Saturday, October 25, 2008

CABS’ AEW & CS Detailed

In a path-breaking development, Brazil and India on July 3, 2008 inked a US$210 million agreement to jointly develop an airborne early warning and control system (AEW & CS) for the Indian Air Force (IAF). The agreement was signed by Dr S Christopher, Director, of the Indian Defence Research & Development’s (DRDO) Bangalore-based Centre for Airborne Systems (CABS), and Luis Carlos Aguiar, Embraer’s Executive Vice President (Defence and Govt Market), in the presence of Marco Brandao, Brazilian Ambassador to India, and M Natarajan, Scientific Adviser to India’s Defence Minister and Secretary, DRDO. India, incidentally, had earlier acquired five EMB-135BT ‘Legacy’ executive jets, under a Rs7.27 billion contract with Embraer, to ferry VVIPs around the country and abroad. Under the latest deal, Embraer will modify its EMB-145 regional jet aircraft to carry the Active Array Antenna Unit (AAAU), developed by the CABS, on the aircraft’s fuselage. Three modified EMB-145s will be developed under this agreement, with the first being delivered by 2011. The various sub-systems of the AEW & CS’ mission management system will be integrated into the ‘modified green’ EMB-145 by CABS and the full-fledged AEW & CS will be flight-tested in India by CABS and the Indian Air Force (IAF) from 2012.

The AEW & CS’ S-band pulse-Doppler active phased-array radar will operate within the 2GHz to 4GHz bandwidth. The 8 metre-long, 900kg antenna (using 1,280 phase shifters) will be mounted on the upper dorsal spine of the aircraft’s fuselage. The radar’s dorsal unit (DU) will include the carbon-fibre radome, antenna array, RF distribution network, and 192 transmit/receive modules that will be cooled by ram-air. Each such module will comprise a power amplifier for the transmitted microwave signal, low-noise amplifiers as front-ends for the receiver channels, and phase shifters for accurate control of the signal phase in both transmit and receive modes. In the latter, amplification of the signal will be controlled as well. The phases and amplitudes will be continuously calibrated. Each T/R module will be connected to one vertical slotted waveguide on each side. An electronic switch in the module will select the side. By feeding the slotted waveguide separately in the upper and lower half, the beam will be shifted in elevation for height measurement. This shifting will be conducted by single-step phase shifters in the front-ends of the modules. A module-control databus will provide control of the modules to achieve instantaneous antenna beam-steering and the very low sidelobes required. A receiver/exciter processor will generate the pulsed microwave signals and send them to the antenna. It will also accept the received signals from the DU and generate both digitised video signals for signals processing as well as data signals for steering the beam. The transmit drive signal will be generated by a frequency synthesizer and will be up-converted and modulated for pulse compression (using polyphase coding), and will be amplified before being sent to the DU. A programmable signal-and-data processor will receive the returned radar signals from the receiver/exciter via optical data links in digitised quadrature video format. The radial velocity of detected airborne targets will be determined from the Doppler frequency via combined signals from the T/R modules. By combining these signals, the processor will modify the effective antenna sidelobe pattern to place nulls in the direction of hostile jammers. The processor will also perform coherent integration by Fast Fourier Transform that will form a Doppler filter bank. This will be followed by pulse compression, constant false alarm rate processing and binary integration. Due to all this, the AESA radar’s processor will generate clutter- and interference-free position data for all targets.

The two identical antennae in the DU will comprise a row of vertical slotted waveguides each with two sections that will each contain five slots providing low vertical sidelobes. By shifting the signal phase from the upper and lower parts respectively, two tilted lobes will be provided for measuring target altitudes. By adjusting the gain, a proper sidelobe in azimuth will be obtained. The AESA radar will provide 270-degree airspace surveillance coverage and have an instrumental range of 450km and detection range of 350km in a dense hostile electronic warfare environment. The radar’s optimum performance (with very low sidelobes) will be over the 120° azimuthal sectors on each side of the aircraft. In addition, the radar will also have a secondary sea surveillance mode. For the IAF, the radar will be configured for detection, tracking and height finding of airborne contacts, automatic track initiation and continuous tracking of up to 300 airborne targets, moving ground target detection and area ground mapping. In a severe EW environment the radar’s adaptive sidelobe cancelling feature will severely diminish the effects of hostile EW jamming. Pulse compression will be resorted to improve range resolution, while frequency agility will be used to avoid the negative effects resulting from hostile jamming. Doppler processing in both low- and medium-pulse repetition frequencies will be the main target detection mode amidst ground clutter, while horizontal antenna polarisation will provide an indication of the altitudes on which the tracked contracts are flying. High instantaneous bandwidth and Doppler resolution will enable the AESA radar to undertake target analysis via non-cooperation recognition techniques. For detecting hostile airborne aircraft, two mean antenna scan rates of 12 degrees/second or 3 degrees/second will be used, while a scan rate of 3 degrees/second will be used for detecting terrain-hugging or sea-skimming cruise missiles. Warships will be detected using a low-PRF without Doppler filtering. An adaptive radar control mode will control beam scheduling to share the total available time between search, confirmation of detections, and track updates. The radar will also include an L-band IFF transponder.

