The country’s busiest airport, Indira Gandhi International Airport (IGIA) in Delhi, faced a major disruption that halted its usual seamless flow of flights — more than 800 domestic and international services were delayed and at least 20 cancelled after a technical failure struck the air traffic control system. On Friday, a technical fault in the airport’s automated flight‐planning infrastructure triggered long queues, cascading flight delays, gate reassignments and slot management chaos. The Airports Authority of India (AAI) later confirmed that the problem had been addressed and operations resumed, but admitted that backlog effects could linger for some time.

What happened

According to AAI and multiple media reports, the disruption began when the Automated Message Switching System (AMSS) — a key backbone used to transmit flight plan data, weather updates and other operational communications to air‑traffic controllers — failed. The Indian Express+3Hindustan Times+3The Financial Express+3 Once the AMSS malfunctioned, controllers lost the automatic feed of hundreds of messages that typically arrive in real time and instead had to revert to manual processes. www.ndtv.com+1 The problem appears to have been detected on November 6, 2025, in the IP‑based AMSS system at IGIA. Hindustan Times+1 As the failure became evident, flight planning and slot decisions, gate assignments and real‑time weather inputs were all affected, slowing operations sharply.

Reports indicate that by Thursday evening the first signs of issues were emerging, and by Friday morning the system failure had translated into large operational delays. The Financial Express+1 AAI stated that the system was “up and functional” by late Friday evening, but warned that due to the backlog of flights and manual processing residual delays could persist. www.ndtv.com+1

Impact on flights and travellers

At IGIA, which handles about 1,500 flight movements per day and in peak hours up to 60‑70 aircraft per hour, the failure of automation meant that each flight plan had to be processed manually. The Times of India+1 With hundreds of flights queued for departures, arrivals and onward connections, the delays soon multiplied. Flight‑tracking data showed more than 500 flights delayed on Thursday evening, followed by additional numbers on Friday morning. The Financial Express

The operational slowdown had knock‑on effects across the country. Because many flights originate, land or connect through Delhi, disruption at IGIA rippled into other airports. For example, at Sardar Vallabhbhai Patel International Airport in Ahmedabad, around 70 flights were delayed and six cancelled after the Delhi glitch forced delays in connecting aircraft. The Times of India+1 Passengers at IGIA and affected airports reported long waiting times, confusion over gate changes, last‑minute cancellations and little clarity about how soon things would return to normal.

Official response and remedial action

AAI issued multiple statements during the event. It acknowledged that the AMSS failure was the root cause and said the OEM (Original Equipment Manufacturer) had been engaged to assist. mint Additional manpower was deployed so that flight plans could be processed manually in the interim while automated systems were repaired. The Financial Express+1On November 7, AAI declared that the AMSS system was “up and functional” at Delhi. The Times of India+1 However, the authority emphasised that “some backlogs” remained and normal operations might take some time to fully recommence. The Times of India

Airlines reacted by issuing advisories urging passengers to check flight status with their carriers, avoid arriving at the airport too late, allow extra time, and expect delays even if the system had been restored. For instance, several carriers operating in Delhi took to social media to apologise for the inconvenience and sought travellers’ patience.

Why the uncertainty remains

Even though the system was declared restored, key questions remain unanswered — creating uncertainty for both airlines and travellers:

1. What exactly caused the outage?
All available public statements from AAI mention a “technical issue” in the AMSS but provide little clarity about the precise nature of the fault or the sequence of events that triggered the failure. The Times of India+1 No official breakdown of hardware failure, software bug, cyber‑incident or human error has been published so far.

2. Why did it take so long to restore?
While the fault was detected late on November 6, the full restoration was announced only around 9 pm on November 7. Considering the importance of the system and the scale of the operation at the airport, many wonder why the automated backup could not immediately take over and accelerate recovery. Media reports note that manual processing slowed down each flight’s clearance, causing queues and delays. The Financial Express

3. What happened to the backup systems?
Aviation norms ordinarily require redundant or standby systems in critical infrastructure such as ATC automation. Why a backup did not prevent or mitigate the disruption is still not clear. There has been no transparent explanation of whether the backup existed, was functional, or why it could not handle the load when the primary AMSS failed.

4. Who is ultimately accountable?
It remains unclear which vendor supplied the AMSS hardware or software in question, and which organization bears responsibility for the breakdown — whether the contracting OEM, a maintenance provider, or the AAI itself. Without such transparency, assigning responsibility or assessing liability is difficult.

5. What about residual effects?
Even after the system was restored, AAI itself acknowledged that residual delays could occur while the backlog clears and automated processing stabilises. Hindustan Times+1 Airlines and travellers alike face uncertainty about how quickly things will return to normal, and how many flights remain in delay or holdover status.

Why this matters

The IGIA disruption is significant for several reasons. Firstly, any failure in the ATC message‑switching system has safety implications: flight‑plan data, weather updates, conflict‑resolution messages and airport slot decisions all depend on automation for speed and accuracy. Without the automatic feed, controllers are forced into slower, manual procedures — which, while safe, reduce capacity and efficiency. www.ndtv.com+1

Secondly, for IGIA—handling tens of thousands of flights and passengers daily—lost automation has immediate ripple effects throughout India’s aviation network. Delays at Delhi affect connecting flights, incoming personnel and aircraft slots elsewhere. The incident exposed the vulnerability of the system in a high‑traffic environment where margins for error are minimal.

Thirdly, it raises questions about resilience, redundancy and maintenance of critical aviation infrastructure. If such a major glitch can bring operations at the country’s busiest airport to a near standstill, aviation authorities, airlines and equipment vendors will face scrutiny on their ability to prevent, detect and resolve such failures.

What now and what to watch

In the immediate term, airlines and the AAI have indicated that operations are back under control but with possible delays while the backlog clears. Travellers with flights to or from Delhi are advised to stay in regular contact with their carrier, reconfirm scheduled times, arrive early at the airport and remain flexible.

In the medium term, the following developments may be worth monitoring:

• An official incident report from AAI or the Ministry of Civil Aviation that explains the root‑cause of the failure, the timeline of events, whether backup systems worked (or didn’t), and the corrective actions being taken.
• The vendor(s) responsible for the AMSS system and the audit of its performance, redundancy and operational readiness.
• Any regulatory or oversight response — for example, whether the Directorate General of Civil Aviation (DGCA) or another body mandates review of ATC automated systems, backup readiness and disaster recovery procedures.
• The impact on airlines’ schedules, including compensation or rebooking policies for passengers whose flights were delayed or cancelled.
• Long‑term infrastructure upgrades at IGIA and elsewhere to bolster resilience of the ATC message‑switching systems, given the increasing traffic volumes and the importance of automation in safety and efficiency.

Final word

While the situation at IGIA is now back on track, the incident serves as a stark reminder of how critical automation is to modern airport and air‑traffic‑control operations—and how disruptive it can be when such systems fail. The lack of public clarity on what exactly went wrong, why backups did not immediately step in, and who holds responsibility leaves unanswered questions for travellers, airlines and regulators alike. As flights resume and the travel system gradually stabilises, the aviation sector will need to focus on both transparency and technical robustness to prevent a recurrence of this scale of disruption.