Here’s what travelers need to know about FAA airport flight reductions

Airlines rushed to provide travelers updates after the Federal Aviation Administration said it would reduce flights across 40 airports as the longest government shutdown in history continues to drag on.

Many major airlines said they would waive cancellation fees for even their most basic tickets, which often come with penalties for changes.

Transportation Secretary Sean Duffy previously said he would reduce flight capacity by roughly 10%, affecting 3,500 to 4,000 flights daily.

The FAA has not yet announced which “high traffic” airports would be affected.

These are the airports that are expected to be impacted, based on preliminary information before the agency meets with airlines to finalize cuts, CNBC’s Phil LeBeau reported. The preliminary list includes some of the country’s largest airports and major international hubs in Atlanta, Chicago, Dallas, Los Angeles and New York City.

On Wednesday, Duffy said the reduction was a “proactive” measure because of the delays and cancellations already occurring due to the shutdown. Air traffic controllers, who are considered essential employees required to work during a shutdown, have missed paychecks, and the FAA has said the closure has also raised concerns about already thin staffing among controllers.

Duffy said he expects more cancellations as a result of the reduction, which has no set end time.

“We thought 10% was the right number based on the pressure we were seeing,” Duffy added.

Earlier this week, Duffy told CNBC’s “Squawk Box” that he could “shut the whole airspace down” if the shutdown drags on.

FAA Administrator Bryan Bedford said Wednesday that additional measures may be implemented after the reduction, which he said he has never seen before in his time in the industry. The officials said they were planning to meet with airlines to discuss which flights would be cut.

In a Wednesday memo to United Airlines employees, CEO Scott Kirby said the carrier will not be reducing long-haul international flying and hub-to-hub flying, instead reducing regional and domestic flights that do not fly between hubs.

The airline also offered all customers refunds even if their flights are not impacted. Kirby said that included “non-refundable tickets and those customers with basic economy tickets.”

In a statement, Delta Air Lines said it expects to operate the “vast majority” of its flights as scheduled and will offer changes, cancellations or refunds for customers’ flights during the impacted period. Delta also said that would include basic economy fares, without penalty.

Frontier Airlines CEO Barry Biffle said he highly recommends travelers flying Friday or in the next 10 days book a backup ticket on another carrier as the flight reductions begin to avoid getting stranded due to cancellations.

“I’m sorry this is happening. Hopefully the shutdown is over soon,” Biffle wrote on LinkedIn. “Just giving everyone practical travel advice.”

American Airlines said it expects that the “vast majority of customers’ travel will proceed as planned,” adding that the carrier will reach out to travelers proactively as schedule changes occur.

The airline also said that it will offer immediate rebooking options for all impacted travelers and that customers whose flights are canceled for any…