The UK is selling off its entire fleet of five Sentinel surveillance aircraft (without replacement) and two of its remaining Sentry airborne early warning aircraft.

The Sentry aircraft, part of a larger fleet that originally numbered 6, are being sold off as the fleet draws down to 3 aircraft before it is replaced by the E-7 Wedgetail aircraft over the coming decade.

New early warning aircraft to be based in Scotland

Jeremy Quin, Minister of State at the Ministry of Defence, recently said in response to a question regarding the size of the Sentry fleet:

“The Sentry has provided excellent service and intelligence capability to both NATO and the UK since its first operational mission in 1991. The drawdown of Sentry is ongoing. Since 2017 the fleet has reduced from six airframes to three. As is normal in fleet transition, the numbers of aircraft and crews needed to support frontline operations naturally reduce approaching the formal out of service date. It will continue to deliver this operational capability and the ability to undertake operational tasking all the way to its out of service date.”

While there is no replacement for Sentinel, the news that the aircraft is being sold off (after many reprieves) isn’t surprising to many.

Sentinel R1 to be scrapped next year due to ‘obsolescence’ say MoD

There’s also a possibility that other aircraft could pick up some of the work.

Analyst suggests replacing Sentinel with additional P-8A Poseidon aircraft

The Ministry of Defence advise that the aircraft being sold off are “not for reuse”.

According to the Ministry of Defence in a potential sales notice:

The Defence Equipment Sales Authority (DESA) is inviting expressions of interest from Companies interested in being considered for receiving an Invitation to Tender (ITT) in respect of the proposed sale of the aircraft for stripping so to harvest all reusable parts for potential resale, recycling or disposal and final dismantling and removal of the remaining platforms. Note these aircraft are not for reuse.

The aircraft available are as follows:

  • 5 x Sentinel Aircraft & a significant number of associated inventory spares and Ground Support Equipment.
  • 2 x Sentry aircraft and associated inventory spares

The aircraft’s may be held at different UK locations including Waddington and it is anticipated that all work will be required to be undertaken at site.

DESA’s preference would be to sell the aircraft and or inventory on mass but partial options may also be considered. The issue of this notice is not a commitment by the Secretary of State for Defence of the United Kingdom of Great Britain and Northern Ireland (acting through the Defence Equipment Sales Authority of the UK Ministry of Defence) (the “Authority”) to commit to a sale as a result of this notice and this process may be discontinued at any time should another sale option be forthcoming.”

What does Sentry do?

The US designed E-3D Sentry AEW.Mk 1 is an airborne early warning (AEW) and command and control aircraft in British service, but what does that mean?


The Sentry monitors airspace to provide threat detection of adversary aircraft and situational awareness on friendly assets.

Information gathered by the Northrop Grumman APY-2 radar is processed by the mission crew and disseminated via a variety of data links and communication systems. Sentry also has the capability to detect ships, relaying information to maritime aircraft or allied vessels for further investigation. Its electronic support measures equipment enables the E-3D to gather emissions from other radar systems and emitters, enhancing the crew’s understanding of the environment in which it is operating.

What does Sentinel do?

The aircraft, described on the Royal Air Force website as “the most advanced long-range, airborne-surveillance system of its kind in the world”, provides long-range, wide-area battlefield surveillance, delivering intelligence and target tracking information to British  forces.

Sentinel R1 in flight.

The aircraft has been operationally deployed in support of operations in Afghanistan, Libya and Mali, and was recently deployed in support of British and Coalition operations in Iraq and Syria as well as surveillance operations near the Russian border.

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Daniele Mandelli

Sentry, ok.

But Sentinel!!! Not a happy bunny.

Also, article says 6 Sentry originally. I thought it was 7 originally?


Sentry is NOT okay. AWACS is one of the most crucial planes an air force can have. And cutting down lower is just so them reducing the E-7 buy doesn’t look as bad. This is 100% a tactic just to get away with buying less to replace it.

John Clark

I don’t think that’s the case, I think all five E7 will be procured, the new money should secure them.

Re the E3, I doubt the RAF use more than three at any one time anyway these days.

The French would probably happily buy them as spares sources for their fleet.

George Royce

Very shocked. Bad decision. Better get a good replacement.


