Advanced Towed Array Sonar contract provides major boost to navy

                              Atlas Elektronik Advanced Towed Array Sonar

On November 12, without announcement or fanfare, the ministry of defence (MoD) signed a small contract with enormous implications for itself and the Indian Navy. This formalized the purchase of six advanced towed array sonar (ATAS) systems from Atlas Elektronik, the German naval systems giant, for just under Euro 40 million (Rs 306 crore).

These ATAS systems will equip three Talwar-class frigates (INS Talwar, Trishul and Tabar) and three Delhi-class destroyers (INS Delhi, Mumbai and Mysore), allowing them to detect enemy submarines in the Arabian Sea, where the warm, shallow waters confound conventional hull-mounted sonars.

Without ATAS, all the warships the navy has built and bought since the 1990s --- each costing a few thousand crore and crewed by a couple of hundred sailors --- would be sitting ducks in war. Enemy submarines, lurking unseen 50-80 kilometres away, could leisurely torpedo Indian warships.

So vulnerable has been India’s fleet that, when INS Vikramaditya, the navy’s new aircraft carrier, was sailing home from Russia, it was escorted through the Arabian Sea by several Indian warships. There was no certainty that Pakistan’s Agosta 90B submarines could be detected by sonar systems other than ATAS.

All that protects India’s 25 latest frontline warships from enemy submarines is a relatively ineffective Passive Towed Array Sonar (PTAS), and an indigenous hull-mounted sonar called HUMSA.

So important is the ATAS contract that the MoD abandoned even the pretence of indigenisation. Atlas Elektronik will build all six ATAS systems in Germany, and has been exempted from offsets.

ATAS is especially vital in the Arabian Sea. Warships detect underwater objects (like submarines) with sonar --- a “ping” of sound emitted into the water that reflects from submarines, just as radar bounces back from aircraft. In our warm, shallow waters, the returning signal often gets lost. Since the water is warm on the surface and cools rapidly as one goes deeper, the sharp “temperature gradient” refracts sonar waves, bending them away from the warship’s sensors. Unable to receive the returning signal, the warship cannot detect the submarine .

ATAS overcomes the “temperature gradient”, since it is towed by a cable that extends deep below the surface, into the cooler layers where submarines lurk. With the sensors themselves in the colder water layers, there is no “temperature differential”. Even the faintest return signal from a submarine is detected.

The navy will fit ATAS externally onto the rear of its warships, which have been built for this reason with an empty compartment at the rear.

With this contract, Atlas Elektronik has taken pole position for supplying the navy a range of high-end sonars. Bharat Electronics Ltd (BEL), which is required to build ten ATAS with foreign partnership, has been encouraged by the navy to tie up with Atlas so that sonar equipment is standardised across warships.

BEL is learnt to be in discussions with Atlas for building ten ATAS for three Shivalik-class frigates (INS Shivalik, Satpura and Sahyadri), three Kolkata-class destroyers (Kolkata, Kochi and Chennai), and four Kamorta-class anti-submarine corvettes (INS Kamorta, Kadmatt, Kiltan and Kavaratti).

That leaves 20 warships that will remain in naval service for some years. These include: three aircraft carriers (INS Vikramaditya, Vikrant and Vishal); three Brahmaputra class frigates (INS Brahmaputra, Betwa and Beas); three Talwar-class follow-on frigates (INS Teg, Tarkash and Trikand); four Project 15-B destroyers (unnamed, under construction); and seven Project 17-A frigates (unnamed, contract being negotiated).

Given its first-mover advantage, the infrastructure and partnerships it will build and its already demonstrated price advantage, Atlas hopes to supply sonar systems for these and for other smaller surface warships and submarines. In April, the MoD tendered for 16 Anti Submarine Warfare Shallow Water Craft (ASWC), which need sophisticated sonar with electronically controlled beams.

Atlas Elektronik sources say they are eager to establish a joint venture company with either BEL or an Indian private sector company to build sonars in India. That would grant majority ownership of 51 per cent to the Indian entity.

ATAS import has been blocked since the mid-1990s because the Defence R&D Organisation (DRDO) was developing an indigenous ATAS called Nagan. In 2012, the Nagan project was officially shut down and work began on another system called ALTAS. With this making slow progress, the DRDO finally okayed import.

In November 2012, two years ago, Atlas was declared the lowest bidder. That was followed by a string of complaints to the MoD against Atlas, apparently motivated, since the MoD found no wrongdoing. Even so, with the ministry painstakingly investigating every complaint, each caused a 3-4 month delay. Earlier this year, with the elections impending, the United Progressive Alliance decided to leave the signing to the next government.

Atlas Elektronik is owned 51 per cent by Krauss-Maffei Wegmann GmbH (KMW) and 49 per cent by Airbus Defence & Space.

- Ajai shukla