Inside the AEW & CS will be five tandem-mounted multifunction display/processor consoles that will make up the Central Tactical System (CTS) for providing tactical data management solutions via tactical aids, cues, alerts and bookkeeping functions. The platform will also have a communications suite comprising dual HF and five sets of V/UHF radios for enabling the exchange of tactical data with friendly land, sea and air forces as well as communicating with civilian ATC networks. A Link 16-type data link will provide automatic clear or secure communications channels via one of the HF radios and one dedicated UHF transceiver. The data link will be used for relaying information such as tracking cues, contact range, bearing, velocity, altitude and intercept vectors to friendly airborne combat aircraft, while the IAF’s ground-based Sector Operations Centres (SOC) will be networked with the AEW & C platform via the Ground Interface Segment (EGIS) that will provide two-way exchange of data between the airborne AEW & C platform and ground-based SOCs.

For self-protection, the AEW & CS will have on board a fully integrated defensive aids suite that will include multi-spectral optronic sensors and an ESM suite, designed for the protection of aircraft against infra-red/laser-guided MANPADS). This will in turn be fully integrated with wingtip-mounted lightweight chaff/flare countermeasures dispensing systems. Designed from the outset as a fully integrated modular system, the fully integrated defensive aids suite will combine radar/laser/infra-red/ultra-violet missile approach warning and countermeasures dispensing functions in a single systems controller. Another component will be the ESM suite that will combine the radar warning receiver and countermeasures dispensers with interferometer antenna arrays, a missile approach warning system, laser warning system, defensive aids controller, and a display-cum-control unit.—Prasun K. Sengupta

38 comments:

Anonymous said...

prasun,

r above pics of drdo aewacs or its ffom foreign aewacs

Prasun K Sengupta said...

The scale-model of the platform is from CABS, while the interior photo is from Embraer.

sachin_sathe said...

Hi prasun,

Can u confirm whether the CABS AEW & CS has an inflight refueling probe & also can u give info on its endurance without refuelling. The ERJ-145 seems to be rather small compared to the G550 on which the new
israeli phalcon is based.
Cheers.
sachin

Anonymous said...

Dear Prasun,

I am a regular reader of your articles in the FORCE magazine and thoroughly enjoy them.

Can you please come up with an article onthe following:-

1.) Current status of the Arjun tank along with updates on prouction and post winter trial assessment by the Indian Army.

2.) Progress mae on the development of an Indigenous Diesel Engine for the Arjun Tank ( Ref http://livefist.blogspot.com/2007/11/homegrown-tank-engine-project-begins.html)

3.) Status of development of Arjun mark II and why isnt the DGMF issuing GSQR requirements for the FMBT? What exactly is the definition of Futuristic as used in the term FMBT?

4.) Why exactly does the army not want to use the arjun tank? Especially so, since it is so fond of Israeli weapon systems. Surely, the DGMF would know that when the Israelis produced the hotch potch assembly of various systems that became known as the MERKAVA - I, the Israeli army was hugely dissatisfied withe the system. However the Gen Yitzhak Rabin chose to nurture than dump the system, and the Israelis incrementally impoved the system to the extent that the MERKAVA - IV is today one of the best MBTs.

5.) Finally, why doesnt the Min of Def simply say a flat NO to the IA's insistence on Tin-90 tanks, and force the Arjun tank down the DGMF's throat.

Surely the IA wont overthrow the Govt for doing this.

Eagerly awaiting your article....

Anonymous said...

I meant please post the article on your blog itself

Anonymous said...

prasun,

can u tell that PL-12 missile has better range than AA-12 OR AA-10 missiles

how does ASTRA MISSILE competes with PL-12

Anonymous said...

http://www.cheriblocksabraw.com/

pls make ur blog like this one... layout n color is very cool

Prasun K Sengupta said...