I’m guessing the Sentrys are no longer serviceable if they canabalised the other 3 to keep the current 3 in operation. It’s not ideal though when there replacements are still 3 years away. Thank goodness for the USA and Nato who will likely cover any gaps during that period.
Sentinal is not ideal, I read somewhere that poseiden can provide the same functionality but that doesn’t make sense unless they have integrated a huge surveillance radar inside the body of the airframe.


Poseidon can provide the same functionality if the AAS radar pod is procured as well as some additional airframes. AAS can also provide low-level cruise missile tracking and standoff electronic warfare capabilities as well as its normal functions. Arguably it would be better than Sentinel as aircraft can be fitted with the system as needed rather than keeping a specialised fleet of unique airframes around on the off chance they’re required as well as it being a larger and more advanced radar. Having MPA, AEW, AAS, and possibly in the future, ELINT all based on a common 737 platform with… Read more »


Thanks for that. I didn’t realise there was a Pod that could be fitted to the Poseiden, that would make sense then instead of having a dedicated aircraft that could only perform one role. Although if the aircraft has already been acquired not sure we are getting the same cost save. Maybe long term we will actually purchase 12 or 15 and have the flexibility to make them multi role

Niall McDonnell

Great idea but won’t work. The P8 and E7 are only about 15-18% compatible for sharing a spares package and the chances the USA will give us access to the AAS pod are slim. Even the Aussies who are full program partners don’t have access to it.


The US Air Force is desperate to retire its E-3ds and is currently debating if there will be a replacement aircraft. Odds are that there won’t be a replacement aircraft but the mission will be incorporated into its planned Advanced Management Battle System.

Alabama boy

It would be interesting to know if the Sentry’s are sold in flyable condition. I find it difficult to see how they can remain certiflyable to fly if major elements are missing such as rotodome and ESM pods. If not is will be even more depressing to see the aircraft being broken down at Waddington not great for moral. I suppose a temporary certification may be possible for a one time flight. I believe one of the airframes is still in storage in a hangar at an NG facility in the US.

Alabama boy

I have answered my own question the MOD wants a contractor to dismantle the aircraft in situ and recover any useable spares.

Always Right

Thank goodness for the USA and Nato who will likely cover any gaps during that period.”

The USA has no ability to cover any “gaps” you idiot since they have the sae aging aircraft and are on the other side of the Atlantic. NATO is no dependable either. Good job their won’t be any gaps then.

Robert Blay

It was 7, but only 6 in service, as one was always in long term maintenance. ?

Daniele Mandelli

Ta mate.

John Clark

The writing has been on the wall for a while now Daniele, the bespoke systems in Sentinel always meant it it would unfortunately be somewhat life limited as upgrading with the complex software rewrites required would be massively expensive. Always the problem when you go for a bespoke solution and build a handful of aircraft. Hopefully the new money will allow additional P8’s and a number of GTR pods to replace the capability. The RAF have been pushing hard for additional P8’s anyway, this is a great way of justifying a rise in the fleet. I wonder if the pod… Read more »


Whilst I claim no expertise in such matters, it does strike me as perhaps less than advantageous to draw down the Sentry fleet before its replacement is ready. This should especially be the case given the experience of 1981, when half of the Shackleton fleet was withdrawn in the expectation of imminent replacement by the Nimrod. And we all know how that went.

Harry Bulpit

So just to clarify we have no current AWACS capacity? With our ground surveillance capabilities left to the R1? Leaving only the r35 as a substantial starting asset? So are ISTAR capability, hailed as our greatest contribution to NATO, is practically gone?

Captain P Wash

Nope….. don’t worry, we have a very active UKDF forum ……… It’ll come up with all thge answers !


Balloons equipped with mark 1 eye balls, fitted for but not with crossbows?




Come now, Graham, we are a 21st century global power…! It shall be fitted for but not with air rifles, as long as they don’t exceed 12 ft-lb of power. Operators will need to bring their own air rifles, but RAF shall provide the pellets.

Harry Bulpit

Well where did I go wrong? We currently have 3 P8 which are dedicated to ASW work, wedgtail has yet to enter service and it is said we may have as few as 3 aircraft, preditor as sffustcated as it is simply can’t carry the sensors of a large aircraft, the R1 us good but vulnerable. Leaving us solely with R35 which can only really perform communication intelligence.

