Which Way Is India’s BMD/AEW System Headed?

By Prasun K. Sengupta


New Delhi, 28 November 2003

Prasun K Sengupta is a defence analyst based in Malasia who writes regularly in TEMPUS magazine. His detailed analysis for a viable ballistic missile defence (BMD) system for India, to counter the threat of attack by WMDs, is both relevant and thought provoking. As always the author's views are his own and we do not necessarily subscribe to them. Comments on the article through our Feedback page or by email to are more than welcome.

Which Way Is India’s BMD/AEW System Headed?

By Prasun K. Sengupta

How does one conceptualise an India-specific ballistic missile defence (BMD) system? According to senior officials of the Indian Army’s Directorate of Field Artillery and the Indian Air Force’s Directorate of Offensive Air Operations (these two Directorates have now become integral ‘operational’ components of India’s Strategic Forces Command), this is how things are envisaged: Since there is no way to distinguish between the types of warheads of attacking tactical/theatre ballistic missiles (TBM), it is impossible to know if an incoming warhead is nuclear, chemical, biological or conventional. Consequently, from the moment a country such as Pakistan possesses nuclear, chemical or biological warhead delivery capabilities with TBMs, India will be forced to assume that the TBMs aimed at its territory are carrying warheads of mass destruction (WMD), and will have to respond accordingly. 

In such an environment of ‘mutually assured destruction’ in South Asia, there will be a need for an immediate lethal response, in order to preserve the credibility of an Indian second nuclear strike. In all cases, India will have to absorb a lethal blow, because of its geographical and demographic characteristics. However, a deadly riposte by India will not save it. It will only inflict a deadly blow on the aggressor, so that both sides will be hit, but the targeted Indian sites will still be wiped out. 

Therefore, in the centre of Indian strategic thinking lies the obligation to neutralize the risk of a WMD first-strike initiated by the belligerent, be it Pakistan or anyone else. If India succeeds in doing so and at the same time possesses the potential of destroying the enemy, the enemy’s motivation to destroy India by using WMDs will be eliminated. The planned India-specific BMD system, which is designed to eliminate the danger of a first strike with WMD-equipped TBMs, is intended to achieve this aim and provide India with a ‘Strategic Depth of Time’, which would allow the Government of India to act, free of apocalyptic threats.

This then brings us to defining the operational and qualitative requirements of an India-specific BMD system. In order for such a system to be able to meet the expectations described above, it must be capable of intercepting a salvo of TBMs attacking from distances of up to 1,500km away, and do this with a maximum leakage rate of one in a thousand, or 0.1%. There is no BMD system existing today that can guarantee an interception probability of 99.9% (which is equivalent to a leakage rate of 0.1%). However, it is possible to achieve an interception probability of 90%. 

The transition from 90% to 99.9% can, however, be performed by using a multi-tiered approach, and by incorporating into the BMD system’s guided-interceptor missile and its fire-control radar (FCR) the attributes that support such a multi-tier operation. The multi-tiered approach can be implemented by providing a minimum of three independent discrete opportunities of interception. The first opportunity is in the first layer at the highest altitude possible. In this case the FCR will monitor the results of the encounter with a single interceptor missile and provide the optimum kill assessment. If there are no kills, two additional interceptor missiles will be launched at short time intervals. These constitute the second and third layers. Using this technique, three independent interception possibilities can be provided, which raise the interception probability of an incoming TBM from 90% to 99.9%, thus satisfying the leakage rate requirement.

Indian defence planners (civilian and military) involved in developing an India-specific BMD network estimate that the capability of existing TBMs currently operated by countries like Pakistan will not exceed a total salvo of 50 TBMs armed with WMD warheads during the next 10 years. On the assumption that India will have to counter an attack on a scale totalling 50 WMD-equipped TBMs, there will be a need for 60 interceptor missiles (the 1.2 ratio mentioned earlier). With an additional assumption that there will be a need to guarantee the overall defence of India in three distinct theatres (the Indo-Gangetic plain, western India and south-western India), the overall number of interceptor missiles required will reach 180. To this number, a technical reserve of one third has to be added, so that the final number is 240 interceptor missiles for a functional and effective India-specific BMD network. 

