ATC glitch throws Delhi airport into chaos, 600 flights delayed

Flight operations at Delhi’s Indira Gandhi International Airport (IGIA), the country’s busiest aviation hub, plunged into disarray on Friday after a major technical fault crippled air traffic control (ATC) systems, triggering massive delays across over 600 domestic and international flights, while a few were cancelled.

The cascading disruption paralysed schedules nationwide and caused heavy financial losses to airline operators, estimated in several crores.

The trouble began with a failure in the Automatic Message Switching System (AMSS), a critical component that relays flight plans, weather data and operational messages between ATC and airlines. The malfunction forced controllers to abandon automated systems and revert to manual operations, a step that, while safe, drastically slowed the pace of flight sequencing and coordination.

Officials confirmed that the glitch had first surfaced late Wednesday, with full-scale disruption beginning by Thursday late evening. “Controllers were compelled to manually process flight plans and calculate safe separation standards, a process that normally runs through automation. This slowed down the entire air traffic network and caused bottlenecks across several airports,” said an Airports Authority of India (AAI) official.

By Friday morning, delays had ballooned. According to live tracking platform Flightradar24, the average departure delay at Delhi was around 87 minutes, while arrivals lagged by an average of around 40 minutes during the day. Over 97 per cent of scheduled flights were delayed through the day, with several international carriers, including Virgin Atlantic and ITA Airways, reporting wait times of up to two hours.

Airline executives said the operational standstill has resulted in massive losses. “When a major hub like Delhi slows down, the entire network bleeds,” said an industry insider. “Aircraft remain grounded longer, fuel burn increases and crew duty limits get stretched, every minute costs money. Initial estimates suggest that cumulative losses across airlines could easily exceed Rs 100 crore, factoring in fuel wastage, passenger re-accommodation and lost slots at destination airports,” said the experts. Shares of IndiGo slipped 2 per cent and SpiceJet declined 1 per cent on Friday.

The AAI confirmed that the AMSS failure also affected flight operations in Mumbai, Bengaluru, Hyderabad and Pune due to interconnected data flows in the national airspace network. “Flight operations at Mumbai airport are currently affected due to a technical issue with the AMSS at Delhi, which supports ATC flight planning. Authorities are actively working to resolve the problem,” read a statement issued by Mumbai’s Chhatrapati Shivaji Maharaj International Airport. Similar statements were also issued by Lucknow and Jaipur airports.

As chaos unfolded at terminals, passengers were left stranded for hours amid long queues and repeated rescheduling announcements. Airlines, including IndiGo, Air India, Air India Express, SpiceJet and Akasa Air, issued rolling advisories urging passengers to check for revised timings and arrive earlier than usual.

“We understand that the ongoing AMSS system issue affecting Air Traffic Control has led to disruptions to travel plans and we fully understand the inconvenience this may be causing. Our teams are doing their utmost to ensure passengers receive timely updates and assistance,” IndiGo said in a statement on X.

Delhi International Airport Limited (DIAL), which operates IGIA, said authorities were working round the clock to restore normalcy. “All airline operations at Delhi airport are currently delayed. Authorities are working on resolving the issue at the earliest. Passengers are requested to follow updates from their airlines regarding revised schedules,” DIAL said in an advisory.

Air traffic controllers continued to rely on manual coordination through the day, relaying flight details over voice circuits and manually entering data that would otherwise be transmitted electronically. “This method preserves safety, but reduces throughput drastically compared with normal automated rates,” said an aviation expert.

IGIA, which handles more than 1,100 flight movements daily and served nearly 78 million passengers last year, is the ninth busiest airport in the world. With the system still unstable late Friday evening, airline sources said recovery could take several hours, if not longer.

By nightfall, controllers were still preparing flight plans manually and coordinating with airlines to ease congestion.