Air carriers, especially on North Atlantic routes, traditionally have used specific commodity rates as the primary rating device for air cargo transportation. This technique has not been successful in segregating traffic to provide cost-related rates for commodities with varying transportation and handling characteristics.
Some air cargo users and government agencies have suggested replacement of specific commodity rates by offering shippers a choice of rates depending upon the level of service provided, such as premium rates for emergency traffic, standard rates for routine air traffic, and low rates for developmental traffic.
In April of 1979, Trans World Airlines replaced specific commodity rates with time-structured rates from the United Kingdom to the United States. This new rate structure has been successful, not only in simplifying the application of air cargo tariffs, but in generating new traffic for air services.