ORLANDO, Fla. — Thousands of Southwest Airlines passengers are stranded at airports across the U.S., including those at the Orlando International Airport, after the airline had to cancel or delay hundreds of flights after a major disruption in operations over the weekend.

Southwest is one of the largest carriers out of Central Florida.

The airline tweeted over the weekend, stating that issues with air traffic control and disruptive weather, stating it is working to re-accommodate impacted customers, as wait times are long.

On Saturday nationwide, more than 800 flights were canceled, and on Sunday it was more than a thousand, with more than a thousand delays each day.

However, look at the departures board on Monday morning, Spectrum News 13 saw about four canceled flights and the rest appear to be on time.

The line to talk to ticket agents and check-in bags is growing on Monday morning.

The airline is also blaming staffing issues in Florida as part of the issue.

The FAA tweeted that "No FAA air traffic staffing shortages have been reported since Friday." 

Southwest has not yet said when its operation will fully return to normal.

Henry H. Harteveldt, president and travel industry analyst at The Atmosphere Research Group, based in San Francisco, points to other causes for the cancellations.

First, he says Southwest has scheduled more flights than it can handle, a problem that started in June. He also noted that Southwest operates what is known as a point-to-point route network, and when a delay occurs, it “cascades” along the remaining flight segments.

That is because, for example, a Southwest flight departing Fort Lauderdale for the airline’s home base of Dallas may make multiple stops along the way.

But Harteveldt says the most troubling reason is the likelihood that some pilots who oppose Southwest’s decision to mandate COVID-19 vaccinations are participating in an illegal job action where they call in sick or are engaging in a “work slowdown.”

In a statement Saturday, the airline’s pilot union, Southwest Airlines Pilots Association, said that’s not the case.

“SWAPA is aware of operational difficulties affecting Southwest Airlines today due to a number of issues, but we can say with confidence that our pilots are not participating in any official or unofficial job actions,” it said.

The airline is asking customers to check their flight status before coming to the airport and try to re-book online.

Scott McLaughlin and his family are trying to head back to Arizona on Monday morning after buying an investment property in Central Florida.

"We had no idea until we got here now we realize flights could be missed, but hopefully we get there safely with no problem," he said.

​On Sunday, the Southwest ticket counter line was crowded with people checking on their canceled flights.

Lilly Sosa and her family from Brownsville, Texas, were supposed to fly home Sunday after a week at Disney World. They were among travelers at Orlando International Airport dealing cancellations.

“They canceled our flight at one in the morning, we were flying to Texas,” Sosa said.

Sosa said they could not get a flight home until Wednesday. They were told air traffic control issues and weather were the reasons.

They then decided to rent a car instead.

“We are going to drive all the way back,” Sosa said. “It’s close to a 20-something hour drive.

The Associated Press contributed to this story.