Nearly 18 million people are expected to travel between now and the Thanksgiving holiday weekend, with 3 million passengers predicted to fly on Sunday alone, according to the Transportation Security Administration. 

That Sunday is projected to be "one of the busiest travel days in TSA history,” said Adam Stahl, an official with the agency, in a press release. 

Airlines are bracing for heavy traffic following the longest government shutdown in history. 

“Things are in the process of getting back to normal,” said Tim Kiefer, assistant professor of air traffic management at Embry-Riddle Aeronautical University.

Now that air traffic controllers are getting paid, the industry won’t face the same number of absences they did during the shutdown. But the air traffic system is still behind when it comes to staffing, even in a normal environment, Kiefer said. 

Earlier in the year, U.S. Transportation Secretary Sean Duffy said the country is short 3,000 air traffic controllers. 

There could still be delays because of this persistent shortage, Kiefer said. 

Weather could also cause disruption. That’s the “real wild card,” said George Hamlin, an aviation consultant.

Bad weather recently led some Texas airports to delay or cancel hundreds of flights while the FAA temporarily halted flights bound for Hartsfield-Jackson Atlanta International Airport.

During busy times like these, Hamlin recommends getting to the airport early, sitting tight and paying close attention to announcements. Hamlin said a flight he was taking several months ago got delayed by a few hours, but he was able to catch another flight that was accommodating other extra passengers.

If you’re worried about traveling, Kiefer said it’s safe to fly now, just like it was during the shutdown. 

“The people behind the scenes are doing everything they can to get you from point A to point B as safely and as quickly as possible,” Kiefer said. 

If you want to keep an eye on any delays or closures, the Federal Aviation Administration’s website lists updates on its website. Those who experience a long delay or face a cancellation can try asking airline staff to pay for their meal or a hotel room, the U.S. Department of Transportation advises. But while some airlines may oblige, others may not, DOT warned.

And if your airline cancels your flight, regardless of the reason, just remember that you are entitled to a refund if you choose not to accept another form of compensation.