FAA to cut thousands of flights a day starting Friday due to shutdown: List of airports here

The Federal Aviation Administration will reduce flight capacity by 10% at 40 major airports across the country, officials announced during a press conference on Wednesday.

The decision could cut thousands of flights per day.

The restrictions will go into effect Friday morning, FAA Administrator Bryan Bedford and Transportation Secretary Sean Duffy said. The airports that will be impacted will be announced on Thursday, officials said.

But ABC News has learned Wednesday night, cuts will start as early as Thursday.

"Our sole role is to make sure that we keep this airspace as safe as possible. Reduction in capacity at 40 of our locations. This is not based on light airline travel locations. This is about where the pressure is and how to really deviate the pressure," said Bedford.

This comes after Duffy said earlier this week that the FAA will be forced to shut down the airspace in some areas if the shutdown continues into next week.

The forthcoming reduction in capacity marks an unprecedented move by the FAA and the Department of Transportation. Bedford said he has never seen this happen before in his 35-year career.

Both Bedford and Duffy emphasized that the decision to cut down flights is a proactive measure based on data the department has reviewed, and the staffing pressures anticipated to grow during the shutdown. Duffy said the action is being taken to "reduce the risk profile in the national airspace."

Echoing him. Bedford added, "We're not going to wait for a safety problem to truly manifest itself when the early indicators are telling us we can take action today to prevent, you know, things from deteriorating. So the system is extremely safe today will be extremely safe tomorrow."

Bedford said the cuts to each airline's flight schedules will be proportionate, adding that the agency recognizes there's "no perfect solution."

The FAA said it will consider various factors when finalizing the cuts, including airlines that already operate a less-than-daily service at an airport.

Airlines for America, a trade association representing many majorU.S. airlines, released a statement after the announcement, saying, "We are working with the federal government to understand all details of the new reduction mandate and will strive to mitigate impacts to passengers and shippers."

White House Press Secretary Karoline Leavitt told ABC News that President Donald Trump is aware of the FAA restrictions.

• ANC Anchorage International

• ATL Hartsfield-Jackson Atlanta International

• BOS Boston Logan International

• BWI Baltimore/Washington International

• CLT Charlotte Douglas International

• CVG Cincinnati/Northern Kentucky International

• DAL Dallas Love

• DCA Ronald Reagan Washington National

• DEN Denver International

• DFW Dallas/Fort Worth International

• DTW Detroit Metropolitan Wayne County

• EWR Newark Liberty International

• FLL Fort Lauderdale/Hollywood International

• HNL Honolulu International

• HOU Houston Hobby

• IAD Washington Dulles International

• IAH George Bush Houston Intercontinental

• IND Indianapolis International

• JFK New York John F Kennedy International

• LAS Las Vegas Harry Reid International

• LAX Los Angeles International

• LGA New York LaGuardia

• MCO Orlando International

• MDW Chicago Midway

• MEM Memphis International

• MIA Miami International

• MSP Minneapolis/St Paul International

• OAK Oakland International

• ONT Ontario International

• ORD Chicago OHare International

• PDX Portland International

• PHL Philadelphia International

• PHX Phoenix Sky Harbor International

• SAN San Diego International

• SDF Louisville International

• SEA Seattle/Tacoma International

• SFO San Francisco International

• SLC Salt Lake City International

• TEB Teterboro

• TPA Tampa International