white clouds above silhouette of clouds at day

NOx Cruise/Climb Metric System Development

Project number: 083
Category: Emissions

The International Civil Aviation Organization (ICAO) is responsible for setting emissions standard for aircraft engines to limit the environmental impacts of these emissions. To limit the impacts of aviation emissions, FAA’s Office of Environment and Energy (FAA-AEE) is working with ICAO’s Committee on Aviation Environmental Protection (CAEP) to establish updated emissions standards for aircraft engines using metrics that are relevant to the full-flight emissions of these species, rather than just those emissions occurring during a standard landing and take-off cycle (LTO). Emissions standards set by ICAO will influence the development of future engine technologies, resulting in a reduction of emissions from future aircraft engines that will lead to improved human health and reduced environmental impacts. To this end, the FAA needs to understand and quantify how current and future standards may impact aviation emissions in the United States and around the globe, and how changes in these emissions may affect the environment and human health. The objective of this project is to provide support for FAA decision-making related to potential certification standards that control emissions during cruise and climb, in addition to the current standards for landing and takeoff.

This project is a continuation of ASCENT Project 48.

Last Updated 3/14/2024


This project will support the FAA decision-making process regarding the development and implementation of an engine emissions certification standard relevant to cruise and climb operations. The project includes analyses which are important in understanding the costs and benefits of both current standards and policies which may be proposed in the future. By providing a rational, scientific basis for decisions on the implementation of emissions standards, this project contributes to an efficient implementation process and provides industry with regulatory certainty. The analyses provided in this project will allow the FAA to identify policy proposals which serve the national interest and advocate for those policies within ICAO.

Program Managers