The U.S. Department of Transportation said Delta Air Lines' regional subsidiary Comair had the worst on-time performance in July.

Overall, however, the nation's airlines were on time more often in July compared to a year ago, and customers filed fewer complaints about their baggage.

Carriers reported a mishandled baggage rate of 4.86 reports per 1,000 passengers in July, an improvement over the 7.96 rate in July 2007 and the 5.15 rate in June of this year, according to the DOT report.

The 19 carriers reporting on-time performance recorded an overall on-time arrival rate of 75.7 percent in July, higher than both July of last year and June of this year.

Regional carrier Pinnacle Airlines had the best on-time rate in July compared to a year ago, at 85.6 parent, according to the government's data.

In July, carriers canceled 1.7 percent of their scheduled domestic flights, a decrease compared with July of last year, which had a 2.1 percent cancellation rate, and June of this year, which had a 1.8 percent rate.

Causes of cancellations included aviation system delays (7.78 percent), late-arriving aircraft (7.17 percent), factors such as maintenance or crew problems (6.30 percent), bad weather (1.01 percent) and security reasons (0.05 percent).