Delhi airport: Nearly 700 flights delayed after AMSS tech glitch

(DELHI, INDIA) Nearly 700 flights were delayed at Indira Gandhi International Airport on November 7, 2025, after a sudden failure in the Air Traffic Control system’s Automatic Message Switching System, triggering hours of disruption across India’s busiest hub and rippling through airline networks nationwide. The Airports Authority of India said a technical problem with the AMSS forced controllers to switch to manual processing of flight plans, creating bottlenecks that affected all airlines and left thousands of travelers waiting on the ground and onboard aircraft.

The Airports Authority of India said in a statement:

“Flight operations at Delhi Airport are experiencing delays due to a technical issue in the Automatic Message Switching System (AMSS), which supports Air Traffic Control data. Controllers are processing flight plans manually, leading to some delays. Technical teams are working to restore the system at the earliest.”

That AMSS malfunction, which feeds essential flight data into the Auto Track System used by controllers to sequence and separate aircraft, pushed the system into a slow lane that could not keep up with peak-hour movements at Delhi airport.

According to Flightradar24 data cited by airlines and airport officials, nearly 700 flights were delayed in Delhi, with knock-on flight delays also reported at Mumbai airport as air traffic managers grappled with similar data-handling constraints. Departures at Delhi ran on average about 50 minutes late, though some aircraft waited more than four hours to push back, and many arrivals were held in the air or diverted to sequence spacing. The widespread delays underscored how a single point of failure in the message-switching chain can throttle a complex operation that depends on precise, real-time data flow.

The disruption hit every major carrier serving Delhi airport, and operations across northern India struggled to recover through the day as ATC staff worked through stacks of flight plans by hand. Air India acknowledged the strain and urged customers to check flight information before traveling.

“Our cabin crew and on-ground staff at the airport are extending immediate assistance to reduce passenger inconvenience. We request you to check your flight status… before heading to the airport,” the airline said, noting that last-minute gate changes and altered boarding times were likely as schedules were rewritten in real time.

IndiGo, India’s largest domestic carrier by market share, warned of extended waits both in terminals and on aircraft already boarded.

“We understand that extended wait times both on the ground and onboard may cause inconvenience. Our teams are working hard to make your experience as smooth as possible,” the airline posted,

signaling that its network control was rerouting crews and swapping aircraft where feasible to keep some services moving. SpiceJet appealed to passengers to watch for updates as the situation evolved, urging travelers to “keep a check on flight status” through its website as its Delhi flights faced delays and potential gate switches.

Inside the terminals and on aircraft parked on the apron, the human toll of the AMSS malfunction was clear. A traveler posting on IndiGo’s X page wrote:

“At the Delhi airport, the flyers are made to wait on board the plane for more than 4 hours. Delays are understandable, at this moment you can rather cancel the flight and spare them the misery.”

Passengers on several Air India services asked for refunds after missing onward connections, while others complained of scant information as airlines raced to update crew rosters and refile plans in a system working at a fraction of normal speed. Some travelers described a shortage of snacks at gates and long lines at customer service desks as hundreds sought alternate flights, overnight accommodations, or help rebooking.

Airport officials said information screens and airline apps would be updated as quickly as the revised plans were accepted by controllers, but they cautioned that data refreshes could lag because of the manual processing required for each flight. The airport operator issued an advisory noting the strain on operations and asked passengers to stay connected to their carrier for the latest updates.

“The inconvenience is deeply regretted. Passengers are advised to stay in touch with their respective airlines for the latest updates,” Delhi airport said,

as on-ground teams tried to ease congestion in departure halls and move delayed aircraft off gates to free parking stands for inbound flights.

The immediate cause of Thursday’s meltdown was focused squarely on the failure of the AMSS, a behind-the-scenes system that routes flight plans, weather bulletins, and other operational messages to the right consoles and control positions. With that system down, air traffic controllers reverted to manual steps, reading and entering flight plans one by one, a slower process that reduces the number of aircraft that can be safely managed at any moment. While controllers are trained for such contingencies, the volume at Delhi airport—one of the busiest in Asia—meant queues formed fast as aircraft pushed back late, missed their departure slots, and then returned to gates or waited on taxiways for clearance.

Airlines said the cascading delays were compounded by crew duty-time limits and aircraft rotations that depend on tight scheduling in and out of Delhi. Once early flights ran late, crews ran up against legal duty-hour caps, forcing some services to await replacements. Ground handlers juggled last-minute shifts in gate assignments and baggage transfers as departures slid and arrivals bunched up, causing long baggage delivery times and additional waits for passengers already stuck in queues.

On social media platforms, frustrated travelers traded updates on gate changes and departure estimates, while some suggested air quality may have contributed to the situation, a claim airlines did not confirm. Several posts highlighted missed business meetings and family events, as well as concerns about elderly passengers and young children waiting onboard for hours while aircraft remained on stands. Customer feedback teams for multiple airlines acknowledged the volume of complaints and asked for patience as network control centers worked with the ATC to push flights through in revised order.

