Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Aero. / Bibliograpy: leaf 154. / by Peeter A. Kivestu. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001. / Includes bibliographical references (p. 199-203). / In order to support the development of improved methods for departure operations, the flow constraints and their causalities --primarily responsible for inefficiencies and delays-- need to be identified. This thesis is an effort to identify such flow constraints and gain a deep understanding of the departure process underlying dynamics based on field observations and analysis conducted at Boston Logan International Airport. It was observed that the departure process forms a complex interactive queuing system and is highly controlled by the air traffic controllers. Therefore, Flow constraints were identified with airport resources (runways, taxiways, ramp and gates) and with air traffic controllers due to their workload and control strategies. While departure delays were observed in all airport components, flow constraints manifested mainly at the runway system, where the longest delays and queues concentrated. Major delays and inefficiencies were also observed due to flow constraints at National Air Space locations downstream of the airport, which propagate back and block the departure flow from the airport. The air traffic controllers' main strategies in managing the traffic and dealing with the flow constraints were also identified. / (cont.) Based on these observations, a core departure process abstraction was posed consisting of a queuing element (representing the delays) and a control element (representing the air traffic controller actions). The control element represents blocking the aircraft flow, to maintain safe airport operation according to Air Traffic Control procedures and to regulate the outbound flow to constrained downstream resources. Based on this physical abstraction, an analytical queuing framework was developed and used to analyze the departure process dynamics under three different scenarios: the overall process between pushback and takeoff, departure sub-processes between controller/pilot communication events and under downstream restrictions. Passing which results mainly from aircraft sequencing and their suspension under special circumstances (such as downstream restrictions) was used as a manifestation of the control behavior. It was observed that Logan Airport exhibits high uncertainty and limited sequencing, hindering the air traffic controllers' ability to efficiently manage the traffic and comply with restrictions. In conclusion, implications for improved methods for departure operations are inferred from the observations and analysis. / by Husni Rifat Idris. / Ph.D.

This dissertation aims at improving the efficiency, robustness, and flexibility of airport operations through intelligent gate assignment. Traditional research on gate assignment focuses on the accommodation of passengers' demands such as walking time of passengers, and the robustness of gate assignment. In spite of its importance on the ramp operations, there is a lack of research to account ramp congestion when gates are assigned. Therefore, this dissertation proposes a new perspective on the gate assignment that accounts for ramp congestion. For that purpose, a ramp operations model based on observations at Atlanta airport is presented to understand the characteristics of aircraft movement on the ramp. The proposed gate assignment problem minimizes passenger-time spent on ramp areas. In addition, this dissertation is conducted to satisfy the needs of passengers, aircraft, and operations from the perspectives of passengers. Using actual passenger data at a major hub airport, the proposed gate assignment is assessed by means of passengers' transit time, passengers' time spent on the ramp, and passengers' waiting time for a gate. Results show that the proposed gate assignment outperforms the current gate assignment in every metric. This dissertation also analyzes the impact of gate assignment on departure metering, which controls the number of pushbacks in order to reduce airport congestion. Then, some of departing flights are held at gates, so it increases the chance of gate conflict, which reduces the efficiency of departure metering as well as ramp operations. In order to analyze the impact of gate assignment on departure metering, this dissertation simulates departure processes at two airports. Results show that the proposed robust gate assignment reduces the occurrence of gate conflicts under departure metering and helps to utilize gate-holding times to some extent.

Prepared for NASA-Ames Research Center. Grant NSG-2180. / Description based on: Sept. 1978/Mar. 1979. Subtitle varies slightly: Semi-annual status report. Principal investigators: 1978/79- Michael Athans, Mark E. Connelly.

