Airlines canceled a dozen flights to and from Portland International Airport on Friday as federal flight safety regulators ordered reductions amid the historic government shutdown.

The cancellations, many of them regional routes to cities such as Los Angeles, Sacramento and Seattle, came on the first day of a phased reduction by the Federal Aviation Administration that will cut air traffic by 10% in 40 so-called high-volume markets, including Portland. The agency is looking to maintain safety as air traffic controllers continue to work without pay during a federal government shutdown that began Oct. 1.

Still, it was not clear if every flight cancellation Friday by Alaska, Southwest, United and Delta, was a result of the FAA order.

Molly Prescott, a spokesperson for PDX operator Port of Portland, said the Port is focused on keeping the airport operations on a smooth glidepath as airlines change flight schedules. Prescott counseled travelers to stay in contact with their airlines.

“All travelers should check directly with their airlines for the most accurate flight information,” Prescott said in an email. “As always, we encourage travelers to arrive to PDX with plenty of time to check in and go through security.”

Flight cuts will step up in phases, according to the FAA. The schedule calls for a 4% reduction Friday, 6% by Nov. 11, 8% by Nov. 13 and the full 10% by Nov. 14.

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