September 30, 2010:
In the last few years, India has made a serious effort to build a nationwide air control radar system. First, they want to build a system covering all the borders (mainly for military reasons), then a more extensive one for the interior. But first, the borders, as this is a matter of national defense, as well as tracking commercial air traffic. To this end, the government is looking for non-military radars to track aerial traffic inside India.
Meanwhile, India's air defense radar system has holes in it, lots of them, and its no secret. But until recently, the problem was not widely known. That changed two years ago, after India announced that it had completed a program that combines radar data from all military and civilian aircraft tracking radars in southern India. This was done using software that merges all the tracing information, eliminating duplication and showing on one screen everything in the air from the Bay of Bengal to the Arabian Sea, the Indian Ocean and northern Sri Lanka. Naturally, this got people asking about the coverage over the rest of India's borders. These questions acquired some urgency, because India's main enemies (Pakistan and China) are in the north. Turned out the radar coverage in the rest of India was very spotty.
This was an old problem and India began buying new surveillance radars in the early 1990s, as an effort to replace systems acquired in the 1970s and to plug the gaps. But the old stuff was wearing out (or just breaking down a lot), and there was not enough money to buy replacements quickly enough. This was kept quiet. For good reason. Knowledge of these gaps would be useful to the commanders of enemy air forces. Perhaps Pakistan and China already know where the gaps are. Pakistan has maritime reconnaissance aircraft that often patrol near the Indian coast. These aircraft can pick up and record data on radar signals. That will show you where the gaps are, and how frequently the gaps appear. It's now known that India only has about a quarter of the transportable radars (to quickly plug gaps) it needs. Making the situation general knowledge puts pressure on Indian politicians to provide the money for more radars, sooner.
Meanwhile, India has ordered 57 ground based radars to complement the AWACS, and provide complete coverage of airspace along its borders with Pakistan and China. These new systems include 19 LLTRs (low-level transportable radars), and four fixed, longer range MPRs (medium-power radars), four Aerostat (tethered blimp) radars and 30 Indian made medium-range Rohini radar systems. Most of the new radars are fixed, and will serve civil aviation, as well as military needs. India is also linking all civil and military ground radars so that military air defense headquarters can have a complete picture of what is flying in Indian airspace.