Control of Air Pollution From Airplanes and Airplane Engines: GHG Emission Standards and Test Procedures

The Environmental Protection Agency (EPA) is proposing greenhouse gas (GHG) emission standards applicable to certain classes of engines used by certain civil subsonic jet airplanes with a maximum takeoff mass greater than 5,700 kilograms and by certain civil larger subsonic propeller-driven airplanes with turboprop engines having a maximum takeoff mass greater than 8,618 kilograms. These proposed standards are equivalent to the airplane CO<INF>2</INF> standards adopted by the International Civil Aviation Organization (ICAO) in 2017 and would apply to both new type design airplanes and in-production airplanes. The standards proposed in this rule are the equivalent of the ICAO standards, consistent with U.S. efforts to secure the highest practicable degree of uniformity in aviation regulations and standards. The proposed standards would, if finalized, also meet the EPA's obligation under section 231 of the Clean Air Act to adopt GHG standards for certain classes of airplanes as a result of the 2016 "Finding That Greenhouse Gas Emissions From Aircraft Cause or Contribute to Air Pollution That May Reasonably Be Anticipated To Endanger Public Health and Welfare" (hereinafter "2016 Findings")-- for six well-mixed GHGs emitted by certain classes of airplane engines. Airplane engines emit only two of the six well-mixed GHGs, CO<INF>2</INF> and nitrous oxide (N<INF>2</INF>O). Accordingly, EPA is proposing to use the fuel-efficiency-based metric established by ICAO, which reasonably serves as a surrogate for controlling both the GHGs emitted by airplane engines, CO<INF>2</INF> and N<INF>2</INF>O.