To Sachin Sathe: If one were to acquire the ERJ-145XR as the CABS AEW & C platform then the endurance would be appreciable and could easily cruise at high altitude for up to five hours. Aerial refuelling is required only for those sorties where the aircraft has to stay airborne for more than eight hours with two sets of crew on-board. This is not the case with the ERJ-145, which will not be required to stay airborne beyond 5 hours. The ERJ-145 AEW & C will not be used for filling up gaps in airspace surveillance, but for acting as airborne battle management systems in support of friendly offensive air superiority operations that will not last beyond 4 hours.

Prasun K Sengupta said...

To Anon@9:43PM: Am working on that article right now. Will soon upload it.

To Anon@6:02AM: The PL-12's range is lesser that for the AIM-120B AMRAAM. The R-77 has a greater range. As far as the Astra AAM goes it is still in the R & D stage and there are no definitive performance figures available. In my personal view there's no value in continuing the Astra's R & D unless the resultant missile is superior to the R-77. At the moment, the Astra looks set to be a clone of the Mica-EM AAM, which itself is inferior to the R-77.

max said...

@Prasun

Thanks for the coverage.

How does this match up with Pakistan's Erieye Saab 2000s? I read that the Saabs have a 360 degree coverage, which looks superior to this, with 270 degrees. All in all briefly compare the 2 systems please.

Secondly, what is the extant of Brazil's involvement? Is it only supplying the airplanes? How about fitting integration of the module and other systems on board? Will integration be done in Brazil or India?

Thirdly, what's the difference between a system like this and one with a rotating disc? Which one is superior?


I guess you may have to type quite a bit to answer these questions, but i don't think I can take these anywhere else :-)

Thanks.

Anonymous said...

prasun can u upload these brochures

http://www.afa.org/ProfessionalDevelopment/IssueBriefs/F-22_v_F-35_Comparison.pdf

Anonymous said...

to prasun,

ya there is no reason to continue ASTRA development unless it beats
r77

and u said

The EL/M-2022V(A)3 multi-mode search radar for the A319MPA is the same as that being proposed for the Tu-142MSD.
----------------------------------
it means tu142 will also b upgraded in future


and u also said that russia is going to provide IL78 tankers but i saw a video that in which
PAK AIR CHIEF himself says that
IL78 tankers will come from ukraine

Prasun K Sengupta said...

To Max@11:05AM: Was wondering if you had gone AWOL (LOL)! OK, each of the 4 PAF Saab 2000 AEW & Cs will have the same type of airspace coverage limitations as the CABS-developed ERJ-145 AEW & CS. It will not provide 360-degree coverage. Secondly, the Saab 2000 being a turboprop will have a lower service ceiling at 31,000 feet versus the ERJ-145's 41,000 + feet. The higher you fly, the greater your over-the-horizon surveillance envelope. In addition, the Saab 2000 will not have the type of airborne data links (Link 16) required for communicating with PAF F-16s (because the US is not supplying such data linkls for either the Saab 2000 or the upgraded F-16s or Block 52 F-16s). The Indian AEW & CS on the other hand will have the same type of TADIRAN-built airborne data links as those on board the Su-30MKI. Therefore, the Saab 2000 will definitely be inferior to the AEW & CS. The four ZDK-03 AEW & C systems (based on the Y-8 platform) that the PAF is acquiring will be able to remain airborne for up to 9 hours. It will have a fixed radome on top and inside it will be a rotating PESA antenna. The ZDK-03 will be able to work only along with China-built combat aircraft like the FC-20 (J-10), F-7PG and JF-17s, and will not be able to communicate with the F-16s and Mirages.
Now, with regard to Embraer's involvement with the AEW & CS, it will structurally modify and certify the ERJ-145 platform and along with CEMILAC & CABS, will issue the certification of airworthiness for the complete platform, which will also be equipped with an integrated defensive suite (similar to the ones on board the existing ERJ-140 Legacy VIP transports of the IAF). The multi-function processors (using BARCO-supplied AMLCDs) on board the AEW & CS will be co-developed by BEL and ELTA Systems.
As far as comparisons between fixed antenna array and rotating antenna go, the former has distinct advantages as the lesser the number of moving parts, the lesser the wear-and-tear of hardware. But if the fixed-antenna arrays have 360-degree coverage (like that on the Israeli G-550 PHALCON) then the AEW & C platform will have distinct advantages over the configuration currently being proposed by CABS for the AEW & CS. I personally prefer the Israeli configuration over that being proposed by CABS.

