Alaska Airlines cut 10% of its remaining January flight schedule Thursday as an “unprecedented” level of employees unable to work because of the omicron coronavirus variant undercut its ability to operate reliably.

“Right now, we need to build more reliability back into our operation as we deal with the impacts of omicron and during a time when guests generally fly less,” the Alaska Air Group Inc. unit said in a statement. The cancellations “will give us the flexibility and capacity needed to reset while continued flexible travel policies enable guests to adjust their plans accordingly.”

Alaska cut 120 flights Thursday, or about 16% of its total, according to FlightAware.com, as more than 1,980 flights were canceled across the industry because of winter weather and employee illness. Alaska grounded nearly 15% of its flights from Dec. 24 through Wednesday, FlightAware data showed. Another 38% were delayed.

Southwest Airlines Co., United Airlines Holdings Inc. and Delta Air Lines Inc. are offering financial incentives for most employees to pick up overtime work as the industry struggles with employees who are ill with omicron or sidelined by quarantine. 

Alaska Air shares fell less than 1% on Thursday.