The travel disruptions are the latest sign of the variantâ€™s increasingly damaging impact on life that seemed only recently to be heading back to normal.
As of Thursday night, United had canceled 131 mainline flights for Friday, or about 7% of its schedule, according to flight-tracking site FlightAware, as rising numbers of workers began calling in sick.
Delta, which is cutting at least 90 flights, also blamed omicronâ€™s impact on personnel â€” along with expected bad weather in its Salt Lake City and Seattle hubs.
The cutbacks are a last-minute blow to flyers heading to see loved ones over the holidays.
â€œThe nationwide spike in omicron cases this week has had a direct impact on our flight crews and the people who run our operation,â€ said a statement from United.
â€œAs a result, weâ€™ve unfortunately had to cancel some flights and are notifying impacted customers in advance of them coming to the airport. Weâ€™re sorry for the disruption and are working hard to rebook as many people as possible and get them on their way for the holidays.â€
Delta said the company has â€œexhausted all options and resources â€• including rerouting and substitutions of aircraft and crews to cover scheduled flying â€• before canceling around 90 flights for Friday.â€
It also cancelled more than 80 Saturday flights, CNBC reported.
The airline is still operating nearly 3,100 flights Friday, though the number of cancellations, now 4% of its total flights, could still increase.
â€œWe apologize to our customers for the delay in their holiday travel plans,â€ Delta said in a statement. â€œDelta people are working hard to get them to where they need to be as quickly and as safely as possible on the next available flight.â€