Sweeping the Skies

Saab is looking for customers for its GlobalEye SRSS with potential interest from Indonesia and Malaysia. (Saab)

Guarding economic zones and watching for incursions, either temporary or as part of a deliberate strategy, has raised the need for wide area and long-range airborne surveillance.

Airborne surveillance and airborne early warning and control (AEW&C) aircraft provide an invaluable force multiplier, improving the combat effectiveness of other assets, and thereby helping smaller air forces to meet some of the challenges posed by the numerical superiority of People’s Republic of China’s air arms. Most traditional AEW&C and AWACS (Airborne Warning and Control System) aircraft also provide some capability to monitor the maritime environment, and can provide warning of possible enemy ballistic missile attacks, making missile defence systems more effective.

Some newer AEW aircraft, like Saab’s innovative GlobalEye swing role surveillance system (SRSS), have a more robust multi-role capability, using electro-optical (EO) sensors and a dedicated surface search radar in addition to the primary airborne surveillance radar sensor. In the case of the GlobalEye, the Erieye ER AESA radar, mounted in a ‘skibox’ radome above the fuselage, is augmented by a FLIR Systems Star Safire 380HD EO/IR turret and an under-fuselage Leonardo Seaspray 7500E radar. The GlobalEye’s multiple sensors allow it to detect and track stealthy airborne targets and small maritime targets, including jetskis and rigid-hulled inflatable boats (RHIBs).

With China’s claims in the South China Sea increasingly impinging on the economic interests and security of its neighbours, and with increased Chinese military activity across the region, there is a growing need to monitor Chinese military operations on the surface, and particularly in the air. Chinese efforts to gain an anti-access/area denial (A2/D2) advantage make it especially important for other nations to be able to conduct surveillance at very long range, where possible.

In the northern part of the region, North Korea poses a more immediate threat than China, especially through its growing ballistic missile capability. This has led to South Korea establishing an AEW aircraft fleet while Japan has reinforced and modernised its AWACS capabilities.

In South Korea the Republic of Korea Air Force (ROKAF) operates four Boeing 737AEW&C Peace Eye aircraft. The first aircraft was delivered to Gimhae Air Base, Busan for acceptance testing on 1 August 2011. The remaining three aircraft were modified by Korea Aerospace Industries (KAI) at Sacheon, and were delivered every six months between December 2011 and October 2012.

The Boeing 737 AEW&C is equipped with Northrop Grumman Multirole Active Electronically Scanned Array radar which can cover an area of 340,000 square miles, scanning at rates exceeding 30,000 square miles per second. Particular sectors of interest can be monitored with extended range and update rates while the radar maintains a 360 degree background surveillance picture. Up to ten battle space managers can be carried on board.

It has been reported that South Korea may augment its Peace Eye aircraft with the smaller Gulfstream 550 MARS2, the Multi Mission Airborne Reconnaissance System, developed by Israel Aerospace Industries (IAI) for persistent stand-off surveillance of the ground, maritime and air domains, using an ELI-3150 system, consisting of an Elta Active Electronically Scanned Array (AESA) radar with a 360-degree coverage, and synthetic aperture radar (SAR)/ground moving target indicator (GMTI) capabilities. This is augmented by an EO/IR sensor and a ‘proven’ SIGINT (Signals Intelligence) package.

The Republic of Korea Air Force (ROKAF) is operating four Boeing Peace Eye 737 Airborne Early Warning and Control (AEW&C) aircraft.

Japan acquired thirteen Northrop E-2C Hawkeye aircraft, which entered service with the Japan Air Self-Defense Force’s Airborne Early Warning Group (AEWG) at Misawa Air Base in January 1987, forming the 601st Squadron.

The E-2C’s limited radius led the Japan Defence Agency to request funds for the procurement of the Boeing E-3 Sentry in 1991, but this was out of production. The following year, Boeing proposed a Boeing 767-based AWACS, using the same Northrop Grumman (formerly Westinghouse Electronic Systems) AN/APY-2 Passive electronically scanned array radar and mission systems as the Block 30/35 E-3. Japan ordered four E-767 aircraft and these were delivered from March 1998, entering service with the Airborne Early Warning Group’s 602nd Squadron at Hamamatsu Air Base in May 2000.

