Revenue passenger miles are defined as the number of available seats sold.
JetBlue's capacity during September rose 15.8%, as measured by available seat miles. The passenger load for the month was 72.6%, compared with 77.7% in September 2005.
The airline flew 1.3 million passengers in the month, a rise of 26% over the previous year.
The company's shares were trading up 2 cents, or 0.2%, to $9.65 Thursday.
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