According to airport sources, one or two radar screens (consoles) -- which shows traffic in the airspace controlled by Delhi tower and gives vital information like aircraft speed, height and call-signs -- suddenly went blank early Tuesday morning.
Unlike January 14 when a similar problem had arisen, all the radar consoles did not blink and the two were revived within a span of a few hours, said an official, who is associated with the maintenance of the system.
However, officials were on their toes as there was a top security alert due to the Republic Day celebrations which was to begin in a few hours. Since there were not many flights when the consoles blinked, the ATC officials managed to control the situation from getting out of control.
Presently, the ATC is using AutoTrack-II radar automation system and it is being upgraded to the advanced AutoTrack-III. On the evening of January 14, all consoles went blank during an exercise to upgrade the system which led to disruption in movement of aircraft over the vast north Indian stretch.
The flights had to be handled manually by the ATC officials by increasing the distance between two aircraft from 5-10 nautical miles to 80 nautical miles. After nearly two hours, the system was restored with communication, navigation and surveillance engineers rebooting the entire system and making it functional.
India's aviation regulatory body, Directorate General of Civil Aviation and the Airports Authoriy of India which handles the air navigation are conducting respective probes. According to sources, the automation system crashed due to suspected faulty manual handling.