8,700+ US flights hit after network failure

An unprecedented outage of a key system forced the United States to ground all departures for hours on Wednesday, leading to delays and cancellations that affected at least 8,700 flights and millions of passengers following a roughly two-and-a-half hour halt that triggered ripple effects lasting throughout the day.

WASHINGTON: 

Close to 1400 GMT (7.30pm IST), the Federal Aviation Administration (FAA) said that normal operations were resuming gradually, but airlines warned of lingering delays.

"Normal air traffic operations are resuming gradually across the US," the FAA said on Twitter.

"The ground stop has been lifted.

We continue to look into the cause of the initial problem." The outage led to more than 7,539 flights being delayed and 1,163 flights being cancelled, data from flight tracking website Flight Aware showed at 11.30pm (IST).

The FAA said it had identified a problem with the Notice to Air Missions system (Notam), which provides information to flight crews about hazards, changes to airport facilities and other essential information. The issue was first spotted late on Tuesday, but the disruptions were limited since those are hours for the few red-eye services.