Passenger complaints about airlines rose sharply in the first half of the year, according to consumer watchdogs. The number of canceled flights declined, but delays and other problems increased.
A major winter storm is continuing to bring heavy snow, blizzard conditions and significant ice from California to the Northeast on Thursday.
The Department of Transportation says it is looking into the airline's flight scheduling practices and will hold it accountable for refunds. The 16,700 canceled flights cost Southwest $800 million.
The transportation secretary is one of the many travelers who had their flights cancelled in recent days. His happened the day after he met with airline CEOs about their operational struggles.