Harry Bulpit

Sorry rc135. Been to preoccupied with model tank making.

Always Right

the E-7 you idiot.

Paul T

The Way I Read The Article is That There Are 3 Sentry Aircraft Available so We Do Currently Have An AWACS Capability.

Daniele Mandelli

Exactly. The rest are being got rid of as they are not used.

Harry Bulpit

Ah that’s good. I thought it was the remaining three they where planning to sell.

Robert Blay

No, E3 still in service until replacement, just down to 3 airframes, which as the article states, we have only been operating 3 since 2017. It was announced in the 2015 SDR Sentinel would retire in 2021, so nothing new. We have P8 coming online, E7 ordered, JSTAR’s with many years ahead of it, and a expanding Shadow fleet, and the arrival of Protect UCAV’S. So it’s out with the old, and preparing for the new.

Niall McDonnell

The RAF does not have any E8s in its fleet. I think you mean the RC135W which is a SigInt plane.

Always Right

So just to clarify we have no current AWACS capacity? “

Other than the Sentry, in case you missed the article? Our greatest contribution to NATO is having the best-trained air force and the only capable one in Europe…

The Big Man

The aircraft, described on the Royal Air Force website as “the most advanced long-range, airborne-surveillance system of its kind in the world”

It’s also described as obsolete.

Is that not an oxymoron?


Not exactly, the Sentinel and Sentry are facing block obsolesce of the systems installed on the aircraft. The Sentinel has not received upgrades to the sub systems fitted to the aircraft making it harder to support over time as spares run out, the aircraft effectively has twenty+ year old systems inside it. Try finding spares for twenty year old computers…the radar might well be world beating but the sub systems that drive it will be obsolete. The Sentry is experiencing the same problems due to the type not receiving Block 30/35 upgrades like the rest of the international AWACS fleet.… Read more »

Fat Dave

This is entirely the consequence of allowing the RN to retain two hugely expensive and manpower intensive obsolete carriers.
It has thrown the defence budget and defence of the realm off balance because now the Army and RAF have to suffer cuts to capabilities to allow the RN to persist with its floating white elephants.
Ironically, the lack of AEW and ISR will only increase the risk to the already massively vulnerable carriers.

john melling

What are you blabbing on about? The Carrier’s are brand new and will be both operational! nothing obsolete about them! With F35 and various helicopters able to use them. The Carrier fleet has enough AEW and ISR and will be improved upon in the future and potent defence with its adaptable task group With T31 and T32 and T26 being built, and the RM amphibious capability being built, bought, organised and trained for. ARMY and RAF are being modernised, f35, Typhoon, UAVs, Challenger upgrade, Warrior upgrade, Boxer, AJAX, Strike Brigades and more. We have plenty going on and with a… Read more »

Meirion X

It’s just the Kremlin scraping the bottom of the barrel!


Fat Dave does have a point. The capital cost of carriers and aircraft (assume only 70) is over £13b. A lot more useful kit for the RAF and army could be bought for this. The RN too might benefit from a less unbalanced fleet. For 2 carriers to operate independently, we would need far more escorts and subs than are planned for. The carriers were announced at the height of Blair’s interventionist idiocy and I felt then we were making a huge mistake. Essential upgrades to army and RAF equipment have been neglected in part to fund the carrier programme.… Read more »

Daniele Mandelli


That is not how defence finances work.

If we are playing the inter services blame game, which I’m not, how many billions on Nimrod? How many billions on armoured vehicles spent by the army, since QEC programme started? Where are they?

At least for that outlay the RN has an asset for it’s money!

Meirion X

Kremlin mouthpiece FD’s last appearance was on STRN some months ago.
I thought Covid might have finished him off!


What exactly has the carrier programme got to do with a number of airframes coming up to there out of service dates. Not really seeing the causality here, you could just as easily blame it on the winter fuel allowance being payed to well off older people….or any other government expenditure… would still not be able to make a causal link between old aircraft being taken out of service and other expenditure……old now if the RAF were not getting a whole host of new platforms then you start talking about winter Fuel allowances ( just saying, I’ve nothing against the… Read more »


“Ignorance is Bliss”,
all the major powers are still investing in obsolete carriers. The fleet without carriers will not survive past day one.
The army has wasted billions (more than total cost of carriers), on vehicle non-procurement and procrastination.
The RAF has at least got airframes, but like the Navy they have been victims of political indecision and cost escalation caused by delays.
Crowsnest will materialise, and provide a reasonable AEW solution until a more robust solution becomes available with drone tech.

