Frontier Airlines continued its year-over-year decline in consumer complaints, though more people filed grievances against the Denver-based company in September than they did in August.

Frontier ranked 10th among the country’s 12 largest airlines for September, according to the monthly Air Travel Consumer Report released Thursday by the U.S. Department of Transportation. Its 2.52 complaints per 100,000 enplanements were ahead only of American Airlines (2.54) and fellow ultra-low-cost carrier Spirit Airlines (6.65), and were a bump from the 1.74 complaints filed with the DOT in August.

However, that rate was still far below the 4.91 complaints per 100,000 enplanements that Frontier received in September 2016. And its 3.09 ratio for the first nine months of this year is pacing below its 3.61 rate during the same time frame last year.

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