The UK Royal Navy is set to make a quantum leap in its airborne early warning capability



The UK's Royal Navy is on course to field a revolutionary airborne early warning (AEW) helicopter early in the next century. It will allow the RN to fight in the so-called digital battlespace alongside allied navies and air forces.

"The Sea King AEW Mk7 solution is a new system that will allow us to deal with more than 600 tracks at a time," says Lt Cdr Stan Hargreaves of the RN/Defence Evaluation and Research Agency (DERA) project team. "Our old Sea King AEW Mk2 is operator intensive, and the crew have difficulty tracking more than 10 contacts at a time. The aircraft has no datalinks, so it has to pass all its information verbally by radio. Sometimes, the old Mk2s are just told to go away when working with datalinked assets, such as the [Boeing] E-3 AWACS [airborne warning and control system] and [Northrop Grumman] E-2 Hawkeye, because their track data is often out of date by the time it reaches other players."

Work on the Mk7 programme is advanced, with the first flight trials to take place at DERA's Boscombe Down test centre in September and full mission system trials to begin next year.

Although a date has not been made public, the RN expects to have its 10 AEW Sea Kings re-equipped with the new Searchwater 2000AEW radar system by early in the millennium. Racal Radar Defence Systems is prime contractor, with GKN Westland Helicopters a major subcontractor to install the new radar and other elements of the mission system.

Inadequate land-based AEW

The RN's current AEW force was fielded in just 11 weeks in 1982, at the height of the Falklands War, after five warships and a merchant vessel were lost to surprise Argentinean air and missile attack. DERA's Colin Richardson was one of the original radar operators, or observers, on the first Mk2s. The lesson of the Falklands War was that land-based AEW assets were inadequate. "We didn't have any with the range to reach the Falklands," Richardson says. "Commanders at sea need control of their own AEW assets."

Since then, the RN has relied on the Mk2, which features a Thorn-EMI Searchwater radar, mounted on the starboard side in a rotating inflatable radome, for its seagoing early warning capability. "Many people think that the Mk2 is obsolete," says Richardson. "At the time, it filled a gap in our capability, but we are working in the digital world. We need to be interoperable with the wider AEW community, so we have to have datalinks."

Littoral operations, close to hostile shores, are increasingly in vogue, so improvements to the Sea King AEW's radar were also required to allow it to track overland targets as well as surface ships. The old Searchwater was optimised to deal with a small number of airborne targets over water, which limited its utility in recent operations in the Gulf and the Balkans.

The RN has been looking to upgrade the Mk2 almost since the day it was introduced. In 1997 a contract was issued to Racal to field the Mk7. The new equipment to be installed includes a high-powered pulse Doppler radar, integrated with MkXII identification friend or foe and inertial/global positioning navigation systems, NATO standard Link 16 datalink and a new suite of consoles, termed the man-machine interface (MMI).

The core of the system is the new radar, which allows almost simultaneous use of different types of radar beams. This means that a variety of target types can be tracked at the same time. The system can normally use three beams, says Hargreaves. One can be high level, looking for hostile, high-flying, surveillance aircraft; another can operate at low level, seeking out enemy missiles or attack aircraft; and a third beam can survey the maritime picture.

The radar sweeps through the three bars and maintains contact with the tracks, then displays it to the operators so that the array appears seamless. The Searchwater 2000AEW has evolved from the version used on the Nimrod MR2P maritime patrol aircraft, so it has a "superb capability" against surface targets.

Hargreaves says: "We desperately needed the datalink to allow almost real-time passage of information." The terminals are provided by Rockwell Collins, while Racal provides the interface with the mission system.

The datalink will provide a quantum leap in the capability of the RN's AEW force. The Mk7 upgrade is progressing simultaneously with a programme to fit Link 16 to the service's British Aerospace Sea Harrier FA2 air defence fighters. UK Royal Air Force Panavia Tornado F3 fighters have Link 16, which will allow the sharing of a common battle picture with the Mk7.

