Major US airlines canceled hundreds of more flights Sunday, the third day in a row of mass cancellations and delays over Christmas weekend, as staff and crew call out sick amid the Omicron surge.

Almost 700 US flights were canceled and another 1,300 were delayed, according to FlightAware. Globally, there were over 2,000 cancellations. Delta and JetBlue each saw over 100 cancellations.

Globally, airlines canceled more than 6,000 flights on Christmas Eve, Christmas and the day after Christmas, according to FlightAware. That includes about 1,700 flights within, into or out of the United States.

Operational snags at airlines are coming as millions are still flying in spite of rising coronavirus cases. The TSA says it screened 2.19 million passengers at airports across the country on Thursday, the highest figure since the uptick in holiday travel started a week ago.

Many people with travel plans to be with family. will have their plans derailed.