NEW DELHI: Flights are facing serious delays at Delhi Airport since Thursday evening due to a software issue in the air traffic control (ATC). Sources say the “Aeronautical Message Switching System” (AMSS) has been facing an issue that has slowed down flight movement, and delays got “stacked up” by Friday morning.Departures have been delayed by about an hour. With planes not able to take off on time, the airport will soon not have place for parking arriving aircraft, which will affect arrivals too. Sources say the AMSS system error may be rectified by the evening.Delhi Airport issued a ‘passenger advisory’ on X Friday morning: “Due to a technical issue with the Air Traffic Control (ATC) system, flight operations at IGIA are experiencing delays. Their team is actively working with all stakeholders including DIAL to resolve it at the earliest. Passengers are advised to stay in touch with their respective airlines for the latest flight updates. We sincerely regret the inconvenience caused.”Meanwhile, SpiceJet alerted passengers about possible delays and disruptions in flight operations from Delhi’s Indira Gandhi International Airport, citing heavy congestion at Air Traffic Control (ATC).Taking to X, the airline in a statement said, “Due to ATC (Air Traffic Control) congestion at Delhi, all departures/arrivals and their consequential flights might get affected. Passengers are requested to keep a check on their flight status.”IndiGo, in a passenger advisory, said flights were experiencing extended wait times both on the ground and onboard as the technical issue affected departures and arrivals.“Our crew and ground teams are actively assisting and doing their best to make your wait as smooth as possible,” the airline said, urging passengers to check flight status on its website for the latest updates.