Airlines' on-time rating drops again in May

airplane interior

Summer travelers should pack plenty of patience: More flights are running late this year than in 2012.

The U.S. Department of Transportation says that only 79.4 percent of domestic flights arrived on time in May, down from 83.4 percent in the same month last year.

Five planes were stuck on airport tarmacs for more than three hours, which is longer than allowed by federal regulations. Cancelations ticked up slightly.

The May results are still better than April, when airlines blamed furloughs of federal air traffic controllers for causing nearly one in four flights to be late.

According to the DOT, Hawaiian Airlines topped the list of on-time arrivals in May, with 92.4 percent. American Eagle was the at the bottom, with 69.9 percent. Mesa Airlines had the highest rates of canceled flights, while Virgin America and Hawaiian came in with the lowest cancellation rate.