquisition for a large number of such systems off-the-shelf. The system can give 360 degrees coverage, providing supplemental arrays can be fitted onto the "conversion" aircraft, with a reported acquisition range of the order of 370 kilometres against fighter-sized targets.
This type of system has the disadvantage of requiring a large platform - remember many US Air Force EC-135s were converted with various phased-array and SLAR systems - but has the advantage of being more electronic jam-resistant and offers both greater redundancy and real-time read-out compared to rotating antenna (rotodome), systems. These systems are enhanced versions of earlier eighties planar array technology, in which the beam was fixed in direction and curvature. Such systems were placed in service to fulfill ballistic missile warning functions (FPS-115 Pave Paws) for the United States and the former USSR had its own counterpart, while today's SPY-1 Aegis naval surveillance system is widely used on US Navy cruiser ("Ticonderoga" class) and onboard one US ("Arleigh Burke" class) and Japanese ("Kongo" class) missile destroyers. This year, Lockheed Martin (Marietta) Government Electronics System (GES) division proposed an 'Aegis" type air warfare system for installation on German Type 124 and Spanish F 100 class anti-air frigates, called the Distributed Advanced Naval Combat System (DANES), based on technologies used in the S-band SPY-1 D phasedarray multi-function radar.
Though phased-array systems are significantly greater in cost, they do offer some distinct benefits. With near-jam resistance, height-finding capability through beam sterring, and a range of beam directional capabilities (sector scanning), plus greatly improved detection and tracking capability against small airborne targets (SLCMS, small civil aircraft, etc.) as well as tracking beam capabilities to following individual airborne targets without degrading the overall surveillance system, it is clear why the limited phased-array APY-1/-2 systems have been successfuil in meeting current AWACS requirements.
Three other atternative airframe conversions involve the use of Lockheed C-130 Hercules and P-3 Orion airframes, which have used both rotodome and nose-and-tail mounted antennas of the GEC Marconi's "Sky Guardian" or "Argus 2000" (US designation is APY-920) S-band radar. The APY920 system was installed onboard an EC-13OV Hercules for trials proposed by Lockheed Ft. Worth Co., with first flight trials in late July 1991. The system was intended for the Nimrod AEW Mk3 programme (cancelled due to rising costs and budget constraints), a variant of the system was sold to China and installed onboard a Yun-8, in direct competition with the Israeli Phalcon system capable of long-endurance missions over the South China Sea and provide both limited airborne warning and sea-surveillance mission capabilities. It is unclear if the proposed "Argus" system has gone further in development, but the Chinese will certainly do what they can to reverse-engineer the system if they can. The very cost involved in either acquiring quantities of British-built system or reverse-engineering the "Argus 2000" may be be one reason behind reports that China has ordered off-the-shelf Beriev A-50 Mainstay aircraft.
Two other airframe conversions, both based on rotodome installations, are Lockheed's Hercules fitted with APS-145 radar and Orion's APS-138 conversion, currently in-service with the US Customs Service. The four aircraft are reconfigure P-3As (designated UP-3A). APS-138 had the addition of a Randtron Corp. low-sidelobe APA-171 antenna called TRAC-A (Total Radiation Aperture Control-Antenna), with the last system delivered in 1987. At first, the Customs Service viewed the aircraft were often considered too large and expensive for the mission involved, i.e. drug interdiction, but have now been successfully integrated into a wide range of airborne and ground-based aircraft and radars. The aircraft outfit is first rate, in all respects comparable with US Navy E-2s. The ARPS (Advanced Radar Processing Sub-system) has proven to have increased sensitivity while minimizing noise, clutter and false alarm rates on aircraft detections, using a coherent UHF Doppler radar. The latest APA171 mod. is fitted high off the upped fuselage deck than on the Hawkeye, which provides better antenna performance from the 16-feet (4.8 metres) antenna, with a 6 rpm rotation rate. A Control Data Corp. AYK-14 processor can handle tracking of some 2,000 individual tracks. Sauders Miligraphics 48 centimetres colour, touch-sensitive screens are used at each control station. The P-3 upgrade included fitting a Rockwell-Collins EFIS-86B electronic fight instrument system, Litton LTN-92 ringlaser gyro (duplicated), five UHF/VHF radio with full air-to-air and air-to-ground data link system, and Texas Instruments AAS-36 infra-red detection set (IRDS). What makes the UP-3As very unique is fitting of a Hughes Aircraft APG-63 multi-mode radar system, as used on the F-15 Eagle, to provide effective track-while-scan intercept capabilities. The UP-3As use Allison uprated T-56-A-14 turboprop engines. The USCG P-3 AWACS conversion has a range of 3,724 kilometres (2,328 miles) and offers 14 hours endurance and crew comfort comparable with existing Orion ASW aircraft.
