More than 3,000 flights were delayed or canceled on Friday morning as the Federal Aviation Administration (FAA) initiated cuts at major airports, according to a flight tracking service.

As of Nov. 7 at 9 a.m. ET, around 850 flights had been canceled and more than 2,400 were delayed within, into, or out of the United States, according to FlightAware.

Among U.S. airlines, Southwest Airlines led the way with more than 650 delayed flights and 129 cancelled flights, the tracker shows.

Worldwide, more than 15,000 flights were delayed and more than 1,200 were canceled, according to the live tracker.

Transportation Secretary Sean Duffy announced earlier in the week that flight cuts were needed to make sure the skies are safe amid a shortfall in air traffic controllers sparked by the ongoing federal government shutdown. On Nov. 6, the FAA listed 40 major airports that would see flights reduced starting on Friday.

The FAA has stated that the reductions would begin at 4 percent and increase to 10 percent by November 14. They are to be in effect between 6 a.m. and 10 p.m. local time, affecting all commercial airlines.

“Even with these cancellations, we plan to operate around 6,000 daily flights,” American Airlines said on Thursday in a statement posted on its website.

“We are continuing to communicate with impacted customers.”

The airline also said that people traveling with the carrier should “check their flight status on AA.com or the mobile app.”

Meanwhile, United Airlines said that people should be aware of updates posted by the company as the cuts take effect.

After the reductions are initiated, United “will continue to make rolling updates to our schedule as the government shutdown continues so we can give our customers several days’ advance notice and to minimize disruption for them and for all of you,” a company statement said.

“No matter what environment we’re operating in, we will not compromise on safety,” it added.

Southwest, in a statement to media outlets this week, maintained that the “vast majority” of its flights won’t be disrupted due to the FAA actions.

“All Southwest Customers with travel booked through next Wednesday, November 12, may choose to adjust their travel plans at no cost or receive a refund if they choose not to travel, regardless of whether their flight is affected,” the statement said.

The FAA order comes as the Trump administration is ramping up pressure on Congress to end the shutdown. Already, some government programs have been suspended or partially suspended due to the lapse in funding, which began on Oct. 1.

In posts on Truth Social on Nov. 7, President Donald Trump again called on GOP senators to remove the filibuster, a Senate procedural hurdle that requires 60 votes to overcome, to end the shutdown.

A day earlier, the president said that he believes Democrats, the minority party in the Senate, would opt to remove the filibuster as soon as they regain control of the upper congressional chamber.

However, earlier this week, Senate Majority Leader John Thune (R-SD) said in an interview with The Daily Caller that there is insufficient support among Republican senators to repeal the rule, noting they are “not even close” to having the necessary votes.

The Associated Press contributed to this report.