The future of Indian Army's Air Defence Corps

The Indian Army's (IA) Air Defence (AD) corps has long been considered the most neglected of its specific arms. However with the induction of the Akash medium range surface to air missile (MRSAM) system developed by the Defence Research and Development Organization (DRDO) the long awaited modernization of this arm has now kicked off. Alongside the Akash, Army AD is also inducting a new generation Russian very short range SAM (SR-SAM).
These two inductions have meant that the IA now can wait for an indigenous offering in the quick reaction SAM (QRSAM) segment which has begun development in DRDL rather than procure that from overseas. The AD corps is however having to make do with interim upgrades of its obsolescent AD guns via domestic industry and is exploring the possibility of crafting a domestic replacement. Meanwhile domestic programs have also yielded sensor spinoffs that have found favour with the AD corps and these are being used to pave the way for greater network centric warfare (NCW) capability.

Despite years of criticism by naysayers, the Akash MRSAM has made it to the IA's stables. The two lead integrators Bharat Electronics Limited (BEL) and Bharat Dynamics Limited (BDL) along with 205 other domestic suppliers are currently executing orders for two Akash Mk-I missile regiments for the IA worth Rs 14,180 crores. And in mid-2014 the IA wrapped up the last round of validation trials for the first-off production units. These final trials included a successful low altitude near boundary intercept of a banshee unmanned aerial vehicle (UAV) target at an altitude ofjust 30 metres validating the systems capability against subsonic cruise missiles such as the Babur.

A typical Akash battery consists of four launchers carrying three missiles each with a range of 30 km and maximum interception altitude of 18 kms. The launchers built by Tata Power SED are now mounted on 8x8 Tatra trucks supplied by BEML. After years of experimenting with tracked launcher vehicles based on BMP and T-72 chassis, the IA has settled for a wheeled configuration now. Each battery has three radar sensors - one 3D central acquisition radar (CAR), a 3D Rajendra Phased Array Radar also known as Battery Level Radar (BLR) and a 2D Battery Surveillance Radar (BSR) which feed information to a mobile battery C4 control center. In autonomous mode deployment an additional BSR is added to a typical Akash battery for providing point defence to mobile assets. The Akash can also be deployed in group mode where four batteries 'report' to a group C4I control center providing coverage over an area of 5000 sqkms.

Early warning in all modes is provided by the S-band CAR which can track while scan 150 targets simultaneously beyond a range of 200 kms and up to an altitude of 18 kms. The BSRs come into action for targets that are up to 100 kms away. The Akash missile itself of course employs a command guided missile with fire control being provided by the Rajendra III which can track 64 targets simultaneously while being able to guide up to 12 missiles at a time to engage 4 different targets. The Rajendra III which is in production is a slewable passive electronically scanned array (PESA) that has a tracking range of 60 km against fighter aircraft flying at medium altitudes.

This order for two initial regiments though seemingly substantial actually represents only the beginning. The Akash was developed to replace legacy ZRK-SD Kub SA-6 systems of which 12 plus regiments still serve in the AD corps. Till not so long ago the IA was even looking to bring in MRSAMs from overseas in addition to the Akash and an RFI was even issued to that end. However the evolution of the Akash system seems to have put paid to that need and it is clear that the Army will order many more Akash regiments. This also means that US attempts to sell the HAWK XXI is unlikely to head anywhere. The Rajendra has demonstrated track and scan capability on the move and the IA is confident that a distributed Akash battery can both keep up as well as provide adequate area AD to its advancing formations. Moreover the MK-2 version of the Akash with a range of 37 km possibly mounting an active radar seeker head is also under development. There is constant work underway to improve the electronic counter counter measure (ECCM) capabilities of the Akash system also.

Even as the IA settles for the indigenous Akash system in the MRSAM segment, it may be bringing in the Russian Sosna-R which is meant to replace current holdings of the SA-13 Gopher (Strela-10) mounted on a MT-LB. The Sosna-R is mean to counter precision guided weapons (PGMs), low flying aircraft and even ground vehicles at short range. The Sosna-R two-stage missile has a range of between 1 and 10 km and carries two warheads with a cumulative weight of 7 kg and of course two fuzes.
The missile can achieve speeds of up to Mach 4 according to some sources. Each Sosna-R vehicle has 12 ready-to-fire missiles and can be reloaded in 12 minutes, according to the Russian manufacturer KBTochmash.
The missile is command guided when in its boost phase and has a laser beam riding guidance system for the end game. Several launcher vehicles typically operate together with a command vehicle carrying a surveillance system that provides off-board target designation. The passive optical fire-control system on each launcher vehicle makes the Sosna-R survivable in a dense electronic countermeasure (ECM) environment and can simultaneously track 50 targets while being able to engage one on the move. It remains to be seen if the IA will simply use Strela-10 carrying MT-LBs to now mount the Sosna-R.
There are over 250 SA-13 launcher vehicles in the IA's inventory at the moment. As an aside, The IA also has a tender underway since 2010 to procure a shoulder launched SAM being fought out between the MBDA Mistral, Saab RBS 70 NG and KBM Igla-S. The order is for up to 1,000 launchers with 6000 missiles procured initially and many more under license production at BDL for a tri-service requirement.