UP-3As are the successors to ex-USN aircraft handed over in the early 1980s. Their mission is more than traditional military AWACS missions, hence the enhanced systems onboard. For this specialized drug interdiction mission, the UP-3s must be able to coordinate with not only ground warning net stations, but a variety of airborne USCG aircraft, including Falcon, Citation 11, Cheyenne lit (CHETs fitted with APG-66 radar).
In the case of the C-130, the US Coast Guard (USCG), already an extensive user of the HC13OH version, considered the conversion more useful than the more expensive E-2C Hawkeyes that were initially handed over from the US Navy for a variety of USCG airborne surveillance missions - again, mostly drug interdiction related. The "coasty" Hercules uses the APS-145, and is otherwise fitted with the latest in Coast Guard avionics and instrumentation. The Hercules conversion is liked by many potential users, in that the CDCs and other equipment is pailetized and the aircraft can, urder emergency situations, revert to its normal transport mission (though the rotodome is permanently mounted). Widely used in Asia, the Hercules or Orion offer users flexible alternatives, a four-engiried long-range platform, utilizing an aircraft already widely in-service with potential new AWACS users (Thailand, South Korea, Australia and 2-3 Middle East air forces, in particular). Hercules HTTB was also tested in the late 1980s with a fuselage phased-array antenna system, measuring 13.7 metres in length and 1.83 metres in height. C-13OH AWACS range would be of the order of 4,400 kilometres.
Both the P-3 and C-130 conversions will be leading contenders in the Australian AEW&C selection, due to familiarity within the RAAF on these aircraft types and their endurance capabilities in support long-range Hornet and Aardvark air operations. Either aircraft can revert to support and transport and transport missions, as did USCG P-3s during Hurricane Andrew in August 1992. Both aircraft can be considered leading contenders, as Australian requirements are understood to be less demanding than is available on the E-3C and E-2C, but are probably not that far removed from those developed by Swedish authorities that resulted in the Erieye system. This will become a key issue in final aircraft and system selection.
Twin-engined concepts
What is interesting in the AWACS market is the growing number of alternatives available in the twin-engined airframe market, mostly conversions of civil aircraft designs to fit a particular electronic suite. This includes the latest version of the lightweight Pilatus Britten-Norman BN2T Defender 4000 and Multi-Sensor Surveillance Aircraft (MSSA) at 3,885 kilograms (8,500 lb max TO) to the larger Northrop Grumman E-2C Hawkeye at 23,556 kilograms (51,993 lb TO), with a growing number of intermediate sized alternatives ranging from Metro III, Embraer EMB-120, Saab 340 and Fokker 50 variants fitted with Ericsson Microwave System AB "Erieye" (PS 890) phased-array antenna. Other alternatives may emerge later in the decade, including other civil air frame conversions offering the Westinghouse APG66SR radar system (a ground-capable surveillance version of standard F-16 Fighting Falcons APG66). In the rotodome category, Martin Marietta (then GE Aerospace) AN/APS-145 will continue to be the standard for rotodome antenna types and has the potential to be innovatively fitted on other civil airframe types.
Russia's Anonov AN-74 (NATO: Madcap) development of the Coaler transport version appeared headed for navy service after mid-decade. Decline of the Russian Navy's aircraft carrier fleet leaves only a single "Kuznetsov" class CTOL ship in service, thus leaving the unique t-tail installed rotodome conversion in the dustbin of aircraft designs unless a foreign country offers to further RDT&E on the design. Given the state of the Russian electronics industry, the aircraft is unlikely to have suitable over-land detection and track performance and therefore would appeal only to a client interested in a maritime air AEW&C mission. And there remains little reliability or cost controls if the radar system is to be delivered from Russian factories.
