The FAA is paving the way for new Stage 5 noise requirements that would align U.S. and international standards. It released a notice of proposed rulemaking (NPRM) late last week that would require companies submitting an application after Dec. 31, 2017, for a new aircraft weighing at least a 121,254 pounds mtow to meet Stage 5 requirements. Applicants for new aircraft weighing less than 121,254 pounds mtow must meet the Stage 5 standard after Dec. 31, 2020.

The NPRM would harmonize U.S. requirements with the new Stage 5 noise standard that the International Civil Aviation Organization (ICAO) published in March 2014. But the FAA stressed that the NPRM is intended only for new aircraft and “should not be interpreted as signaling the start of an action aimed at phasing out the existing noise standards that apply to the production or operation of current models. There are no operational restrictions nor production cut-offs on the use of Stage 3 or Stage 4 airplanes in the U.S.”

Following in step with ICAO, the FAA provided an extended timeline for smaller aircraft at the requests of manufacturers, which said they needed more time to develop the technology required to meet Stage 5. “Recently, there have been technological advances in the lower weight classes such as the geared turbofan engine and the development of quieter control surfaces,” the FAA said. “Given these recent technological advances in lighter airplanes, the FAA expects all manufacturers to be able to meet the new standards by the Dec. 31, 2020 date.”

The FAA, however, requested comments on whether the time frame would be sufficient since “this expectation is crucial” to the agency’s minimal cost determination. With advances in technologies, the agency determined that the proposal would have “minimal, if any, cost.”

The FAA noted that several large aircraft currently in production already meet the Stage 5 noise limits, including the Airbus A380 and Boeing 787. “For many of the new airplane programs announced prior to…2013, analysis shows that such airplanes will be able to meet the proposed Stage 5 standard without any additional cost,” the agency said.

The FAA is accepting comments on the proposal through April 13 at www.regulations.gov (Docket Number FAA-2015-3782).