By CBS 2 Chicago Staff

CHICAGO (CBS) — Southwest Airlines has canceled hundreds of flights nationwide, blaming air traffic control issues and the weather, leaving passengers confused and frustrated.

On Sunday, the airline canceled 53 arriving flights and 34 flights were delayed. For departures, there were 41 cancellations and 46 delays.

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Nationwide, Southwest has dropped more than 1,000 flights, or 28 percent of its schedule.

Southwest said it is working to recover. On Saturday and again on Sunday, it said weather delays in Florida caused a ripple effect across the country. No other airline experienced delays or cancellations on that scale.

Both the pilots and flight attendants unions say there are no official, or unofficial job actions.

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The pilots union has objected to the airline’s recent announcement that it would mandate COVID-19 vaccinations.

“We can say with confidence that our pilots are not participating in any official or unofficial job actions,” the pilots’ union said in the statement.

Passengers were confused about the weather cancellations on Sunday and some suggested that Southwest employees were calling in sick to protest the vaccine mandate.

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In a statement, the airline said there was no “sick out:”

We experienced weather challenges in our Florida airports at the beginning of the weekend, challenges that were compounded by unexpected air traffic control issues in the same region, triggering delays and prompting significant cancellations for us beginning Friday evening. We’ve continued diligent work throughout the weekend to reset our operation with a focus on getting aircraft and crews repositioned to take care of our customers.

CBS 2 Chicago Staff