The AMSS malfunction also touched operations beyond the capital. Airlines said they anticipated delays at Mumbai, where controllers and airline operations centers were syncing schedules for aircraft arriving from Delhi and other northern routes. Several carriers warned connecting passengers to allow extra time at hubs and to watch for gate changes as the day wore on. In practical terms, that meant longer queues at check-in and security, and occasional pauses at boarding while crews waited for updated clearances to arrive from ATC via the manual pipeline.

Despite the breadth of the challenge, the Airports Authority of India said technical teams were working to restore the system “at the earliest,” and by late afternoon airlines reported that operations were gradually returning to normal as backlogged plans were cleared and the message-switching function stabilized. The rate of departures improved as controllers processed more flights, but carriers told passengers to prepare for lingering delays into the evening as aircraft and crews returned to their planned positions across the network.

This was the second major operational shock at Delhi airport in a week, following earlier disruptions linked to GPS spoofing incidents and a sudden shift in wind direction that forced runway configuration changes. While Thursday’s problem was different in nature—rooted in a systems failure rather than external navigation interference or weather—it added to the strain on air traffic operations that were still smoothing out after the previous week’s turbulence. Frequent flyers said the back-to-back disruptions had eroded buffer time built into schedules and left little room for recovery when another issue hit.

Airlines’ messaging reflected a balance between acknowledging the disruption and guiding passengers to the most reliable sources of information. The IndiGo post emphasized that teams were “working hard to make your experience as smooth as possible,” while Air India’s note underscored the importance of checking live status before leaving home. SpiceJet’s brief advisory to “keep a check on flight status” was echoed by other carriers, including those not named publicly, as social teams directed travelers to official apps and websites. The airport’s appeal for patience was consistent with the view inside operations centers that accuracy mattered more than speed in a manual environment where data entered incorrectly could create safety issues or further delays.

The impact rippled through customer service and retail as well. With aircraft out of sequence, some gate areas were packed while others sat quiet awaiting delayed arrivals. Food outlets reported waves of demand aligned with delayed boarding calls, and passengers stuck for hours sought charging points and seating in crowded lounges. Airline staff moved through the halls fielding questions about missed connections, hotel accommodation policies, and rebooking fees. Several Air India passengers asked for refunds after missing connecting flights, while others sought meal vouchers when delays stretched beyond multiple hours. The absence of detailed, up-to-the-minute ETDs in some instances—an unavoidable result of manual flight plan approval—made it hard to provide precise timelines, adding to stress for travelers trying to plan the rest of their journeys.

As the day’s delays accumulated, the incident spiked online interest in the hub, with Google Trends logging more than 500 searches for “Delhi Airport” within an hour as people tried to understand what went wrong and how long it would last. That surge mirrored the chatter on X and other platforms where travelers posted images from departure halls and shared updates about newly assigned gates or revised boarding times. Several posts urged airlines to permit voluntary cancellations without penalty for those who no longer needed to fly after long waits. Others praised on-ground staff for helping elderly travelers and families navigate packed terminals and shifting queues.

Air traffic controllers, working under pressure, prioritized safety as they filtered the growing queue of flight plans into the Auto Track System, slotting aircraft into available windows as soon as clearances could be issued. With manual reviews replacing automated checks, each plan took longer to validate, a reality that airline operations teams factored into their rolling estimates. The close coordination between ATC units, airline dispatch, and airport operations was apparent in the gradual easing of congestion by late afternoon, though carriers cautioned that network effects would be felt into the night as aircraft and crews returned to normal rotations.

While the full technical analysis of the AMSS malfunction was not immediately available, the Airports Authority of India said specialized teams were addressing the error and monitoring stability as services were restored. Past incidents have shown that message-switching systems can be sensitive to configuration faults or network issues, but airline officials avoided speculation and deferred to AAI engineers on root-cause findings. With a view to rebuilding confidence, some carriers said they would adjust crew rosters and add spare aircraft where possible on Friday to help absorb residual delays and protect early-morning departures.

For travelers, the most practical step remained straightforward: check with the airline before leaving home, then keep checking. That advice was reiterated across the day in airline posts and airport messages, along with reminders that gate numbers could change quickly and that boarding times might be brought forward once clearances came through. For those already at Delhi airport, the emphasis was on staying near the assigned gate and watching display boards and airline apps for live updates, since a flight delayed for hours could suddenly be cleared once controllers processed its plan.

As normalcy edged back, the question turned to resilience. The episode showed how a fault in a single node—the AMSS—can create system-wide flight delays when traffic is dense and margins are thin. It also highlighted the role of manual backups and the human capacity to keep a complex operation safe while technology is restored. Passengers bore most of the inconvenience, from sitting on planes waiting for pushback to queuing for rebookings that depended on shifting schedules. Yet by evening, many of those who had waited longest were finally on their way, while airlines and the airport prepared for a night of schedule repairs and a morning push to reset operations.

The Airports Authority of India directed passengers seeking official updates to airline channels and airport advisories, and maintained that restoration work would continue until full stability was confirmed. For information about air traffic systems and operational advisories, travelers and industry stakeholders can refer to the Airports Authority of India, which posts official notices and updates related to aviation operations. As of late afternoon, airlines and ATC officials said the worst of the backlog was clearing, though schedules would likely reflect residual changes into the next day as aircraft and crews repositioned and controllers worked through the final wave of manual plan approvals.