On-time arrivals were up and consumer complaints were down for Frontier Airlines in August, as the Denver-headquartered airline had one of its better months in what has been an up-and-down year, according to the Air Travel Consumer Report from the U.S. Department of Transportation.

The number of complaints consumers filed with the DOT against Frontier fell significantly, from 3.34 per 100,000 enplanements in July to 1.74 in August. That still ranked Frontier just ninth of the 12 national airlines that are compared in the report, but it ranked higher than Denver International Airport’s largest carrier, United Airlines, who came in 11th at 2.26 complaints per 100,000.

Frontier is the third-largest carrier at DIA. Southwest Airlines (NYSE: LUV), the No. 2 carrier, was the best of the big three in regards to complaints, recording just 0.77 per 100,000 enplanements.

Southwest did not do so well for landing flights within 15 minutes of their scheduled arrival time, however. The Dallas-based carrier was 10th nationally with an on-time arrival percentage of just 70.8 percent in August, significantly below its 78.4 percent average over the past 12 months. It also had the highest clip of regularly scheduled flights that were late 70 percent of the time or more — 6.9 percent.

Read more at the Denver Business Journal: http://bit.ly/2iiRpes