Volaris (VLRS) said Thursday that its passenger demand, measured as revenue passenger miles, fell 11.5% year over year in September.

Capacity for the month, measured as available seat miles, dropped 12.8% on an annual basis, the low-cost carrier said. It attributed the decline to accelerated Pratt & Whitney engine inspections and the resulting aircraft groundings.

The company said the load factor in September was 85% compared with 83.8% a year earlier.

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