(Associated Press) — Flight cancellations surged again on the last day of 2021, with airlines blaming it on crew shortages related to the spike in COVID-19 infections.

By late morning Friday on the East Coast, airlines scrubbed more than 1,550 U.S. flights, according to tracking service FlightAware.

The disruptions are likely to inconvenience hundreds of thousands of air travelers over the New Year’s holiday weekend.

Already airlines have canceled 1,500 flights for Saturday.

Canceled flights began rising shortly before Christmas, driven by the remnants of the delta variant and the rise of the new omicron variant of COVID-19.