Saab’s Erieye radar has proved to be an affordable, adaptable and versatile airborne early warning platform for several operators. Jon Lake details this system and its latest application in the new GlobalEye.
Saab’s innovative Erieye airborne early warning and control system (AEW&C) achieved perhaps its greatest success to date in 2015, when the United Arab Emirates announced it had selected the GlobalEye. This latest-generation AEW&C platform is arguably one of the Swedish defence giant’s greatest products – combining the Global 6000 business jet with Saab’s new Erieye Extended Range (ER) radar to meet a long-standing requirement for a surveillance aircraft.
The UAE selected the GlobalEye (with the latest version of the Erieye radar) over the Boeing 737 AEW&C (known as the E-7A Wedgetail in Australian service) and Northrop Grumman’s E-2D Advanced Hawkeye because “it was the best” according to Abdulla al Hashimi, the executive director for UAE military communications.
More recently, however, the Boeing has enjoyed something of a resurgence, being selected by the RAF to replace its ageing Boeing E-3D Sentry AWACS aircraft. The Erieye of ering was rejected without a formal evaluation.
In a letter to Julian Lewis MP, the chairman of the Parliamentary Defence Select Committee, on November 1, 2018, Stuart Andrew, then Minister for Defence Procurement, wrote: “In considering the E-7 Wedgetail there was such a clear distinction over any other options it was felt that running any type of competition would unnecessarily consume MOD [Ministry of Defence] and industry resources.”
UK Sentry Force insiders said while the Erieye of ered interesting multirole capabilities, its inability to provide 360° coverage without ‘blind spots’ made it operationally unacceptable. A business-jet-based solution, such as the GlobalEye, was rejected because the number of operators was said to be insuf icient to provide the command and control (C2) capabilities required by the RAF. This forced Saab to of er an Airbus A330 MRTT Voyager-based solution, which struggled to overcome perceptions of risk.
Looking ahead, there will be interest in how the GlobalEye performs in service – if this ever becomes widely known, given the UAE’s penchant for secrecy.
The GlobalEye is the latest member of the Erieye family and is very dif erent to the original Erieye-equipped Saab 340. These dif erences go beyond those associated with the performance characteristics of the aircraft platforms themselves, and between the original radar and the new ER (Extended Range) derivative used by GlobalEye. The very concept of the original Erieye was markedly dif erent to traditional AEW&C aircraft, which tend to operate with a high degree of autonomy and carry their own surveillance operators and fighter controllers.
By contrast, the original Erieye – developed for the Swedish Air Force – was seen as a mobile radar in the sky that would be integrated with the total air defence network. It fed its radar ‘picture’ to operators and controllers on the ground, with only a radar technician and pilots on board the aircraft. The intention was to plug ‘gaps’ in the coverage provided by Sweden’s network of ground-based radars, or if part of the ground-based air defence radar network was out of action. The use of an airborne radar also promised to extend the overall reach of the system.
In 1985, the Swedish Defence Materiel Administration (FMV) contracted Ericsson Microwave Systems to develop what became the PS-890 Erieye AEW radar. A mock-up dual-sided phased array antenna was test flown on a Fairchild Metro aircraft before a real radar was installed for flight trials from 1987.
For the production Erieye system, Saab built the aircraft (Saab 340s, known in Swedish Air Force service as the TP 100), while the radar system was supplied by Ericsson and FMV was responsible for integration.
Six aircraft were ordered for the Swedish Air Force, and the original plan was to base two aircraft with each of three radar flight groups spread across the country.
In the end, only four aircraft were fitted with radar, and two were given provision for, but were not fitted with, the radar. These two were instead used for transport missions during peacetime or until a need for more airborne radars materialised. In 1995, it was decided that the Saab 340 AEW&C would be designated as the S 100B Argus (or as the FSR 890), to dif erentiate it from the transport TP 100.
The first two production radars were delivered in 1996 for final testing of the system in its series production form, and the complete system was handed over to the air force in 1997.
