With Delta Air Lines' massive outage in August that caused 2,300 flight cancellations over a few days came an increase in complaints filed with the U.S. Department of Transportation, according to data released Friday.

Delta saw an increase in consumer complaints to the federal government in August, with 167 complaints filed with the DOT against Delta, compared with 103 a year ago. It's unusual for customers to officially file airline complaints with the federal government, making complaint totals to the DOT relatively low. Of the 167 complaints filed against Delta in August, 92 of them dealt with flight problems.

American Airlines saw a higher DOT complaint rate, with 412 complaints filed against American in August, including 200 on flight problems.

Overall, Delta still ranked No. 4 out of 12 carriers for on-time performance in August.

But with the outage, Delta and Delta Connection carrier ExpressJet had the two highest cancellation rates of the industry in August. For the full month, ExpressJet canceled 1,609 flights, or 3.7 percent of its total operations, while Delta canceled 1,807 flights, or 2.1 percent of its total operations.

ajc.com

Credit: Kelly Yamanouchi

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Credit: Kelly Yamanouchi

Delta in the week after the outage said it bounced back quickly, and had canceled no flights on its mainline operation on the Saturday after the outage.