New Delhi, 8 Nov

Airline operations at the Delhi airport, the country's busiest airport, were slowly returning to normalcy on Saturday morning, a day after a glitch with the air traffic control system delayed more than 800 flights.

The technical problem with the Automatic Message Switching System (AMSS), which supports the air traffic control's flight planning process, continued for over 15 hours from around 5:45 am on Friday before the Airports Authority of India (AAI) said at around 9 pm that the issue has been addressed.

The Indira Gandhi International Airport (IGIA) in the national capital that has four runways, handles more than 1,500 flight movements daily.

Delhi airport operator DIAL on Saturday morning said the technical issue which affected the AMSS is gradually improving.

"Airline operations at Delhi Airport are returning to normal, and all concerned authorities are working diligently to minimise any inconvenience caused," it said in a post on X.

Apart from over 800 flights that faced delays, some services were also cancelled on Friday, impacting hundreds of passengers.

The country's largest airline IndiGo on Saturday morning said the airport operator and Air Traffic Control (ATC) teams were working on priority to fully restore systems and stabilise operations.

"The situation is expected to be normalised over the next few hours. During this period, some departure and arrival timings may continue to be adjusted," it said in a post on X.

Information available on flight tracking website Flightradar24.com showed that over 200 flights were delayed at the airport, including arrivals and departures, on Saturday morning.

It could not be immediately ascertained whether the flight delays were only due to the AMSS issue which is gradually improving.

While the AMSS started facing the technical issue Thursday late afternoon, the outage with the system happened at around 5:45 am on Friday, following which air traffic controllers had to prepare flight plans manually, according to sources.

The AAI, which provides navigation and other services, had also deployed additional manpower to prepare the flight plans manually which is a time-consuming process.

On Friday evening, the AAI said it has addressed the "technical issue in the AMSS, which caused delays in processing flight plan messages".

The issue was detected in the IP-based AMSS system on 6 November.

"The OEM (Original Equipment Manufacturer) was engaged, and additional staff were deployed to manually process Flight Plans for the Air Traffic Control system to ensure uninterrupted and safe air traffic operations immediately.

"A team of ECIL officials and AAI personnel is still on site. The AMSS systems are up and functional now. Due to some backlogs, there may be some delays in the normal functioning of automated operations, but the situation will be normal soon," the AAI had said.