San Francisco International Airport was seeing widespread delays, though not extreme ones, Friday morning, and a ground stop of over four hours was ordered for incoming flights that began at 4 am.

The government shutdown has come for your travel plans, and the impacts began to mount Friday with the implementation of a 4% reduction in flight traffic that was ordered this week by the FAA — rising to 10% possibly next week — in order to address low staffing levels among air traffic controllers.

At SFO Friday, a ground stop was ordered between 4 am and 8:45 am that delayed a number of incoming flights, which in turn caused delays for departing flights that were waiting on those inbound aircraft.

Air traffic control staffing was blamed for the ground stop, as NBC Bay Area reported, but SFO spokesperson Doug Yakel tells Bay Area News Group that the ground stop was primarily due to low clouds and fog, and it was mostly affecting short-haul flights along the West Coast.

As of 10 am, SFO had seen 45 canceled flights, and 90 flight delays, as the Chronicle reports. United Airlines, the largest carrier at SFO, vowed Thursday to keep its hub-to-hub and long-haul international schedules as normal, making cuts only to regional flights, and those flights appeared to be taking off on time early Friday.

Yakel told Bay Area News Group that the flight cancellations, because they were mostly announced to passengers in advance, appeared primarily to have been caused by the FAA-ordered reduction in traffic.

Oakland Airport had seen 21 delays and 12 cancellations as of 10 am, per the Chronicle.

United and Delta Airlines have both offered passengers fee-free cancelations and flight changes during this period.

"I think people are anxious right now, and this is one of the reasons why we wanted to do this,” says Lori Augustine, vice president for United Airlines airport operations at SFO, speaking to the Chronicle. “We’re here for you," she adds.

Even without the ordered flight reduction, airports have been seeing delays across the country for several weeks during this shutdown, as already understaffed air traffic control towers saw controllers call in sick or outright quit as their paychecks were missed.

FAA administrator Bryan Bedford has said that 20% to 40% of controllers have failed to report to work at the FAA's 30 largest airports, per the Chronicle. And as Nick Daniels, president of the National Air Traffic Controllers Association, told CNN this week, "Controllers are resigning every day now because of the prolonged nature of the shutdown."

Daniels added that even after the shutdown ends, "It will take us months to come out of all the impacts that it’s causing," as air traffic contollers still need to be hired and trained to fill empty roles.

Previously: United and Delta Say That Mostly Regional Flights Out of SFO Will Be Impacted By Air Traffic Restrictions

Photo by David Syphers