Delta Air Lines had the highest on-time arrival rate in August, according to the most recent federal data. But Atlanta-based Delta also had the longest tarmac delay among all domestic flights for the month.

A flight from Orlando to Atlanta on Aug. 20 was stuck on the ground for nearly four hours with customers on board, according to the the U.S. Bureau of Transportation Statistics' report on August airline performance.

Delta said the tarmac delay occurred because the ramp area at Orlando International was closed due to a thunderstorm over the airport.

"This was a rare circumstance," according to Delta spokesman Morgan Durrant, who added that the flight crew gave updates to customers on board.

Overall, Delta had the best on-time performance among U.S. airlines with 85.5 percent of flights arriving on time in August. It came in ahead of Alaska Airlines in the No. 2 position and Hawaiian Airlines in the No. 3 spot. Delta also had the lowest rate of flight cancellations.

ajc.com

Credit: Kelly Yamanouchi

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Credit: Kelly Yamanouchi

The airlines with the worst on-time performance were Spirit Airlines, JetBlue Airways and Frontier Airlines, while those with the most cancellations were Envoy Air, Spirit and SkyWest Airlines. Envoy Air and SkyWest are regional carriers that operate flights on regional jets for other airlines.