http://hdl.handle.net/1721.1/34280 http://hdl.handle.net/1721.1/47923 Assuring Safety through Operational Approval: Challenges in Assessing and Approving the Safety of Systems-Level Changes in Air Transportation Hansman, R. John Weibel, Roland E. To improve capacity and efficiency of the air transportation system, a number of new systems-level changes have been proposed. Key aspects of the proposed changes are combined functionality across technology and procedures and large physical scale of deployment. The objective of this work is to examine the current safety assessment processes for systems-level changes and to develop an understanding of key challenges and implications for the assessment and approval of future systems-level changes. From an investigation of current U.S. and international safety regulatory policies and processes, a general model was created describing key processes supporting operational approval. Within this model, a framework defined as an influence matrix was developed to analyze key decisions regarding the required scope of analysis in safety assessment. The influence matrix represents the expected change in levels of risk due to changes in behavior of elements of a system. It is used to evaluate the appropriate scope of analysis in safety assessment. Three approaches to performing safety assessment of systems-level changes were analyzed using the framework: the risk matrix approach, target level of safety approach, and performance-based approach. Case studies were performed using eight implemented and pending systems-level changes. In this work, challenges expected in safety assessment of future systems-level changes were identified. Challenges include the large scope of proposed changes, which drives a need for a broad and deep scope of analysis, including the multiple hazards and conditions and complex interactions between components of a change and the external system. In addition, it can be expected that high safety expectations will increase the required accuracy of models and underlying data used in safety assessment. Fundamentally new operational concepts are also expected to expand the required scope of safety assessment, and a need to interface with legacy systems will limit achievable operations. The large scope of analysis expected for future changes will require new methods to manage scope of safety assessment, and insights into potential approaches are discussed. http://hdl.handle.net/1721.1/46711 Experimental Studies of Cognitively Based Air Traffic Control Complexity Metrics for Future Operational Concepts Hansman, R. John Li, Lishuai New procedures and technologies of Air Traffic Control (ATC) under development in Next Generation Air Transportation System (NextGen) will change controllers' tasks, roles, and responsibilities. However, cognitive complexity will remain one of the limiting factors in future system's capacity and none of existing complexity metrics can be directly extended to evaluate cognitive complexity under future operational concepts. Therefore, complexity metrics, applicable to future operational concepts, need to be developed. This thesis developed the structure for a cognitively based complexity metric, Modified Aircraft Count (MAC). Cognitive complexity is decomposed based on individual aircraft complexity factors and sector specific factors. The complexity contribution of each aircraft is summed and adjusted by sector level complexity factors. Cognitive principles, such as controller strategies, may be incorporated in aircraft specific complexity factors and sector level complexity factors. To investigate complexity factors in Modified Aircraft Count, two simulations were developed to explore two proposed NextGen operational concepts, including Time-Based Control at a Metering Fix and Dynamic Route Structure Control. Two experiments were designed to evaluate controller performance and subjective workload under the simulated operational concepts. The Time-Based Control at a Metering Fix was found to have enhanced schedule conformance, reduced operational errors and lower perceived complexity. The Dynamic Route Structure Control introduced longer hand-off acceptance times, however, no other significant changes of controller performance and subjective workload were found. A new complexity probe technique was developed and applied in the two experiments to explore individual aircraft complexity factors in Modified Aircraft Count. In the new complexity probe, participants were asked to identify high complexity aircraft from the screen shot of a traffic situation they had experienced. It was shown to be an effective tool to assess aircraft specific complexity factors. Four complexity factors (proximity to other aircraft, membership of a standard flow, proximity to weather, and projected proximity to other aircraft) were examined by the relationship between their corresponding observable factors and high complexity aircraft percentage. The chance of an aircraft being considered as of high complexity increased if the aircraft was closer to another aircraft, off the standard route structure, closer to the area impacted by weather, or more likely to be in a conflict in the future. http://hdl.handle.net/1721.1/44957 Analysis of the Interaction Between Air Transportation and Economic Activity: A Worldwide Perspective Hansman, R. John Ishutkina, Mariya Air transportation usage and economic activity are interdependent. Air transportation provides employment and enables certain economic activities which are dependent on the availability of air transportation services. The economy, in turn, drives the demand for air transportation services resulting in the feedback relationship between the two. The objective of this work is to contribute to the understanding of the relationship between air transportation and economic activity. More specifically, this work seeks to (1) develop a feedback model to describe the relationship between air transportation and economic activity and (2) identify factors which stimulate or suppress air transportation development. To achieve these objectives this work uses an exploratory research method which combines literature review, aggregate data and case study analyses. First, this work uses data at the individual country level to identify different types of growth patterns between air transportation passengers and GDP for 139 countries. This analysis is then used to identify twenty-two representative countries which span a range of possible interaction behaviors, geographies and income categories. The case study analysis at the individual country level is performed to describe the air transportation impact for each individual economy. These findings help develop a feedback model which describes the relationship between air transportation and economic activity. Specifically, the analysis is used to describe (1) how air transportation flows of passengers and cargo enable the flows of goods, services, knowledge, tourism, investment, remittances and labor among economies and (2) how air transportation flows can affect the country’s factor, demand and business conditions. The feedback model is then extended to perform quantitative analysis of the evolution of the enabling impact of air transportation in a particular economy. Specifically, a quantitative system dynamics model is developed to describe the interaction between the demand for leisure travel and the resulting enabling impact of tourism on Jamaica’s economy. Case study analysis is also used to identify factors which may stimulate or suppress air transportation system development. The factors are identified both from the air transportation supply and demand sides. The following supply side change factors are identified: changes in the regulatory framework, infrastructure capability, vehicle capability and airline strategy. The air transportation demand is found to be directly affected by exogenous demand shocks, economic downturns, political and economic sanctions, and the development of other transportation modes. The analysis also identifies the following change factors which affect the demand indirectly by changing the country’s economic attributes: economic liberalization, institutional and political reforms, supporting infrastructure investment, exchange rate fluctuations, political and macroeconomic stability, growing consumer demand, and changes in management practices. This analysis of stimulating and suppressing factors helps to describe the role of government intervention in changing air transportation system development and its impact on economic activity. The results of this work can help guide further development efforts, investment and policy decisions pertaining to air transportation usage especially in developing economies. http://hdl.handle.net/1721.1/42838 Encouraging Technology Transition through Value Creation, Capture and Delivery Strategies: The Case of Data Link in the North Atlantic Airspace Campos, Norma This thesis studies the problem of data link in the NAT under a technology transition framework of value creation, capture, and delivery. Creating value through a new technology, such as data link, refers to designing competitive value propositions for stakeholders. Capturing value means recovering an investment in a technology through the value it creates. Delivering value refers to developing policies and business strategies to enable value capture. Realization of these concepts is necessary to guarantee technology transition.