DENVER (CBS4)Denver International Airport ranks as one of the worst airports for on-time departures among the 16 busiest airports in the nation. Earlier in the fall, we saw long lines causing travelers to wait hours to get through the security lines.

Lines at Denver International Airport

(credit: CBS)

On Thursday, the CoPIRG Foundation released a new analysis of more than 200,000 complaints to the U.S. Department of Transportation dating back to 2016.

The complaints across the board showed the industry didn’t properly deal with customers with cancelled flights. Many complained about refunds.

Frontier, United and Hawaiian airlines registered the most complains while Southwest and Allegient had the fewest.