Risk-benefit analysis of new systems for use in the Next Generation Air Transportation System (NextGen) is complicated by the large number of alternatives that must be analyzed. The alternatives are generated by combinations of system design options, CONOPS variations and changing assumptions about the evolving state of the NextGen environment. We present here a demonstration of the use of Logic Gate Models (LGMs) to represent and perform a risk-benefit analysis for an advanced ATS technology in NextGen. An LGM is a generalization of a class of hierarchical models that includes event, fault and decision trees. Solution of the LGM yields a set of scenarios; each one is a unique combination of initial conditions, system specifications and ATS environment. An important aspect of our LGM implementation is the ability to perform path wise calculation of risk-benefit metrics for each scenario. Path wise metric calculation allows for a consistent and practical treatment of solution dependencies that are difficult or cumbersome to treat with less general LGMs.
A systems model for Airborne Precision Spacing (APS).was developed to demonstrate the application of LGMs to aviation systems analysis. APS is a NASA-developed technology for Flight Deck Merging and Spacing. Models for risk and benefit metrics are presented. The risk model combines accident scenarios obtained from the LGM with historical data for operational incidents and human error rate estimates. The benefit model uses reduction in arrival bank delay time and the increase in airport arrival rate to evaluate changes in system performance. Risk-benefit calculations for each scenario are performed during solution of the LGM. The analysis showed that APS-based merging and spacing operations exhibit significantly lower risk and improved benefit relative to current practice over a range of demand states and system design variations. The interaction of APS with a second, advanced technology and the extension of the approach to larger systems models are discussed
Theme: Innovative Methods for Safety Assessment
Keywords: logic gate models, merging and spacing, risk-benefit analysis, systems analysis
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