Software crash grounds IGI for 2 hrs

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.

“There was no problem with the radar system.”

Sources said a shadow stand-by system,Auto Track-III,was put in place in the interim period.

Twenty-seven flights were able to land and only six could take off during these two hours. On an average,about 80 flight movements (landing and take-off) take place in a two-hour period,officials said.

Delhi ATC officials said flight-handling capacity of the ATC was severely affected during this period. But the voice communication system with the aircraft was intact during the disruption,sources added.

An ATC official said: “The ATC allowed more arrivals during the period as there were aircraft hovering above. We could hold on to departures,as the aircraft were still on ground.”

Explaining the disruption,another senior ATC official said the computers had failed to display aircraft movement in the air. For runway-29,this is the only system which assists in landings and take-offs,as the new runway is not visible from the ATC tower.

“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.”

Though only runway-28 was being used — for both departures and arrivals — all departures were put on hold each time a flight landed,an official said.

Somasundaram said,“It was an unusual situation (and) the reason would be known only after a thorough probe.”

The technical problem came on a day when many flights were cancelled,diverted,rescheduled and delayed due to dense fog over the Capital and surrounding areas since Wednesday night. The systems crash is expected to lead to longer delays; they have a cascading effect on the rest of the network connecting Delhi.