Continuous Descent Arrival (CDA) is a procedure where aircraft descend, at or near idle thrust, from their cruise altitude to their Final Approach Fix without leveling off. By eliminating inefficient leveling off at low altitude, CDA provides benefits such as fuel savings, flight time savings, and the significant noise reduction near airports, but the usage of CDAs has been limited in low traffic condition due to difficulty in the separation management. For the successful CDA without degradation of the runway throughput, air traffic controllers should know the performance bound of the CDA trajectory and control the time of arrival for each aircraft, which is interpreted as Required Time of Arrival (RTA) from the aircraft standpoint. This thesis proposes a novel trajectory optimization methodology to meet RTA constraint. The CDA trajectory optimization problem in the flight management system is modeled as a path constrained optimal control problem of switched dynamical system. A sequential method that performs mode sequence estimation and parameter optimization, sequentially, is proposed to solve this problem. By analyzing the relaxed optimal solution with simplified dynamics, a computationally efficient algorithm to find the optimal switching structure is proposed and applied for the mode sequence estimation. This thesis also proposes a performance-bound analysis methodology using optimal control techniques to help controllers make a feasible schedule for CDA operations at a meter fix. The feasible time range analysis for a wide variety of aircraft is performed by using the proposed methodology. Based on the analysis result, a single flight time strategy is proposed for the application of CDA in high traffic conditions. The simulation with real traffic data has been shown that the single flight time strategy, combined with the proposed fixed RTA trajectory optimization, guarantees the conflict free CDA operation.

Continuous Descent Arrival (CDA) procedures have been shown to minimize the thrust required during landing, thereby reducing noise, emissions, and fuel usage for commercial aircraft. Thus, implementation of CDA at Atlanta's Hartsfield-Jackson International Airport, the world's busiest airport, would result in significant reductions in environmental impact and airline operating costs. The Air Transportation Laboratory at Georgia Tech, Delta Air Lines, and the local FAA facilities (Atlanta Center and Atlanta TRACON) collaborated to design CDA procedures for early morning arrivals from the west coast. Using the Tool for Analysis of Separation and Throughput (TASAT), we analyzed the performance of various aircraft types over a wide range of weights and wind conditions to determine the optimum descent profile parameters and to find the required spacing between aircraft types at a fixed metering point to implement the procedure. However, to see the full benefits of CDA, these spacing targets must be adhered, lest there will be a loss in capacity or negation of the noise, emissions, and fuel savings benefits. Thus a method was developed to determine adjustments to cruise speeds while aircraft are still en route, to achieve these spacing targets and to optimize fleet wide fuel burn increase. The tool in development, En route Speed Change Optimization Relay Tool (ESCORT), has been shown to solve the speed change problem quickly, incorporating aircraft fuel burn information and dividing the speed changes fairly across multiple airlines. The details of this tool will be explained in this thesis defense. Flight tests were conducted in April-May of 2007, where it was observed that the spacing targets developed by TASAT were accurate but that delivery of these aircraft to the metering point with the desired spacing targets was very challenging without automation. Thus, further flight tests will be conducted in 2008 using the en route spacing tool described above to validate the improvement it provides in terms of accurately delivering aircraft to the metering point.