The AN/APY-2 is a Pulse-Doppler radar providing a three-dimensional ‘picture’, measuring azimuth, range, and elevation simultaneously, with superior surveillance capability over water compared to the AN/APY-1 system used on earlier E-3 models. The radar antenna is installed back-to-back with the antenna for the Identification Friend or Foe (IFF) Mk XII system. The rotodome rotates at around six revolutions per minute (rpm) during operation and at 0.25rpm when the radar is not being used, in order to lubricate the mechanism.

In November 2006, Boeing was awarded a $108 million contract to deliver Radar System Improvement Programme (RSIP) kits for Japan’s E-767 aircraft, bringing them to much the same standards as the USAF’s upgraded E-3s.

The Republic of China (Taiwan) acquired four E-2T aircraft from the US on 22 November 1995, using these to provide wide area surveillance of the Taiwan Straits, East and South China Seas.

On 15 April 2006 Taiwan ceremonially inducted two new aircraft in Hawkeye 2000 configuration (designated as the E-2K) at Pingtung, with new radars and software. In 2010-2013, the RoCAF’s four original E-2Ts were upgraded to the same E-2K standards.

Several of the ‘frontline states’ with competing claims in the South China Sea do not currently have a robust AEW&C capability. Indonesia operates three ageing Boeing 737 Surveillers, which have a surface-only surveillance capability using the AN/APS-135 (V) high resolution Side Looking Airborne Modular Multi Mission Radar (SLAMMR) but lack any datalink or air surveillance capability. The Tentara Nasional Indonesia-Angkatan Udara (TNI–AU), or Indonesian Air Force, is known to have evaluated Saab’s GlobalEye and Boeing’s Challenger-based Maritime Surveillance Aircraft (MSA).

Malaysia has an unfunded requirement for up to four AEW aircraft, and has also been targeted by Saab as a potential customer for the GlobalEye, but the Malaysian government’s budget constraints have prevented the launch of a formal procurement process.

The Vietnamese Air Force has long been expected to be the launch customer for the Airbus C295 AEW&C aircraft, which made its first flight in June 2011, and press reports suggest that two aircraft have been ordered.

The C295 AEW&C is equipped with a mission system developed jointly by ELTA and Airbus based on an IAI/ELTA fourth-generation active electronically scanned array (AESA) radar with integrated identification friend-or-foe (IFF) in a fast-rotating rotodome mounted on top of the fuselage. The aircraft has four operator workstations.

In its Airborne Early Warning version, The Airbus C295 AEW aircraft carries a state-of-the-art AESA radar for 360-degree coverage (Airbus).

The Republic of Singapore Air Force was an early regional operator of AEW&C aircraft, purchasing Grumman E-2C Hawkeye aircraft in 1987. These were assigned to No.111 ‘Jaeger’ Squadron at Tengah.

In April 2007, Singapore announced that the four E-2C Hawkeyes would be replaced by four Gulfstream G550 Nachshon Aitam early warning aircraft. These are also known as the G550-EL/W-2085 CAEW (Conformal Airborne Early Warning) aircraft. The new aircraft officially took over from the Hawkeyes in 2011, re-equipping No.111 Squadron.

An E-2D Hawkeye assigned to Carrier Airborne Early Warning Squadron (VAW) 125 and four F-35 Lightning II aircraft assigned to Marine Fighter Attack Squadron (VMFA) 121 fly in formation during Exercise Balikatan 2019. (US Navy)

The G550 carries semi-conformal L-band AESA radar antennae on the left and right sides on the fuselage and S-band antennae in the nose and tail. The phased array radar allows the picture to be updated every 2–4 seconds, rather than every 20–40 seconds as would be the case with a traditional mechanically steered AEW array.

Thailand also enjoys an independent AEW capability, employing a pair of Swedish-supplied S100B Argus AEW aircraft, equipped with the Erieye radar, and sometimes referred to as Erieyes. Three Saab 340s were taken from the Swedish inventory and were supplied to Thailand as a “no cost option” via Sweden’s Defence Materiel Administration (FMV), accompanying Thailand’s purchase of the Saab Gripen fighter. Two of the Saab 340s were equipped with the Erieye airborne early warning (AEW) radar.

The first AEW platform and the transport aircraft were flown to Surat Thani Air Base in southern Thailand in December 2010, with the second arriving in mid-2012. These equipped 702 ‘Orca’ squadron.

The Erieyes are operated by a crew of five, consisting of two pilots, a radar operator, a radar technician and an aircraft technician – relaying information to a ground station using the Swedish-supplied Link T system.

