The interactive and cyclical design, evaluation, and operational system that conceives transport airplanes is described. Some economic consequences of preliminary design variable choices are displayed, followed by an inspection of the 1967 ATA Method and actual direct operating costs. Uses and misuses of the formula costs, as compared to actual cost levels, are considered. Finally, the impact of airplane choice on airline profitability is examined. It is seen that the profit consequences are great enough to require careful attention to economic trades in every step of the design, evaluation, and operational process.