Since Global Express manufactured by Bombardier (RAF –

Since the First World War,
intelligence from the air has been a vital asset in how battle commanders have
fought wars. Today the RAF has a specialised fleet of aircraft focusing solely
on intelligence- these aircraft provide a vital service to battlefield
commanders. One of which is soon to be retired Sentinel R1.

In the 1980s, the Ministry of
Defence sent out a procurement requirement for a new ISTARi
platform (RAF –
Sentinel R1, n.d.), from operations in First Gulf War it was confirmed there
was gap in capabilities for collecting intelligence of battlefield surveillance.
From this identification of deficiency in capability, Sentinel was born, a Global
Express manufactured by Bombardier (RAF – Sentinel R1, n.d.) highly modified with “electronically-scanned array ‘dual mode’ surveillance radar, combining
the best in ground moving target indicator and synthetic aperture radar imagery”.
(Raytheon, 2018)
In having this new capability, it was
thought plug the gap left by the
cuts of numbers in Challenger II tanks. By providing an airborne asset that can
view the whole battlefield to help protect the man on the ground against enemy
forces; whether this support be in the form of leading ground attack assets or
directing ground forces away from danger. This concept
has been proven to work effectively by the USAFii
and their JSTARiii aircraft based on the much
older Boeing 707, which incidentally is the aircraft base for the new Airseeker
aircraft. Due to the old age and high operating of these airframes, the USAF is
procuring a new aircraft to fulfil this role and is allegedly looking at the Sentinel
due to. As well as the USAF, India’s Air Force has contacted the MoD over the feasibility
of supplying the Sentinel basic platform with the ability to have Indian-built.

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Originally announced in the
SDSR of 2010, the retirement of the Sentinel fleet was from being “no longer required to support operations in
Afghanistan” (Ministry Of Defence, 2010). This was changed in the SDSR of 2015 to an unspecified
date due to the reliance on the platform in new operations. This extension of
service life shows the unfathomable reliance on this platform the armed forces
has placed on it which is being conveyed over to the Ministers elected to
manage the finances. A compromise was met in 2017 to allow the fleet to
continue flying until a minimum of 2021 with the retirement of one aircraft
from the fleet of five. This commitment also came with an additional £131.5
million support contract to maintain the four remaining aircraft. (Allison, 2017)

With the Arab Spring, new
theatres of operations suddenly appeared overnight for Sentinel to excel in
compared to the relative repetitiveness of the Afghanistan theatre. Operation ELLAMY
in Libya (United
Nations, 2011) was the UK military’s response to the United Nations
Security Council Resolution 1973. Another two countries affected by the Arab
Spring was Syria and Iraq who came under the suppression of Da’esh, before combat
aircraft were sanctioned to operate and employ their weaponry, the ISTAR fleet was
operating in these countries. The main two including Airseeker and Sentinel who
both achieved 100 operational sorties (Century of sorties for RAF Airseeker and Sentinel,
n.d.) before the December 2015 vote approving airstrikes in Syria. (UK Parliament, 2015)


The Lancaster House agreement
of 2010 provided a basis for more inter-military cooperation with French armed
forces as highlighted with the Sentinel deployed to the Mali theatre in 2014. (UK Government, 2013)This deployment was not the only time the Sentinel has operated
from Africa. After the Boko Haram kidnapping of 200 school girls, the Nigeran Government
sent out a request for assistance for the follow up search with the international
committee. The United Kingdom sent a Sentinel aircraft to assist the effort to find
these school girls, (UK Government, 2014) due to the high operating ceiling of the airframe used the aircraft
can comb many hundreds of miles as used in Operation ELLAMY. An extremely useful
ability due to the large size of Nigeria compared to the relatively smaller operating
size of Operation Shader in Afghanistan. Where Sentinel achieved a

A prolonged search for an aerospace
company to provide a airframe fitting to the specifications of the ASTOR led  In comparison
the JSTAR program only cost £6,506,905,600 – £406,681,600  £1,2000,000- £2,400,000

After the eventual retirement
of Sentinel there will be a gap in our ISTAR capabilities within this field of
there are suggestions within the defence community to equip the new P8
Poseidons with ASTOR. (Jennings,
2017) The deep underlying
problem with this idea is the lack of airframes which is being purchased. In
only purchasing nine aircraft for the sole purpose of maritime patrol, adding a
further capability on what will be an already overstretched fleet will
potentially decrease the accuracy of the intelligence.

Subsequently, there are only
two viable options for the RAF in this ISTAR field, maintain and upgrade the
Sentinel or purchase more Poseidons for a mixture role of ASTOR and maritime
patrol. The



Allison, G.
(2017). Sentinel surveillance aircraft to be retained to 2021. UK Defence
Journal. Retrieved from

Sentinel surveillance aircraft to be retained to 2021

Century of
sorties for RAF Airseeker and Sentinel. (n.d.). Retrieved 1 7,
2018, from
Committee, H. o.
(2012). Operations in Libya . London : House of Commons. Retrieved
Jennings, G.
(2017). UK assessing Poseidon as potential Sentinel replacement. Jane’s
Ministry Of
Defence. (2010). Strategic Defence and Security Review. UK
Government. Retrieved from–2
RAF – Sentinel
R1. (n.d.). Retrieved 1 7, 2018, from RAF:
Raytheon. (2018).
SENTINEL R1 (ASTOR). Retrieved from Raytheon:
UK Government.
(2011). Army assisting Libya operations with RAF. Ministry of
Defence. Retrieved from
UK Government.
(2013). RAF Sentinel aircraft deploys to Africa. Ministry of Defence.
Retrieved from
UK Government.
(2013). UK Sentinel aircraft mission in Mali. Ministry of Defence.
Retrieved from
UK Government.
(2014). UK deploys RAF Sentinel to help search for missing schoolgirls.
Ministry of Defence. Retrieved from
UK Parliament.
(2015). MPs approve motion on ISIL in Syria. Retrieved from
United Nations.
(2011). United Nations Security Council Resolution 1973. Retrieved


ISTAR, is an acronym for Intelligence, Surveillance, Target Acquisition and

ii USAF,
United States Air Force

Joint Surveillance Target Attack Radar System

ASTOR, is an acronym for Airborne Stand-off Radar