The bulk of flights scheduled for Thursday morning at Hartsfield-Jackson International Airport have been canceled as airlines gradually resume service in Atlanta, while snow continued to fall in the area.

As airlines began resuming flights in the early afternoon, lines for security screening stretched from the switchbacks in the checkpoint area into the airport atrium.

Transportation Security Administration spokesman Mark Howell said the agency is augmenting staff at checkpoints to try to keep lines short, but warned travelers to check security wait times on the airport’s website to determine how early to arrive at the airport. During the storm two weeks ago, some security waits topped an hour in Atlanta.

Hartsfield-Jackson International Airport officials say they expect airlines on Thursday will operate some 60 percent of their normal schedule of more than 2,000 flights in and out of Atlanta.

Atlanta-based Delta Air Lines canceled nearly all of its flights in Atlanta scheduled for Thursday morning, but plans to gradually restart its flight schedule in the afternoon. The airline is bringing some flights into Atlanta mid-morning and adding more departures after 2 p.m. Delta normally operates nearly 2,000 flights in and out of Atlanta, but on Wednesday canceled nearly all of them save for a few dozen.

The gradual ramp-up of Delta’s megahub will continue into Friday.

Delta has extended its waiver of change fees for travelers who want to alter their flight plans, to cover flights through Friday in Atlanta and seven other airports in the Southeast.

Southwest Airlines and subsidiary AirTran Airways said they canceled all Thursday departures until 1 p.m., when they plan to resume a normal flight schedule. Southwest and AirTran typically operate more than 300 flights a day in and out of Atlanta, but on Wednesday canceled all of their Hartsfield-Jackson flights.

On Wednesday evening, the ATL SkyTrain — which goes from the airport to the rental car center, Georgia International Convention Center and nearby hotels — stopped operating amid icy conditions. The airport ran shuttles for passengers and employees instead. SkyTrain operations restarted Thursday morning.

Hundreds of passengers spent the night at the Atlanta airport on Wednesday night, filling the airport atrium and spreading out in the terminal and concourses, lying out on the floor and trying to sleep in chairs.

And hundreds of airport workers have also been staying overnight at Hartsfield-Jackson, working overtime to cover shifts.

Brenda Kelly was returning to Michigan after a vacation in Punta Cana when she got waylaid during her layover in Atlanta. Her flight scheduled for Wednesday evening was canceled, and now she doesn’t expect to depart until Thursday afternoon. She called into work to tell them she wouldn’t be able to make it in.

In the airport, Kelly found a spot on the carpeted floor of the upper level of the airport atrium to settle in for the night, after finding out that all the hotels were booked or “charging crazy prices,” she said.

“It really can’t be helped because of the weather,” Kelly said. “I’m not in dire stress. What happens, happens…. I just hope I’m not here for a long time.”

Some travelers who spent Wednesday night at the airport weren’t trying to catch a flight at all.

They arrived on flights in Atlanta to an ice-covered city, and were stuck waiting until the roads clear. MARTA stopped train service early Wednesday night, MARTA buses and some shuttle operations suspended service and officials warned motorists to stay off the roads.

“After three cancellations I’m finally home,” said Yvonne Robinson, as she sat in the airport atrium Thursday morning, two days after she was supposed to arrive. Robinson said after the ordeal, she didn’t mind waiting a few more hours for her ride, who was waiting for road conditions to clear.

Naynesh Patel of Marietta learned earlier this week that his flight home from San Francisco scheduled for Wednesday was canceled, then was rescheduled with a more than eight-hour long layover in Los Angeles. He arrived back in Atlanta early Thursday morning, but then found himself waiting in the airport for the weather to warm up.

“I’m just stuck here trying to figure out how I’m going to get home,” Patel said. He’s counting on a friend with four-wheel drive to pick him up.

Stanley Jefferson flew in Wednesday night from Manila but found it difficult to get home to Decatur, so he spent the night dining in the airport food court, checking his email and walking around the terminal, before taking a nap at around 4 a.m.

“I decided to wait out the ice storm,” Jefferson said.

The mix of people occupying Hotel Hartsfield-Jackson Wednesday night ended up being a mix of travelers from across the country and around the world, some trying to get to vacations and others just trying to get home.

The mood among marooned passengers was mostly friendly, as people looked for ways to pass the time and chatted with strangers.

“I met some pretty good people,” Kelly said. “It all works out in the wash. A little good with the bad.”

Photo Credit: A view of Atlanta from the icicles hanging from the Jackson Street Bridge railing Wednesday, Feb. 12, 2014. John Spink / Atlanta Journal-Constitution/MCT