If the government shutdown continues, flight cancellations will begin. That’s according to the Federal Aviation Administration, which has directed airlines to reduce traffic by 10%.

United, Delta, and American Airlines have said in statements that long-haul international flights will largely be unaffected. The cuts will be clustered across 40 major U.S. airports.

Security lines may be longer than usual, but for most of the shutdown, flights themselves have largely been departing on time, according to airline industry commentator Mike Arnot.

“In recent days, there has been a bit of a slowdown at major airports, like at Newark and Orlando, and pockets of disruption in California as well, but they've also bounced back,” he said, according to data from aviation analytics firm Cirium.

Arnot said usually cancellations are weather related, so airlines don’t have as much time to plan. But with this much heads up, he expects airlines to prioritize long-haul flights, which carry a lot of people and make a lot of money.  

“There's a lot of business travelers that rely on … those flights, and so they'll try to protect those operations at the expense of smaller regional jets which carry less passengers,” Arnot said.

Disruptions in regional flights could trickle elsewhere, said Sharky Laguana, chairman of the American Car Rental Association.

“If you're a car rental operator, you're going to have a bunch of cars in an airport and no customers there to pick them up,” he said.

Laguana said rental companies may attempt to move their fleets to places where travelers will be. And where car supply exceeds passenger demand, rates may drop. 

Airlines are trying to get ahead of any disruptions by offering flexibility for proactive passengers, including refunds or the opportunity to change their flights. 

And if travelers do get stuck, Sean Cudahy at The Points Guy said, they shouldn’t worry about lines or phone calls.

“A lot of time you can rebook yourself with just a few taps in the app. Airlines have said they're going to try and accommodate as many passengers as possible. It’s possible your airline may just rebook you on another flight,” he said.

Cudahy recommends nervous travelers consider non-stop or refundable backup flights, and check to see if their credit cards offer travel insurance, which may be able to cover costs including hotels and meals.