Air traffic control system failure, staff shortages expose stress points in India’s aviation network

The Ministry of Civil Aviation has acknowledged a software-related disruption in Air Traffic Control (ATC) operations at Delhi’s Indira Gandhi International (IGI) Airport earlier this month, which led to widespread delays affecting hundreds of flights over two days.

The episode has also renewed attention on deeper structural issues in India’s air traffic management system, including a nationwide shortage of ATC personnel. According to data shared by the Ministry of Civil Aviation, 22.75% of sanctioned ATC posts across the country remain unfilled.

Data provided by the Ministry in Parliament show 396 vacancies in the Northern Region, 331 in the Southern Region, 286 in the Western Region, 199 in the Eastern Region, and 48 in the North-eastern Region.

While a consolidated national figure for the total number of Air Traffic Control officers (ATCOs) is not publicly available, the Northern Region has historically housed the highest concentration. According to 2020 data, IGI Airport alone had 305 ATCOs, followed by Varanasi with 90.

Despite IGI Airport’s dominant role in the Northern Region, training output remains uneven across regions. Among the four Regional Training Centres (RTCs), the Delhi RTC recorded only 91 graduates in 2025–26 up to December 11. In comparison, RTC Mumbai produced 478 graduates, RTC Kolkata 894, and RTC Chennai 562 during the same period.

What caused the disruption

Minister of State for Civil Aviation Murlidhar Mohol, responding to an unstarred question raised by multiple MPs, said that “high latency in processing and delivering Air Traffic Service (ATS) messages was observed on November 6 at around 11 AM”.

The issue affected the Air Traffic Management Automation System (ATMAS), resulting in delays to critical Aeronautical Fixed Telecommunication Network (AFTN) messages, including flight plans, mandatory Flight Information Centre numbers, and Air Defence Clearances.

While around 800 flight delays were initially reported, the Minister told Parliament that 397 scheduled passenger departures between November 6 and 8 were officially recorded as delayed.

The government said the Airports Authority of India (AAI) has begun replacing the existing IP-based Automatic Message Switching System (AMSS) with a new Air Traffic Services Message Handling System (AMHS) to improve operational reliability.

On airline losses, Mohol said carriers incur additional expenditure during disruptions caused by weather, congestion, or technical failures, making it difficult to attribute losses to a single cause.

AAI has also been directed to carry out a comprehensive audit of all Communication, Navigation and Surveillance (CNS) equipment across airports to assess condition, reliability, and lifecycle requirements.

Separately, the Directorate General of Civil Aviation (DGCA) conducted its own inspection of the AMSS following the incident. The regulator subsequently ordered the replacement of existing database servers with upgraded versions to improve system performance and resilience.

GPS spoofing and safety concerns

The Ministry of Civil Aviation also disclosed that India recorded 1,951 cases of GPS interference on aircraft over the past two years, raising concerns over flight safety and navigation reliability.

Mohol said the Wireless Monitoring Organisation is investigating the matter. Earlier, on November 10, the DGCA issued a new standard operating procedure for real-time reporting of GPS spoofing and Global Navigation Satellite System (GNSS) tampering around Delhi Airport.

GPS is critical to aviation, providing aircraft with precise information on position, direction, and altitude. When signals are disrupted, aircraft can drift from planned routes, increasing safety risks. Recent cases of GPS spoofing and signal tampering have been reported at major airports including Delhi, Mumbai, Kolkata, Amritsar, Hyderabad, Bengaluru, and Chennai.

Union Civil Aviation Minister Rammohan Naidu has also flagged rising global threats from ransomware and malware attacks, saying AAI is upgrading cybersecurity systems to protect its data centres and critical infrastructure.

The day the system failed

A major technical fault in the AMSS disrupted flight operations at Delhi Airport for over 12 hours on Friday, leaving thousands of passengers stranded in crowded terminals and long queues.

The glitch surfaced around 9 AM and was resolved by approximately 9:30 PM. Complaints had begun arriving as early as Thursday evening. By the end of the day, more than 800 domestic and international flights were delayed, and at least 20 were cancelled.

AAI announced at 8:45 PM that the AMSS had been restored and was functioning normally. Until then, passengers faced repeated schedule changes, long waits at boarding gates, and confusion over revised departure timings.

According to flight-tracking platform Flightradar24, the average delay across flights was nearly 50 minutes. The disruption had a cascading impact on airports in Mumbai, Bhopal, Chandigarh, Amritsar, and several other cities, where flights to and from Delhi were also delayed.

Airlines including IndiGo, Air India, Air India Express, SpiceJet, and Akasa issued frequent advisories as they attempted to manage the backlog.

A senior GMR spokesperson said disruptions at Air Traffic Control facilities do not fall under the airport operator’s jurisdiction. “We are mainly meant for maintenance and infrastructural developments of the airport, hangar, and runways. We do not have any jurisdiction to interfere in how ATCs function,” he said.

Manual operations revived

An Air Traffic Control official said that before the AMSS was introduced, airlines submitted flight plans manually, a process later replaced by automated messaging that improved efficiency in managing take-offs and landings.

However, following the system crash, ATC staff were forced to revert to manual operations.

Airport authorities issued advisories informing passengers that the AMSS was being restored and improved, urging them to remain in contact with airlines for the latest updates.

ATC Guild flags systemic gaps

In a letter to the Civil Aviation Minister, the ATC Guild said the episode exposed serious inadequacies in India’s aviation communication and navigation preparedness.

The disruption, which occurred between November 6 and 8, 2025, required controllers to manually manage more than 2,500 daily aircraft movements, including over 1,500 scheduled flights and about 1,000 overflying aircraft.

Describing the failure as “infrastructural — a clear lapse in system maintenance and timely replacement”, the Guild said the AMSS, supplied by Electronics Corporation of India Limited, failed due to technical reasons. It was restored only after direct intervention by ECIL. The system had exceeded its original equipment manufacturer-supported validity period, while procurement and upgradation had been delayed.

The letter criticised AAI’s manpower-intensive approach to managing CNS systems. It noted that while OEMs such as Thales, Indra, Raytheon, ECIL, Honeywell, and BEL provide global lifecycle support with lean teams, AAI employs around 500–600 CNS personnel to manage about 50 MSSR radar systems. By contrast, OEM ELDIS Pardubice operates radar systems worldwide with roughly 250 staff.

The Guild argued that this model doubles costs without improving competence and called for OEM-backed maintenance contracts to ensure accountability and reliability.

It also warned that outdated infrastructure and procurement delays could have serious safety implications. “ATC is the only real-time safety-critical service in AAI governed by ICAO and DGCA guidelines, where minor errors have direct safety consequences.”

The Parliamentary Committee’s 380th report, tabled in August 2025, had already recommended an urgent review and modernisation of air traffic automation systems.

Also Read: Heritage Transport Museum – where vintage cars find new life

To prevent future breakdowns, the Guild proposed structural reforms including a government-led probe into the AMSS failure, accountability for lapses, and a review of automation upgrades at major airports such as Mumbai and Bengaluru. It also called for redundancy systems, including parallel AMSS servers and modern automation tools, to ensure operational continuity.

The Guild said that despite the AMSS malfunction, air traffic controllers ensured safe operations under extreme pressure by manually generating flight plans and coordinating closely with Air Defence authorities and ECIL engineers during the restoration process.