Though the number of passengers boarded fell 3.9 percent last month on American and its regional carrier affiliates, passenger revenue per available seat mile, or unit revenue, rose 4 percent in September from a year earlier.

The unit of AMR Corp (AAMRQ.PK), which filed for Chapter 11 protection last November, said without challenges from the halted flights in the second half of the month, the improvement in unit revenue would have been 0.4 point higher.

In recent weeks, American cancelled hundreds of flights, citing increased pilot maintenance reports and sick leave usage. The Allied Pilots Association union, with which American is currently negotiating a labour contract, has said it has called no work action at the carrier.

American Airlines said its unit revenue has outperformed other major U.S. airlines for the past six months as it restructures in bankruptcy. For example, Delta Air Lines Inc (DAL.N) said its unit revenue rose 0.5 percent in September, while Southwest Airlines Co (LUV.N) estimated a fall of 2 percent to 3 percent in that measure for the month. US Airways Group Inc (LCC.N) reported flat unit revenue for last month.

Traffic at American Airlines, measured by revenue passenger miles, fell 2.8 percent in September on a consolidated basis. Domestic traffic fell 7.1 percent while international traffic rose 3.2 percent.

The airline's capacity, as measured by available seat miles, was down 3.4 percent. Load factor, or the percentage of seats filled, rose to 81.1 percent last month from 80.7 percent a year earlier.

(Reporting by Karen Jacobs; Editing by Gerald E. McCormick)

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