Delhi's Indira Gandhi International Airport witnessed flight disruptions on Saturday afternoon due to closure to airspace over the city for nearly one hour.
At least 50 flights, including both international and domestic arrivals and departures, were delayed by one to two hours.
Though the air traffic control and airlines are informed well in advance about such closures, on Saturday the NOTAM (Notice to Airmen) was issued only in the morning.
This caught both the air traffic services and airlines off guard and resulted in the delays, as most flights couldn't be rescheduled at the last moment.
Sources at the airport said the airspace was closed for the calibration of radar that belongs to the Indian Air Force. The NOTAM, which was issued late on Friday and received by most airlines at 8am on Saturday, said the airspace had to be closed for two hours, between 1pm and 3pm. However, flight operations began for departures at 1.45pm and arrivals started from 2.03pm.
Though more than 50 flights were delayed and many had to be rescheduled, there were no flight diversions due to the closure. The sudden announcement of closure had given little time to airlines to reschedule their flights, especially some of the incoming international ones. However, airlines managed to successfully reschedule many departing flights.
"We received the NOTAM around 8am today. We have had to reschedule the arrivals and departures to and from Delhi," an airline official said.
"We were under tremendous pressure as we also had to inform the passengers about the rescheduling of their flights," he added.
"It is usual for the airspace to be closed during celebration and rehearsal for the Republic Day or during other drills but in that case, the NOTAM is issued well in advance and both airport authorities and airlines plan flight schedules accordingly," an airport official said.