The FAA has issued a proposal that would govern maximum takeoff
and landing noise levels for next-generation supersonic aircraft. The move is
an early step in the development of a new certification and regulatory regime
that would allow for the recommencement of civilian supersonic flying in the
U.S., perhaps sometime in the second half of this decade.
The proposed noise standards would govern aircraft with a
maximum operating speed of up to Mach 1.8 (1,381 mph). They’d be separate from
rules formerly laid down for the Concorde, which was last flown in 2003.
The rulemaking has been put forth pursuant to a Congressional
mandate from the 2018 FAA Reauthorization Act. It comes as start-ups Boom
Supersonic, Spike Aerospace and Aerion Supersonic are working toward
development of new supersonic commercial or private aircraft.
The FAA proposal would set various maximum takeoff and
landing noise levels depending on how many engines a supersonic aircraft has.
The rule would allow for planes to be louder than modern generation subsonic
civilian aircraft. However, the noise standard would be more stringent than the
certification rules that were in effect for subsonic planes up to late 2017.
In general, the standards would limit the aircraft to
perceived takeoff and landing decibel levels similar to the sound of a
motorcycle engine.
Under longstanding U.S. law, civilian aircraft are not
allowed to fly at supersonic speed over land. NASA is in the midst of a
multi-year project designed to determine acceptable noise levels for overland
sonic booms from civil aircraft. However, the FAA stressed that this rulemaking
does not address overland flying.
“Allowing civil airplane operation at speeds in excess of
Mach 1 over land in the U.S. may become possible in the future, but it is not
expected before the development of new technologies reducing the impact of
sonic boom generation or eliminating sonic boom exposure,” the agency said.
The S-512 jet under design by Spike Aerospace would be an
18-seat plane with a maximum speed of Mach 1.6. Aerion’s 12-seat AS2 would travel at Mach 1.4.
Boom’s 55- to 75-seat Overture is being designed for a top
speed of Mach 2.2, which would be outside the parameters of this regulatory
proposal. The FAA said that the rule could eventually be broadened to include
larger and faster aircraft, or such planes could come under a separate regulation.
The agency is accepting comments on the proposal through
July 13, docket number FAA-2020-0316.