Power outage leads to partial shutdown of Atlanta airport

Hundreds of flights were delayed or cancelled at Hartsfield-Jackson Atlanta International Airport on Sunday as a power outage left passengers at the world's busiest airport stranded in darkened terminals or in aircraft idling on tarmacs.

The partial shutdown at the start of one of the busiest travel weeks of the year forced the Federal Aviation Administration to ground flights bound for Atlanta. Departures from Atlanta were delayed as well because gates and other equipment inside terminals were inoperative, the agency said.

The FAA flight control tower was operating normally, but at least three major airlines - United Air Lines, American Airlines and Southwest Airlines - suspended operations at the airport for the rest of the day.

"We know that today has been challenging to all of our customers travelling in and out of Atlanta, and we regret your disappointment," Southwest said in a statement.

Georgia Power, the utility that provides electricity to the sprawling airport, said it believed the failure was linked to a fire in an underground electrical facility which damaged substations serving Hartsfield.

The cause of the blaze was not yet known, the utility said in a statement issued about six hours after the outage began, but it expected to restore service by midnight.

Photos and videos posted on social media showed passengers huddled in partial darkness inside crowded terminals.

"Stuck on a plane at Atlanta Airport as the power is out there ... bedlam inside and boredom out here!" Jack Harris wrote on Twitter.

Delta Air Lines said on Twitter it was working to allow customers to deplane as quickly as possible, with only a limited number of open gates available.

In response to a question from a customer, the Atlanta-based carrier said it expected service to be restored by Sunday night, although it cautioned that the airport had yet not identified the cause of the outage.

The airline, which operates its largest hub at Hartsfield, said it cancelled more than 450 mainline and regional flights on Sunday.

For all carriers, more than 600 flights scheduled to fly out of Hartsfield, or 54 per cent, were cancelled on Sunday as of 7 p.m. EST (0000 GMT), while 449 of all scheduled inbound flights were scratched, according to FlightAware, an airline tracking service.

International flights due to land at Hartsfield were diverted to other Atlanta-area airports, US Customs and Border Protection said on Twitter.