AMR said traffic rose slightly in August, up 0.1 percent, as the carrier reduced capacity by 1.5 percent.
As a result, flights were fuller with its load factor up 1.4 percentage points to 85.8 percent.
The carrier added that its unit revenue - or revenue per seat mile flown - continued to increase, up 4.1 percent versus the same period last year.
"Excluding the unique impact on AMR's Miami hub operation due to Hurricane Isaac in August 2012, and the effect of the 2011 FAA excise tax suspension, unit revenue improvement in August 2012 would have been approximately 1.8 points higher," AMR said in a statement.
Domestic traffic dropped 0.7 percent as AMR cut domestic capacity by 2.0 percent. International traffic rose 0.6 percent on 1.4 percent less capacity.