TSA agents are working without pay again as DHS shuts down, and experts warn of flight delays even though air traffic controllers aren’t affected

A shutdown of the U.S. Department of Homeland Security that took effect early Saturday impacts the agency responsible for screening passengers and bags at airports across the country. Travelers with airline reservations may be nervously recalling a 43-day government shutdown that led to historic flight cancellations and long delays last year.

Transportation Security Administration officers are expected to work without pay while lawmakers remain without an agreement on DHS’ annual funding. TSA officers also worked through the record shutdown that ended Nov. 12, but aviation experts say this one may play out differently.

Trade groups for the U.S. travel industry and major airlines nonetheless warned that the longer DHS appropriations are lapsed, the longer security lines at the nation’s commercial airports could get.

Here’s what to know about the latest shutdown and how to plan ahead.

What’s different about this shutdown?

Funding for Homeland Security expired at midnight. But the rest of the federal government is funded through Sept. 30. That means air traffic controllers employed by the Federal Aviation Administration will receive paychecks as usual, reducing the risk of widespread flight cancellations.

According to the department’s contingency plan, about 95% of TSA workers are deemed essential personnel and required to keep working. Democrats in the House and Senate say DHS won’t get funded until new restrictions are placed on federal immigration operations.

During past shutdowns, disruptions to air travel tended to build over time, not overnight. About a month into last year’s shutdown, for example, TSA temporarily closed two checkpoints at Philadelphia International Airport. That same day, the government took the extraordinary step of ordering all commercial airlines to reduce their domestic flight schedules.

John Rose, chief risk officer for global travel management company Altour, said strains could surface at airports more quickly this time because the TSA workforce also will be remembering the last shutdown.

“It’s still fresh in their minds and potentially their pocketbooks,” Rose said.

What is the impact on travelers?

It’s hard to predict whether, when or where security screening snags might pop up. Even a handful of unscheduled TSA absences could quickly lead to longer wait times at smaller airports, for example, if there’s just a single security checkpoint.

That’s why travelers should plan to arrive early and allow extra time to get through security.

“I tell people to do this even in good times,” Rose said.

Experts say flight delays also are a possibility even though air traffic controllers are not affected by the DHS shutdown.

Airlines might decide to delay departures in some cases to wait for passengers to clear screening, said Rich Davis, senior security adviser at risk mitigation company International SOS. Shortages of TSA officers also could slow the screening of checked luggage behind the scenes.

What travelers can do to prepare

Most airports display security line wait times on their websites, but don’t wait until the day of a flight to check them, Rose advised.

“You may look online and it says two-and-a-half hours,” he said. “Now it’s two-and-a-half hours before your flight and you haven’t left for the airport yet.”

Passengers should also pay close attention while packing since prohibited items are likely to prolong the screening process. For carry-on bags, avoid bringing full-size shampoo or other liquids, large gels or aerosols and items like pocketknives in carry-on bags.

TSA has a full list on its website of what is and isn’t allowed in carry-on and checked luggage.

At the airport, Rose said, remember to “practice patience and empathy.”

“Not only are they not getting paid,” he said of TSA agents, “they’re probably working with reduced staff and dealing with angry travelers.”

Will the shutdown drag on?

The White House has been negotiating with Democratic lawmakers, but the two sides failed to reach a deal by the end of the week before senators and members of Congress were set to leave Washington for a 10-day break.

Lawmakers in both chambers were on notice, however, to return if a deal to end the shutdown is struck.

Democrats have said they won’t help approve more DHS funding until new restrictions are placed on federal immigration operations after the fatal shooting of Alex Pretti and Renee Good in Minneapolis last month.

In a joint statement, U.S. Travel, Airlines for America and the American Hotel & Lodging Association warned that the shutdown threatens to disrupt air travel as the busy spring break travel season approaches.

“Travelers and the U.S. economy cannot afford to have essential TSA personnel working without pay, which increases the risk of unscheduled absences and call outs, and ultimately can lead to higher wait times and missed or delayed flights,” the statement said.

This story was originally featured on Fortune.com