Passenger revenue continued its freefall for US operators, tumbling 21% in August versus the same period last year as the weak economy again stunted demand for air service.

The latest data from the Air Transport Association of America (ATA) show the tenth consecutive month in which passenger sales fell from the previous year. ATA's estimates are based on reports from roughly 30 carriers.

The number of passengers travelling on US carriers fell 6% year-over-year in August even with double-digit declines in fare prices. The average price to fly one mile fell 17% last month from August 2008, a slight improvement from the 18% year-over-year decline recorded in July.

ATA notes that faltering revenues were recorded beyond US domestic markets to transatlantic, transpacific and Latin markets, as also happened in July.

"The industry continues to see a reduction in the number of air travellers, despite double-digit declines in fares. While there are signs that improvement may be on the horizon, regrettably the demand for air travel remains weak," ATA president and CEO James May says in a statement.

On top of soft passenger demand, US airlines recorded the 12th consecutive month of declining cargo activity. Airlines experienced a 13% year-over-year drop in cargo traffic in July-an 11% drop domestically and a 15% drop internationally.

July cargo data, the latest available, is based on reports from nearly 15 operators including all-cargo carriers and passenger airlines.

Source: Air Transport Intelligence news