Southwest Airlines canceled thousands of flights nationwide Sunday, according to flight-tracking site FlightAware.
On Saturday, 50% of Southwest flights out of Denver International Airport were either canceled or delayed after the airline grounded more than 800 flights nationwide.
The Dallas-based airline said the disruptions were due to air traffic control issues and weather.
“We’re working diligently to accommodate affected Southwest Customers as quickly as possible. We’re asking our Customers whose travel is affected to explore our self-service rebooking options and to check their flight status on Southwest.com,” an airline spokesperson wrote in a Facebook post.
FAA spokesperson Steve Kulm said there were no staffing shortages reported.
"No FAA air traffic staffing shortages have been reported since Friday," Kulm said in a statement to KMGH. "Flight delays and cancellations occurred for a few hours Friday afternoon due to widespread severe weather, military training, and limited staffing in one area of the Jacksonville Air Route Traffic Control Center. Some airlines continue to experience scheduling challenges due to aircraft and crews being out of place. Please contact the airlines for details about current flight schedules."
Social media speculation surrounding the disruption centered on possible labor action taken by Southwest employees due to the recent vaccine mandate imposed by the airline.
However, the union representing Southwest pilots told The Denver Post that its members were not participating in any strike.
Robert Garrison at KMGH first reported this story.