Last night, Delhi’s Indira Gandhi International Airport (VIDP) and its enroute air traffic centre (Delhi Center, VIDF) lost radar data and had to revert to the old-fashioned method of separating air traffic:
“With no radar available, the radio system was the only way of knowing their position,” said a senior air traffic control officer, refusing to be identified, about the situation in the tower.
The radar shows to air traffic control the exact coordinates of planes in the air, or those waiting to take off, their altitude, their speed and the distance between them — it can get bumper-to-bumper up there.
Air control switched to something called a “manual” process: traffic controllers obtain the position of each plane from its pilot on radio, put it down on a chit of paper and stick it to a scrabble kind of a board.
“We knew the exact position of the aircraft and had to segregate them further so they stay away from each other,” said the traffic control officer, admitting a small human error or an oversight could have proved disastrous.
— “Airport radar crash: 60 mins on brink of disaster.” Hindustan Times, 14 January 2010.
Needless to say, nothing went horribly, fatally wrong or you’d be seeing it on the news this morning. The procedures for dealing with communications or radar failure are well-known and part of pilot and ATC training.
The Hindustan Times is sort of overselling the risk factor, given that 1) Delhi was able to switch seamlessly from the old, crashed Raytheon AutoTrack II system to the brand-new AutoTrack III, which was conveniently already installed and being-shadow-trialled for six months; and 2) most commercial airliners these days fly with their own onboard traffic collision avoidance systems (TCAS).
Indian Express has a less breathless and saner account of the goings-on.
V Somasundaram, executive director (air traffic management), Airports Authority of India, told Newsline: “The computer system that provides all aircraft-related data to the Delhi ATC failed at 5.44 pm on Thursday. The system was rebooted and put in place by 7.30 pm. But the controller used other channels of communication with pilots and aircraft in this period.
“Aircraft that usually maintain a distance of five nautical miles from each other in the air were forced to fly 12 to 15 nautical miles apart as a precautionary measure,” the official said. “This led to a delay in landing, and the subsequent chaotic situation.”
— Gupta, Geeta. “Software crash grounds IGI for 2 hrs.” Indian Express, 15 january 2010.