U.S. airlines are posting better results for on-time performance and fewer cancelations but complaints are still rising.

The Department of Transportation said Thursday that 78.1 percent of flights on the leading airlines arrived on time in July. That's up from 74.8 percent the previous month and 75.6 percent in July 2014.

Hawaiian Airlines, Alaska Airlines and Delta Air Lines topped the on-time rankings for the 10th straight month - the fifth straight month in that precise order. Spirit Airlines had the lowest on-time rate in July, followed by Frontier Airlines.

Spirit and Frontier, a pair of no-frills, low-fare airlines, also had the highest complaint rates among the 13 airlines covered in the report. Alaska had the best rate, with less than one passenger in 400,000 filing a formal complaint with the government.

Consumers filed more than 2,000 complaints with the government about the 13 largest airlines, a 5 percent increase over the previous month and 31 percent higher than a year ago.

Cancelations fell to 0.9 percent of flights, about half the rate for June and for July 2014. The government said it was the lowest July cancellation rate in 21 years of comparable records.