This work constitutes a basic study of aircraft access to the terminal area queue. It has grown out of the increasing concern in developing methods to increase airport runway. acceptance rate to alleviate the problem of airspace bottleneck. Considering mainly airline traffic in principal passenger transport, a method is presented to specify the relationship between the total waiting time, on one hand, and the number of gate positions and aircraft parking spaces on the other. This relationship enables one to derive a feasible configuration of terminal gate facilities under various saturation levels. An attempt is then made to characterize an environment under which a proposed flow strategy will be implementable. / M.S.

This study outlines the development and use of several techniques providing an automated landing, roll out and turnoff of an aircraft, in an airport environment. A maximum runway occupancy time and a certain level of reliability are achieved by the use of a computer software called the Probabilistic Computer Model of Optimal Runway Turnoffs. A bunching of eight optimal high speed exits, representing four TERPS categories, is performed on a single runway. Feasibility of the system is determined by the use of Inertial Navigation and other aids such as the Microwave Landing System, Filtering Devices, Electronic Cockpit Airfield Display Formats, Real Time Flight Simulation and Field Testing, and a Braking Guidance Policy. It is suggested that future testing and a review of the Model be done. / M.S.

As air traffic congestion grows, air traffic flow management (ATFM) is becoming a great concern. ATFM deals with air traffic and the efficient utilization of the airport and airspace. Air traffic efficiency is heavily influenced by unanticipated factors, or uncertainties, which can come from several sources such as mechanical breakdown; however, weather is the main unavoidable cause of uncertainty. Because weather is unpredictable, it poses a critical challenge for ATFM in current airport and airspace operations. Convective weather results in congestion at airports as well as in airspace sectors. During times of congestion, the decision as how and when to send aircraft toward an airspace sector in the presence of weather is difficult. To approach this problem, we first propose a two-stage stochastic integer program by emphasizing a given single sector. By considering ground delay, cancellation, and cruise speed for each flight on the ground in the first stage, as well as air holding and diversion recourse actions for each flight in the air in the second stage, our model determines how aircraft are sent toward a sector under the uncertainty of weather. However, due to the large number of weather scenarios, the model is intractable in practice. To overcome the intractability, we suggest a rolling horizon method to solve the problem to near optimal. Lagrangian relaxation and subgradient method are used to justify the rolling horizon method. Since the rolling horizon method can be solved in real time, we can apply it to actual aircraft schedules to reduce the costs incurred on the ground as well as in airspace. We then extend our two-stage model to a multistage stochastic program, which increases the number of possible weather realizations and results a more efficient schedule in terms of costs. The rolling horizon method as well as Lagrangian relaxation and subgradient method are applied to this multistage model. An overall comparison among the previously described methodologies are presented.

Abstract: This thesis addresses the problem of graceful degradation for air traffic management systems (ATMS). The graceful degradation is the process by which the safety of the airspace is ensured in the event of failures or operational degradation in the system. After listing the main areas where failures and degradation can affect the ATMS, an ontology of the ATMS is proposed. The ontology allows to introduce failures at different levels, track their propagation throughout the system, and measure their operational impact. Then, two operational degradations are studied: The first degradation studied is a reduction in the landing capacity at San Francisco International Airport. The aircraft queueing process for terminal area is modeled and optimized to ensure a graceful degradation. The second degradation encompasses Communication, Navigation and Surveillance systems failures. The graceful degradation is ensured by increasing the spacing distance between aircraft, using novel algorithms of avoidance under uncertainties. Those algorithm also serve as probes to compare the degradation capabilities of different traffic configurations such as Miles-In-Trail and Free-Flight arrivals. Finally, this thesis focuses on monitoring the airspace for potential degradation. The ability and the difficulty of en-route traffic configuration are evaluated using degradation maps. Those maps can be used controller to rapidly and efficiently steer traffic from nominal mode of operations to mode of operations under abnormal conditions. Finally, a monitoring tool for terminal area is presented: the conformance of current flight to pre-identified typical operations is determined in real time. As the number of non-conforming aircraft increases, the complexity seen by air traffic controllers increases, and can become a threat for the airspace safety.