The Global Hawk UAV system comprises an air vehicle segment consisting of air vehicles with sensor payloads, avionics, and data links; a ground segment consisting of a Launch and Recovery Element (LRE), and a Mission Control Element (MCE) with embedded ground communications equipment; a support element; and trained personnel.
The Integrated Sensor Suite (ISS) consists of a synthetic aperture radar (SAR), electro-optical (EO), and infrared (IR) sensors. Either the EO or the IR sensors can operate simultaneously with the SAR. Each of the sensors provides wide area search imagery and a high-resolution spot mode. The SAR has a ground moving target indicator (GMTI) mode, which can provide a text message providing the moving target's position and velocity.Both SAR and EO/IR imagery are processed onboard the aircraft and transmitted to the MCE as individual frames. The MCE can mosaic these frames into images prior to further dissemination.
Navigation is via inertial navigation with integrated Global Positioning System updates. Global Hawk is intended to operate autonomously and "untethered" using a satellite data link (either Ku or UHF) for sending sensor data from the aircraft to the MCE. The common data link can also be used for direct down link of imagery when the UAV is operating within line-of-sight of users with compatible ground stations.
The ground segment consists of an MCE for mission planning, command and control, and image processing and dissemination; an LRE for controlling launch and recovery; and associated ground support equipment. (The LRE provides precision differential global positioning system corrections for navigational accuracy during takeoff and landings, while precision coded GPS supplemented with an inertial navigation system is used during mission execution.) By having separable elements in the ground segment, the MCE and the LRE can operate in geographically separate locations, and the MCE can be deployed with the supported command's primary exploitation site. Both ground segments are contained in military shelters with external antennas for line-of-sight and satellite communications with the air vehicles.
The "R" is the Department of Defense designation for reconnaissance; "Q" means unmanned aircraft system. The "4" refers to it being the fourth of a series of purpose-built unmanned reconnaissance aircraft systems. "A" refers to this being the first revision. See also RQ-1 Predator, RQ-2 Pioneer, RQ-3 Dark Star, RQ-5 Hunter, RQ-6 Outrider, and RQ-7 Shadow.
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The Global Hawk is the first UAV to be certified by the FAA to file its own flight plans and use civilian air corridors in the United States with no advance notice. This potentially paves the way for a revolution in unmanned air flight, including that of unmanned civil passenger airliners.
As of August 2003, Australia is considering the Global Hawk for maritime surveillance, to replace their Lockheed Martin P-3 Orion patrol aircraft, with deliveries in 2004-2005. Joint USAF/RAAF exercises in 2001 demonstrated the utility of the Global Hawk in Australian waters. Germany is considering a Global Hawk variant (dubbed "Euro Hawk") equipped with an EADS SIGINT package to fulfill their desire to replace their aging Dassault Atlantique electronic surveillance aircraft. Canada is also a potential customer.
The USAF has ordered a larger version of the Global Hawk, the RQ-4B, with a higher payload and range. The US Navy has ordered two examples to be used to evaluate maritime surveillance capabilities. This role would be similar to Australian usage.New section
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