Denver International Airport (DIA) is conducting reviews of Southwest, United, and Frontier airlines after a holiday winter storm brought historic cold to the area and left thousands of passengers stranded. DIA passengers continue to experience issues getting to where they need to go and getting their bags back in large part due to a nationwide meltdown by Southwest Airlines that’s been ongoing for days. DIA CEO Phillip Washington is requesting the airport’s three major carriers participate in the review so they can identify, challenges, impacts, and successes. The U.S. Department of Transportation is also investigating widespread cancellations by Southwest.