After canceling around 60 percent of its flights over the Christmas holidays, sparking chaos across the country, Southwest Airlines claimed Thursday that it would be back to regular programing on Friday. The airline, one of the largest passenger carriers in the U.S., struggled to recover after it bungled the vast majority of its air travel late last week. On Thursday, about 58 percent of flights were canceled again, adding to a staggering tally of 15,000 canceled flights in the past week, according to the Wall Street Journal. Employees have largely pointed blame at decades-old software and employee management systems that experts predict will take years to upgrade. “We are encouraged by the progress we've made to realign Crew, their schedules, and our fleet,” Southwest said in a statement on Thursday, apologizing to customers and employees for the historic disruption. “With another holiday weekend full of important connections for our valued Customers and Employees, we are eager to return to a state of normalcy.”