NEW DELHI(National Times)- Hundreds of flights were delayed at Delhi airport, one of the world’s busiest, after an air traffic control messaging system suffered a technical problem on Thursday evening, India’s airport authority and a source familiar with the matter said. The glitch, which delayed departures by an average of an hour, could cascade and lead to logjams at other airports in the country. Arrival delays were also inching upwards due to congestion on the ground, Flightradar24 data showed. Shares of IndiGo closed 2% lower on Friday, while SpiceJet lost 1% after the airlines, along with Air India Group, warned of delays. Carriers face the prospect of higher costs from passenger care expenses and refunds due to the delays, which are expected to spill over to Saturday. The Airports Authority of India said a technical issue in the Automatic Message Switching System, which is used to generate flight plans, forced controllers to develop them manually, leading to delays. The problem with the system started on Thursday evening local time, the source said. “Technical teams are working to restore the system at the earliest,” AAI said in a post on X. The agency did not respond to additional requests for comment on what caused the malfunction. Some airlines, such as Air India Express, have deputed their own personnel to air traffic control to generate flight plans manually, another source familiar with the matter said. Broadcaster CNN NEWS 18 reported that authorities were investigating if computer malware could be a cause. Reuters couldn’t immediately verify the report. The incident follows a ransomware attack that disrupted some of Europe’s biggest airports, knocking out automated check-in systems and affecting flights in September. The glitch in India delayed about 25 flight departures on Thursday and more than 175 on Friday at Delhi airport, the first source said. Delhi airport handles 60-70 aircraft movements per hour. Data from Flightradar24 showed the average departure delay was 60 minutes. The malfunction also hit several international airlines, with an ITA Airways flight to Rome delayed by nearly two hours and a Virgin Atlantic flight to London by more than an hour. The AAI has not yet told carriers when the glitch would be fixed, two airline sources said. Delhi airport handled about 78 million passengers in 2024, making it the ninth busiest airport in the world, according to Airports Council International. The operator of the airport is majority owned by GMR Airports, while air traffic control is managed by the AAI.