In order to achieve the deterrent effect based on an active defence strategy which finds expression in the capability of an India-specific BMD system, India needs to publicly declare that any attack made against her by ballistic missiles will be interpreted as an attack using nuclear, chemical or biological warheads, with the intention of annihilating India. To this end, an India-specific BMD network must be seen as an extension of India’s ‘no first-strike with WMD’ policy. Thus, a White Paper on India’s proposed BMD system is long-overdue and needs to be tabled by the Government of India without any further delay.

As far as R & D efforts undertaken thus far by the state-owned Defence Research & Development Organisation (DRDO) to develop an India-specific BMD system are concerned, the only credible step undertaken so far has been the acquisition of two EL/M-2080 ‘Green Pine’ radar systems from Israel Aircraft Industries (IAI). Ordered in 1998, both the radars were delivered in 2001. The Green Pine is an L-band active phased-array search, acquisition and FCR all rolled into one, which can detect and track incoming TBMs as far way as 500km and can guide the Arrow 2 hypersonic interceptor missiles within an engagement envelope of 16km and 48km. The complete radar system comprises the trailer-mounted radar and antenna array, power generator, cooling system, and a radar control centre. It is similar in concept to the Raytheon-built Theatre High Altitude Air Defence (THAAD) radar, which is an X-band, active phased-array, solid-state radar system. Based on operational inputs from the Indian Air Force (IAF), the DRDO has been tasked with developing a complete integrated BMD system, including missile launchers, missiles, multi-purpose radar, computers, and associated battle management command-and-control elements, all of which are required to work in concert to detect, identify, assign, and destroy incoming TBMs.

Clearly, based on the operational requirements and the available military-industrial infrastructure available within India, it is obvious that a ‘domestic/indigenous’ deployable solution is out of the question in the foreseeable future. The DRDO’s Akash surface-to-air missile (SAM) and its associated ‘Rajendra Battery-level active phased-array FCR, the 3-D Central Acquisition Radar (CAR), and associated engagement control centres, which have been frequently touted by many as one with potential BMD capabilities, is at best a SAM system capable of engaging hostile airborne combat aircraft and air-breathing/subsonic land attack cruise missiles, provided the Rajendra and CAR systems are supplemented by an integrated network of ground-based passive optronic search-and-track systems. Here too, the necessary core technological competencies have yet to be attained by the DRDO.

Originally conceived as a SAM to counter manned, manoeuvring airborne platforms, the medium-range Akash, which was first test-fired in 1990, underwent developmental test-flights till March 1997. Operational tests and evaluations are still continuing. The 27kg-range missile, armed with a 60kg blast-fragmentation warhead with an effective radius of 20 metres, uses an integral ramjet rocket propulsion system to give a low-volume, low-weight (700kg launch weight) missile configuration, and has a reaction time (from detection to missile launch) of 15 seconds. The SAM’s solid-propellant booster accelerates it within 4.5 seconds to Mach 1.5, and is then jettisoned. The ramjet motor is next ignited for 30 seconds to propel the SAM to a top cruising speed of Mach 3.5 at 20g and up to a service ceiling of 15km. The SAM is equipped with four long, tube-ramjet inlet ducts mounted mid-body between four clipped triangular moving wings for pitch/yaw control. Forward of the tail are four inline clipped-delta fins with ailerons for roll control. All flight control surfaces are operated by pneumatic actuators. The fuse is of the Doppler radar proximity/contact type. The missile has tail-mounted G/H-Band transceivers to assist its tracking by the Rajendra multi-purpose FCR. Boost-phase guidance is inertial, with mid-course correction updates coming from the Rajendra using the track-via-missile guidance technique, with an on-board semi-active radar taking over for the terminal phase (the final 3-4 seconds).

