US Air Force Request for Funds to Buy E-7 Should Prompt a Rethink on RAF Fleet Size

For many years, the US Air Force E-3G Sentry fleet airborne warning and control system (AWACS) has continued its role as the backbone of NATO’s airborne situational awareness and C2 capabilities without a specific replacement system lined up. There were hopes among many in the US Air Force and the wider Defense Department that the E-3G could be the last ‘big-wing’ AWACS procured by the service. It was hoped that the E-3 would eventually be replaced by a cheaper and less vulnerable distributed system of sensors on UAVs and other combat aircraft coordinated and fused using the advanced battle management system (ABMS) construct.

The early development phases of ABMS have shown great promise in terms of enabling potentially revolutionary levels of information sharing between large numbers of aerial and multi-domain assets. However, a purely distributed ABMS-dependent solution does not yet offer a viable pathway to replacing all the roles for which the E-3G fleet is the primary enabler. For a start, the E-3G brings a mission crew of between 13 and 19 people, and an almost unequalled multi-band communications suite to the area of operations. The mission crew receive a huge amount of information from not only the E-3G’s primary AN/APY-1/2 radar but also via satellite communications (SatComms), VHF and UHF radios, Link 16 and a range of other communications and datalink systems. This, coupled with their training as dedicated airspace battle-managers and fighter-controllers allows them to generate high levels of situational awareness. This situational awareness, and their capacity as a large mission crew, is what enables the US Air Force to coordinate in real time the extremely complex multinational air operations which the US and other NATO countries sometimes take for granted, but which most other countries struggle to conduct. The E-3 also typically acts as the Link 16 management function during complex operations, coordinating which data is pushed where and which users can send to others.

Linking distributed strike and ISR assets together via a construct like ABMS allows them to benefit from increased collective situational awareness, but does not replace this coordinating function, nor the capacity provided by a large, dedicated AWACS mission crew trained for the task and operating in theatre. Rather, a distributed AWACS system would either have to automate these functions – a task significantly beyond current AI capacity or that likely to be available in the medium term – or rely on reach-back in real time to ground-based mission crews at an air operations centre. Both approaches have serious problems, not least of which is their inherent vulnerability to the denial of SatComms and other beyond-line-of-sight (BLOS) communications links by hostile electronic warfare or direct attack on key nodes. A wide-bodied AWACS is itself vulnerable to electronic and physical attack, but its proximity to the assets it is controlling relative to hostile jammers and the range of communications capabilities it can employ make it harder to deny than BLOS links. For now, at least, the US Air Force has decided it cannot wait for ABMS to mature sufficiently to make a purely distributed AWACS replacement viable. Instead, it has requested funds to procure a new AWACS to replace at least half of its E-3G fleet as an urgent priority. The E-7A Wedgetail is the acknowledged frontrunner, and the US Air Force issued a sole-source contract to Boeing in 2021 to examine its ability to meet the requirement.

The Boeing E-7A Wedgetail is a smaller AWACS aircraft than the E-3, being based on the 737 airframe. As such, it offers somewhat less time on station compared to an E-3 with modernised engines, but greater than the US Air Force and NATO E-3G/A aircraft which still use inefficient TF33 turbofans which were designed in the late 1950s. The E-7A is also capable of aerial refuelling to extend time on station and carries far more modern and efficient mission systems and crew stations – redesigned for the RAF in the light of over a decade of service with the Royal Australian Air Force (RAAF). The E-7A carries a Multi-role Electronically Scanned Array (MESA) radar as its primary sensor, which consists of two main side-looking arrays and two smaller lobes covering the ‘blind spots’ to the direct front and rear of the aircraft. The MESA array offers better resolution against all targets than the E-3’s AN/APY-1/2, and significantly better performance against targets with a low radar cross-section, such as modern cruise missiles or fifth-generation fighter aircraft. As a large electronically scanned radar, the MESA also has significant latent capability to be developed into a powerful electronic warfare tool for both standoff jamming and self-defence. Northrop Grumman, which makes the current MESA for Australian, South Korean, Turkish and British E-7As, has also been working on an upgraded array which would offer significantly improved frequency-agility – allowing it to exploit additional parts of the radar spectrum for even better performance against the most challenging targets. A US Air Force order would likely seek to make use of this next-generation array as well as additional communications and self-defence equipment.

If the US does proceed with an order for the E-7A to replace at least part of its E-3G fleet, the RAF should definitely seek to work with the US Air Force on developing future upgrades for its own E-7 fleet, and leverage the reduced unit costs which would come with a large US order to purchase additional airframes itself. The RAF’s initial requirement for E-7A was calculated at five airframes to replace the remaining seven E-3Ds – with the reduced figure partly due to higher anticipated aircraft availability rates, and partly simple budget constraints. However, the Integrated Review reduced this order to three – which is simply too few to guarantee an aircraft on station 24/7 when required for a single orbit. This was largely about the political side punishing the RAF for what was perceived as either dishonest or incompetent budget management, coupled with a lack of confidence in the longevity of the E-7A due to the lack of US orders and fears that Australia would retire its E-7s early. However, the RAAF has just spent over AUS$580 million on a mid-life upgrade programme for its E-7 fleet and will operate the type until at least the mid-2030s. If the US Air Force does proceed with an E-7 purchase, the UK should take the cue and take advantage of the reduced unit cost and increased global support architecture implications to order additional aircraft.

The E-7A is a mature, currently available replacement for the E-3D which offers excellent performance and significant capability growth potential. The US is not convinced that distributed solutions such as ABMS offer sufficient confidence to forgo ordering a viable modern AWACS fleet to replace the E-3G, despite the vast resources and world-leading expertise which it can throw at datalinks, UAVs and AI development. The serious security challenges posed by Russia and China over the coming decade mean that the UK should do the same – and a viable AWACS fleet requires more than three airframes.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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