Transportation Secretary Sean Duffy announced in a news conference that there will be a 10% reduction in flights at 40 major airports at the end of the week due to the impacts of the ongoing federal government shutdown.

Duffy's comments came two days after he warned there could be far-reaching flight cancellations and disruptions to air travel, pointing to the pressure on the country's air traffic controllers.

"I think it's going to lead to more cancellations, but we are going to work with the airlines to do this in a systematic way," Duffy said on Nov. 5 in response to reporters' questions.

“This is data-based," he added. "This is not based on what airline travel has more flights out of what location. This is about where is the pressure and how do we alleviate the pressure.”

Duffy did not specify how long these restrictions might last or which airports would be impacted, but officials stated that they will begin on Friday morning, Nov. 7.

Officials said they will work with the airlines to figure out how to implement the reductions. "We’re trying to be prescriptive, surgical, put the relief where the relief will do the most good," said Federal Aviation Administrator Bryan Bedford in the conference. "Again, we’re not going to do anything that will compromise the safety of air travel in the United States."

USA TODAY reached out to major U.S. carriers, including JetBlue, for comment. United Airlines and Delta Air Lines did not provide an immediate comment.

"Southwest Airlines is evaluating how the planned FAA flight restrictions will affect our schedule and will communicate directly with customers as soon as possible," a Southwest Airlines spokesperson told USA TODAY in an email statement. "Nothing is more important to Southwest than the safety of our customers and employees. We continue to urge Congress to immediately resolve its impasse and restore the National Airspace System to its full capacity."

An American Airlines spokesperson told USA TODAY that flights on Nov. 6 will operate as planned and are waiting for the FAA to provide additional information to "determine which flights will be impacted."

"We expect the vast majority of our customers’ travel will be unaffected," American Airlines said. "We will proactively reach out to customers who are impacted. As always, we encourage all customers to check their flight status on AA.com or the mobile app. In the meantime, we continue to urge leaders in Washington to reach an immediate resolution to end the shutdown."

Alaska Airlines said that they're also aware of the FAA's plan to reduce flights as soon as Nov. 7 due to the government shutdown.

"We’re staying close to the FAA and awaiting further guidance. More information will be shared as it becomes available, and we continue to call for an end to the government shutdown," Alaska Airlines said in a statement.

How does the shutdown affect air traffic controllers?

Air traffic controllers and many other Federal Aviation Administration employees are considered essential workers, so they're required to report for duty even though they're not earning paychecks during the government shutdown.

While employees at both agencies are expected to get back pay for the duties they performed once the shutdown ends, many advocates say going weeks without pay puts them under additional stress and can result in them having to find other ways to earn temporary income.

When air traffic controllers or Transportation Security Administration officers fail to show up for work, it can result in flight delays and longer security lines.

Bedford said during the news conference that air traffic controllers continuing to work during the shutdown are covering longer hours and more days. "We are starting to see some evidence that fatigue is building in the system in ways that we feel we need to work towards relieving some of that pressure," he said.

“Many (air traffic controllers) are already working six days a week, and now they are facing the impossible choice of taking on extra jobs just to feed their families. Meanwhile, Congress is leading us towards what could be the longest shutdown in our nation's history, and introducing risk into an already fragile system," National Air Traffic Controllers Association President Nick Daniels said in a statement Oct. 29.

What else has been causing flight delays?

While staffing has caused some delays during the shutdown, even before the government funding taps ran out, weather was also causing issues.

"Check the weather," Mike Arnot, a spokesperson for Cirium, an aviation data analytics company, said in a statement on Oct. 31.

Up until now, storms – especially strong winds – remained one of the biggest causes of flight delays, even as air traffic controllers dealt with the effects of the shutdown.

FAA staff shortages

The FAA has had longstanding staffing shortages, with controllers in many facilities working mandatory overtime to compensate.

The Department of Transportation, under multiple administrations, has attempted to address the shortage but has struggled to attract sufficient numbers of recruits to the air traffic control organization.

Even before the shutdown began, staff shortages occasionally triggered flight delays.

This spring, following a series of equipment failures at Newark Liberty International Airport's control facility, some air traffic control operators took time off to recover from the stress, leading to a spike in delays and cancellations at that airport.

Staff shortages have led to flow control programs to keep flights safe in other areas, too, like the airspace controlled by Jacksonville Center.

The shutdown may contribute to some of these staff issues as controllers need to find other sources of income, but it's not necessarily the root cause of all the staffing-related problems in air travel even now.

What you're entitled to if your flight is delayed or canceled

If your flight is affected by shutdown-related staffing issues, you may not be entitled to much. FAA staffing is seen as outside of an airline’s control, so carriers aren’t on the hook in the same way they would be for delays caused by mechanical issues or other problems on their end.

Still, if your flight is canceled for any reason, including a shortage of air traffic controllers, you’re entitled to a full refund if you choose not to fly on alternative itineraries offered by your airline.

(This story was updated to add new information.)

This article originally appeared on USA TODAY: Flight cuts coming to major airports due to shutdown, Transportation Department says

Reporting by Kathryn Palmer, Kathleen Wong and Zach Wichter, USA TODAY / USA TODAY

USA TODAY Network via Reuters Connect