Lastly, here's wishing you all and you loved ones a happy and joyous Deepavali!

Anonymous said...

prasun,

mirage upgrade is a desaster cuz its too costly

air force could also upgrade the mirage2000 with russia i mean with ZHUK ME radar and our own choosen avionics with r77,r27 missiles,if
r77 is superior to MICA EM

russia also said that RD33 MK engine can b equipped on
mirage 2000

v need to just buy airframe spares from france,

now MICA EM will cost more but will have inferior range,french PGM r too costly as well

V could save millions

Prasun K Sengupta said...

To Anon@11:53AM: What you are suggesting is impossible for the same very reason the IAF chose to upgrade its MiG-21bis with Russia instead of Israel. It is not simply a question of installing and integrating the systems of your choice. Even if you were to, who will flight-certify them? Who will assume responsibility and liabilities in case of a crash? That's the reason why the IAF has rightly decided that when it comes to aircraft upgrades (for imported aircraft) the best solution is to always team up with the aircraft's OEM. Also, it won;t make any sense to replace the existing M53P2 engine with the RD-33MK since the total technical service life (TTSL) of the M53P2 is still double that of the RD-33MK. remember, the figures being quoted about the RD-33MK are still unproven and uncertified figures. The actual figures will be established only the first two years AFTER they enter service, based on the operator's operating conditions and pattern of employment. Therefore, Klimov is being conservative about the RD-333MK's performance parameters and will be able to release the definitive figures/parameters only by 2010. Those figures may well be superior to what has already been established for the M53P2, but we don't know that for sure for now. The same goes even for the AL-31FP, whose TTSL is 2,000 hours now, but maybe after another five years, NPO Saturn may re-certify them to 4,000 hours, based on the usage data made available by the IAF in future.

Anonymous said...

to prasun

engine life doesn't matter speacially if the upgrading of aircraft is much cheaper to similar other aircraft and cheaper upgrade compensates for the life of engine

just like upgrade of mirage2000 cost twice as much the mig29 upgrade deal with no new engines on mirage2000

v r paying 2 billion to french just for avionics and stuctural upgrade and some new weopans

v r just paying 1 billion for mig29 upgrade deal with all aircraft with new engines and each aircraft has two engines

engine of an aircraft can b changed many times if specially the engine cost is very cheap but it is highly unlikely that engine is changed in an aircraft many times just like its first time v r going to change the engines of
mig29

even if the m53 engine has better life time hours its alost 3-4 times costlier than rd 33-3 engine

new rd 33-3 engine just costs bit over 2 million and its no way inferior,if older rd33 can work till now the new and upgraded
rd33-3 engine will work very well

the new rd33mk, al31 117s engine has 4000 life hours and MTBO of 1000 hours
and europe possess no engines like
al31, al31 117s,al 41 class,only US has them

both ej2000 and m88 2-3 r built around ge404,414 series

max said...

@Prasun

Thanks. No I've not dissapeared. Very much follow your blog, but what interests me more are indegenous Indian developments like this one. Nevertheless I read all your articles.

Few more questions:

How long can this CABS system and Phalcons stay in air?

The Chinese AWACS is based on a Beriev A50 isn't it?

Thirdly, I did read in several websites that the Erieye has a 360 degree coverage. Are you sure it's restricted to 270 degrees?


Happy Diwali to you too!

Enjoy..

Anonymous said...

the amount of mistakes in this single post are staggering, not to mention the incorrect technical jargon. has it been copy pasted from someplace?
to begin with, the cabs awacs wont even have a slotted array antenna, but a printed one. much lighter and more power efficient. not to mention several other errors.
anyways heres hoping future articles will be better.

Prasun K Sengupta said...

To Anon@12:40PM: You are missing the main point, which is, who will flight certify the Mirage 2000 after it has been retrofitted with Russia-origin engines and avionics? And who will supply all the airframe-related structural data to the Russians that is required for the upgrade? Only the airframe manufacturer has such data which it does not share with the aircraft operators. So where will such data come from? And at what cost? Do you ever think the French will give such data away just so that Russia-origin avionics and engines can be fitted on to a Mirage 2000? Will the Russians similarly allow French engines and the complete avionics suite to be fitted on board the MiG-29 or Su-27/30? Don't forget that the RMAF originally wanted the Mica IR/EM for its Su-30MKMs, but the prohibitive systems integration costs quoted from Rosoboronexport scared the RMAF and this option was eventually dropped.