The Akash and the Sosna procurements have meant that the IA now has the space to consider the the indigenous QRSAM being developed by DRDO's Defence Research and Development Laboratory (DRDL) to replace the 50 plus OSA-AK SAM units it has in the AD core. In 2012, the defence acquisition council had given the IA the go ahead to issue request for proposals to foreign vendors who had responded to its RFI for a QRSAM with a range of not less than 15 km, altitude capability of not less than 6 kms, reaction time of 6 seconds or less, guidance package consisting of an onboard seeker and the ability to engage targets flying at 0-500 m/s as well as hovering helicopters. Up to eight regiments of this QRSAM were sought to be procured. For this particular tender, DRDO was expected to bid with the Maitri missile that was slated to co-develop with MBDA. It is believed that the Israelis would have offered the Spyder SR and the Russians the TOR-M2KM mounted on a Tata vehicle.

However the Maitri project is now as good as dead because both the IA and the Indian Air force feel that its specifications would lie more or less within the capabilities of the Akash Mk-I itself and the IA's fire on move requirements are being met by the Sosna-R. So at the moment an indigenous QRSAM option is being pursued in earnest with elements of this system already starting to coming together in the form of both new radar as well as IIR seekers under development at DRDO's Research Centre Imarat (RCI) Laboratory and a stabilized electro-optical sight (SEOS) developed by DRDO's Instruments Research and Development Establishment (IRDE). IRDE's SEOS has two-axis stabilisation and integrated automatic video tracker facility.
Three electro-optical sensors-3rd generation 3-5 μm (640 x 512 FPA) thermal Imager (TI) with optical zoom, colour day TV with optical zoom camera and eye-safe laser range finder (ELRF). The day TV camera and TI are having a narrow field of view (NFOV) of 0.8° x 0.6° and wide field of view (WFOV) of 5° x 4° with additional 2 X electronic zoom in TI. These sensors provide a recognition range of 7 km for a NATO type of target. ELRF provides range of the target from 200 m to 9995 m with an accuracy of ± 5 m. The SEOS will complement the Ka-band radar that will guide the QRSAM in dense ECM environments. The SEOS

enables steering of line of sight with an azimuth angular freedom which enables the system operator to carry out independent surveillance over a wide area with target acquisition and tracking from a moving or static vehicle, with wide/narrow field of view in day and night. The sight is integrated with a robust automatic video tracker, to track the aerial and ground targets with the tracking accuracy of ±3 pixels and maximum tracking rate of 0.1 mil/sec to 70 mil/sec.

Meanwhile even as new missile systems begin to find their way into the AD core, there is still no clarity on what exactly will replace the IA's large holding of L-70, L-60 and ZU-23 anti-aircraft guns. In the first decade of this century this seemed like a done deal what with the Ordnance Factory Board(OFB) all set to produce Rheinmetall AD's Oerlikon-Contraves 35 mm Skyshield system firing the proprietary AHEAD ammunition round to be acquired in both towed as well as vehicle mounted configuration on trucks supplied by Tata. But the OFB scandal which broke in 2009 derailed this plan since it led to the blacklisting of Rheinmetall AD itself. To make the best of a bad situation the IA is considering various upgrades to the L-70 offered by domestic players such as Larsen and Toubro with optical payload, auto-tracker, fire control computer and an electromechanical gun laying system. Meanwhile Punj Lloyd is offering similar upgrade packaged for the ZU-23.

Even as IA mulls over its future towed and truck mounted AD gun situation, it is also going ahead with the upgrade of the legacy Schilka ZSU-23-4 with new electro-optical sights, radiation hardened electronics and a new diesel engine instead of old gas guzzling gas turbine. The upgrade is being executed by BEL for over 90 systems and it remains to be seen whether the same route will be used to upgrade the AD cores Tungushka regiments as well eventually.
The upgrade is supposed to enable the Schillka to operate in a more networked environment something that both the Akash Systems and Sosna-R obviously are capable of. Indeed, in a boost to bring in more NCW enablers the IA also has several 3D Tactical Control radars (TCR) on order derived from the Akash system's CAR developed by the Electronics and Radar Development Establishment (LRDE) which are more compact and have a range of about 90 km. TCR is Tatra VVL mounted, mobile stand-alone and all weather. Interestingly, pertinent data can be collected at a Target Data Receiver (TDR), located 20 Kms away from the TCR itself. The radar operates in S-band and its antenna is mechanically rotated in azimuth to provide 360 deg and 50 deg elevation coverage up to a height of 10 kms.

The AD core has also opted for the low level light weight L-Band 2D Bharani Radar which is a battery powered compact sensor providing 2D surveillance solutions to alert AD weapons mainly in mountainous terrain against hostile aerial targets like UAVs, helicopters and fixed wing aircraft flying at low and medium altitudes. The radar can be transported by vehicles, animal transport, a group of men or as helislung loads. It can be dismantled into packages to facilitate quick installation and re-location in mountainous terrain. It will act as an early warning element to AD weapon systems employed to provide protection to vulnerable areas or vulnerable points.
The Bharani consists of radar, Commander Display Unit (CDU) and messaging unit Target Designation Unit (TDU) and TDRs. One radar can service up to 10 TDRs using existing combat radio resources/ network. The CDU can be located up to 750m from the radar. The radar with modular architecture, advanced ECCM features, ruggedness as per Mil standards can be operated in varied conditions including extreme climactic and geographical conditions and in battle field situations, especially in an offensive EW environment.

All of these elements ultimately feed into the Air Defence Control and Reporting System (ADC & RS) developed by the DRDO is "to detect all aerial targets and neutralize the threat well away from the vulnerable area/vulnerable point (VA/VP) by effective integration of all AD Weapon Systems". This in turn will be an element of the Tactical Command Control Communication and Intelligence (Tac3I) System developed for the IA by DRDO's Centre for Artificial Intelligence and Robotics.

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