The Ericsson PS-890 Erieye radar is an electronically scanned, S-band, 3GHz, side-looking radar, which uses an active array with 192 solid state transmit/receive modules. The Erieye was the first AEW radar to use an active electronically scanned antenna.
The 1,985lb (900kg) dorsal antenna is housed in a 29ft 6.3in (9m) long, plank-like radome mounted on top of the fuselage. The radar beam can be steered as required within a 150°-160° sector on each side of the aircraft (one side at a time). Outside these sectors, performance is reduced in forward and aft directions. Erieye has some ability to detect aircraft in the 20°-30° sectors fore and aft of the aircraft heading but has no track capability in these sectors.
From its standard operational altitude of 20,000ft (6,000m) the radar has a claimed maximum range of 450km (279 miles) against “a range of air and surface targets” The air force cites a detection range of more than 243nm against airborne targets, and up to 173nm for surface ships. Fightersized targets can be detected out to about 200nm. Cruise missile-sized targets can be seen from 108nm, and the Erieye radar has a claimed ability to detect hovering helicopters. The aircraft’s IFF (interrogation friend-orfoe) system has a range of more than 270nm, and the system is capable of tracking up to 1,000 airborne and 500 maritime targets simultaneously.
Most vitally, the major advantage of Erieye’s electronically scanned antenna is that it allows sectors of interest to be scanned very frequently, while others are still being monitored, and the same sector can be scanned in dif erent modes at the same time.
Brazil was the first international customer for Erieye, but chose to mount the system on the Embraer ERJ-145LR, giving rise to the EMB-145 AEW&C or EMB-145SA (surveillance aircraft). Unlike the S 100B Argus, the EMB-145SA has consoles for use by on-board fighter controllers. The aircraft made its maiden flight in 1999 and entered service in 2001. It was known locally as the R-99A but was redesignated as the E-99 from 2008. The five E-99 Erieyes are not to be confused with three R-99 SIGINT (signals intelligence) Embraer 145RSs. The Força Aérea Brasileira (Brazilian Air Force, FAB) claims the E-99 has 95% of the capability of larger AWACS aircraft. Five were built for the FAB and one for export to Mexico. The Brazilian aircraft are currently being upgraded to E-99M standard.
Greece ordered four similar aircraft, locally designated as the Erieye EMB-145H AEW&C, in 1998, but also leased two S 100B Argus aircraft from the Swedish Air Force from 2000, to allow the Hellenic Air Force (HAF) to gain experience of operating the Erieye radar. These aircraft served with 380 Mira at Elefsis air base from September 2001 until 2004. The first EMB-145H was delivered to Ericsson Microwave Systems in Sweden where the Erieye radar and associated systems were fitted before being delivered to Greece in 2004.
The two S 100B aircraft leased to Greece were modified, gaining two onboard operator consoles, as well as NATO IFF, communications and data links. Swedish ECCM equipment and a cockpit display to show uplinked processed information from Swedish ground stations were removed.
Following their return to Sweden, the aircraft were further modified, gaining another operator console and Link 16 and NATO-standard IFF systems from 2006, in order to allow them to operate away from Sweden on international missions. The updated aircraft were redesignated as the ASC 890 (and as the S 100D), and re-entered service with F 7 Wing at Såtenäs, though they actually operated from Malmen air base.
The ASC 890s are used to monitor the growing military air activity over the Baltic from both east and west. One is kept on a permanent ground alert, ready to launch within 30 minutes. Real-world launches are conducted several times a week. The aircraft use the radio callsign ‘Skibox’ due to the shape of the radar array’s distinctive fairing.
Thailand announced an intention to buy two S 100Bs from the Swedish Air Force in November 2007, and these were delivered in December 2010 and October 2012, while Saab revealed the UAE had placed an order for two Saab 340-based AEW aircraft in November 2009. These were intended to provide a ‘gap-filler’ surveillance capability while the UAE conducted longer-term assessments on more capable aircraft.