A newer Russian entry followed cancellation of development of the AN-72 programme, the Yakoviev Yak-44E. This aircraft was first demonstrated ih full-scale mock-up form in 1993. The aircraft model featured twin-engined contra-rotating turboprops, a high-wing plan and twin-fins mounted on a high set tailplane, with the rotodome sited above the rear fuselage. The configuration was designed for below deck storage onboard 'Kuznetsov" class CTOL aircraft carriers. Dimension would make the aircraft slightly larger than its counterpart Hawkeye - 3 metres longer and 0.6 metres of great wingspan. It is expected the model will again be shown at this year's Paris Air Show, as Yakoviev OKB continue promotion of the design in hopes of obtaining foreign RDT&E support. No immediate candidate appears likely.
Northrop Grumman E-2C Hawkeye
In the words of Air Force Magazine, the Hawkeye "fills a unique slot in the spectrum of combat aircraft,infinitely more capable than smaller surveillance platforms yet a fraction of the price of an E3 AWACS" (AFM, July 1993, p. 77). Under normal radar detection ranges, the E-2C Hawkeye can provide warning of 30 minutes against hostile intruders flying at Mach 1.0 speed. In addition to US Navy and Coast Guard service, the Hawkeye is in service with a number of Asian air forces, including Japan (13), Singapore (4), and Taiwan (4, completed delivery in December), plus Israeli (4; No. 192 Squadron) and Egyptian (5) air forces. Most of these aircraft are Group 0 series, which was the standard of the late eighties. Japan's aircraft fly with the 601st Hikotain at Misawa Air Base. Those of Singapore equip No. 111 Squadron at Paya Lebar. Taiwan's aircraft will remain in the US for personnel training until late 1995.
France has also selected two aircraft (Design 123HH), having been offered four new aircraft under a $773 million package in April 1993, and according to Northrop Grumman, which is "expected to lead to procurement of Hawkeyes in 1995". Combined demands for US Navy and foreign customers have led to an average of six aircraft per year production rate.
Singapore is also judged to have a requirement for at least one or two more Hawkeyes. Company presentations have also been made to a number of Middle East clients, including Oman, Kuwait, Bahrain and the United Arab Emirates (UAE) to fulfill pressing airborne threat warning requirements. Firm export orders now number 31 aircraft.
The first E-2A entered service in 1964 and the current E-2C were delivered in 1973. Despite this apparent age, the Hawkeye has focused developments on continued system improvements throughout its lifetime, resulting in three-radar system replacements - beginning with AN/APS-1 38 replacing APS-125 ARPS in 1983 and was supplanted by APS-1 39 in 1988, with APS-1 45 (40 percent increase in range over -138 system) order into new production aircraft under fiscal year 1989. In parallel with radar improvements have been other system upgrades, including Hazeitine APX-76 IFF system; expanded data processing system for ATDS; new colour CDCS. JTIDS for improved secure anti-jam voice and data link communications; a global positioning satellite system (GPS) for improved navigation and target location; ASN-92 Carrier Aircraft Inertial Navigation System (CAINS) for ASN-36 INS of earlier aircraft; and, Litton Advanced Technology Division AN/ALR73 Passive Detection System (PDS) replacing earlier ALR-59 ESM. ALR-73 antennas are mounted in the nose and tailcone, vertical stabilizers, as well as fuselage fittings for side-coverage. The Litton system allows emitter detection at twice the range of radar coverage (600 miles).
Most significant AEW and C2 capability improvements have come in the form of upgrading to Group II standard, which included fitting APS145 radar and uprated Allison T56-A-427 turboprop (5,250 shp) engines. Greatly improved over-land detection and track capability came with the introduction of APS-120 radar (replacing original APS-96) and incorporated into follow-on radars, whereby the APS145 monitor 6 million cubic miles of airspace and more than 150,000 square miles of sea surface. Improved data handling capability allows the system to maintain files and tracks on more than 2,000 airborne targets (upgrade from 600 targets with APS-125), including course, speed, altitude, IFF and passive ESM data. As an integral part of the US Navy's air defence team, E-2s can also receive date link inputs from F-14 and F/A-18 aircraft to the ATDS, thus allowing interceptors to automatically be vectored onto correct intercept tracks, increasing air surveillance capability by sorpe 200+ miles. This data link compatibility offers some distinct advantages for air forces already operating the F/A-18 aircraft.
