Current jet fuel prices of twice the 1972 level have significantly changed the characteristics of airplane design for best economy. The results of a contract with the NASA Ames Advanced Concepts and Missions Division confirmed the economic desirability of lower design cruise speeds and higher aspect-ratio wings compared to designs developed in the by-gone era of low fuel price. Evaluation of potential fuel conservation for short-haul aircraft showed that an interaction of airfoil technology and desirable engine characteristics is important: the supercritical airfoil permits higher aspect ratio wings with lower sweep; these, in turn, lower the cruise thrust requirements so that engines with higher bypass ratios are better matched in terms of lapse rate; lower cruise speeds (which are also better for fuel and operating cost economy) push the desired bypass ratio up further. Thus, if fuel prices remain high, or rise further, striking reductions in community noise level can be achieved as a fallout in development of a 1980s airplane and engine.Analyses of the above trends are presented, along with the effects on fuel consumption of design field length, powered lift concepts, and turboprop as well as turbofan propulsion. Assessment is made of the most appropriate aircraft developments in the low/medium density short-haul arena as well as the high density short and intermediate range markets.Recommendations are made for further work which will support fuel conservation, including active controls for high aspect ratio wings, and development of engines which are most suitable for lowest system costs at high fuel prices.