Identification of Causal Paths and Prediction of Runway Incursion Risk using Bayesian Belief Networks

In the U.S. and worldwide, runway incursions are widely acknowledged as a critical concern for aviation safety. However, despite widespread attempts to reduce the frequency of runway incursions, the rate at which these events occur in the U.S. has steadily risen over the past several years. Attempts to analyze runway incursion causation have been made, but these methods are often limited to investigations of discrete events and do not address the dynamic interactions that lead to breaches of runway safety. While the generally static nature of runway incursion research is understandable given that data are often sparsely available, the unmitigated rate at which runway incursions take place indicates a need for more comprehensive risk models that extend currently available research. This dissertation summarizes the existing literature, emphasizing the need for cross-domain methods of causation analysis applied to runway incursions in the U.S. and reviewing probabilistic methodologies for reasoning under uncertainty. A holistic modeling technique using Bayesian Belief Networks as a means of interpreting causation even in the presence of sparse data is outlined in three phases: causal factor identification, model development, and expert elicitation, with intended application at the systems or regulatory agency level. Further, the importance of investigating runway incursions probabilistically and incorporating information from human factors, technological, and organizational perspectives is supported. A method for structuring a Bayesian network using quantitative and qualitative event analysis in conjunction with structured expert probability estimation is outlined and results are presented for propagation of evidence through the model as well as for causal analysis. In this research, advances in the aggregation of runway incursion data are outlined, and a means of combining quantitative and qualitative information is developed. Building upon these data, a method for developing and validating a Bayesian network while maintaining operational transferability is also presented. Further, the body of knowledge is extended with respect to structured expert judgment, as operationalization is combined with elicitation of expert data to create a technique for gathering expert assessments of probability in a computationally compact manner while preserving mathematical accuracy in rank correlation and dependence structure. The model developed in this study is shown to produce accurate results within the U.S. aviation system, and to provide a dynamic, inferential platform for future evaluation of runway incursion causation. These results in part confirm what is known about runway incursion causation, but more importantly they shed more light on multifaceted causal interactions and do so in a modeling space that allows for causal inference and evaluation of changes to the system in a dynamic setting. Suggestions for future research are also discussed, most prominent of which is that this model allows for robust and flexible assessment of mitigation strategies within a holistic model of runway safety

Connecticut in the American Civil War: Slavery, Sacrifice, and Survival

Understanding the Importance of Connecticut’s War Experience In 1965 John Niven published a well-researched book Connecticut for the Union as part of the centenary commemoration of the Civil War. The momentous African-American protest movements, a Second Reconstruction, were at ...

William Lloyd Garrison: Abolition, Democracy, and Radical Reform

Story of an Unlikely Duo Since the international entanglements commencing with the Second World War, an exclusive national history of the United States has proven to be a woefully parochial and an inadequate paradigm. Comparative analysis, particularly a focus on the Atlantic world, is n...

The Wright Patent Lawsuit: Reflections on the Impact on American Aviation

The Wright brothers, it must be conceded, were the first to fly a powered, heavier-than-air machine in sustained flight and under control. To deny them this rightful distinction is to willfully ignore fact (Hayward, 1912). Their contributions to aviation are innumerable, and without their insight, man may have been years awaiting what they accomplished in 1903. The Wrights\u27 status as first in flight notwithstanding, their treatment of the issues surrounding the patent which was taken on their aircraft was harmful to the progress of aviation in the years following their success at Kitty Hawk. To claim that they owed the world the whole of their invention, and by extension, the profits arising from it, is unreasonable; but to suppose that in pursuit of their rightful gains, they would not impede any other from pursuing experimentation and improvement of aircraft is an expectation that is difficult to argue. In litigating against all those they deemed infringers upon their basic ideas, the Wrights forestalled what may well have been more collaborative and productive progress in aircraft design

Tracing the History of the Ornithopter: Past, Present, and Future

Since the earliest recorded history, humans have shared a nearly universal desire for the freedom of flight. This obsession with escaping gravity\u27s unblinking gaze to somehow slip aloft, even for a fleeting moment, has inspired many to wax poetic about the dream of flight. Looking to nature\u27s design, man for years attempted to replicate the flight of the bird, and even its predecessor, the pteranodon, in many a bid to break free of his earthly bonds. Though science eventually shifted its focus to balloons, and then to fixed-wing flight, as a means of sustaining flight, the freedom and effortless grace of birds is as captivating now as it ever was. From the earliest days of man\u27s dreams of launching himself skyward to today\u27s advanced designs, flapping-wing craft, known generally as ornithopters, have held a constant place in the quest to achieve the flowing elegance of flight so easily mastered by nature\u27s own aeronauts. In the past several years, aircraft which capitalize on the mechanics of bird flight have enjoyed a renaissance of sorts. From the recent first flight of a human-powered ornithopter, to flapping-wing designs incorporated in nano-scale unmanned vehicles, aviation design has in many ways come full circle. This paper examines the history of, and influences on, ornithopters and their design, and investigates developments and future trends of this uniquely inspired aircraft

Using Data Envelopment Analysis to Benchmark Safety Culture in Aviation Organizations

While organizations are increasingly encouraged to evaluate safety culture in the context of measurement of leading safety indicators within a safety management system, there remains no generally agreed upon means by which this should be accomplished. In fact, few tools exist that allow an operator to make such measurement with any substantial practical value. Data envelopment analysis (DEA) has been used extensively to compare organizational production efficiency, with techniques such as stochastic frontier analysis or the double-bootstrapped form of DEA infusing the process with a stochastic element. This study applies native DEA methodology toward the evaluation of safety culture and safety program effectiveness among similar organizations and proposes future research directions utilizing stochastic DEA methods toward achieving more reliable, generalizable results upon which statistical inferences may be based. This research produces and tests a model for the evaluation of efficiency in creating a positive safety culture along an estimated efficiency frontier using DEA and further extends the model for future research in applying double-bootstrapped DEA methods to the problem. The results of this study offer evidence that DEA is a viable means of comparison of safety culture measures among organizations or organizational units, and show that it provides a tool for empirically-based prioritization of safety climate intervention at an operational level

Diagnosis of endometrial cancer complicated by morbid obesity—a case report

A 47 year old morbidly obesity nulligravid female presented to a local hospital with chest pain and shortness of breath, CT of the chest confirmed pulmonary embolism, and endometrial biopsy performed showed grade 1 endometrioid adenocarcinoma with squamous differentiation. CT scan performed demonstrated pelvic, retroperitoneal, inguinal and right axillary lymphadenopathy, and hepatomegaly with grossly unremarkable uterus and ovaries. Due to the burden of disease, axillary and inguinal lymph node biopsy was attempted, however due to depth of nodes, the tissue was not reached and biopsy efforts were abandoned. It required a great deal of discussion with the radiology department to decide which lesion would be least morbid to biopsy. After failed attempts at several methods, the gastroenterologist consulted felt the retroperitoneal lymphadenopathy adjacent to the duodenum was a possibility. The sample was sparse, but confirmed a metastatic adenocarcinoma and ruled out an inflammatory or granulomatous process. Ultimately, this unfortunate woman’s obesity caused her to have a worse outcome, not only due to medical comorbidities, but also with regards to delayed diagnosis and treatment and progression of disease. As the obesity epidemic worsens, this is likely to occur more commonly. It is important to realize the limitations of our consults as all aspects and fields of medicine are limited by morbid obesity