(CNN) — Airlines continue to cancel and delay flights by the thousands as their operations struggle with an untold number of workers calling out sick with coronavirus.

Carriers have canceled more than 1,620 flights as of Thursday afternoon and delayed more than 1,350 nationwide according to flight tracking site FlightAware. On Wednesday, US airlines canceled a total 1,790 flights and delayed another 6,097 flights.

Southwest Airlines has canceled 562 flights, or 18% of its total schedule, as of noon Thursday, more than any other US carrier.

United Airlines has canceled 227 flights, 11% of its Thursday schedule. United is now offering pilots who pick up extra trips up to three times their normal pay through the end of the month.

Airlines have said they were doing their best to accommodate passengers in the face of widespread problems. Many of the flights were canceled in advance to allow the greatest possible notice to passengers. And all the airlines say they are doing what they can to hire the staffing needed so that they don’t have future problems.

But these widespread challenges have become far more frequent, with airline employees complaining that they’ve been stretched to the breaking point by difficult work conditions.

(Copyright (c) 2022 CNN. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Join our Newsletter for the latest news right to your inbox