The Cargo/Logistics Airlift System Study (CLASS) is an outgrowth of the widespread interest in an advanced air cargo system. In this program NASA seeks to determine more specifically the nature of user requirements for expanded air freight capability. The purpose of the study is to examine the nature and degree of air cargo demand in the 1990 period, assuming that an advanced air freight system were available to the shipping community. NASA wishes to determine whether the requirement for such an airplane is sufficient to justify continued or accelerated research and development activities. In-depth “case studies” were conducted of a number of companies who are representative of potential users. As a part of this study, Lockheed developed a domestic and international air freight forecast, using case study results, for an advanced dedicated air cargo system. A representative domestic and international route structure has been developed from the forecast. An analysis of fleet mix and economics of current and advanced cargo aircraft will be presented.