Rapid Integrated Interdependent Fleet-Level Environmental Model (RIIFLE)

What is it about?

The purpose of this paper was to establish a new modeling framework taking advantage of decades of work in enabling better screening fidelity fleet-level analysis of aircraft technology options. We provide the conceptual structure of the model, and show some demonstrations of how it should be used.

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Why is it important?

Evaluating technologies at the aircraft-level is an important part of the technology selection process. However, the ultimate metrics that matter are the fleet-level metrics; those that tell us what was the system level impact of a technology infused aircraft. For example, if your new aircraft burns almost no fuel but you cannot convince an airline to invest in one, then the system perceives no benefit due to your development. Fleet-level analysis is a huge combinatorial problem, comprised of factors with substantial uncertainty. There is uncertainty in how technologies will perform once integrated into the aircraft, how the market will respond to these and other competing designs, and how the forecast of operations will grow, shrink, or shift. All of these factors are best treated via a probabilistic approach, allowing us to evaluate the robustness of technology packages under uncertainty of all components. However, both detailed and state-of-the-art screening fidelity fleet-level modeling methods suffer from a conceptual brick wall standing between aircraft-level technology probabilistic assessment, and forecast and market-level probabilistic assessment. These models require the combinatorial problem to be simplified to a manageable subset of point-design technology-aircraft. As a result, these methods lose the ability to examine aircraft technology probabilistically with forecast and market factors. The Rapid Integrated Interdependent Fleet-Level Environmental (RIIFLE) model breaks these barriers by combining the best aspects of screening fidelity fleet-level models and pairing these with Copula Theory. Copulas allow the modeler to enforce dependence between any number of probability distributions, without requiring the underlying model complexity. Copulas allow us to mimic aircraft-level technology probabilistic assessment with copula-dependent distributions for the aircraft environmental performance metrics. The RIIFLE model provides an unparalleled freedom and flexibility to examine technology, forecast, and market factors probabilistically, while simultaneously enabling the introduction of system dynamics concepts. The result is a broader more complete assessment of potential technology scenarios early in the decision process, ensuring that our detailed modeling investment and ultimately dollar investments in technology are based on sound analytical foundations.

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