Updated at 5:35 p.m. ET
Travelers experienced significant flight delays at New York's LaGuardia Airport and at New Jersey's Newark Liberty International Airport on Friday due to a shortage of air traffic control center workers. Philadelphia International Airport also saw slight staffing-related delays.
The staffing problems took place against the backdrop of the 35th day of the partial government shutdown, which President Trump announced Friday would come to an end with a three-week stopgap funding measure.
Airlines for America, a trade group representing the commercial airline industry, praised the reopening of the government.
"As we have seen over the past 35 days, the pressures and strains of a shutdown are not sustainable; the disruptions to passengers, commerce and the economy are not tolerable," Airlines for America President and CEO Nicholas Calio said in a statement Friday afternoon. "We urge elected leaders to continue working together to identify a solution that will keep the government open beyond February 15 and will continue paying the dedicated federal employees."
LaGuardia attributed the problem to a shortage of workers "at FAA air traffic control centers along the East Coast." Flights originating from other airports were affected Friday morning as the FAA sought to control the pace of planes arriving at LaGuardia. Some of those flights were delayed by an average of 1 hour and 26 minutes.
"We have experienced a slight increase in sick leave at two facilities," the Federal Aviation Administration said in a statement. "We've mitigated the impact by augmenting staffing, rerouting traffic, and increasing spacing between aircraft when needed. The results have been minimal impacts to efficiency while maintaining consistent levels of safety in the national airspace system."
Delta said 200 of its flights were affected by the delays.
Travelers can monitor can air traffic delays on a map at the FAA's website. The FAA suggested travelers check with airline carriers for more information.
The White House said officials were keeping an eye on the delays.
"The President has been briefed and we are monitoring the ongoing delays at some airports," White House press secretary Sarah Sanders said in a statement Friday morning. "We are in regular contact with officials at the Department of Transportation and the FAA."
The National Air Traffic Controllers Association, the union that represents 20,000 air traffic controllers and other aviation safety workers, said in a statement Friday that it "does not condone or endorse any federal employees participating in or endorsing a coordinated activity that negatively affects the capacity of the National Airspace System."
Because of the interconnectedness of that system, it said, delays at one major facility can cause far-reaching ripple effects.
"Air traffic controllers take their responsibility to protect the safety of the flying public at all costs very seriously. Nothing else matters except safety," NATCA President Paul Rinaldi said in the statement. "[I]n the past few weeks, we have warned about what could happen as a result of the prolonged shutdown. Many controllers have reached the breaking point of exhaustion, stress and worry caused by this shutdown. Each hour that goes by that the shutdown continues makes the situation worse."
There is already a 30-year low in fully certified air traffic controllers, he added.
As the government shutdown has stretched on, many air traffic controllers and transportation security officers have been working without pay.
"And when your job is to do something like separate aircraft safely in the sky over a crowded city, those are not the folks you want who are distracted by what is really a preventable stressor," Erin Bowen, an expert in aviation psychology at Embry-Riddle Aeronautical University, told NPR.
NPR transportation reporter David Schaper contributed to this report.