This system improvement process continues. At the end of 1994, Northrop Grumman began work on a mission computer upgrade programme, designed to be smaller, lighter and more powerful for platform mounting. The Swedish designation using the latest chip technology. A future programme is the Cooperative Engagement Centre (CEC) upgrade, which would allow an airborne E-2 to operate as the information centre, fusing information from multiple sources (including sat and shipboard systems), and then distribute data to needed friendly users. Northrop Grumman also has a $155 million contract for engineering development and manufacture of upgrades to the Raytheon Model 940 computer, which will replace the L-304.
Hawkeye was designed to operate at 30,800feet (9,390 metres) altitudes, with operating normal cruise speed of 496 kmph (308 mph). Normal Group 0 operating range is 2,500 kilometres (1,605 miles), with time-on-station 325 kilometres from its carrier being 3.5 to 4 hours, and endurance of some 6 hours, while an extended range version offers over 9 hours. Group 11 aircraft have an on-station time of 4 hours plus operating at 322 kilometres (200 miles) from operating base.
The US Navy's inventory of 139 E-2 Hawkeyes, with a planned total of 154 aircraft, guarantees a long future for the aircraft. Of these, 36-40 of the first one hundred production E-2Cs are Group 0 standard, with 18 Group I aircraft , also scheduled to be upgraded to Group 11 during retrofit. Current fund plans for four new E-2Cs per year from FY 1995 through at least FY 1999. The December 1994 US Navy contract award to Northrop Grumman ($122.5 million) provides long-lead procurement and initial start-up for seven new production Group 11 aircraft, deliveries being from the St. Augustine, Florida plant. Initial deliveries will be four aircraft in 1997 and three in 1998. Continued delays in the services plans for an Advanced Tactical Support Aircraft (ATAS), to handle cargo, electronic warfare, AWACS and other missions on a common airframe, ensures a continuing Navy requirement for more aircraft in the late 1990s. According to US Navy sources, the service plans to procure. a further 36 aircraft in a multi-year contract, which will ensure airframe and sys tem support well past the year 2025.
Ericsson Radar's "Erieye"
A decade ago, then Ericsson Radar Electronic AB (now Ericsson Microwave Systems AB), began development of a phased-array antenna that could fulfill Swedish air defence requirements for a high performance, long-range AEW system, light in weight, enough to utilize relatively small commercial aircraft PS-890, is intended to be an integral part of Sweden's StriC-90 command and control (C2) system. First flight tested in 1990 using a Fairchild Metro III airframe, the system's rigid mounted antenna offers direction-specific airborne target detection at 350 kilometre ranges and surface ship targets a slightly greater ranges. Small cruise missile targets can also be detected at sight under 200-kilometre range, under ideal conditions.
The S-bank frequency-agile pulse-Doppler uses solid-state transmitters and phased-array antenna. According to Ericsson Microwave, "Compared to the more conventional rotodome solution the fixed, phased array antenna gives improved radar performance, higher system availability and . . . provides for easy installation in smaller and less expensive aircraft." Such systems offer high resistance to ECM interference, which may have been an added reason for phased-array antenna selection in view of the high-ECM threat area that existed around the Baltic Sea regions from the then USSR and Warsaw Pact countries. Being mounted on a rigid beam on the upper fuselage deck of the aircraft, the system offers optimal performance in 150-degree side sectors, therefore, it is almost imperative that one knows the likely direction of "threat" to maintain optimal air warning. Like airborne SLAR systems, there remains 'a hole" under the aircraft and in certain forward and rear directions changing aircraft flight directions offers protection in covering these coverage gaps but also raises the prospects of losing continuous coverage of previously detected targets on the prior course.
The radar scanning technique allows for near real-time continuous tracking, as against delays in rotating antenna configurations. The E/F band radar, together with the large aperture antenna is mounted in a 9.7 metre long fairing (radar weight 1,200 kilograms). Clutter is suppressed with no degradation of detection range due to an adaptive waveform and signal processing techniques. The antenna contains 200 solid-state transmit/receiver modules. The track initiation range can be extended in one or more high-priority sectors by increasing the dwell-time in the desired sector(s).
