TSA lines are so bad at some airports that United and Delta are letting passengers move their flights

• Houston and Atlanta airports are warning travelers of four-hour security lines.
• Delta, United, and Allegiant have waived some fees to give passengers rebooking flexibility.
• TSA agents have been calling out of work as they aren't being paid due to a government shutdown.

Some airlines are waiving change fees for passengers affected by hourslong waits at airport security.

Delta Air Lines, United Airlines, and Allegiant have issued advisories giving travelers more flexibility during the ongoing travel chaos.

Due to a partial government shutdown, TSA agents have been working without pay since February 14. As a result, more of them have been calling out of work.

As many as 10% of all TSA agents called out on several days last week, the Department of Homeland Security said. Immigration and Customs Enforcement agents have been deployed to some major airports.

The shutdown persists as Republicans and Democrats are at loggerheads over funding for the DHS. Republicans want to allocate billions more to ICE, but Democrats want it to be reformed in the wake of January's violence in Minnesota.

Here are the airlines that are offering waivers:

Delta Air Lines

In a travel advisory, Delta said that travel from its main hub, Atlanta's Hartsfield-Jackson International, "may be affected" by longer security wait times. The airport is advising passengers to allow at least 4 hours for domestic and international screenings.

Delta customers flying from Atlanta on Monday or Tuesday can rebook to travel on or before March 30, and the fare difference will be waived.

Within a year of the ticket being issued, passengers could rebook without a change fee but would still need to pay the fare difference. Or, they could apply any unused value of the ticket toward the purchase of a new one.

A Delta spokesperson said this only applies for people on flights originating from Atlanta, not connecting through the hub.

United Airlines

United issued an alert for Houston's George Bush Intercontinental Airport, saying travel "may be affected."

Tickets purchased on or before Sunday, for travel on Monday or Tuesday, can be rescheduled for a United flight until March 31. "Tickets must be in the same cabin and between the same cities as originally booked."

The airline didn't immediately respond to a request for comment on whether this was directly related to TSA staffing shortages. A banner on the airport's website on Tuesday said security wait times could exceed 4 hours.

Allegiant Air

Allegiant announced a "travel with confidence" policy that allows customers with new and existing tickets through the end of the partial government shutdown to change or cancel their flights at no extra charge.

This includes "no change fees for eligible bookings" and the "option to cancel and receive a refund without penalty."

JetBlue

"With the exception of Blue Basic, all JetBlue fares are flexible — meaning no change or cancellation fees for customers who want to adjust their travel plans ahead of time," an airline spokesperson told Business Insider.

Customers who miss their flight due to long security lines will be rebooked on the next available flight, they added.

JetBlue advises customers to arrive earlier than normal, and said that it's working closely with TSA and continues to monitor the situation.

Southwest

Southwest said it is rebooking passengers who miss their flights due to long TSA lines at no cost.

The airline added that customers are also being offered change waivers and that it's "accepting checked bags well in advance of scheduled flights."