Australia issued a request for proposals (RFP) for an AEW&C aircraft for the RAAF under Project Wedgetail, in 1996, and ordered four Boeing 737 AEW&C aircraft in 1999. Australia subsequently exercised two additional options.

The aircraft, known as the E-7 Wedgetail in Australian service, carries a Northrop Grumman Electronic Systems L-band (1-2GHz) Multi-role Electronically Scanned Array (MESA) radar, whose antenna is carried in a dorsal ‘top hat’ radome mounted above the fuselage.

After a delay of around two days, Boeing delivered the first two 737 AEW&C aircraft to the Royal Australian Air Force on 26 November 2009, though they initially remained Boeing owned and operated, until they were accepted into service on 5 May 2010. Deliveries continued until June 2012, when the sixth Wedgetail was delivered to No.2 Squadron at RAAF Base Williamtown. The squadron maintains a permanent detachment at RAAF Base Tindal. The RAAF’s Wedgetail achieved Initial Operational Capability in November 2012, and Final Operational Capability (FOC) on 26 May 2015. The type saw operational service during Operation Okra, flying more than 100 sorties in the fight against Daesh.

Locally owned AEW&C aircraft are augmented by platforms from US and other allied forces, including carrier-borne US Navy E-2D Hawkeyes, and land-based E-3 Sentries. These include the E-3s of the 961st Airborne Air Control Squadron, part of the USAF’s 18th Wing based at Kadena AB, Japan since 1979.

China has made great efforts to field its own AEW aircraft, launching a series of programmes. This has resulted in the fielding of a succession of different designs, usually in small numbers.

The Y-8J airborne early warning (AEW) variant of the Y-8 (Project 515) was first spotted near Shanghai in 2000, using a British Racal Skymaster surveillance radar housed in an enlarged, partially dropped nose radome. With a range of 400km and an ability to track up to 100 targets, the Y-8J also has four operator workstations. Four examples were delivered to the PLAN, and these fly missions over the East China Sea facing Japan.

The Y-8W (also known as the KJ-200/200A Moth/High New 5) is based on the new Y-8 “Category III Platform”, like the Y-9 transport, and has a new AESA antenna in a so-called ‘balance beam’ radome mounted above the fuselage, like the Erieye’s Skibox antenna. At least five Y-8Ws have been delivered to the PLAAF and six to the PLAN. The derived ZDK-03 (Y-8P) was developed for the Pakistani Air Force with a traditional rotodome on top of its fuselage, housing a mechanically-rotating PESA radar antenna inside, scanning electronically in elevation and mechanically in azimuth. The Y-8P prototype flew to Pakistan and was evaluated by Pakistani AF in 2006, and the four production ZDK-03s were delivered from December 2011 to 2015.

The ‘balance beam’ antenna configuration was abandoned for China’s next AEW&C aircraft, the KJ-500 (also known as the High New 10). This is based on the Y-9 platform using some KJ-200 hardware but with a new fixed disc-like radome. This contains three AESA antennas arranged in a triangular configuration, providing full 360° coverage.

Two KJ-500 prototypes were constructed by late 2013, and at least seven have been delivered to the PLAAF with five more going to the PLAN.

As well as its turboprop-powered AEW aircraft, China has also developed two jet-powered aircraft. The first was the KJ-2000 prototype, which was produced by the conversion of four China United Airlines Il-76MD transports. Further production was impossible due to the limited quantity of available Il-76 airframes. The AEW version was based on the cancelled A-50I/Phalcon, whose prototype was salvaged from Israel via Russia in 2000. The aircraft is fitted with an indigenous AEW and C4ISR system developed by the Nanjing Research Institute of Electronic Technology/14th Institute. The radar is similar to the Israeli Phalcon system and uses a fixed rotodome housing three AESA antennas in a triangular configuration. The first two KJ-2000s were handed over to PLAAF in 2005, and the design was certified in 2007. The four KJ-2000s are stationed in Jiangsu Province. A new KJ-3000 is reportedly under development, based on the indigenous Y-20 transport aircraft.

China’s 603 Institute/XAC has developed a new shipborne AWACS aircraft which is similar in size and configuration to the American E-2D. The H-600 is based on experience gained in the earlier JZY-01 technology demonstrator programme. The aircraft uses a single mechanically rotating AESA antenna inside a traditional rotodome, but the status of the programme is unknown.

by Jon Lake