Though still much smaller than air passenger transportation, air freight is an increasingly important revenue source for the air transportation industry. It includes both freight handled by dedicated air cargo handlers and air cargo shipped on combined passenger and air freight carriers (passenger luggage is not considered cargo for this purpose).
Unused ton-miles are the difference between available ton-miles and revenue ton-miles utilized. Changes in the level of spare capacity might be an indicator of the timely availability of air freight services. For example, a shipper with a sudden need for service will be more likely to obtain an appropriate flight when spare capacity is higher. Space limitations also affect the availability of air freight services.
|Domestic Freight Aviation||May-00||May-01|
|Available ton-miles (billions)||3.40||3.53|
|Available ton-miles percent change from same month previous year||7.14||3.84|
|Unused ton-miles (billions)||2.22||2.46|
|Unused ton-miles percent change from same month previous year||5.63||11.16|
|Revenue ton-miles (billions)||1.19||1.07|
|Revenue ton-miles percent change from same month previous year||10.08||-9.83|
NOTES: The current value is compared to the value from the same period in the previous year to account for seasonality.
A revenue ton-mile is equal to one ton carried one mile and measures utilization of air-freight services. The data do not include international flights by U.S. domestic carriers or domestic flights by foreign carriers.
For those planes that carry both freight and passengers, available freight ton-miles are calculated by subtracting available seat-miles times 0.1 from total available ton-miles. The data have been adjusted to have a standard 30-day month by multiplying the data for each month by the ratio: 30/(actual days in month). These indicators are components of freight and overall aircraft load factors displayed in Aircraft Capacity Utilization-Passengers and Freight.
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, Air Carrier Traffic Statistics Monthly, May 2001.