<div class="htmlview paragraph">Commercial airlines in the supersonic age must decrease total operating cost if they are to survive. The most obvious way in which saving can be realized is in lower consumption of an economically priced fuel. This paper suggests that present aviation kerosenes can and should be used, but it also points out that the choice required concerted effort by the airframe, engine, and petroleum industries, as well as by government to produce a more efficient air traffic control system.</div>