Southwest Airlines canceled 5,400 flights in less than 48 hours, reportedly due to operational failures. The exact cause of the cancellations is unclear, but some speculate that a semi-automated system failed to support the load of cascading changes resulting from weather disruptions. The airline's scheduling system has been described as antiquated and fragile. The cancellations have also led to a significant backlog of checked bags, with some passengers reporting that their luggage has been lost for extended periods.