Power has been restored at Hartsfield-Jackson Atlanta International Airport after an outage caused more than 1,200 flights to be cancelled.
Passengers were left stranded on planes on the tarmac and in darkened terminals at the world's busiest airport following the blackout on Sunday.
Even though power was finally restored at close to midnight Sunday, the incident continued to wreak havoc on holiday travel plans for thousands of people hit by airline cancellations extending into Monday.
Delta said it was cancelling about 300 flights on Monday, on top of the 900 Sunday cancellations as a result of the Atlanta outage.
A statement on the Delta website reads: 'Most of the 300 cancellations Monday are early morning, inbound flights to Atlanta to give the operation there an opportunity to more quickly return to normal. Delta’s flight schedule in Atlanta is expected to return to normal by Monday afternoon.'
United Airlines also warned on social media that travel on Monday may be affected.
Robert Mann, an aviation consultant and former American Airlines executive, said it likely will be Tuesday before Delta's operations in Atlanta return to normal, and for passengers 'it could be most of the week' because there aren't many open seats on other flights in the last week before Christmas.
'Tomorrow is going to be a long and difficult day for everybody,' Mann said.
All passengers had safely disembarked from aircraft by approximately 10pm, or nine hours after the outage began, Atlanta Mayor Kasim Reed said on Twitter.
The city was providing shelter to stranded passengers at the Georgia International Convention Center and said Chick-fil-A would be providing food for passengers. By late Sunday the city said it had provided 2,000 meals.
Passengers wait in a dark terminal at Hartsfield-Jackson Atlanta International Airport on Sunday following a power outage
'We´re just focusing on the comfort of our passengers,' Reed told a news conference. 'We know they have had a very, very long and difficult day.'
Georgia Power, the utility that provides electricity to the sprawling airport, said the failure was linked to a fire in an underground facility that damaged substations serving Hartsfield.
The blaze damaged access to a backup system, Reed told reporters, adding the cause remained unknown.
For all carriers, nearly 700 flights scheduled to fly out of Hartsfield, or 60 per cent, were canceled on Sunday as of 10.30pm EST, while 477 of all scheduled inbound flights were scratched, airline tracking service FlightAware said.
During the power outage, passengers inside the airport were forced to light their way with their cell phones and people in wheelchairs had to be carried down stairwells. People were reportedly stuck on planes for more than seven hours.
Twitter user @VolsGuy2 wrote: 'Try being stuck on a plane for over 7 hours... still stuck no food, no water, bathrooms full. No updates... get us out of here!'
CNN producer Betsy Klein was stuck on a plane for more than six hours and live-tweeted her ordeal.
She wrote: 'Pilot, just now: "I still think we're quite a ways from getting deplaned... I certainly thought it'd be taken care of by now... not really sure how long it's gonna take for us to get there." Still no food/water. Toilets have been dumped so won't overflow. We passed 6-hour mark.'
After deplaning, she added: 'Hartsfield looks like a war zone. People sleeping on the floor, fighting mostly civilly over outlets, elderly people and small children struggling with stairs... It is SWELTERING inside the airport... There are people sleeping on baggage claim belts. The line for delta support is VERY long.'
Twitter user Marietta claimed there was no water inside the terminal.
'Why doesn’t Atlanta have an “emergency backup system”?' she wrote. 'The mayor said that they had passed out water but my son never saw it. What about the old people or children with no food water or place to sleep but a cold, barely lighted terminal. THEY SHOULD BE ASHAMED!!!'
Jason Rabinowitz, who describes himself as an AV geek, shared this image showing there are just two flights which departed from the Atlanta airport in the sky
Aviation consultant Mann said there is one bit of good news: Delta has more spare planes and available crews in Atlanta than anywhere else, which will help it to recover.
Still, when flights at Atlanta were grounded for most of one day last spring, it took Delta five days - and about 4,000 cancelled flights - before it fully recovered.
Like Sunday's outage, that April storm hit Delta's largest hub at a busy travel time when there weren't many empty seats to accommodate customers from cancelled flights. At the time, CEO Ed Bastian vowed that Delta would make 'significant improvements' to its system for scheduling and tracking aircraft crews to recover more quickly from disruptions.
American Airlines canceled 24 departures and an equal number of arrivals, said spokesman Ross Feinstein. The airline also diverted three planes that were headed to Atlanta when the outage struck, sending them instead to Dallas, Nashville and back to Philadelphia.
