Southwest Airlines denies that pilot "sick out" drove weekend of delays

Dallas-based Southwest Airlines canceled more than 1,000 flights over the weekend, leaving passengers stranded across the country.

Why it matters: The mass cancellations come after its pilots asked a court to block the company's new COVID vaccine mandate.

Between the lines: Airline insiders and conservatives are are wondering if the cancellations are part of a "sick out" in response to the vaccine policy.

Southwest's pilots' union said the cancellations were not part of a planned labor demonstration.

More than 25% of the airline's flights were canceled on Sunday per the FlightAware tracker.

"We can say with confidence that our pilots are not participating in any official or unofficial job actions," it said in a press release. "Our pilots will continue to overcome SWA management’s poor planning, as well as any external operational challenges."

The other side: Southwest said the cancellations and delays were caused by "disruptive weather" and air traffic control "issues," though no other airlines were impacted so dramatically.

The airline is usually proactive with customer support on social media, but as cancellations and delays mounted, its Twitter account was silent on the topic for more than 24 hours.