US Air cargo revenue in ton miles fell 12 per cent in September from August, according to America's Air Transport Association (ATA).

Passenger volume was less affected as September numbers showed 2 per cent fewer people took to the air than in August. But little boosted the trade, despite the 10th month of ticket price reductions that has the brought price per mile to a record low for the year.

"The demand for air travel remains weak, as evidenced by the untenable pricing environment, said ATA chief James May. "While other sectors may be seeing signs that the economy is getting back on track, the airline industry has faced challenges in its effort to generate revenue."

ATA airline members and their affiliates move 90 per cent of all US airline passengers and cargo.