Meirion X

It’s the Kremlin calling in another disguise, very much so!

Harrod, is it?

James Fennell

Oh God inter service rivalry, give it a break

Graham Moore

The QEC carriers at £3.8bn each are about a quarter the cost of a US carrier and less than 2 weeks NHS spend. They are not manpower intensive due to their high degree of automation (679 crew vs 2600 on a Ford class – crew only, not air wing). The £3.8bn spend is for a carrier that will last well over 30 years, maybe even 50 years.

Always Right

There is no lack of it Dave you moron. You are clueless on military matters if you think aircraft carriers are obsolete.


And the consequences of Iraq and Afghanistan keep going on, to lose a capability that we use is unforgivable but no surprise from the MOD sadly.


Surely the Navy paid in part for the new carriers by losing the three invincible class and their harriers


I wonder if they’re going to replace Sentinel with G550 (Israeli Shavit) before the production line ends . . .


Britain hasn’t upgraded their E-3Ds in a very long time. NATO and U.S. ones are much more capable being as they have been through major upgrades the last 10 years. Sad to see the Sentinel go though. Hate to see the Brit’s give up an important capability and have no plans on how they will fill that lost role….


And herein lies the problem….. the RAF got the E3D it wanted, after huge amounts of money were wasted on the doomed Nimrod AEW, but have subbsequently failed to ensure they were updated, and acquire necessary spares to ensure we kept all 6 in service. With Setinnel, we have again failed to update the aircraft at regular intervals, but it has soldiered on doing a great job, and scrapping it without a replacement is very unwise.

Always Right

Britain hasn’t upgraded their E-3Ds in a very long time. NATO and U.S. ones are much more capable “

Yes it has. The US and NATO E-3Ds are not more capable in any way you idiot. The US ones don’t even have missile countermeasures.

Ryan Brewis

Does the Poseidon have the capability to fill the Sentinel’s role? I’m no expert but using a MPA for AGS/ISTAR seems suboptimal. Though presumably it has a pod or something? Can’t imagine that would be as effective as built in gear though then again, likely to be newer.
How many would that kick the required number to? 16?

Trevor W Hogg

Sorry in the Article is state they are selling Sentinel as it is Obsolete, However it then goes on to say it is the most Advanced radar system in the world. Something does not add up.

John Clark

It’s got to do with systems obsolescence Trevor, the electronics are apparently getting harder and harder to support. A technology refresh would be a very expensive undertaking indeed. Moving forward, such capabilities will be carried out via bolt on sensors to the P8, plus extensive use of the F35 and upcoming Captor E radar on the Typhoon. Clearly fighter radar can’t offer the very wide area coverage (no matter how advanced, it can only see where it’s being pointed) or resilience in the area of interest as Sentinel, but this is somewhat offset by generational leap in technology and the… Read more »

Meirion X

Yes, alternatives require a lookdown radar.

David Nicholls

I would believe that the new Protector (?) UAVs may well provide a “replacement” for the Sentinels? this disposal would be aligned (approximately) with their IOC?

John Clark

I don’t think so David, it cant carry powerful enough sensors for the mission.
Protector will be more of a general use asset, looking at specific areas of interest and providing kinetic effect when needed, in a reach out and say hello sort of way….

It might well be one of the key future tools used in conjunction with data from this type asset though.

Nick Harriss

I would guess that this is a further move towards unmanned aircraft. The Global Hawk would be the most obvious replacement, but is very expensive. While the sensor load of the Protector is not as large, with technology improvements since the Sentinel came into service 12 years ago, I wonder how close the capability would be?

James Fennell

Yes I agree. Triton, Global Hawk or something similar can do the role.

Alabama boy

The UK bought 7 E3s in a joint purchase with France who bought 3 all off the same production line. Seven E3s were needed to satisfy the formal Air Staff requirement for AEW capability.