Investigation of potential fuel savings due to continuous-descent approach

The continuous-descent approach is among the key concepts of the Next Generation Air Transportation System. Although a considerable number of researchers have been devoted to the estimation of potential fuel savings of the continuous-descent approach, few have attempted to explain the fuel savings observed in field tests from an analytical point of view. This paper focuses on the evaluation of the continuous-descent approach as a fuel-reduction procedure. This research gives insights into the reasons why the continuous-descent approach saves fuel, and design guidelines for the continuous-descent-approach procedures are derived. The analytical relationship between speed, altitude, and fuel burn is derived based on the base of aircraft data total-energy model. A theoretical analysis implies that speed profile has an impact as substantial as, if not more than, vertical profile on the fuel consumption in the terminal area. In addition, the continuous-descent approach is not intrinsically a fuel-saving procedure: whether the continuousdescent approach saves fuel or not is contingent upon whether the speed schedule is properly designed or not. Based on this model, the potential fuel savings due to the continuous-descent approach at the San Francisco International Airport are estimated, and the accuracy of this estimation is analyzed.