Flight schedules in Delhi's IGI airport were on Saturday affected as the airspace over the national capital was shut down for two hours for an IAF communication drill.
The airspace was closed for two hours between 1:00 PM and 3:00 PM, according to a NOTAM (notice to airmen).
Airlines said they where informed about the closure only on Saturday morning, which gave them little time to reschedule their flights, especially the incoming international ones.
Departures from the IGI Airport were re-scheduled by several carriers, they said.
"We received the NOTAM around 8 AM and hence we have to reschedule the departures and arrival," an airline official said.
According to officials, the closure has been done for re-calibration of the radar communication system of the IAF.