United Airlines is taking a subtle dig at rival Southwest Airlines’ massive number of holiday season cancellations in an ad it’s airing during the Super Bowl on Sunday. United’s ad features a family from Denver gathering, with the on-screen text saying at the end of the 30-second spot, “United got more families in and out of Denver this holiday than any other airline. Despite the weather.” The Chicago-based carrier said it would run the ad in the Denver and Colorado Springs TV markets. Southwest’s massive end-of-the year meltdown resulted in the company canceling roughly 15,000 flights. More than 27% of its scheduled seats on flights out of Denver were cancelled between December 18 and January, compared to 5% of United’s scheduled seats. Severe winter storms — as well as Southwest’s outdated technology — were considered to be major causes of Southwest’s large number of flight cancellations.<br/>