The aircraft system includes two mission consoles (CDCS) and necessary signal processing and datalink black boxes. As fitted on the Metro III, the concept Was based on Ericsson's Airborne Surveillance, Ground Control (ASGC) concept, whereby the airborne platform provides primarily the threat warning and reporting function, processing radar signals onboard and data linking to a central ground control centre for handling aircraft and missile warning, and intercept functions. The existing prototype Metro III has an endurance of 4 to 6 hours, on-station 185 kilometres from operating base. Such a system is probably quite suitable for patrolling straits (Taiwan, Malacca, etc.) and other over-water bodies of water (Arabian Sea, etc.) from where known threats are likely to come.
The more extensive Airborne Surveillance, Airborne Control (ASAC) system is designed to provide autonomous C2 capability, with four consoles to handle more traditional AWACS mission functions. Fitted onboard a Saab 340 aircraft, the large aircraft has 7 to 9 hours on-station time at 185 kilometres from operating base. Another proposal is fitting a larger antenna onto a Fokker 50 (designated KingBird Mk.2E) aircraft and even large antenna could be fitted to C-130 category aircraft. The latter platforms are more likely to appear to countries with larger national borders and sea frontiers to patrol, including Pakistan, India, Indonesia, Malaysia, Thailand, and South Korea (ROK) in Asia. While four aircraft are currently under test or design proposal, the Erieye would seem adaptable to a number of other commercial aircraft platforms, including the Jetstream 41 and -61 (ATP), Donier 328, Hawker Siddeley HS -748, and de Havilland Canada Dash8 (larger aircraft, such as Saab 2000 or C-130s, could be adopted with larger antenna systems). Farnborough 1990 also demonstrated a concept drawing of a Bell-Textron V-22 Osprey VTOL fitted with Erieye, a fitting that should have great appeal for the Royal Navy's VSTOL carriers, as well as in Italy, Spain and elsewhere.
In January 1992, Sweden's Defence Material Administration (DMA) authorized a Saab 340B aircraft conversion, which first flew in mid-January 1994. The Government took options for five more aircraft, which has since been taken. Tests with Erieye mission system installed will begin next year with two Erieye systems due for delivery during 1996, with first aircraft IOC due the same year. Ericsson Microwave contracts are valued at 1,200 million SwCr ($200 million) from this order. Final delivery will be in the late 1990s. Brazil has become the first export customer, ordering the system to be fitted to five Embraer 120 aircraft - comparable with the Metro III installation. The Brazilians will integrate the aircraft into the SIVAM air traffic and air defence system, mostly over the Amazon regions.
Pilatus Britten-Norman
The Pilatus Britten-Norman Defender 4000 is largely a maritime or overland surveillance aircraft but can be configured with external AEW warning radars, having been tested with a pod mounting similar to the Thorn EMI Electronics "Searchwater" system used onboard eight Royal Navy SeaKing AEW.2 helicopters. In addition, the nose structure has been designed to accommodate a high-performance 360-degree rotating antenna. In the AEW configuration, internal space is sufficient for two consoles and operators on one cabin side, and easily reconfigured for the light transport mission with 16 seats or paradrop fittings. The aircraft is already widely used in Europe, Africa and Asia, including recent acquisition by Pakistan's Maritime Safety Agency (MSA) for offshore patrol work.
More to the missions described above is the BN2T conversion to Multi-Sensor Surveillance Aircraft (MSSA) configuration, whereby the nose is highly modified to accommodate a Westinghouse APG66SR radar. The planar array antenna is 2.5 times larger than the fighter version, and therefore offers ground surveillance, mapping and moving target indicator (MTI) features. In addition, the radar has four maritime surveillance mode, design for detecting, identifying and tracking small craft (including wooden craft). In the air-to-air surveillance mode, the radar can track upto 148 kilometres (80 nautical, miles) under ideal conditions, with capability to maintain records on 100 airborne targets and data link detections into a ground-based air defence command centre.
