RAF Sentinel R1 (© UK MOD Crown Copyright 2021 / SAC Shauna Martin RAF )

Royal Air Force Sentinel R1 aircraft conducts last operational flight after 14 years of service

Royal Air Force Sentinel R1 aircraft has carried out the last operational flight of the aircraft type from RAF Waddington after 14 years of service. The Sentinel R1 aircraft of V (Army Cooperation) Squadron have flown circa 32,300 hours conducting approximately 4,870 sorties during its service life.

The withdrawal from service was first announced as part of the 2015 Strategic Defence and Security Review. The UK continues to invest heavily in NATO ISTAR capabilities, not least Maritime Surveillance (Poseidon), Airborne Early Warning and Control (E-7 Wedgetail), Armed ISTAR (Protector), SIGINT and ELINT capabilities (Rivet Joint and Shadow) – all of which have either entered service or will do in the near-term.

The Sentinel aircraft was commissioned through engineering firm Raytheon to provide an Airborne Stand-off Radar (ASTOR) system and first saw service during Operation HERRICK in 2008.  Five aircraft were acquired and V (AC) Squadron was reformed to operate the aircraft.

The squadron has been committed since then to numerous operations around the world, notably Op SHADER and Op TELIC, whilst closer to home they provided support to the Civil Authorities during the UK’s flood emergency in southern England in 2014. Raytheon have worked closely with the RAF in maintaining this capability and were a very welcome part of the whole force at RAF Waddington.

On the squadron’s recent return from Op SHADER, the UK Commander of Joint Operations, Vice Admiral Sir Ben Key said“Right to the end of its commission, V(AC) Squadron has been a constant among my deployed Force Elements. It is a record to be proud of.”

The Sentinel has been involved in multiple operations including:

  • Op HERRICK – Afghanistan.
  • Op TELIC – Iraq.
  • Op SHADER – Iraq/Syria.
  • Op TURUS – West Africa.
  • Op ELLAMY – Libya.
  • Op NEWCOMBE – North Africa.
  • Op PITCHPOLE – UK Floods.
  • Op KIPION – Middle East.

Sentinel’s longest flight of 12 hours and 30 minutes was achieved on 30 March 2011 during Operation ELLAMY (Libya). Sentinel has flown circa 32,300 hours over approximately 4,870 sorties – most of which have been flown on operations. All Sentinel deployments have been operationally successful due to the professionalism and dedication of the Whole Force, including the Raytheon Field Service Reps. V (AC) Sqn is based at RAF Waddington, the main operating base in the UK for Intelligence, Surveillance, Target Acquisition and Reconnaissance assets.

Royal Air Force Sentinel R1

The Sentinel R.Mk 1 provides long-range, wide-area battlefield surveillance, delivering critical intelligence and target tracking information to British and coalition forces.  The aircraft has been operationally deployed in support of operations in Afghanistan, Libya and Mali, and is currently deployed in support of British and Coalition operations in Iraq and Syria.

Using its powerful multi-mode radar, the Sentinel’s mission crew identifies, tracks and images numerous targets over great ranges, passing the information in near real time to friendly forces.  A team of intelligence imagery analysts from 1 Intelligence, Surveillance, Reconnaissance (ISR) Wing backs up the Sentinel crews, conducting in-depth forensic analysis of collected data, and using it to generate intelligence products for time-critical dissemination to commanders and decision makers, enabling them to execute current operations and plan future strategies.

During the early 1980s, the UK government identified a need for a battlefield reconnaissance system to provide awareness over a broad area.  Expressed in the Corps Airborne Stand-Off Radar (CASTOR) requirement, the programme elicited responses from Thorn-EMI and Ferranti.  The former’s radar was tested in an English Electric Canberra from 1982, while a Britten-Norman Islander modified to take the latter, first flew in 1984.


By 1988 the programme had become ASTOR and, with a Thorn-EMI radar installed, the Islander flew low-altitude trials examining its compatibility with the USAF’s prototype E-8 J-STARS (Joint-Surveillance Target Acquisition Radar System).  This work was part of a definition phase which, it was hoped, would enable a contract award in 1994.

Finally, in 1999, Raytheon was contracted to develop a five-aircraft ASTOR system, using Bombardier’s Global Express business jet as the airborne platform and basing the mission system on its ASARS-2 radar, developed for the USAF’s U-2.  Raytheon took a first Global Express for modification in 2002 and re-flew it with the ASTOR system installed in May 2004.  Service trials began in 2007 and V(AC) Sqn flew the first operational Sentinel R.Mk 1 mission in November 2008.

The aircraft immediately proved its worth over Afghanistan and again during Operation Ellamy in 2011, becoming a vital link in the chain of target identification and prosecution, especially where fleeting or ‘pop-up’ targets were concerned.  The 2010 Strategic Defence and Security Review nominated Sentinel for withdrawal as soon as the Operation Herrick commitment ended, but such was the system’s value to British and allied commanders that it was given a reprieve.  Since then it continues to prove its worth in Operation Shader and as a result of the 2015 Strategic Defence and Security Review, its out of service date has been moved back to 2021.

Photo credits: UK MOD Crown Copyright 2021 / SAC Shauna Martin RAF; SAC James Skerrett RAF