Forewarned is forearmed: Analysis of airborne early warning from RUSI’s Justin Bronk


Airborne early warning, and command and control, are a vital part of modern air warfare. Justin Bronk, from the Royal United Services Institute (RUSI) think-tank gives us a quick heads-up on the state of airborne early warning, and looks at the shortcomings of the RAF’s AWACS fleet. 

Those wishing to read more about the subject should read Justin’s full paper ‘The Future of Air C2 and AEW’ here

 AEW, what’s that and does the RAF need it?

AEW stands for airborne early warning and is one part of the broader AWACS mission set which also includes increasing command and control (C2) capacity for the air commander. Whereas fighter radars can be likened to using a very bright but narrow beam torch in a large dark warehouse, an AEW radar like the big AN/APY-1/2 array on the RAF’s E-3D Sentry is rather like turning on a lightbulb on the ceiling in this analogy – providing 360-degree long range coverage to enable it to give situational awareness and coordination to all other participants in an air battle in terms of what friendly and enemy aircraft are doing.


So, does the RAF needs its own- could it not just use the NATO aircraft? 

The RAF operates 6 frontline E-3Ds as a core part of the UK’s sovereign capability to conduct complex air operations. The French Air Force and US Air Force also operate modernised E-3s and there is a communal NATO fleet of E-3As. However, for a nation that still prides itself on fielding a ‘reference air force’ which can conduct high end warfighting, some form of AEW and even more crucially Air C2 capacity is essential.

Datalinks, is that the transfer of digital tactical information by radio? 

Datalinks involve the transfer of information – be that text, imagery, voice or digital code through the electromagnetic spectrum across a variety of frequencies which have different capabilities and limitations. Link 16 is the most commonly used datalink standard for NATO aircraft.


Are we becoming overly dependent on datalinks, is it theoretically possible to jam datalink signals? 

Almost all aspects of modern air warfare as practiced by first-line NATO air forces depend to a large extent on having access to datalinks of various types for all sorts of purposes. Those might be between fast jets within a formation, between fast jets and their AWACS and other surveillance enablers such as UAVs, ground and naval forces, communications with the COAC etc. It is certainly possible to disrupt and jam datalinks just as with any form of radio-based communications. However, certain modern datalinks use waveforms that are frequency agile, directional and hard to detect and disrupt. The F-35’s MADL is a good example.

 Is the equipment of the RAF’s E-3D any good?

The RAF’s E-3D was state of the art amongst AWACS during the 1990 and early 2000s but has been seriously neglected since then with planned midlife upgrade programmes falling foul of ‘efficiency savings’ being pressed on a cash-strapped MoD. It is now facing serious reliability problems and carries mission systems that are extremely out of date in terms of computing power and capacity compared to the modernised E-3s of the French Air Force and US Air Force.


How should it be updated? 

There is an ongoing capability sustainment programme (CSP) which will cost about £2bn between now and 2025 which aims to upgrade the aircraft’s computing power, address as many of the chronic mechanical reliability issues as possible and perform various other upgrades to allow the E-3D to serve out to its nominal out of service date in 2035 when the US will replace its own E-3Gs. However, the most serious limitation for all E-3s is the AN/APY-1/2 radar itself which is a capable mechanically scanning array but cannot compete in terms of detection of low-observable, hypersonic and other difficult targets with modern AESA technology.


How vulnerable are AWACS or AEW aircraft to:

A. Hostile SAMs?

They simply have to stay outside their missile engagement envelopes. AWACS types are all medium-large airliner derivatives with a huge RCS and emissions signature – they have no significant defensive capabilities against modern SAM systems and so must avoid them.

B. Hostile fighters?

Normally a valuable and vulnerable target like an AWACS will be well protected from hostile fighters. However, with the maturation and possible proliferation on non-Western stealth fighter technology and very long range air to air missiles (VLRAAMS), it is becoming harder to ensure their total protection against really serious opponents. This is especially true if the AWACS in question does not have an AESA array and so is really limited against LO targets…

 lne_rafm_x002_5933_large.jpg© Royal Air Force Museum. Photo credit: Royal Air Force Museum

Has AEW ever been used in peer-peer warfare? How did it fare? 

The E-3 was one of the defining advantages of the US-led coalition against Iraq in 1991 and gave coalition pilots an overwhelming situational-awareness edge over their Iraqi opponents. It was almost always the E-3s which detected Iraqi fighters and verified their IDs so that they could be engaged at beyond visual range. However, China and Russia have learnt from this and developed very long range missiles to try and keep E-3 and other AWACS types far enough away from their territory that their radar coverage would be less useful in the event of a conflict.


