NEW YORK (AP) - Travelers endured widespread flight delays in the Northeast as federal officials grappled with a shortage of air traffic controllers, who missed paychecks Friday because of the partial government shutdown.

LaGuardia Airport in New York and Newark Liberty International Airport in New Jersey were the hardest hit, but delays rippled across the nation's air-travel system.

The disruptions are the strongest evidence yet that the 35-day government shutdown threatens to snarl the nation's air travel system.

Air traffic controllers and airport security agents have been working without pay since the federal shutdown began in December, and rising absentee rates have led to longer airport lines.

 

 The Federal Aviation Administration saw delays Friday because of a "slight increase in sick leave" at air-traffic control centers that handle traffic over New York and Florida, said agency spokesman Gregory Martin. He said the FAA adjusted to meet available staffing by, among other things, rerouting flights and putting more space between planes in the air.

 

At the center in Leesburg, Virginia, six of the 13 controllers scheduled to work Friday were absent. That center handles air traffic on its way to and from the New York area and the Mid-Atlantic states.

The result was "minimal impacts to efficiency" while maintaining safety, Martin said.

President Donald Trump was informed of the situation.

"The President has been briefed and we are monitoring the ongoing delays at some airports," spokeswoman Sarah Sanders said in a statement. "We are in regular contact with officials at the Department of Transportation and the FAA."

At LaGuardia, travelers learned of delayed flights from announcements over PA systems.

"The shutdown hit home, finally," said Sanjay Shetty, a management consultant from Ann Arbor, Michigan, as he waited to board a delayed plane to Detroit.

Shetty tried to shrug it off. "I travel every week, and nothing surprises me."

By early afternoon, more than 2,400 U.S. flights had been delayed, according to tracking service FlightAware, although the situation seemed to be improving from earlier in the day.

The government shutdown is now the longest ever, as Trump and congressional Democrats remain deadlocked over the president's demand for $5.7 billion to build part of a barrier on the border with Mexico. About 420,000 government employees including air traffic controllers and TSA agents are working without pay; another 380,000 are furloughed.

They will be paid once the shutdown ends, but in the meantime, many are describing financial hardships, relying on food banks, and worrying whether they can pay the rent or mortgage.

The National Air Traffic Controllers Association said staffing was already at a 30-year low before the shutdown, forcing controllers to work overtime and six-day weeks.

Union President Paul Rinaldi said Friday that the union does not condone a coordinated action that would reduce the capacity of the nation's airspace. In 1981, President Ronald Reagan fired air traffic controllers who conducted an illegal strike, dealing a major and long-lasting defeat to organized labor.

Rinaldi added, however, that the union has warned about the possible effects of a long government shutdown.

"Many controllers have reached the breaking point of exhaustion, stress, and worry caused by this shutdown," Rinaldi said. Each passing hour makes the situation worse, he said.

The FAA did not indicate how many controllers are missing work. The Transportation Security Administration said that 7.6 percent of its airport screeners scheduled to work Thursday did not show up, down from last Sunday's peak of 10 percent, but more than double the 3 percent absence rate of the comparable day last year.

Hartsfield-Jackson Atlanta International Airport had maximum wait times Thursday of 42 minutes, the highest of the nation's top 42 airports, TSA said in a statement Friday.

Baltimore/Washington International Thurgood Marshall Airport had the second-longest wait time, of 19 minutes.

As it has for several days, TSA added that many screeners say they can't report to work because of financial strain.

TSA has been moving agents to airports where there are shortages, and occasionally consolidating checkpoints, to prevent lines from getting too long.

The situation is almost certain to get worse the longer aviation workers go without paychecks.

"There are locations where FAA engineers have quit, TSA agents have quit, air traffic controllers have quit. It's starting to happen," said Chuck Banks, an FAA safety inspector in Florida. "We were already short-handed in all areas."

As news of Friday's disruptions spread, leaders of aviation unions sent a message: I told you so.

"This is exactly what AFA and other aviation unions have been warning would happen," said Sara Nelson, president of the Association of Flight Attendants. Government workers "are fatigued, worried, and distracted, but they won't risk our safety," and will instead keep some planes on the ground, she said.

Airlines reacted cautiously to Friday's disruptions, trying to avoid alarming their customers.

Delta Air Lines had about 200 flights delayed at LaGuardia and other airports in the Northeast on Friday morning, a spokesman said.

In a statement, a United Airlines spokesman said the carrier was working with the FAA and airports to minimize the impact on flights and travelers.

"At this point, we don't anticipate significant schedule disruptions, but it is another good illustration of the escalating impact of the government shutdown and the need for the federal government to promptly re-open," the United statement read.

Even before Friday, airline executives were warning about turbulence from the shutdown.

Delta has said it will lose $25 million this month because of the shutdown, which has grounded many federal employees and contractors. Southwest Airlines CEO Gary Kelly called the shutdown maddening, and said his airline has already lost up to $15 million.

"This is crazy," Kelly told analysts and reporters on Thursday. "It just absolutely needs to end. If left as it is, it will harm the economy, it will harm air travel."

JetBlue Airways CEO Robin Hayes said, "We are close to a tipping point" as government workers faced missing paychecks for the second time in January. "The longer this goes on, the longer it will take for the air travel infrastructure to rebound."