U.S. airlines' on-time performance in June dipped from the month prior but showed improvements from a year ago, the Department of Transportation said Tuesday, while long tarmac delays decreased significantly.

The 18 reporting carriers posted overall on-time arrival rate of 76.4% in June, up from 76.1% a year ago, but down from 79.9% in May.

The highest on time airlines were Hawaiian, with 93.6% on time, Alaska, with 88.9%, and US Airways (NYSE:LCC), with 83.4%.

The worst on time arrivals were Comair, with 64.9% late, American Eagle Airlines, with 67.9%, and ExpressJet Airlines, with 69.7%.

Only three flights in June reported tarmac delays of more than three hours compared with 268 flights a year ago, according to the Air Travel Consumer Report released by the DOT.

The only tarmac delays longer than three hours reported by the nation’s largest airlines were three United Airlines flights departing Chicago’s O’Hare airport on June 18, a day in which the Chicago area experience a severe thunderstorm, according to information filed with the bureau of Transportation Statistics, a part of the DOT’s Research and Innovative Technology Administration.

June was the second month of data since the new aviation consumer rule that prohibits U.S. airlines operating domestic flights from keeping an aircraft on the tarmac for more than 3 hours without deplaning passengers went into effect on April 29.

None of the three tarmac delays exceeded the three-hour mark by more than 3 hours, down from 34 in May.

At the end of the month there were 17 chronically delayed flights, those that are more than 30 minutes late 50% of the time, for two consecutive months. Prior to that there had been no chronically delayed flights for three or four consecutive months, the DOT said.

Reasons for delays reported by the filing carriers were aviation system delays, late-arriving aircraft, factors within the airline’s control, such as maintenance or crew problems, extreme weather, and security.

In June, 40.43% of late flights were delayed by weather, down 7% from the year prior and up 3.22% from May.

The federal agency said it received 1,419 complaints about airline service from consumers, up 89.7% from 748 complaints a year ago, and up 77.1% from 801 complaints in May.

There was no increase in the year over year rate of canceled flights, which remained steady at 1.5%.