Radars might be shut again for maintenance

V Ayyappan TNN

Jan 27, 2009

Chennai: After a lull of a couple of months, the ageing radars have started to give trouble at the airport. The radars failed twice a week ago and this has put pressure on the Airports Authority of India (AAI) to consider shutting them down completely for maintenance. Though a decision on when to shut down is yet to be taken, air traffic controllers are worried that soon they might have to switch to the pen-and-paper mode. Aircraft movement is controlled by two radars — a primary radar with a range of 60 nautical miles and a secondary radar with a range of over 250 nautical miles — at the airport. Both the radars are old. And the secondary radar often fails to detect signals from transponders of aircraft, especially at the edge of its range — over Bellary and Hyderabad. “We need strong signals at these spots because it is here that most of the air routes intersect. But many a time the blips go off at these intersecting points and air traffic controllers have to call up the pilots on VHF communication system to find out their location,” sources in the ATC said. The Chennai-Mumbai route intersects air routes out of Bangalore to Hyderabad, Kolkata, Delhi and Mumbai; similarly the Chennai-Hyderabad-Delhi route intersects the Bangalore-Kolkata route. The intersections take place at different levels of height. Landings and take-offs at Chennai, Bangalore and Hyderabad airports make things more complicated. That’s not all. The range of the primary radar is now being affected by the fast-developing neighbourhoods around the airport. Most airports across the country are located in the middle of urban areas. But the case with Chennai is different, where the radars are nearing expiry date as they where installed more than 15 years ago. Sources said the signals from the radars have become weak over the years, and that the mushrooming of buildings around the airport was making things worse. At a time when aviation depends on pinpoint measurements, the 122 air traffic controllers at the Chennai airport keep chart papers and pencils beside their monitors, because the ageing radars and slow computers often force them to depend on manual calculations. “Paucity of automated electronic tracking and communication systems and state-of-the-art computer equipment and shortage of personnel hamper efficient handling of flights and slow down relay of accurate information to aircraft,” an airport insider said. AAI has decided to replace the radars with a stateof-the-art system that will include two long-range monopulse secondary surveillance radars (MSSR), and one primary radar that will control landing and take-off. The new system will cost Rs 120 crore. But the problem is, no one is certain when it will be installed. But sources say it might take at least two years. Of the two MSSR, one will be installed at Porur, where the airport once had a radar but which was de-commissioned several years ago. This additional radar away from the airport, to its north, will add to the range and also act as a back-up facility.