A Royal Air Force E3D Sentry is pictured on a sortie from RAF Waddington. The RAF operates seven E-3D Sentry aircraft in the airborne surveillance and command-and-control role. The aircraft are based at RAF Waddington, where they are operated by Nos 8 and 23 Squadrons as the UK’s contribution to the NATO Airborne Early Warning and Control Force. The E-3D also forms one arm of the UK Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR) triad of Sentinel R1, E-3D and Nimrod R1 aircraft. Whilst primarily procured as an airborne early warning aircraft, the E- 3D has been extensively employed in the Airborne Warning and Control System (AWACS) role. The E-3D Sentry, known to the RAF as the AEW1, is based on the commercial Boeing 707-320B aircraft, which has been extensively modified and updated to accommodate modern mission systems. Mission endurance is approximately 11 hours (over 5000nmls), although this can be extended by air-to-air refuelling. The E-3D is the only aircraft in the RAF’s inventory capable of air-to-air refuelling by both the American ‘flying-boom’ system and the RAF’s ‘probe-and-drogue’ method.