The Mk7's primary tasks will be airborne early warning and intercept direction of fighters, and maritime surface surveillance. Secondary roles will include data relay, over-the-horizon target reporting, humanitarian operations, search and rescue co-ordination and surface search for submarines.

It is the first time a high power pulse Doppler surveillance radar has been fittedto a helicopter, says Hargreaves. "We are doing a lot of risk reduction here to get it right because of worries about the effect of vibration. Early trials on the transmitter will take place in September, when we put elements of the system in a DERA hack aircraft to see what happens in a vibrating environment. We have no reason to think it won't work - we've done five to six years of modelling work. By mid 2000, all the parts of the system will be put in a test aircraft."

The Sea King Operations Whiskey Working Group (SKWOWG), made up of representatives from DERA, front line squadrons and the Maritime Warfare Centre, meets Racal regularly to monitor work. The group serves as the technical adviser to the UK's Ministry of Defence Procurement Executive - the customer. A requirement for regular meetings to discuss MMI issues is written into the contract.

"This pre-dates the smart procurement integrated project team approach," says Hargreaves. "It is the way projects should go. Frequently in the past, the first time that operators saw a bit of kit was when it arrived at the squadron."

The SKWOWG is also advising on the development of a full mission trainer and a ground support element, to allow the easy loading of computer data into the system.

Development of the MMI is advanced. It has been designed to requirements laid down by the SKWOWG and centres on a large 50cm (20in) flat panel screen and two smaller interactive control panels. The Mk7 programme is the first for UK military use of flat screen technology of this size. "We tried to make the MMI as simple as possible for the operator," says Hargreaves. "You only need to press three keys to go to any function, no matter where you are in the system."

The Mk7's three-person crew requirement - one pilot and two observers - has heavily influenced the MMI's design. "The MMI has got to be simple, in case one of the observers has to leave his station and help the pilot on the flight deck in bad weather or icing conditions," says Richardson. "A single observer has to be able to take on the war load."

The large colour screen shows symbology for the air and sea picture, overlaid on geographic representations of the theatre of operations. On-screen menus display navigation, communications and other information, to allow operators to make sense of the battle picture.

Fewer key strokes

When the operators have to pass intercept orders to fighters or other combatants, a minimum of key strokes is required to open up a window on one of the control panels to allow the preparation of the message and its transmission by the datalink. In the other command systems, it often takes multiple switch actions to prepare a mission order. Says Hargreaves: "On our system, it takes just six key strokes to develop intercept information, which is a complex mission, and the operator never has to look away from the screen. To cancel an intercept only takes two key strokes. In most other systems it would take a lot longer. You would, in effect, have to create a new mission order."

The Weapon Target Fighter Global Overview produces on-screen graphic information, detailing which players are engaging which targets, and the assets controlling them. Richardson says: "US Navy E-2C people who have been here just love that - they've got nothing like it.". A major function is its electronic flight reference card capability, to allow start-up checks and system monitoring. "Previously, we had all that information on reference cards in hideously large nav bags," he adds.

The designers have also tried to take the science out of the system management and monitoring controls, such as transmission conditioning or datalink controls, by installing simple switches, or graphic displays of radar beams, rather than including pages of computer menus containing technical information.

From the beginning, the Mk7 system, and the MMI in particular, has been designed with growth potential. Possible near term options include electronic support measures to allow information on hostile radar and other emissions to be integrated.

"The RN/DERA team is keen to install a target profile library in the MMI, so radar returns can be identified as specific types of aircraft or ships. We would be the only people to have it," says Hargreaves. "It would be a world beater."

In the longer term, the RN plans to field the Future Organic Airborne Early Warning system to complete the air groups of its two new super carriers from 2012. The Bell/Boeing V-22 Osprey and GKN Westland/Agusta EH101 Merlin are leading contenders. "Our system has been designed so it can be transferred to another airframe," says Richardson.

Source: Flight International