To Max: The AEW & CS will be able to stay airborne for 5 hours unrefuelled while the PHALCON will be able to stay airborne for up to eight hours unrefuelled. The Chinese have three AEW & C systems: one is the IL-76-based KJ-2000, then there is the Y-8-based KJ-200, and lastly, the ZDK-03 that is mounted on the Y-8. An rest assured, the Saab 2000 AEW & C, like the CABS AEW & CS will not have 360-degree coverage. Both systems employ sideways-looking AESA-based radars, and they're blind in the frontal and rear sectors.

To Anon@1:02PM: Instead of making generalised and unsubstantiated remarks, can you list out in detail the 'factual errors' and 'incorrect technical jargon' in the article? I hope you can list them out so that I can cross-reference them with the IAF's ASQR for the AEW & CS which is in my possession (yes, I copy-pasted the data from the ASQR) and which I will upload ONLY AFTER you have convinced me that your 'detailed' clarifications/corrections are indeed irrefutable. And please don't refer me to any non-existent technical paper presented by someone from CABS during some prior symposium in some undetermined location and undetermined time-frame.

Anonymous said...

to prasun

my point is just that its not me
but it was said by russia that rd33 engine can b fitted on mirage2000
russia has experience in makin aircraft so they better know about this

by the way not going into this detail that rd33 engine can b fitted on mirage or not,

my point was that engine life doesn't matter when two engine of similar class and one of them costs only 1/3 the price of other then that 1/3 cost of cheaper engine compensates for its life cycle and MTBO hours just like
rd33-3 and al 31 engines

e.g rd33-3 engine cost bit over 2 million while similar western engines cost arount 6-7 million per piece

now u can buy 3 rd33-3 engines for 6 million

but it is highly unlikely that an aircraft need more than 1 engine change in its life,russia has said that new rd33mk engine has 4000 hours of life and 1000 hours of MTBO and it doesn't smoke

if old rd33 can work till now there should b no problem with new rd33-3,mk engines

shriya said...

happy divali

trisha said...

divali greetings!!

namitha said...

Happy divali dear!

Anonymous said...

No i'm not that anon who says your article is WRONG, but please if u don't mind let us have a look at that AQSR?

thx

Anonymous said...

if u follow asshole shiv's blog called LIVEFIST, u'll come across this article with mostly pictures about acc training in the us. i asked asshole shiv these questions but as usual he nvr answers. i hope u can gimme a short xplanation.

1. doesnt india have its own training facility for naval airplane launch? in fact IN can train on the current acc Viraat in service. Why go to USA?

2. Doesn't USA uses CATAPULT take off and arrested landing. The new carriers we r buying / building are ramp take off, arrested landing. so whats the point of doing CATAPULT training? Short/ramp tae off drills can be done, as i say above, on our current carrier / facilities.

tq.

Anonymous said...

prasunji, are you a native Bengali? Only Bengalis call Divali as Deepavalli.

Regards,

Santosh Gupta

Prasun K Sengupta said...

To Anon@11:13PM: The problems for the IN as far as flight training goes are the following:
1) The Viraat for the past two years has not been available for prolonged periods and is currently undergoing another refit to extend its service life.
2) The IN does not have a dedicated tandem-seat flying training aircraft and has yet to place firm orders for an aircraft like the T-45C Goshawk. Therefore, the only other option available is to train on similar aircraft in similar operational conditions. Hence training on board the T-45C Goshawk.
3) If the IN had ordered a few T-45Cs and had constructed a shore-based ramp-based short takeoff and arrested landing facility, then all MiG-29K-related flight training could have been conducted in-country. Since this infrastructure has not yet been built in-country, those pilots destined to convert to the MiG-28K have no choice but to go to the US.
4) The most complicated component of aircraft carrier-based flight operations is the landing and recovery phase, which is akin to a controlled 'crash landing'. The takeoff component is easier and it doesen't matter whether it is accomplished by the aircraft's own power or via a catapult. But the arrested recovery simulation is far more important to master before flying aircraft like the MiG-29K. Hence, the need to send the trainee pilots to the US to get a sense and feel of the real operating environment. Had the IN set up such shore-based training facilities and had it acquired a few T-45Cs about two years ago, then all such flying training facilities could have been localised.

