In a notice of proposed rulemaking, the agency would require that aircraft weighing at least 121,254 pounds mtow, for which new type certification applications are submitted after Dec. 31, 2017, meet new Stage 5 noise levels that would be added to FAR Part 36. Newly designed aircraft weighing less than 121,254 pounds mtow must meet the Stage 5 standard after Dec. 31, 2020. The FAA emphasized 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.” Comments are due by April 13, 2016.