The US Federal Aviation Authority has briefly issued a ground stop for arriving flights at New York's LaGuardia Airport as the government deals with staffing shortages at two air traffic control facilities.
The FAA says it has seen an increased number of workers calling in sick, a sign that the 35-day partial government shutdown is having a tangible impact on everyday American life.
- US shutdown to end - but only temporarily
- Pornhub reports traffic increase amid US government shutdown
- Government shutdown now longest in US history
Hundreds of thousands of federal workers have been furloughed or, as with some airport workers, required to work without pay.
The FAA said earlier that staffing shortages among air traffic controllers were delaying flights at Newark Liberty International Airport and Philadelphia International airport.
The FAA issued a notice that it was halting flights into LaGuardia due to staffing issues on Friday, but lifted it around 10.45am local time.
The FAA said it was instituting a program to manage traffic that would result in significant delays for arriving flights of nearly 90 minutes.
The delays immediately became a new flashpoint in the political stand-off between the Democrat-controlled US House of Representatives and President Donald Trump over the shutdown.
The stand-off is caused by a dispute about funding for Mr Trump's plan to increase barriers on the US-Mexico border.
Democrats in the House are demanding that the government be reopened before negotiating with Mr Trump on border security.
The disruptions come the day after the US Senate rejected two shutdown-ending bills as hundreds of thousands of federal workers missed a second pay cheque 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 Mr Trump to "stop endangering the safety, security and well-being of our nation".
Mr Trump announced on Saturday (NZ time) the shutdown would be ending for three weeks to allow more time to negotiate.
It could shut down again on February 15.
The White House said Mr Trump had been briefed on the delays at LaGuardia and was monitoring the situation at the airports.
On Thursday, three major US airlines - American Airlines, Southwest Airlines and JetBlue Airways - said the impact of the shutdown on their business had so far been limited but was nearing a tipping point.