Means are described of improving the fuel consumption of current engines by as much as 5 percent through improved component performance and reduced engine deterioration. The advanced turbofan configuration, however, has the potential of providing a 20 percent reduction in fuel burned relative to todays designs for high bypass ration turbofans for 1990. Modifications to the JT8D and JT9D engines which improve their fuel consumption are described. Comments are also made on Pratt and Whitney's long term turbofan engine technology development. The optimum direct operating costs are also discussed.