One of the Royal Air Force’s most effective Intelligence, Surveillance and Reconnaissance (ISR) aircraft of recent times, the Raytheon Sentinel R1, was withdrawn from service at the end of March and the unit operating it V (Army Cooperation) Squadron, disbanded.
The Sentinel, based on the Bombardier Global Express aircraft and completed for role by Raytheon, utilised an active electronically-scanned array ‘dual mode’ surveillance radar which delivered ground moving target indicator and synthetic aperture radar imagery, which allowed it to gather intelligence while detecting and tracking targets both on land and in the air.
The United Kingdom operated five Sentinel R1s ASTOR (Airborne STand-Off Radar) aircraft which began their service with an initial operational flight over Afghanistan on 15 November 2008. Since then they have been deployed to support numerous operations including Op Herrick (Afghanistan), Op Telic (Iraq), Op Shader (Iraq/Syria), Op Turus (West Africa), Op Ellamy (Libya), Op Newcombe (North Africa) and Op Kipion (Middle East).
The final operational sortie was conducted on 25 February 2021, when a Sentinel was tasked to fly near Kaliningrad Oblast and Belarus
According to the RAF, the longest operational flight by a Sentinel aircraft lasted 12 hours and 30 minutes during Op Ellamy during the conflict in Libya. The Sentinel fleet has flown around 32,300 hours and conducted 4,870 sorties.
A final tribute came from RAF Waddington Station Commander, Group Captain Steve Kilvington who said that the Sentinel R1 force had “delivered exceptional support to numerous operations across the globe. Whether tackling insurgency in the Middle East or supporting NATO on Europe’s flanks, the Squadron’s output has truly epitomised the Whole Force concept.”
There is no direct replacement for the Sentinel R1, although the Ministry of Defence points to a range of capabilities currently serving or on order that it believes will deliver the UK’s future ISR requirements. These include: nine Boeing P-8 MRA1 Poseidon maritime patrol aircraft, five Boeing E-7 Wedgetail Airborne Early Warning and Control (AEW&C) based on a 737 fuselage, up to 16 General Atomics Protector Remotely Piloted Air System (RPAS) ISTAR Protectors which will be armed, three RC-135W Rivet Joint electronic surveillance aircraft and five Beechcraft King Air 350CER Shadow aircraft.