Hundreds of flights were grounded or delayed at three New York-area and Philadelphia airports as more air traffic controllers called in sick on Friday in one of the most tangible signs yet of disruption caused by a 35-day partial federal government shutdown.
The Federal Aviation Administration briefly issued a ground stop for arriving flights at New York's LaGuardia Airport on Friday before lifting it about an hour later. Staff shortages also delayed flights at Newark Liberty International Airport and Philadelphia International Airport, the FAA said.
Hundreds of thousands of federal workers have been furloughed or, as with some airport workers, required to work without pay. Some federal agencies have reported much higher absence rates among workers as they face an indefinite wait for their next paychecks.
The delays immediately became a new flashpoint in the political standoff between the Democrat-controlled U.S. House of Representatives and U.S. President Donald Trump over the shutdown, caused by a dispute about funding for Trump's plan to increase barriers on the U.S.-Mexico border.
Democrats in the House are demanding a reopening of the government before any negotiations with Trump and his Republican allies in Congress on border security.
The disruptions come the day after the U.S. Senate rejected two shutdown-ending bills as hundreds of thousands of federal workers missed a second paycheck on Friday.
Nancy Pelosi, the speaker of the House, wrote on Twitter that the shutdown "has already pushed hundreds of thousands of Americans to the breaking point."
"Now it's pushing our airspace to the breaking point too," her message said, calling on Trump to "stop endangering the safety, security and well-being of our nation."
The White House said Trump had been briefed on the delays and was monitoring the situation at the airports.
John Hitt, a 51-year-old lawyer based in Boston, had expected to fly to Milwaukee via LaGuardia on Friday morning to visit his terminally ill aunt, but Delta Air Lines told him his flight was delayed for at least two and a half hours.
"I've had to scratch the trip, eat the cost of a rental car cancellation and now I'm starting over to figure out when I could get there," Hitt said in a telephone interview. "With the uncertainty now created by the shutdown, it's making me hesitant to fly."
Delta said about 200 of its flights were delayed at LaGuardia and other Northeast airports.
Unions representing federal workers said staff shortages were the result of severe stress affecting employees who are not being paid during the shutdown.
David Cox Sr., president of the American Federation of Government Employees, said Transportation Security officers are "struggling mightily" to keep the American public safe.
"But doing so while worrying about eviction, the ability to feed themselves and their families, to keep the heat on, to pay bus fare to get to work, puts this safety at risk," he said in his statement.
Sara Nelson, president of the Association of Flight Attendants-CWA, said in a statement that airport safety workers "have been doing unbelievably heroic work even as they are betrayed by the government that employs them."
At LaGuardia, the FAA said it was bringing in extra staff, increasing spacing between aircraft and rerouting traffic, but warned of delays for arriving flights of nearly 90 minutes. About a third of incoming flights to LaGuardia were delayed as of late Friday morning, according to the FlightAware tracking service.
On Thursday, three major U.S. airlines - American Airlines Group Inc, Southwest Airlines Co and JetBlue Airways Corp - said the impact of the shutdown on their business had so far been limited but was nearing a tipping point.
The financial fortunes of airlines are closely tied to the health of the economy. In addition, airlines with hubs in Washington have said they are losing government business as a result of the shutdown.