The Royal Thai Air Force Erieye aircraft operate with a five-man crew – two pilots, a radar operator, a radar technician and an aircraft technician. These relay information to ground stations using the Swedish Link T system. The Emirati aircraft are believed to have been equipped with consoles for at least one onboard fighter controller. Both Thailand and the UAE each took one existing S 100B and one of the S 100B aircraft used as transports by the Swedish Air Force, though all four were delivered with the Erieye radar installed.
Saab 2000 Erieye
The need to incorporate onboard operator consoles led Saab to of er an Erieye mounted in the larger Saab 2000, using converted surplus airliners. The first customer for the Saab 2000 AEW&C may have been what Saab coyly refers to as ‘Country X’ – now widely known to be the Royal Saudi Air Force. Sweden and Saudi Arabia signed a memorandum of understanding to begin ‘military co-operation’ in late 2005. Delivery dates for the two Saudi aircraft remain unknown, but they are believed to be allocated to 60 Squadron at Prince Sultan Air Base, Al Kharj.
Pakistan ordered four Saab 2000-based Erieyes in 2006, and the first was delivered in December 2009, with the remainder following in 2010. The Pakistan Air Force had initially planned to acquire six aircraft, but instead augmented its Erieyes with less capable Chinese KE-03/ZDK-03 Karakorum Eagle AWACS aircraft, based on the Shaanxi Y-8F-600 four-engined turboprop transport. These were ordered in 2008 and delivered from 2011.
The Pakistani Erieyes serve with No 3 (AEW) Squadron, part of No 33 (Tactical) Wing at Minhas. One aircraft was destroyed, and two more were badly damaged during an attack on Minhas by nine members of the Tehreek-e-Taliban Pakistan (TTP) group in August 2012. The two damaged aircraft were returned to service following a domestic rebuild, testing and certification programme undertaken by the Pakistan Aeronautical Complex (PAC). The PAF returned the first aircraft to service in 2015 and the second in 2016. Pakistan ordered three further Saab 2000-based Erieye aircraft in May 2017, and deliveries began in December 2017.
The UAE finally ordered a bespoke Erieye system in November 2015, but opted for the new, extended range Erieye ER version of the radar as it became the launch customer for the GlobalEye. The UAE calls the resulting aircraft a Swing Role Surveillance System (SRSS) and two aircraft were originally ordered under a US$1.27bn deal, with a third added in February 2017 for US$238m. The first GlobalEye made its maiden flight at Linköping, Sweden, on March 14, 2018, and a second followed on January 3, 2019.
Pair of GlobalEyes
The UAE announced plans to procure a further pair of GlobalEyes on November 19, 2019, during the Dubai Airshow. Saab said it will enter negotiations and that it has not yet signed the contract amendment or received a formal order relating to the announcement, but the agreement has an estimated cost of US$1.08bn.
The Erieye ER uses gallium nitride technology, can detect smaller and faster targets, and has 70% more range than the original. The antenna fits inside the same roof-mounted radome as the original Erieye. Unlike earlier platforms, the GlobalEye is a multi-sensor system that is additionally fitted with a Leonardo Seaspray 7500E X-band maritime search radar, a FLIR Star SAFIRE electro-optical sensor, as well as AIS (automatic identification system), and IFF/ADS-B systems. Its baseline configuration features five onboard operator stations.
Saab examined the option of providing full 360° coverage, but found it of ered limited operational benefit for the additional cost. Its omission allows the ER radar to fit into the existing dorsal fairing. Despite the UK’s recent selection of the rival Wedgetail and the implied criticism of the Erieye, each solution of ers advantages, and operators are likely to favour one or the other depending on their requirements.
While the 737 may represent a better pure AEW&C platform, with its larger mission crew giving it an enhanced C2 capability, the GlobalEye (and other Erieye ER solutions) arguably provide superior multi-role and multi-domain surveillance performance, adding robust overland and maritime capabilities. Some have characterised the competition between the 737 AEW&C and the GlobalEye as being between a niche air defence/ABM (airborne battle management) capability on the one hand and a broader-based and more versatile cross-domain surveillance tool on the other.