Delhi airport ops resume, but uncertainty remains: 5 unanswered questions

While the Airports Authority of India (AAI) has said that the issue at the Delhi airport was fixed, there is no clarity yet on what caused it.

Updated on: Nov 8, 2025, 11:14:53 IST

By HT News Desk

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The Indira Gandhi International Airport, the country’s busiest, saw serpentine queues on Friday after a major technical failure in the air traffic control system delayed more than 800 domestic and international flights, and led to cancellations of 20 flights.

Aircraft waited for takeoff at Indira Gandhi International (IGI) Airport on Friday. Flight operations at the Delhi airport were delayed due to a technical glitch in the Air Traffic Control (ATC) system, which supports air traffic data. (Hindustan Times)

The Airports Authority of India (AAI) later said the issue had been fixed, but warned that some backlogs could continue to affect automated operations before things fully normalize.

Over 800 flights were delayed at the Delhi airport and at least 20 were cancelled.

Also Read | Travel chaos hits Delhi's IGI airport as vital network collapses

What happened?

Automatic Message Switching System (AMSS) failed, cutting off automatic transmission of flight plan data to air traffic controllers’ screens.

Controllers had to prepare flight plans manually, slowing down operations dramatically.

A glitch was reported on Friday morning, and by 8.30 pm, 15 flights had been cancelled over 800 had been delayed.

The following operations took a hit due to the glitch:

Flight plan updates
Real-time weather data
Slot decisions: when a flight can depart
Gate assignments based on accurate arrival/departure data

The system was finally restored at 9 pm, the Airports Authority of India (AAI) said.

Also Read | Delhi airport: Air traffic system 'up and functional' after glitch; 800 flights delayed

Even as airports systems have returned back to normalcy, some key questions regarding the chaos remain unanswered. Here they are:

1. What caused the outage?

Every time the Airports Authority of India (AAI) shared an update, it only cited a “technical issue” with the AMSS, but there was no clarity on what the issue was or what caused it. The authorities only said that the technical issue caused delays in processing flight plan messages thus causing flight delays.

2. Why did it take so long to restore?

While the first signs of a system failure appeared around 3 pm on Thursday, and flight delays started on Friday morning, it was only at 9 pm that the AAI at Delhi airport said that the issue had been resolved.

Many flights were delayed due to "technical issues" at the Delhi airport on November 7. (HT)

3. What happened to the backup?

Aviation norms require standby systems to be ready at all times. Why wasn’t the backup operational at India’s busiest airport?

4. Who is responsible?

There is still no clarity on which company’s systems were involved or who is accountable for the failure.

ABOUT THE AUTHOR
HT News Desk
Follow the latest breaking news, major developments and agenda-setting stories from India and around the world with the newsdesk at Hindustan Times. Operating round the clock, the desk brings together experienced editors, reporters and correspondents to deliver fast, accurate and contextual reporting across subjects that influence public policy, governance, business, society and international affairs. The HT News Desk covers politics, elections, government policies, the economy, business and markets, science and technology, the environment, law and order, infrastructure, education, climate issues and geopolitics, while closely tracking developments across states, institutions and global capitals. The team also leads coverage of major breaking news events, policy announcements, court proceedings, natural disasters, public emergencies and significant international developments. Reports published by the newsdesk are based on information gathered from reporters on the ground, official statements, government agencies, court records, regulatory filings, recognised institutions and other authoritative sources. Stories undergo editorial scrutiny and verification processes to ensure accuracy, fairness and relevance, and are updated as events evolve and additional information becomes available. Whether covering a key political decision in New Delhi, an economic policy shift affecting millions, a landmark court ruling or a major global event, the HT News Desk aims to provide readers with reliable, fact-based journalism that delivers not only the latest developments but also the context and analysis needed to understand their wider implications.Read More

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