The Rajendra FCR, being developed by the DRDO’s Hyderabad-based Electronic Research & Development Establishment (LRDE), comes mounted on a modified BMP-2 tracked armoured infantry fighting vehicle chassis, like that of the Akash SAM launcher. Rajendra, whose early warning antenna array contains 2,000 ferrite phase shifters (operating in the G/H-Band or 4-8GHz), can track 64 airborne combat aircraft at medium-altitude out to a range of 60km in the sector-scan mode. The radar’s engagement antenna array with 1,000 phase shifters operating in the I/J-Band (8-20 GHz), and a 16-element IFF array, can engage four airborne targets simultaneously with 12 SAMs. A typical Akash SAM Battery will comprise three SAM launch vehicles (each containing one triple-round swivelling launcher on a modified BMP-2 chassis), a Rajendra FCR vehicle, a TATRA 8 x 8 vehicle mounting the 3-D CAR, and an armoured command vehicle, also mounted on a TATRA 8 x 8.

Consequently, the only viable and ‘proven’ solution, and one preferred by the IAF, is the ‘Homa’ (Fence) system developed by IAI’s MLM Division, which has been operational since 2000. The entire system comprises the Green Pine radar, Citron Tree battle management centre (built by Tadiran), 1.3-tonne Arrow-2 interceptor missile, and Tadiran’s containerised ‘Hazelnut Tree’ launch control centre. The Homa system is designed to simultaneously intercept as many as 14 incoming TBMs. Citron Tree, which is trailer-mounted, downloads data from Green Pine along with data from other sources (like long-endurance unmanned aerial vehicles such as the IAI-built HERON and manned airborne early warning & control platforms like the PHALCON, both of which India is acquiring), using powerful signal processing tools to manage the interceptions automatically, including against single and multiple threats. The Citron Tree has workstations for the Sky Situation Coordinator, Intelligence Officer, Post-Mission Analysis Officer, Resource Officer and Senior Engagement Officer, as well as the Commander’s workstation. The workstations display a large electronic map showing the area of battle. Predicted and confirmed launch sites are colour-coded to show priority sites. When a TBM launch is detected, its launch site, the TBM’s position and trajectory, and the predicted impact point are displayed on the electronic map. The predicted impact point is displayed as an ellipse on the map. The size of the impact ellipse shrinks as the TBM’s trajectory stabilises and the trajectory data becomes available. The trajectory image is colour-matched to the image of its launch site. The optimum intercept point is also displayed.

The two-stage Arrow-2 interceptor missile, equipped with solid-propellant booster and sustainer rocket motors, uses an initial burn to carry out a vertical hot launch from the container, and a secondary burn to sustain the missile’s trajectory towards the target at a maximum speed of Mach 9, or 2.5km/second. Thrust-vector-control is used in the boost and sustainer phases of flight. At the ignition of the second stage sustainer motor, the first stage assembly separates. The Arrow-2 is launched before the hostile TBM’s trajectory and intercept point are accurately known. As more trajectory data becomes available, the optimum intercept point is more precisely defined and the Arrow-2 is guided towards the optimum intercept point. The kill vehicle section of the Arrow-2, containing the RAFAEL-built high-explosive, directed blast-fragmentation warhead, fusing and terminal dual-mode seeker (incorporating a Raytheon-built passive infra-red sensor containing an indium antimonide focal plane array for the acquisition and tracking of TBMs, and an active radar seeker used to home on to air-breathing targets like land attack cruise missiles at low altitudes), is equipped with four aerodynamically-controlled moving fins to give low-altitude interception capability. The warhead is capable of destroying a target within a 50-metre radius.

As can be seen from the above-mentioned data, essential elements of a functional ‘Homa’ derivative specific to India are already in place, i.e. the Green Pine and HERON, with up to six PHALCON AEW & C platforms to be delivered by IAI to the IAF between 2006 and 2010. Financial and operational prudence therefore demands that the remaining elements of ‘Homa’ be acquired and deployed in the near future by India’s Strategic Forces Command. The only ‘indigenous’ mission-critical inputs required to make an India-specific ‘Homa’ BMD system with truly Indian characteristics are in the areas of network-centric data fusion and aerospace battle management solutions--areas in which the DRDO and India’s private-sector Information and Communications Technology (ICT) corporate entities already have considerable core technological competencies.

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