The onboard surveillance console is at the rear of the aircraft, using common Microsoft Windows to display multiple images on a single screen. The map display can be augmented by an FLIR system, if fitted to the aircraft. While the aircraft was not intended as a primary AEW platform, the aircraft is intended for ground and maritime surveillance - in both civil and military usages. However, the aircraft is being considered for lease or purchase by the US Army to replace OV-1 Mohawks for surveillance along the Demilitarized Zone (DMZ) border between North and South Korea. If the Army retains this mission (which is not clear it will), a decision which will be taken under FY 1996 funding. While capable of detecting high flying aircraft, its normal operating altitude makes the aircraft better placed in detection of low-flying targets - and in the Korean DMZ region, this mean North Korean AN-2 Colt and MD 500 helicopters! The high hills and low valleys that dominate much of the border are ideal for penetration below normal radar surveillance, giving the MSSA aircraft a unique crisis and wartime mission, if adopted for either the US Army or by the South Korean military. In other Asian regions, the aircraft would also have great potential in the Karakoram mountains and the Eastern border regions of India, as well as Thailand's borders adjacent to Myanmar, Cambodia and Laos.
This survey only provided broad capabilities of each of the aircraft discussed and has not focused on the successful track record developed by existing AWACS aircraft in both war and peacetime operations. In conclusion, the best thing to remember is a quote from former Australian defence minister, Kim Beazley: "It's simple, with AEW&C you win the air war . . . without AEW&C, you lose it!"
Australia's "Air 5077"
Australia has revived earlier plans for a new Airborne Early Warning & Control Aircraft (AEW&C) and a project definition study, "Air 5077" was approved last year. The requirement will be defined in terms of operational capabilities and other issues, with the objective that a project can be included in during the 1996-97 budget years.
Whatever requirements are established, they will be in consort with the nation's Jindatee Over the-Horizon Radar Network (JORN) system. The latter provides long-range surveillance capabilities but lacks some necessary close-in capability and is unlikely to be of broad use in aiding maritime forces in tactical situations. While some Australian legislators have argued JORN was sufficient,operational commanders do not concur. The key is to get an aircraft that will meet endurance and airborne C2 needs operating in the Northern Territory region alongside No. 75 Squadron's F/A-18 aircraft, with sufficient ability to also control strike operations by F-111C aircraft. First operational base is not likely to be "in the bush" at RAAF Base Tindal, but it must be within reasonable flying distance for ease of operations into the region. As Australian Aviation (June 1983) noted, "There is only one way of policing-such a vast area as the North, in wartime or peacetime, that being via the use of AEW."
The Air 5077 will be development in concern with other defence programmes, and not just as a Royal Australian Air Force (RAAF) programme. As such,it will take into consideration Navy requirements for maritime surveillance and possibly some Army interests in airborne C3 with regard to special forces operations. The 1994 Australian White Paper endorsed the airborne AEW&C concept. Assistant Air Chief of Staff Material Air Vice Marshal Bill Collins has noted a Requirements Definition Study should be followed by a similar "project" study - all of which could take another year or so to dust off old studies!
Former defence minister Beaziey's preference may have been for utilizing new planar array or phased-array technologies - to the detriment of already popular rotodome systems - but uniformed officer preferences may think otherwise. In the case of both RAAF and RAN experience, these officers have wide-ranging experience during joint exercises with American E-3 Sentry and E-2 Hawkeye aircraft. And, all alternatives from Sweden, the United Kingdom and Israel, remain essentially untested and would require far more years to place in service.
Who might be the leading contenders? First, the platform probably would have commonality with some of Australia's current civil or military equipment. Leading candidates are considered to be the Lockheed P-3; Lockheed C-130 and Northrop Grumman E-2C Hawkeye. Not far behind candidate is the Boeing E-767 or at the lower-cost spectrum, a Saab 340 variant. "Commonality", combined with cost, will rule the day.
Australian officers already have extensive operational experience with P-3 and C-1 30s, which have differing models of Allison T-56 turoprops, while the same basic powerplants is used on the E-2C. Other RAAF officers have experience with US Air Force E3 Sentrys during exercises, while the Boeing E767 offers similar system capability, acquisition of new airframe and engines becomes an issue. The RAAF has already committed to keeping and upgrading five Boeing 707 tanker/transports, but has had flight training programme deficiencies and is may be less than enthused about acquiring a new aircraft which the RAAF is not familiar with.
