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Contrail Avoidance Decision Support and Evaluation

Project Number: 078
Category: Emissions

Contrails are the white, line-shaped ice clouds that form behind aircraft. These contrails and subsequent contrail cirrus have been understood to contribute around half of the climate warming attributable to aviation. There is potentially a cost-effective way to mitigate aviation’s climate impacts due to contrails by avoiding their formation through small vertical and horizontal flight path changes with minimal or no fuel burn penalty. However, contrail avoidance has not been demonstrated at scale, and a comprehensive toolset to support the approach has not been developed. The goal of this project is to create a contrail avoidance decision support and evaluation tool that can be tested to optimize and evaluate the benefits, costs, and practicality of contrail avoidance. The project will focus on four specific objectives: (1) develop the capabilities necessary to predict the formation and impacts of contrails from a given flight; (2) evaluate the financial costs and environmental benefits of deviating from that path to avoid a contrail, including uncertainty; (3) integrate these capabilities into an operational tool which can provide near-real-time estimate of the costs and benefits of a contrail avoidance action, informed by automated, coordinated observational analysis and modeling; and (4) evaluate the effectiveness of these tools in a safe, scientifically-sound real-world experiment. Subject to agreement with industry partners, the team will also seek to test contrail avoidance in a way that has no implications for air traffic control or safety.


Because contrails result in around half of the warming from aviation, it is important for the industry to develop approaches to reduce or eliminate this warming in addition to reducing CO2 emissions. Contrail avoidance through small vertical and horizontal flight path changes has been shown to be effective for reducing these impacts with minimal fuel burn penalty. This project will be the first to provide the tools and data to show that this approach is indeed an effective and efficient approach for contrail avoidance under real-world operating conditions and at scale.

Last Updated 10/19/2021

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