Explained: What’s behind massive Delhi airport chaos that led to 800 flight delays?

Over 800 flights at Delhi’s IGIA were delayed by up to two hours on Friday due to a software glitch, affecting thousands of passengers. Airlines cancelled around 100 flights till 6 pm, while delays rippled across northern airports, Mumbai, and other hubs, leaving passengers frustrated and disrupting weekend schedules.

The Air Traffic Services Message Handling System (AMSS), used to file flight plans for arrivals, departures, and overflying aircraft, malfunctioned. The glitch began Thursday evening and worsened Friday morning, forcing air traffic controllers to manually enter all flight plans, causing slower processing and delays across India’s busiest airports.

With the AMSS system down, flight plan data had to be manually input, a process taking four times longer than automated handling. Manual feeding of thousands of flight plans introduced delays for departures, arrivals, and overflying aircraft, increasing congestion in Delhi airspace and impacting airline schedules nationwide.

The Airports Authority of India (AAI) acknowledged the issue and said the system was detected on Thursday. A review meeting was held, additional staff deployed, and the original equipment manufacturer was engaged. Manual processing ensured safe air traffic operations while AMSS was restored, but intermittent functioning continued

The AMSS software has experienced issues before, causing operational delays. Senior airline officials highlighted that the installation of the new Air Traffic Services Message Handling System (AMHS) has been long overdue. Repeated delays in system upgrades have created recurring bottlenecks at major airports, risking efficiency and safety margins.

Even after partial restoration of AMSS, airlines warned of ongoing disruptions over the weekend. Delays at IGIA affected flights at other airports due to interconnected flight schedules, highlighting the heavy reliance on automated systems for timely air traffic management across India.

The Delhi AMSS failure caused delays at Mumbai, Jaipur, and other northern airports, as flight arrivals and departures were affected. Airlines reported operational disruptions across India, showing how a single system at the country’s busiest airport has nationwide implications for schedules and passenger safety.

The Directorate General of Civil Aviation (DGCA) has initiated an investigation into the AMSS failure. Officials confirmed there was no cyberattack and are assessing technical lapses. The probe aims to understand why a critical automated system crashed, affecting hundreds of daily flights and impacting passengers, airlines, and airport operations.

The Air Traffic Controllers’ Guild of India had warned in July about performance degradation in ATC systems at major airports, including slowness and lag affecting operational efficiency. They had urged periodic upgrades and alignment with global benchmarks like EUROCONTROL and FAA standards to ensure safety and smooth air traffic management.

Industry experts and the Guild emphasised that India’s automation systems must be modernised. They called for centralised flight plan submission, AI-enabled conflict detection, real-time data sharing, and full AMHS implementation. Timely upgrades are critical to prevent recurring delays, enhance operational efficiency, and maintain safety standards at major airports like Delhi and Mumbai.