Watchkeeper Ready for Duty

November 2005
By Henry S. Kenyon

The surveillance platform for the United Kingdom’s Watchkeeper program is the Hermes 450 unmanned aerial vehicle (UAV). Designated WK450 by the U.K. Ministry of Defence, this medium-size UAV can stay aloft for almost 20 hours. The aircraft uses optical, infrared and radar sensors to observe stationary and moving targets
in all-weather day and night conditions.
Unmanned surveillance aircraft provides British forces with sophisticated sensors in a long-endurance platform.

A new airborne tactical reconnaissance system soon will provide the United Kingdom’s warfighters with an around-the-clock, all-weather surveillance capability that can be tailored to meet a variety of missions. Based on an operational unmanned aerial vehicle but with more sensors and longer endurance than existing British tactical platforms, its real-time data feeds will offer commanders greater situational awareness and operational flexibility.

Over the past several years, governments worldwide have been acquiring or developing unmanned aerial vehicles (UAVs) for battlefield reconnaissance and surveillance duties. Coalition forces operating in the Balkans, Middle East and Central Asia have accumulated enough experience to begin issuing new operational doctrines for the use of unmanned aircraft. At the tactical level, older platforms are beginning to be replaced with more capable systems.

One example of this ongoing transition to new systems is the Watchkeeper program. The contract was awarded in August, and the system is designed to meet U.K. Ministry of Defence (MOD) intelligence, surveillance, target acquisition and reconnaissance (ISTAR) requirements, explains Alan Gordon, head of business development for ISTAR and UAV systems, Thales U.K., Crawley, England. Watchkeeper not only meets the need for real-time, 24-hour image intelligence for warfighters, but also it is designed to operate in all types of conflict and in a variety of missions, from combat to peacekeeping.

In its requirements, the MOD did not specify system details such as the size of the aircraft or exact production numbers, which provided competing firms with a great deal of flexibility. Thales’ system features a medium-size tactical UAV based on the Hermes 450 manufactured by Elbit Systems Limited, Haifa, Israel, but it is significantly modified for use by the British military and is designated WK450.

Watchkeeper is more than just a UAV sensor platform, Gordon insists. It is an integrated system consisting of a support and control infrastructure linked to brigade and battle group headquarters. He explains that the aircraft is a reliable and cost-effective way to get sensors to the right place for more effective surveillance. Persistent battlefield surveillance requires performance characteristics that cannot be matched by the Phoenix, the only UAV currently in service with the United Kingdom’s armed forces. The Phoenix has an operational endurance of less than five hours.

Designed for long-endurance tactical missions, the WK450 can stay airborne for close to 20 hours, so two aircraft flying in shifts could constantly observe a target. A second UAV can be used as a radio relay to a ground control station, allowing an aircraft to operate beyond the normal limit of its line-of-sight datalink. Gordon observes that for tactical operations, the size and range of the WK450 provides commanders with more flexibility for long-duration surveillance missions.

Reliability is vital for a platform that must remain airborne for many hours and operate from rough airfields. Gordon notes that Thales’ Watchkeeper system is designed to meet MOD requirements at the lowest possible life-cycle cost. “Procuring UAVs is one thing. Keeping them flying for extensive periods of time—years of operational use—is where older UAV systems have become far too expensive,” he says.

Thales chose the Hermes 450 platform based on its operational record; it has logged more than 20,000 flying hours with the Israeli military. The UAV can be pre-programmed for fully autonomous missions, and an operator can redirect it in flight to acquire new targets. It is equipped with global positioning systems, dual computers and dual datalinks. For increased reliability, the WK450 is fitted with redundant electrical and avionics systems. A wideband satellite link also can be installed on the UAV to provide extended operational range without the use of a separate radio relay aircraft.

Because a reliable airborne platform was available, company designers could focus on the systems that allow the UAV to carry out its mission, gather data and pass it on to users. “Watchkeeper is about reliable air vehicles giving persistent air surveillance and then allowing the rest of the system to do its job—the sensors and the communications system that distribute the disseminated intelligence around the battlefield,” Gordon says.

The WK450 has a maximum payload capacity of 150 kilograms (330 pounds), and the Watchkeeper system includes a sensor pod housing electro-optic and infrared cameras, and a laser target designator. It also can carry a combination synthetic aperture radar and ground moving-target indicator radar for all-weather surveillance. Radar gives Watchkeeper a significant advantage over other tactical UAV systems, Gordon notes. Very few radars are small enough to fit into tactical UAVs, and very few tactical UAVs possess the size and reliability to carry complex sensor packages, he says.

A line-of-sight datalink transmits imagery and telemetry data from the WK450 to a ground control station housed in a container that can be mounted on the back of a truck. The station crew consists of a mission controller and a payload operator receiving information and mission requests from Watchkeeper tactical parties embedded in battalion and brigade headquarters. Gordon notes that these parties act as an interface and liaison with the system. Watchkeeper is designed to integrate fully with U.S. Defense Department network-centric warfare enabled systems and the MOD’s Network Enabled Capability.

The WK450 has an automatic takeoff and landing capability. It also has automated flight functions, allowing the non-pilot-trained mission operators to concentrate on surveillance tasks. Gordon notes that the UAV can operate from runways, but it also can fly from prepared airstrips on grass or smoothed desert terrain.

Watchkeeper is designed to operate with and support three command headquarters levels, from battle group through brigade and division. It can distribute information and real-time imagery to individual warfighters on the battlefield if needed, but Gordon explains that the system’s primary purpose is to provide operational headquarters with battlefield intelligence. Because it is designed for mobility and transportability, an entire Watchkeeper system can be deployed into an operational theater in one C-130 transport aircraft.

Watchkeeper’s ground control station allows missions and payload specialists to direct the WK450 UAV and its sensor package. Designed to be fully compatible with network-centric systems, the stations can relay live data feeds from the UAV to brigade and division headquarters.
Launched in 2000, Watchkeeper is among the first programs delivered under the MOD’s Smart Procurement process, Gordon says. Valued at £700 million ($1.2 billion), the program is now moving into an accelerated post-award phase with initial operational deployment scheduled for 2010. However, Gordon notes that under current British procurement standards, all lines of development in a program must be fulfilled. “It’s not just delivery of the equipment; it’s making sure all the training and infrastructure are there and in the right place,” he says.

Program aspects such as synthetic training and initial logistics support are all part of the overall program, which will be in place before the MOD declares an initial operating capability, he says. Although exact operational numbers have not been defined, Gordon notes that the MOD envisions several dozen UAVs and a number of ground control stations to be available for the British military. He adds that Watchkeeper is designed for use by all of the United Kingdom’s military services, although it is mainly intended to support land operations.


Web Resources
U.K. Ministry of Defence:
Thales Group, United Kingdom:
Elbit Systems Limited:


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