With the UK considering a replacement for the aging Sea King 7 airborne, surveillance and control (ASaC) aircraft for the Royal Navy, a number of aircraft with airbourne early warning mission capabilities have been suggested as potential candidates.

Airbourne early warning and control (AEW&C) has long been an important factor of any defence strategy, using a radar system often attached to a military aircraft to detect enemy aircraft from long distances. Allowing the operator to distinguish between hostile and friendly targets, AEW&C can provide tactical information to pilots whilst also being able to direct fighter to target locations.

The Sea King 7 was first launched in March 2002 and, by 2004, all 13 ASaC.7-converted helicopters were operational aboard Invincible Class carriers. However, with the launch of the Queen Elizabeth Class carrier, the Royal Navy commenced the maritime airborne surveillance and control (MASC) initiative in order to identify a surveillance system to support the new carriers.

Although the Royal Navy has seen its budget significantly capped by the Strategic Defence and Security Review, a number of aircraft could fulfil the navy’s needs and replace the Sea King when it leaves service. This, however, remains undecided with many suggesting it could remain in service until as late as 2022 following budget cuts, leaving the ASaC.7 to be incrementally upgraded as new systems become available.

AgustaWestland AW101 Merlin

The AgustaWestland-produced AW101 Merlin was introduced in 2000, 13 years after its first flight in 1987, and costing an estimated $21m per unit. With the Merlin already in service within the Royal Navy, the experience of using the craft could be an attractive proposition. It is powered by three Rolls-Royce / Turbomeca RTM3222 Turboshafts that allow the helicopter to hover reliably in winds exceeding 80km/h, something of huge benefit to any potential Sea King replacement.

“A number of aircraft could fulfil the navy’s needs and replace the Sea King when it leaves service.”

In order to defend itself, the AW101 Merlin contains two hard points for weapon carriers that are capable of carrying and deploying four Sting Ray torpedoes or three depth charges, although it is currently unable to equip the Sea Skua missile. Mk1 and mk3 variants are capable of mounting general-purpose machine guns (GMPGs) in five locations, including the main cabin, and door and window apertures.

Navigation systems aboard the Merlin consist of a GPS and inertial navigation system, tactical air navigation (TACAN) and automatic direction finding.

The mk1 and mk3 varieties are also equipped with a Doppler velocity system for when conventional pressure instruments are unreliable in measuring accurate airspeed.

Bell-Boeing V22 Osprey

Introduced in 2007, 18 years after its first flight, the Bell-Boeing V-22 Osprey is another contender. The world’s first production tiltrotor aircraft underwent an extensive design and development programme that cost $27bn in order to ensure its effectiveness for military use.

The Osprey possesses both vertical take-off and landing (VTOL) and short take-off and landing (STOL) capability, but, with a planned unit cost of $67m, would certainly prove costlier than the Sea King and would not appeal to a post-defence-review defence sector.

The Osprey was designed to replace the CH-46 Sea Knight and traditionally operates as a helicopter for take-off and landing before rotating the nacelles 90° for horizontal flight. The V-22 is powered by two Rolls-Royce AE1107C engines, both connected by drive shafts to the centre gearbox so that, in the event of engine failure, one engine can power both prop rotors.

Four multifunction displays and one shared central display unit are incorporated in the aircraft’s cockpit, allowing pilots to display multiple images including FLIR imagery, flight instruments and navigation status. The Osprey can also be equipped with one 7.62mm×51mm Nato M240 machine gun on the loading ramp, allowing it to be fired rearward when the ramp is lowered. BAE Systems has developed a belly-mounted, remotely operated gun turret system for the craft, known as the interim defence weapon system.

Northrop Grumman E-2C Hawkeye 2000

Although the E-2 Hawkeye may have served as the eyes of the US Navy for more than 30 years, the fifth-generation E-2C Hawkeye 2000, manufactured by Northrop Grumman, possesses the most advanced airborne early warning and battle management capabilities in service today.

Significant enhancements to its data management, system throughput, operator interfaces, connectivity and situational awareness systems have been made to the Hawkeye 2000. Included in the fully integrated system are the AN/APS-145 radar system, improved identification friend / foe (IFF) system, joint tactical information distribution system (JTIDS) and the carrier aircraft inertial navigational system (CAINS) II navigation system.

“The navy’s airborne early warning needs could be fulfilled by one or a number of unmanned aerial vehicles.”

The cooperative engagement capability (CEC) system was a further integration for the Hawkeye 2000, becoming a key element of the theatre air and missile defence mission. The system provides high-capacity data exchange of detailed target information for enhanced fleet-wide connectivity and situational awareness.

The technology does, however, come at a cost, and at $80m a unit, it would certainly be among the costliest of replacement candidates and could dissuade any potential suitors.

AgustaWestland AW159 Lynx Wildcat

The AW159 Lynx Wildcat, previously dubbed the Future Lynx, has the benefit of already being on order by the Royal Navy. In June 2006, the UK Ministry of Defence awarded AugustaWestland a £1bn contract for 70 Future Lynx helicopters, with 30 designated for naval use, which was then reduced in 2008 to 62 AW159 Lynx Wildcats, with 28 chosen for the purposes of the Royal Navy.

The AgustaWestland Wildcat promises to be one of the most cost and fuel-efficient aircraft in current production, with only 5% of onboard components, such as the fuel system and main rotor gearbox, retained from previous aircraft.

Powered by two LHTEC CTS800 turboshaft engines, each possessing 1,362shp, the Wildcat features a composite tailboom, tailplane, tail rotor, nose structure and avionics suite, while the naval version is also equipped with the SELEX Galileo Seapsray 700E active electronically scanned array (AESA) radar.

The AW159 will also be equipped with forward-firing CRV7 rockets and machine guns, a pintle-mounted machine gun, depth charges and an air-to-surface missile system, possibly utilising the Lockheed Martin-developed Hellfire.

In theory, the navy’s airborne early warning needs could be fulfilled by one or a number of unmanned aerial vehicles, however, it was initially estimated that the costs and technical challenges of developing a UAV suitable for naval use would be greater than equipping existing technology.

The increase in UAV technology and recent investment into programmes such as BAE’s Taranis vehicle, coupled with the use and success of UAVs in the Afghanistan and Iraq conflicts, could leave the door open for a future system to be developed and utilised. Another avenue that could also be investigated is the use of a satellite navigation system operated from a carrier or vessel.