A fast-time study on increasing the capacity of continuous descent approaches through airborne precision spacing

Due to projectedincrea ses in air traffic, there are several research efforts underway to evaluate ways to safely increase the capacity of the National Airspace System (NAS), improve operational efficiency, andre duce aircraft noise. At NASA Langley Research Center (LaRC) in Hampton, Virginia, two parallel research efforts have focusedon terminal area research: one is Airborne Precision Spacing (APS), and the other is the Quiet Aircraft Technologies (QAT) project. The APS objective is to increase terminal-area capacity without adversely affecting safety, whereas the QAT project objective is to develop noise- and fuel-efficient approach trajectories. The APS project developed a cockpit tool, called Airborne Merging and Spacing for Terminal Arrivals (AMSTAR), that issues speedco mmands to aircraft to maintain desired spacing between aircraft pairs. The APS studies showed an ability to increase runway capacity; however, capacity increases may negatively impact noise andemissio n levels in airport areas. The QAT project created efficient Continuous Descent Approaches (CDAs), which showedred uctions in aircraft ground noise and fuel consumption. Previous research has shown that CDA trajectories have adverse effects on runway capacity because aircraft must be spacedf urther apart at long distances from the runway to prevent separation losses at the runway threshold. To date, the APS and CDA concepts have been evaluated independently at LaRC.In this study, three different approaches to combining APS and CDA operations were evaluatedto determine the feasibility and benefits of combining these concepts. These methods combined AMSTAR with 3◦-flight-path-angle-CDA approach routes, 3◦-CDA routes with spoilers, and2 ◦-CDA routes without spoilers. Adding the use of spoilers allowedf aster responses to large speedr eductions issued by AMSTAR. This improvement was contrastedwith the effects of a shallower flight-path angle for greater deceleration capabilities. This research indicated that AMSTAR improved the performance of CDA operations, although full capacity improvements were not achieved. Whereas the 2◦-CDA routes were expectedto show the best results, the 3◦-CDA case with spoilers showed the least variability in thresholdspacing errors. All of the CDA routes were more noise, fuel, and time efficient than traditional step-descent routes that are commonly usedto day