Both P-3 and C-130 can recent to transport configuration for disaster relief and other peacetime missions, but the clear edge goes to the Hercules for this secondary mission (and the RAAF has opted for C-13OJ Hercules 11 aircraft to replace "E" models).
The twin-engined E-2 Hawkeye is a premier platform in conducting maritime surveillance as well. Needing not to repeat what has been said before, 'The E-2C offers a lot of advantages that the RAAF did not fail to observe. It has a powerplants commonality with the P-3 Orion and the C-130 Hercules, both major types in the RAAF inventory. All employ the Allison T-56. Being built for US Navy carrier operation, the E-2C has a rugged undercarriage and airframe, allowing for rough field operation. This is enhanced by full prop pitch reversal. E-2Cs operated by the USN are usually parked on the carrier flight deck, exposed to the elements; the aircraft was designed to cope with prolonged exposure to a hostile environment, which will enhance its lifetime in a less demanding land-based role.
"As the E-2C is the key element in the USN's air defence system . . . at a current cost advertised as US $33.6 million, the. E-2C is a very good buy. It can offer the RAAF a whole new dimension in air to air operations, bolstering the capabilities . . . the F/A/-18's effectiveness in the air defence role hinges on the E-2C, it was designed from the outset to interface with it. If the USN regards the E-2C/F-18 combination as adequate to defend its naval forces from aerial and surface threats, in high density environments, it is fair to assume these types can tackle any regional threat which may appear in the near future" (Australian Aviation, June 1983, p. 84).
AEW by helo:
Thorn EMI's "Searchwater"
Thorn EMI Electronics Ltd. met the demands for an airborne 360-degree search radar that could be deployed onboard Royal Navy "Invincible" class VTOL aircraft carriers, which are unable to handle conventional takeoff and landing aircraft. As a direct result of the Navy's experience during the Falklands/ Malvinas War in 1982, which saw extensive penetration of fleet task forces by land-based strike aircraft, two Westland Sea King helicopters were fitted with modified "Searchwater" radars.
The installation onboard the Sea King helicopter involves two side-by-side consoles. The helicopter installed system is a modified AEW version; standard surface search radar is installed in Nimrod MR.2 aircraft. The system has frequency agility, pulse compression, a ground stabilized tactical display, pitch and roll stabilized antenna, a Racal MIR2 (Orange Crop.) electronic support measures (ESM) and an integrated Cossor 3570 IFF system. Return signals in near real-time are handled in the digital computer for automatic tracking and analysis on tracks, with the radar operator presented with A and B-scope and TV-type PPI scope presentations. Weather and navigation presentations can be overlaid onto track-while-scan screen presentations. Racal Doppler 91, Racal RNS-252 tactical navigation computer, Smiths/Honeywell AN/APN-1 98 radar altimeter, Homer Cheiton 7 system, Rockwell-Collins AN/ARC-182 and HF-9000 HF radio system comprise the standard helicopter equipment fit. A four-man crew includes two flight officers and two console operators, with a maximum takeoff weight of 9,707 kilograms (21,400 lb).
The Royal Navy 849 Squadron operates 8 Sea King AEW Mk.2 helicopters, deployed in three helicopters per aircraft carrier when deployed. The 13 airframes (which also comprises 3 HAS.5 conversions from Culdrose storage and No. 771 Squadron) on hand will be upgraded to AEW.7 standard beginning this year, to include a Radar System Upgrade, IFF Mode 4 Combined Interrogator/Transponder, ring laser/GPS gyro and integrated JTIDS/Link 16 system. The Spanish Navy ordered three Searchwater radars for outfitting on SH-3H helicopters, conversion work being conducted by CASA. These helos operate with Escuadrilia 005 onboard VSTOL carrier Principe de Asturias, with two deployed onboard at any one time and one kept at Rota.
SeaKing flight performance characteristics dominate tactics and employment, with helicopters normally deployed 150-185 kilometres at 2,000-3,000 metres altitude from task forces they are intended to provide alert for. Direct overhead time-on-station can be upto 4 hours; however, 2 hours is a more practical flight time at a standoff range of 185 kilometres in order to provide reasonable warning time against attack aircraft or anti-ship missiles.
Back to