 Mech scan radars, are they a dead technology? 

Certainly a limited one in the modern world. Against fourth generation combat aircraft, mechanically scanned radars can still be highly effective but as more and more low-RCS missile and fighter threats appear, they are less and less capable of ensuring a representative threat picture. Furthermore, a mechanically scanned radar is much easier for an opponent to detect and jam than an electronically scanned array.

Why is AESA better for a AEW aircraft? 


Massively increased simultaneous search, track and targeting capabilities, frequency agility makes it harder for opponents to detect or jam. Furthermore, AESA radars offer the potential to function as high-powered jamming devices and even cyber payload insertion vectors since they are essentially software-limited at present rather than hardware limited. Also AESA arrays have a much lower number of moving parts compared to mech-scans and so are in general more reliable assuming mature software.

What is the most capable AEW aircraft in the world and why? 


In terms of a fully functioning system, I would suggest the US Navy’s E-2D Hawkeye given its capability to interface with Aegis vessels and other fleet assets, coupled with an interesting and apparently highly capable AESA-Mechanical scanning hybrid array. However, in terms of pure radar array capabilities I would say the latest Erieye ER array from Saab which the UAE have just ordered using Saab’s gallium nitride technology is the most technically capable AEW array in production. Power levels are very impressive and its backed up by characteristic Swedish ingenuity in terms of signal post-processing.

12. What kind of detection ranges would the best AEW aircraft have against an F-35? A B-2? A F-22? A F-15? 

F-35: Top secret and aspect-dependent, but better than an E-3.

B-2: Top secret and impossible to speculate on meaningfully

F-22: Top secret and aspect-dependent, but better than an E-3

F-15: At least the radar horizon so altitude dependent but minimum 370km+

 Could a data-linked force of several fighters provide the same coverage as a AEW aircraft? 

No. However, modern fighters like the F-22 and F-35 are increasingly capable of providing a higher fidelity picture within their arcs of radar coverage than an E-3. Furthermore, passive tracking using ELINT, RWRs, IRST, EO sensors and the like coupled with impressive computer-enabled sensor fusion and interpretation capacity is increasing the 360 degree awareness of modern fighters significantly. I’d commend the torch vs lightbulb analogy from the start…

What are the most exciting technologies in AEW?

Large electronic-warfare capable AESA arrays for traditional airliner-derived AWACS, and distributed UAV/HAPS based sensor clusters linked to ground stations (see China’s Devine Eagle concept) as an alternative to traditional AWACS. Also the potential offered by modern computing power to fuse data from multiple sources and multiple sensors across different spectra in order to ‘fill in the gaps’.

What will the British aircraft carriers use for organic AEW, is it the right choice? 

Initially a mix of the F-35B and the Crowsnest system on the Merlin HM.2 medium lift helicopter. However, both lack endurance on station and the Merlin cannot attain anything like the operational altitudes of a traditional fixed wing AWACS so suffers from a much closer radar horizon and corresponding decreases in possible threat detection ranges.


The E-2D is considered very capable, how does it compare with the best Russian and Israeli equivalent aircraft? 

E-2D Advanced Hawkeye aircraft (9)

I really don’t know beyond confirming (as above) that the E-2D is amongst the most capable AWACS systems in the world at present. The Russians and Israelis are both very secretive about the performance of their radar technology on the frontline. I would suggest that in part on the Russian side that is because their radars’ technical potential is not reached due to out of date mission systems and reliance on (now unavailable due to sanctions) foreign electronic components.

What is the most common myth about AEW or C2 aircraft? 

That the E-3’s prominent AN/APY-1/2 radar dish is really heavy. It is but only on the ground – it is actually shaped as a circular aerofoil to generate its own lift and so at cruise speeds is effectively weightless.

What should I have asked you? 

What would I personally recommend for the RAF as an alternative to E-3D…?

I won’t point to specific companies’ offerings but I’d say any replacement should certainly be based on either the 737-800max like the P-8 or the A330 like the Voyager for commonality with existing fleets and needs to have a modern AESA array which limits options somewhat.

Those wishing to read more about the subject should read Justin’s full paper ‘The Future of Air C2 and AEW’ here

Justin Bronk, is a Research Fellow specialising in combat airpower and technology in the Military Sciences team at the Royal United Services Institute (RUSI) and Editor of the RUSI Defence Systems online journal


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  1. Pingback: AWACS being upgraded for detection and tracking of new threats and employing them in increasingly complex missions - IDST - International Defence, Security and Technology
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