Travelers able and determined to keep their Christmas plans in spite of the rapidly spreading omicron variant of Covid-19 have been met with a fresh obstacle: canceled flights.
A growing number of airlines have been forced into cancellations as the new variant surging across the globe brings thousands of people's hopeful holiday travel plans to a halt.
As of Friday morning, global airlines had collectively cancelled more than 2,000 flights, according to flight tracking website FlightAware.
Of those cancelled, at least 454 had been scheduled within, into or out of the U.S.
A number of airlines, including United Airlines, Delta Air Lines and Alaska Airlines, have said they were forced to cancel hundreds of Christmas Eve flights due to the omicron variant affecting employees and crew.
United Airlines said it cut 112 flights from its Friday schedule as the variant spread across the country and affected its workforce.
"The nationwide spike in omicron cases this week has had a direct impact on our flight crews and the people who run our operation," the airline said in a statement.
It said it would rebook as many travelers as possible.
Delta Air Lines apologized, blaming the omicron variant and potentially severe weather in places like Seattle and Salt Lake City for canceling 90 flights scheduled for Friday.
"Delta teams have exhausted all options and resources — including rerouting and substitutions of aircraft and crews to cover scheduled flying — before canceling," the airline said in a statement Thursday.
Alaska Airlines canceled 17 flights Thursday after some employees reported possible exposure to Covid. Additional cancellations were possible Friday "during this dynamic situation," the airline said in a statement.
An American Airlines spokesperson said no cancellations were planned. Other airlines did not immediately respond to inquiries about Friday's schedule.
Meanwhile, German airliner Lufthansa said it was forced to cancel a number of long-haul transatlantic flights due to illness among its crew members, though a spokesperson told NBC News they could not confirm whether the illnesses were due to Covid.
“Currently there is a massive increase in sick leave," a spokesperson said. "Therefore, we have canceled individual flights across the North Atlantic, e.g. to Washington, Boston and Houston from Frankfurt." They said efforts were underway to rebook passengers on other flights.
Although the holiday season brings more air travelers, Christmas Eve is usually one of the slower days of the stretch, according to the trade group Airlines for America.
The organization said U.S. travel during Thanksgiving weekend grew to nearly 90 percent of pre-pandemic levels.
AAA said Dec. 14 that holiday air travel would nearly triple compared to last year, when the pandemic's deadly spread discouraged flights and tourism. An estimated 109 million U.S. residents were expected to travel in planes, vehicles and other forms of transportation this month.
After millions of people made December travel plans, the omicron variant quickly grew to account for nearly three-fourths of Covid cases and triggered new pandemic measures, including travel restrictions around the world.