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E-3 Sentry AEW.Mk 1

The RAF’s Sentry aircraft are a vital presence over land and sea where UK forces are operating, collecting information which is used to understand the environment and control troop activity.

The Sentry monitors airspace to provide threat detection of adversary aircraft and situational awareness on friendly assets.  Information gathered by the Northrop Grumman APY-2 radar is processed by the mission crew and disseminated via a variety of data links and communication systems.

Sentry also has the capability to detect ships, relaying information to maritime aircraft or allied vessels for further investigation.  Its electronic support measures equipment enables the E-3D to gather emissions from other radar systems and emitters, enhancing the crew’s understanding of the environment in which it is operating.

Seeking a modern, jet-powered replacement for the piston-engined types it was operating in the AEW role, on July 23, 1970, the US Air Force chose the Boeing 707-320 airliner as the base airframe for a new Airborne Warning And Control System aircraft.

Modified with a Westinghouse AN/APY-1 radar system, its antenna covered by a massive rotating radome held over the rear fuselage, the first of two EC-137D prototypes completed its initial flight on February 5, 1972. After an extensive test programme, the E-3A production version entered service in March 1977.  Although the type is officially named ‘Sentry’, the USAF designates it E-3 AWACS.

In January 1972, just days before the EC-137D took off for the first time, 8 Sqn, RAF, re-formed to operate the Avro Shackleton AEW.Mk 2, a conversion of the Shackleton MR.Mk 2 to accommodate radar systems recently removed from Fleet Air Arm Fairey Gannet AEW platforms.  With its dedicated and highly skilled crews, the Shackleton provided a useful stopgap capability and it was expected that the Nimrod AEW.Mk 3 would replace it sometime in the early to mid-1980s.

A dramatic modification of the Nimrod MR.Mk 1, the AEW.Mk 3 first flew on July 16, 1980, but suffered insurmountable technical problems, primarily caused by the incompatibility of its avionics and airframe; it was finally cancelled early in 1987.

With an urgent need to replace the piston-engined Shackleton, the Ministry of Defence looked to a solution that had previously been suggested during the Nimrod AEW.Mk 3 programme and ordered seven E-3s.

The E-3D is a USAF E-3A aircraft purchased by the UK and modified with CFM-56 engines and various other equipment. Managed by the Airborne Warning and Control System program office, the cooperative effort to upgrade the performance and reliability of the United Kingdom's fleet of E-3D Sentry AWACS aircraft is known as the Radar System Improvement Program, or RSIP. The program provides increased air defense and command and control through significant improvements in: radar sensitivity and electronic counter-counter measures performance; radar performance monitoring and control; and reliability and maintainability. In 1996 Boeing Defense and Space Group was awarded a firm fixed price contract to provide for integration and installation of Radar System Improvement Program systems into seven E-3D Airborne Warning and Control System aircraft. The first three of the United Kingdom's airborne early warning aircraft received RSIP by the end of 1999.

A major upgrade of the UK Royal Air Force's Boeing E-3D Sentry fleet, dubbed Project Eagle, was planned for the 2010 timeframe. The aim is to transform the airborne radar aircraft into the hub of the UK's network-centric warfare capability. At the heart of the upgrade, potentially costing $500 million, is the incorporation of the US Network-Centric Collaborative Targeting (NCCT) technology, which compresses the sensor-to-shooter loop by allowing a much wider range of information on ground targets to be inserted into the displays currently used by E-3D crew members to monitor air activity.

Boeing is one of two companies selected in January 2005 by the United Kingdom's Ministry of Defence as a preferred bidder to compete in a technology demonstration program as part of Project Eagle. Boeing's technology demonstrator is based on the Block 40/45 upgrade. This provides new mission hardware and software to integrate information from on-board and off-board sources and provides the airborne operators with improved situational awareness and automated battle management tools. These upgrades dramatically enhance the capability of the global AWACS fleet, making it a prime catalyst for network-enabled capability and an extraordinary force multiplier across the entire operational theater.

Officially designated Sentry AEW.Mk 1 in RAF service, but commonly known as E-3D, the new aircraft differed from the US fleet in its powerplant of more efficient CFM56 engines.  The Shackleton remained on strength until 1991, 8 Sqn taking its first E-3D at RAF Waddington, Lincolnshire in July. Boeing delivered the first AWACS for the United Kingdom in March of 1991 and delivered the seventh aircraft in May 1992. Recent upgrades include installation of radar system improvement program kits, a Global Positioning System, and enhanced identification friend or foe and collision avoidance systems. Little more than a year later, the type was in action over the Balkans, before making a valuable contribution to Operation Warden over northern Iraq in 1994.

The Sentry is fully integrated into the ISTAR Force, yet retains its core competencies of airborne early warning and airspace management.  Its capability is no more appreciated than in the skies over Iraq and Syria, where an ongoing commitment to Operation Shader sees the E-3D deconflicting airspace, providing ‘big picture’ situational awareness for Coalition aircraft and early warning of aircraft movements outside Coalition control.  The 2015 Strategic Defence and Security Review called for Sentry to remain in service until 2035.

The RAF's fleet of Sentry aircraft have contributed to every major UK Air Operation since its introduction to service with the RAF in 1991. However, they are now ageing and as is eventually the case with all military aircraft, the decision was taken to replace them with a more modern and capable aircraft to meet the UK's future needs. As at 31 December 2019, the Sentry fleet comprised four aircraft (including ZH104), split between three in the forward fleet and one in the sustainment fleet.

The Sentry fleet continues to routinely conduct NATO missions as part of the. UK's broad commitment to NATO Intelligence, Surveillance and Reconnaissance (ISR) operations. The out of service date for Sentry is being kept under review as the transition plans are refined.

“The Sentry has provided excellent service and intelligence capability to both NATO and the UK since its first operational mission in 1991. The drawdown of Sentry is ongoing,” Jeremy Quin, Minister of State at the Ministry of Defence, said responding to a question in the UK parliament. “Since 2017 the fleet has reduced from six airframes to three. As is normal in fleet transition, the numbers of aircraft and crews needed to support frontline operations naturally reduce approaching the formal out of service date. It will continue to deliver this operational capability and the ability to undertake operational tasking all the way to its out of service date.”

On 21 December 2020 the Defence Equipment Sales Authority (DESA) invited expressions of interest from Companies interested in being considered for receiving an Invitation to Tender (ITT) in respect of the proposed sale of the aircraft for stripping so to harvest all reusable parts for potential resale, recycling or disposal and final dismantling and removal of the remaining platforms. Note these aircraft are not for reuse.

The aircraft available are as follows: 5 x Sentinel Aircraft & a significant number of associated inventory spares and Ground Support Equipment. 2 x Sentry aircraft and associated inventory spares The aircraft’s may be held at different UK locations including Waddington and it is anticipated that all work will be required to be undertaken at site. DESA’s preference would be to sell the aircraft and or inventory on mass but partial options may also be considered.

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Page last modified: 30-06-2021 12:04:48 ZULU