The story so far: Air traffic operations at New Delhi’s Indira Gandhi International (IGI) Airport were affected on November 6, after the Automatic Message Switching System (AMSS) experienced a technical issue. It took over 24 hours for it to be restored. The Civil Aviation Ministry is reported to have asked the Airports Authority of India (AAI) to upgrade the system.
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What was the issue in Delhi?
The Air Traffic Controllers’ Guild (India) raised its concerns, highlighting how the disruption forced Air Traffic Controllers (ATCOs) to manually handle over 2,500 daily aircraft movements, including more than 1,500 scheduled flights and 1,000 aircraft overflying Indian airspace. An aviation source who is closely associated with Air Traffic Control (ATC) told The Hindu that the automation systems used by ATCOs derive the data from the Flight Data Processing System (FDPS), which in turn is fed by the AMSS. When the AMSS experienced failure, the automation systems did not get the required data, including flight plans. Yogendra Gautam, CCM, Air Traffic Safety Electronics Personnel Association (ATSEPA) India, has told The Hindu that the AMSS is a core communication backbone for air traffic operations, used in all the major ATC centres including Delhi, Mumbai, Chennai and Kolkata, to handle aeronautical messages. These include flight plans, departure and arrival messages, delay and cancellation messages, meteorological and NOTAM updates and coordination messages between ATCs and airlines. Essentially, it receives, stores and forwards these messages automatically through the Aeronautical Fixed Telecommunication Network and Aeronautical Message Handling System (AMHS) links.
It works using input sources, from airlines, ATC centres, meteorological offices, and AAI stations, which send digital flight or operational messages. The AMSS also converts various formats into a unified format. There is a routing logic, where the system decides where each message must go, whether to the ATC tower or other airports. Messages are temporarily stored in a central database and can be retrieved in case of transmission delays. The official said that the AMSS runs 24X7, processing thousands of flight-related messages.
Technical and procedural issues can trigger AMSS failure. Delhi’s AMSS, which was supplied by a Spanish organisation, is built on an older server architecture with legacy message-switching software — there have been patches and upgrades. The system has some India-made content. Database or server overload, especially during peak hours, can cause delays or loss of communication. Other reasons include inadequate synchronisation between standby systems leading to message blackout periods, and integration issues with other systems. As the AMSS interfaces with air traffic service automation, aeronautical information service and network routers, any network fault or delayed interface response can choke the AMSS message flow. The official said there is also limited local technical manpower trained on this legacy system. In Delhi, the glitch was reportedly due to a synchronisation failure between the primary and standby servers, compounded by delayed switch-over and corrupted message queues. The result was an inability to transmit/receive flight plans and NOTAMs, he said, adding that a migration to a modern, cloud-supported AMHS/ATS integrated system is long overdue.
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How busy is Delhi airport?
In 2024, under the ‘total passengers’ category, IGI Airport was ranked ninth among the world’s busiest airports, handling 77.8 million passengers, according to the Airports Council International (ACI) World list. It was ranked 15, for its 4,77,509 aircraft movements. The ACI represents over 2,181 airports across 170 countries. Due to the glitch, over 500 flights were affected and several cancelled.
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What has the parliamentary report said?
In its ‘Three Hundred Eightieth Report – Overall Review of Safety in the Civil Aviation Sector’ (presented to the Rajya Sabha on August 20, 2025), the Parliamentary Standing Committee on Transport, Tourism and Culture observed that “existing automation systems used for air traffic control, particularly at high-density airports such as Delhi and Mumbai, have begun to exhibit significant performance degradation. This includes issues of system slowness, data processing lags, and a lack of modern decision-support features”. It adds: “The existing Indian ATC systems lack many of the advanced, integrated capabilities that are now standard in modern air traffic management systems used by global counterparts like Eurocontrol or the FAA. These missing features include sophisticated, AI-enabled conflict detection and alerting tools, predictive analytics for traffic flow management, and seamless, real-time data sharing capabilities between different control units and with aircraft.” This deficit, it said, places an enormous additional cognitive strain on already-overworked ATCOs, who are forced to manually compensate for the system’s shortcomings. This “increases the risk of human error and limits the overall capacity of the airspace”.
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How is it in Europe for instance?
Professor Marina Efthymiou, Professor of Aviation Management, Business School, Dublin City University, Ireland, has told The Hindu that Europe’s Air Traffic Management (ATM) system, coordinated through Eurocontrol and implemented through national air navigation service providers, operates on a complex network of legacy and modernised systems that must seamlessly integrate under the Single European Sky framework. While initiatives such as SESAR (the technological pillar of the Single European Sky) aim to digitalise and harmonise ATM across Europe, the coexistence of outdated radar systems, fragmented communication protocols, and inconsistent data-sharing platforms continues to expose vulnerabilities to technical glitches and cyber threats. There have been disruptions, such as system outages in flight data processing or communication networks, highlighting the fragility of Europe’s current ATM infrastructure and the need for resilient, cloud-based and AI-driven coordination tools to ensure continuity. And a growing shortage of qualified ATCOs compounds these technical risks.
The future of air navigation in Europe is likely to rely on satellite-based navigation (GNSS) and automation-enhanced traffic prediction, but these advances will require robust cybersecurity frameworks and redundancy systems to mitigate the risk of data corruption or signal interference, she said.
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Are there plans to upgrade?
In February 2025, Minister of State for Civil Aviation, Murlidhar Mohol, listed a series of initiatives being undertaken by the AAI in air traffic and air navigation management. These include the installation of a new pan-India AMHS to replace the existing AMHS and AMSS systems and Automatic Dependent Surveillance-Broadcast ground stations at 21 airports which utilise GPS and satellites for determining aircraft positions. Their installation at 15 other locations has been completed.
In a detailed note (updated August 29, 2025), the AAI has said that it has drawn up plans to upgrade the ATM infrastructure in terms of automation systems and technology upgrades, which also involve shifting from ground-based to satellite-based navigation.
Published – November 16, 2025 01:56 am IST
