The strategic defence and security review and the national security strategy

Written evidence from Raytheon UK


The Airborne Standoff Radar (ASTOR) program that includes the Sentinel R Mk1 as the aircraft element was launched in December 1999 as a key component of the Armed Forces Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR) capability to become the country’s future key ground surveillance capability. It meets the joint RAF/Army threefold requirement in one airframe for: surveillance over a wide area; the ability to focus on a discreet area of interest; and identify moving targets. Using a business jet enables the sensor to be flown much higher than larger aircraft thus greatly extending the range of radar coverage.

Raytheon delivered the programme to the original target cost of £850 million and went from concept to operational capability, deployed in theatre in just over eight years, a significant achievement for what was an extremely complex and technically ambitious programme.

The Strategic Defence and Security Review (SDSR) announced the retirement of the RAF’s fleet of five Sentinel R Mk 1 aircraft on completion of the support to ongoing operations in Afghanistan circa April 2015.

The Defence Select Committee is investigating the SDSR and National Security Strategy (NSS). One of the areas for investigation is to identify the capability gaps that will be created as the SDSR policies are implemented, the assessment process that led to these decisions, and the impact this may have on the UK’s defence planning assumptions and the ability to adapt to changing threats or unforeseen occurrences.

Current Support to Operations

The Sentinel R Mk1 aircraft passed 300 successful operational missions in theatre milestone last October. It is now achieving a rolling average Duty Carried Out (DCO) rate in theatre of 95%: this with only two aircraft, one ground station, very lean staffing and a supply chain using UK Main Operating Base criteria. It compares very favourably to the significant cost and infrastructure required by coalition forces to keep their equivalent ISTAR capability in theatre.

Reports from in theatre, openly available, demonstrate that Sentinel is a proven life saver and route protector in the current battle space, with a capability unmatched by other platforms. Its ability to scan very large swaths of land over great distances in very short time provides information and pattern of life intelligence that would take hours, even days, to compile using other UK platforms in theatre. Its pattern of life intelligence has therefore become a vital tool in the battle against Improvised Explosive Devices (IEDs).

The Sentinel R Mk1 has been an operational success story, delivering a wide area surveillance capability that is relied upon by UK, US and other coalition forces in Afghanistan today. Sentinel is one of the few systems that the UK deploys that the UK is able to add real value to the coalition’s overall operational capability.

Resulting Capability Gaps

The Strategic Defence and Security Review announced the retirement of the RAF’s fleet of five Sentinel R Mk 1 aircraft on completion of the support to ongoing operations in Afghanistan circa April 2015.

This decision leaves the UK without a viable wide area ground surveillance capability. Raytheon’s understanding is that the MoD believes that wide area surveillance can be provided by a combination of the Scavenger capability, currently in procurement, and the Joint Strike Fighter (JSF).

However, whilst these programmes may provide a ground surveillance capability, they are intended to provide coverage complementary to Sentinel’s wide area capability. JSF and Scavenger will be optimised for local area surveillance provided by smaller sensors and less powerful processing capability. Unmanned assets like Scavenger need cueing from very wide area pattern of life based product libraries and without Sentinel, another means will be needed to update these databases in near real time. We are not aware of MoD plans to provide this capability.

With the JSF not due to enter into service until between 2017 and 2020 and Scavenger not planned to deliver an operational capability until 2018 at the earliest, there remains a risk of no capability in this area for a significant period of time.

The Sentinel system also has a valuable role in communications. The Ground Station currently provides the coalition forces with the only means of interoperation with JSTARS which will be lost when Sentinel is retired.

Furthermore this loss will have an effect on potential plans for the long range deployment of UAVs, for which radio relay of data may be required, especially if SATCOM bandwidth is limited or not available. Sentinel’s high altitude ceiling has been utilised in this way by the USAF using the original ASTOR demonstrator GEX 9001 as a trials aircraft operating out of Afghanistan.

The Battle Against IEDs

In addition to its pattern of life picture that Sentinel currently provides, the system could assist further in the battle against IEDs due to the inherent quality of the raw data provided. Offboard post processing trials have proven that there is the capability to identify disturbed earth and cue the identification of IED locations. The Sentinel aircraft does not require any modifications in order to deliver this near real-time IED detection capability. Therefore, with minimal additional outlay, further trials could be undertaken with in theatre data to refine this capability, and potentially help to reduce the casualty figures in theatre.

Such a capability is considered essential given the latest trend in warfighting scenarios, and would be valuable, not just for current operations, but wherever the next theatre of interest lies. Afghanistan has proven that terrorism will likely continue to revolve around insurgency and IED based threats, a scenario that the current platforms have difficulty in addressing over wide areas.

Future Potential

The ASTOR System has untapped capability that with incremental investment could deliver significantly enhanced capabilities. This spiral capability development would be a more cost effective and lower risk way of delivering new capability, rather than investing in the development and entry into service of new platforms.

The SDSR decision to cancel the Nimrod MRA4 leaves the UK with maritime capability gaps that the Sentinel R Mk 1 capability could address, including:

· Deep sea search and rescue maritime target detection;

· Scene of Action presence for maritime emergencies beyond the range of current Sea king helicopters;

· Overhead naval force protection; and

· Wide area submarine threat detection.

The Sentinel Dual Mode Radar Sensor (DMRS) could be modified to accept a a high sea state target detection capability that would match and possibly even surpass that lost by the cancellation of the Nimrod MRA4. This capability is already in service in the US.

In addition the ASTOR Ground Station could be upgraded, with relatively little investment, to provide a multi ISTAR hub for the reception of information feeds from Watchkeeper, Reaper and, in the future, Scavenger. This would fit well into the future plans for the Solomon programme, as we understand them, maximising reuse of existing assets, saving valuable resource and costs.


The SDSR decision to retire Sentinel leaves the UK with capability gaps covering significant wide area pattern of life surveillance, long range target detection and coalition force interoperability. It also offers cost effective opportunities to plug maritime surveillance gaps and high altitude wide area IED detection. Some of these may be filed in the 2018 -2024 timeframe, but not all.

In addition spiral development of the proven Sentinel capability could deliver solutions to future capability gaps such as maritime search and rescue, and deep sea threat detection at significantly lower cost and risk, than developing and deploying new platforms.

February 2011