NEW DELIH: Delhi airport on Saturday said that the operations are returning back to normal a day after a glitch in Air Traffic Control flight planning process caused over 300 flight delays.While issuing a advisory, Indira Gandhi International Airport asked the passengers to stay in touch with their airlines for the latest flight update.“The technical issue which affected the Automatic Message Switching System (AMSS), that supports the Air Traffic Control flight planning process, is gradually improving,” the advisory read.“Airline operations at Delhi Airport are returning to normal, and all concerned authorities are working diligently to minimise any inconvenience caused. Passengers are advised to stay in touch with their airlines for the latest flight update,” it added.The glitch occurred in the AMSS system that prompted the ATC to abandon automation and switch to manual procedures. The slowdown began showing network-wide effects from Thursday afternoon.Air traffic control (ATC) refers to a ground-based service in which controllers manage and guide the movement of aircraft both on the ground and within controlled airspace.As India’s busiest hub, IGIA typically manages about 1,500 aircraft movements a day with peak rates near 60–70 per hour in normal conditions, leaving little slack when automation falters.The problem started at the Automatic Message Switching System, a system responsible for transferring the flight plan data to the air traffic controllers’ screens, which crashed. This caused the controllers to process each data manually, significantly delaying the arrival and departure process. The disruption that began to impact the operations since Thursday 3pm, had been occurring since Wednesday evening.