Significant flight delays were rippling across the Northeast on Friday because of a shortage of air traffic controllers as a result of the government shutdown, according to the Federal Aviation Administration.
The delays were cascading along the Eastern Seaboard, reaching as far north as Boston. But La Guardia was the only airport that had been closed off to departing flights from other cities because it was so crowded with planes taking off and landing on a weekday morning. Delays on flights into La Guardia were averaging almost an hour and a half, the F.A.A. said.
The delays seemed to be easing late Friday morning.
The F.A.A. said it was slowing traffic in and out of the airports because of staffing problems at two of its air-traffic control facilities on the East Coast, one near Washington and one in Jacksonville, Fla. Those facilities manage air traffic at high altitudes.
The agency said there had been a slight increase in the number of controllers calling in sick at those facilities on Friday morning.
The control towers at the airports that serve New York City and the central air-traffic control facility on Long Island that monitors those airports were fully staffed, said a person who had been briefed on the situation.
“The President has been briefed and we are monitoring the ongoing delays at some airports,” said Sarah Huckabee Sanders, the White House press secretary. “We are in regular contact with officials at the Department of Transportation and the F.A.A.”
In Washington, Democratic leaders pounced on President Trump, blaming him for the air traffic slowdown.
“The #TrumpShutdown has already pushed hundreds of thousands of Americans to the breaking point,” Speaker Nancy Pelosi wrote on Twitter. “Now it’s pushing our airspace to the breaking point too. @realDonaldTrump, stop endangering the safety, security and well-being of our nation. Re-open government now!”
Representative Steny H. Hoyer of Maryland, the No. 2 House Democrat, echoed the speaker — and also sought to assign blame to Senator Mitch McConnell, the Republican leader.
“The Trump-McConnell shutdown is not a game and has real-world consequences to our economy and the well-being of millions of Americans,” Mr. Hoyer said in a statement, adding, “If this shutdown does not end immediately, the harmful impact will continue to grow.”
At La Guardia, Amy Howell of Indianapolis, who was waiting for a flight home on Delta Air Lines that was scheduled to leave at 11:30 a.m., said, “I can’t worry about the things I can’t control. But I would like to get home.”
Ms. Howell was not casting blame on anybody for the government shutdown. “I’m not mad,” she said. “But I would like to see my family.”
Mayor Bill de Blasio learned about the issues at La Guardia Airport during a radio interview Friday as he attended the United States Conference of Mayors in Washington.
“I wish I could say I was shocked. But this is the cost of the shutdown,” Mr. de Blasio said, adding that for days now there had been warnings about potential staffing issues at air traffic control and security. “What tragic reality,” he said. “That’s horrendous.”
The union that represents flight attendants on Friday said they had been warning that the lengthy government shutdown would start harming the nation’s air travel system.
“The aviation system depends on the safety professionals who make it run,’’ the union said in a statement. “They have been doing unbelievably heroic work even as they are betrayed by the government that employs them. They are fatigued, worried, and distracted — but they won’t risk our safety. So the planes will stay on the ground.”
On Wednesday, unions representing air traffic controllers, pilots and flight attendants offered an urgent warning that the lengthy government shutdown had created serious safety concerns for the nation’s air travel system. Like many other federal employees, the controllers have been working without pay for more than a month.
A spokesman for the Federal Aviation Administration confirmed that it was rerouting planes and slowing air traffic to cope with an increase in the number of controllers calling in sick.
The spokesman said the changes were having “minimal impacts to efficiency.”
On Friday morning, the departures screen at one of the terminals at La Guardia Airport in New York began to show ‘Delayed’ across arriving flights.
The partial shutdown, nearing five full weeks, has caused strain across the air travel system. For more than a month, thousands of transportation security officers and air traffic controllers have been working without pay. Many have taken on side jobs driving for ride-hailing apps or in restaurants to try to pay their bills.
Staffing among air traffic controllers, who are responsible for keeping planes from colliding, was already an issue even before the shutdown, according to the National Air Traffic Controllers Association, the controllers’ union
The number of certified controllers is at a 30-year low, the union said, and staffing at the centralized radar facility for the airports that serve New York City, which is known as a Tracon, has only about 130 controllers, far short of its full complement of 228.