BA reported a 8.6% drop in its premium traffic for September.
The British flagship carrier said non-premium traffic during the month had also dropped by 4.1%.
The airline said its revenue forecasts for the current financial year now "carry some risk."
BA said that traffic in September when measured in revenue passenger kilometres, was 4.8% down on the figure for the same month last year.
Load factors also fell compared to September 2007 by 4.8% to 74%.
The airline said in a statement: "Trading conditions continue to be challenging.
"Long haul premium traffic has softened after the summer and forward bookings are being affected by the increased anxiety in financial markets and by the uncertain economic outlook.
"Revenue forecasts for the year carry some risk, although current good yields and the stronger dollar are broadly offsetting the volume impact.
"The target continues to be for the business to break even at the operating level. "
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