Hundreds of flights were cancelled across the US on Friday after the Trump administration ordered reductions to ease strain on air traffic controllers working without pay amid congressional paralysis over the federal budget.
Major hubs in Atlanta, Newark, Denver, Chicago, Houston and Los Angeles were among the 40 airports slated for the slowdown.
With Republicans and Democrats in a bitter standoff over spending priorities, including healthcare, Congress has ground to a standstill, leaving the entire federal funding spigot closed.
Vast numbers of government employees, including vital airport staff, are either working without pay or furloughed at home, waiting for the nearly six-week crisis to end.
The flight reductions were to take effect gradually over the coming days, starting at four per cent and rising to 10 per cent next week if Congress still had not reached a funding deal.
About 840 flights scheduled for Friday were cancelled, according to tracking website FlightAware.
The most affected airports were Chicago O'Hare, Hartsfield-Jackson in Atlanta, Denver and Dallas-Fort Worth, according to data analysed by AFP.
"This is frustrating. We don't need to be in this position," American Airlines CEO Robert Isom told CNBC.
The upheaval meant ordinary Americans were directly feeling the impacts of the Washington fight, where the funding shutdown began October 1, increasing pressure on both parties.
The Senate was expected to try for the 15th time on Friday to approve a short-term, House-passed funding measure that would reopen the government — but the vote was expected to fail like the previous 14.
US Transportation Secretary Sean Duffy blamed Democrats, saying they should vote to reopen the government.
"If Democrats are going to go home this weekend, and they've kept the government shut down, that's shameful," Mr Duffy told reporters at Reagan National Airport.
However, Republicans control Congress, and Democrats have said they will refuse to sign off on the majority party's budget plans, including severe healthcare cuts.
'Hurting people'
The flight reduction measures come as the country enters its busiest travel time of the year, with the Thanksgiving holiday just weeks away.
"This will get serious if things drag on to Thanksgiving," retiree Werner Buchi told AFP at New York's LaGuardia airport as he waited for his daughter to arrive on a flight from Wilmington, North Carolina.
Rhonda, 65 — who arrived at LaGuardia without a hitch from Portland, Maine — worried about holiday plans "that could be ruined because people won't talk to each other".
"This is hurting a lot of people," she said.
American Airlines said in a statement that its scheduled reduction amounted to 220 flight cancellations each day.
Delta Air Lines said it was cutting about 170 flights scheduled for Friday, while broadcaster CNN reported Southwest Airlines axed about 100 flights set for that day.
More than 6,800 US flights were delayed Thursday with some 200 cancellations, FlightAware data showed, with passengers facing long lines at security checkpoints.
Travellers at Boston and Newark airports also faced average delays of more than two hours, and those at Chicago's O'Hare and Washington's Reagan National more than an hour.
Authorities said they wanted to act before an accident occurred.
"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 things from deteriorating," said FAA Administrator Bryan Bedford.
'Safe to fly'
President Donald Trump's administration sought to reassure people that flying remained safe.
"It's safe to fly today, tomorrow, and the day after because of the proactive actions we are taking," Mr Duffy said on social media late Thursday.
But many in high-stress aviation-related jobs have been calling in sick and potentially working second jobs to pay their bills.
AFP