Passengers affected by the power outage are pictured waiting in long lines at Hartsfield-Jackson Atlanta International Airport
Hartsfield-Jackson, which serves 104 million passengers a year, is the world's busiest airport, a distinction it has held since 1998
Robert Mann, an aviation consultant and former American Airlines executive, said it likely will be Tuesday before Delta's operations in Atlanta return to normal
At Southwest Airlines, about 70 Atlanta departures out of 120 scheduled for Sunday were cancelled, an airline spokesman said in an email.
The FAA said it would staff the airport control tower throughout the night so that it can handle flights once they resume. The FAA said the tower could operate normally but flights were affected because airport equipment in the terminals was not working.
Delta passenger Emilia Duca, 32, was on her way to Wisconsin from Bogota, Colombia, when she got stuck in Atlanta.
She said police made passengers who were in the baggage-claim area move to a higher floor. She said restaurants and shops were closed.
'A lot of people are arriving, and no one is going out. No one is saying anything official. We are stuck here,' she said. 'It's a nightmare.'
Mozell Smith, 58, of Atlanta arrived at the airport hours after the electricity went off. He was headed to Las Vegas with a sister and a friend.
'This is terrible. I wish someone would've given us a heads-up before we got to the airport,' he said. 'I wish there would have been better communication.'
Twitter user Ciara Leilani wrote: 'Literal pandemonium at the @ATLairport with power completely out and electric exit doors unable to open.
'Baggage claim stuck, passengers can go no where! Which means traffic can’t either. GBI and other law enforcement on site now. Talk about delays!'
Hartsfield-Jackson, which serves 104 million passengers a year, is the world's busiest airport, a distinction it has held since 1998.
The airport serves an average of 275,000 passengers daily, according to its website. Nearly 2,500 planes arrive and depart each day.
The airport has consistently been the busiest in both the nation and the world. The airport serves an average of 275,000 passengers daily, according to its website
Departing international passengers look as planes wait on a taxiway after widespread power outage at Hartsfield-Jackson Atlanta International Airport
Record number of Americans expected to travel this Christmas and New Year
U.S. travelers will hit the roads, rails and skies this Christmas holiday in the largest numbers on record, lured by cheap plane tickets and a growing economy, the nation's largest motor advocacy group said on Thursday.
Roughly 107.3 million Americans will journey 50 miles or more from home during December 23 through January 1, a 3.1 per cent increase from a year earlier and the most ever recorded, AAA said in a report.
That would be the sixth consecutive record high for the holiday season, the Heathrow, Florida-based organization said.
'More expensive gas prices are not swaying holiday revelers to stay home,' AAA Senior Vice President Bill Sutherland said.
'In fact, across the board this year, travel has increased year-over-year for every major holiday weekend – Memorial Day, Independence Day, Thanksgiving – and we project the same for the year-end holiday period. We’ve seen the strong economy and growing consumer confidence fuel holiday travel all year long,' Sutherland added.
The largest share of travel, roughly 90.7 per cent, will be on U.S. roads. Energy traders watch this activity closely because it accounts for 10 per cent of global oil demand.
U.S. motor trips will rise to 97.3 million for this holiday season, the seventh consecutive annual increase, AAA said.
Since many Americans will be traveling by car, it could cause traffic chaos in some of the bigger cities.
INRIX, a global transportation analytics company, worked with AAA to determine the worst times for travel in 10 major U.S. cities.
It found that the most congestion will happen before the Christmas holiday, in the early afternoon as workers leave their jobs early to try and beat traffic. Instead they could spend up to three times longer on the road getting to their destination.
'With record-level travelers hitting the road this holiday, drivers must be prepared for delays in major metros,' says Dr. Graham Cookson, chief economist & head of research at INRIX. 'Our advice to drivers is to avoid peak times altogether or consider alternative routes.'
AAA expects air travel to grow by 4.1 per cent to 6.4 million trips, the highest since 2004 as passengers take advantage of lower ticket prices.
Air travel now accounts for 5.9 per cent of all travel, following four consecutive years of share increases, AAA said.
For 2017, motorists are on pace to break the record for most vehicle miles driven on U.S. roads, helping spur potential record demand for gasoline.
U.S. gasoline demand and vehicle miles traveled both set records in 2016.
Gas prices jumped more than 10 per cent after Hurricanes Harvey and Irma, peaking on September 8 at an average of $2.67 a gallon. Prices were at $2.45 a gallon on Thursday, up about 9 per cent from a year earlier, AAA said.