Santosh, throughout Southeast Asia, Diwali is referred to as Deepavali.

Anonymous said...

to prasun,

any info on GPS version of
KAB 1500/500 series like JDAM

Anonymous said...

Santosh, problem is most northern indian / nepali guys call DEEPAVALI as DIWALI, which is a corrupted version of the original version.
Deepavali in sanskrit translates to row of lamps (DEEP means lamp, AVALI means in a row). Hence, DEEPAVALI.
In South East Asia, indians are mostly of tamil / south descent. there it is also called DEEPAVALI but they take it to mean (DEEPAM - which means festival, and OLI which means lamps). For spelling purposes they say DEEPAVALI or DEEVALI but in news they still emphasize a clear DEEPAM-OLI.

So generally, DIVALI / DIWALI is none but a generic term for ease of pronounciation that has no 'real' meaning from what i know.

And yes, Bengalis call it correctly as DEEPAVALI. I'm sure Prasun is a Bengali from his name. Sengupta to my knowledge is a distinct name from that region.

ok now Back to defence:

How many crews would man this Embrear Awacs? And is it on schedule to completion? Whats progress now? Has the Main module been made ready?

void walker said...

happy diwali. lets not take to heart our tussles on this auspicious day.

Prasun K Sengupta said...

To Anon@10:18AM: The AEW & CS will be manned by 2 eight-man mission management crew complement. The average mission duration will be five hours. The mission management consoles will be in tandem configuration (one behind the other), whereas on the Saab 2000 they would be side by side. The first aircraft will be delivered only by late 2010 and only after that will systems installation commence.

Happy Deepavali to you too & all your loved ones, Void Walker. Rest assured, I never took any of our 'tussles' to heart.

RAJ said...

RE PRASUN

for effective use of CABS AEW E-145, it will also fly at an altitude of 26,000 feet otherwise its capacity/range to detect ground hugging cruise missiles would be reduced.


Regarding israeli configuration their is problem of interference by wings in radar waves and increased required of cooling equipment as natural flow of air to cool the radar is missing.

Anonymous said...

ok tq for that info.. pls teach shiv some manners too.... and fundementals of blogging which is to reply / acknowledge ppls comments. he s been doing it 4 donkey yrs n dont seem 2 know.

and some more, is sitara hjt36 = goshawk?

ok happy divali 2 u

Prasun K Sengupta said...

For cruise missile defence it would be unwise to deploy the AEW & CS as airspace surveillance even against cruise missiles is a 24/7 job. For this, aerostat-mounted radars will be more desirable. The service ceiling of the ERJ-145 is 41,000 feet and this would be exploited to the hilt when tactical air dominance operations are undertaken by the IAF.

To Anon@12:11PM: Much as you would like me to 'teach manners' to others, I'm afraid I'm unable to do so as I do not control their lives or lifestyles. Regretably, you will have to take this up personally with them. I will try as far as possible to answer as many genuine queries as possible as my time permits.

Prasun K Sengupta said...

The HAL-built HJT-36 Sitara is an intermediate jet trainer, whereas the T-45C Goshawk is more of a lead-in fighter trainer, much like the Hawk Mk132. Also, the HJT-36, which the Indian Navy will procure in future, will be used for shore-based flying training and is therefore not being developed for carrier landings/takeoffs.

Anonymous said...

ya, thats y i only asked u to teach him. not control him.

but i doubt he'll change anyways.

Anonymous said...

thanx 4 ur answers anyway. appreciate it

Anonymous said...

Hi Prasun, just one question on the A-50EI with the Israeli Phalcon for the IAF. I saw some pictures of it on airliners.net, and noticed that these carry the Aviadvigatel PS-90A engines as opposed to the older Soloviev D-30s. This use of PS-90As for a small fleet of 3 (or is it 6 eventually?) aircraft didn't seem to make sense when we already have about 40 airplanes (76, 78MKI) with the D-30s and I would assume the fuel efficiency afforded by the PS-90As would be pretty much offset by engine commonality with an existing fleet. Now my question is this, is this an isolated development, or is there a possibility that the Garjraj and Midas fleets could be re-engined with the PS-90s somewhere down the line? FYI, there is a similar programme underway for civilian Il-76s, wherein they are converted to Il-76 MD 90s, or TD90VDs.. Any views you have would be appreciated.