Federal regulators on Tuesday took the first step in repealing the 53-year-old ban on civil supersonic flight over the continental U.S.
The FAA established the limitation in 1973 to protect the public from sonic booms. It has faced significant pressure from Congress and the White House to reverse it, citing advancements in technology. In a notice of proposed rulemaking (NPRM) published Tuesday, the regulator said it agrees with the ban’s detractors that the provision is “outdated and no longer appropriate.”
“Advances in aerospace engineering, materials science, noise reduction, and new operational concepts will eliminate the old sonic boom,” said FAA Administrator Bryan Bedford in a statement. “This means we can ultimately repeal the ban from the 1970s on supersonic flight over U.S. territory while minimizing noise impacts to residents in communities along the route and near airports.”
The NPRM would replace the 1973 ban with a set of interim, noise-based certification standards. It reasons that this would open continental U.S. airspace to “safe, efficient, and commercially viable” civil supersonic flight without an operation-specific authorization, such as the special flight authorization (SFA) that Boom Supersonic used for flight testing with its XB-1 demonstrator in 2025.
Per the NPRM, only four companies have supersonic SFAs—Boom for the XB-1, Scaled Composites for its SpaceShip One, Hermeus for its Quarterhorse Mark 2.1, and Gulfstream Aviation for the G650.
“With today’s FAA action, a renaissance in supersonic passenger air travel is now inevitable,” Boom CEO Blake Scholl told FLYING. “We’re proud to have demonstrated boomless supersonic flight aboard XB-1 last year—making it the airplane that led directly to the legalization of supersonic flight.”
Boom flew its XB-1 13 times in early 2025, and Hermeus recently conducted the inaugural supersonic flight of the uncrewed Quarterhorse. Under the proposed rule, more companies could begin flight testing.
Boom, the leading developer of civil supersonic aircraft, hopes to begin commercial service with Overture—its flagship airliner for 64 to 80 passengers—toward the end of the decade. Hermeus aims to introduce the Darkhorse, an uncrewed, hypersonic jet for defense missions, around the same time.
How It Would Work
To fly supersonic over land without an SFA, operators would need to prove that their aircraft produce less than 0.11 pounds per square foot (psf) of sonic boom overpressure at surface level, about the same as a SpaceX Falcon 9 rocket at launch.
Overpressure is how researchers quantify sonic booms. For comparison, Concorde produced about 2 psf when traveling at Mach 2 and 52,000 feet. According to NASA, supersonic aircraft operating under normal conditions typically produce booms with 1 to 2 psf, which can create headaches for humans—and the regulators working to certify them.
In other words, 0.11 psf is very, very quiet.
The figure derives from a 2012 NASA study that used an F/A-18B to investigate a phenomenon called Mach cutoff. Boom used this technique to reduce the noise of the XB-1’s sonic booms to what NASA describes as a “low ‘rumbling’ noise at the level of street background noise.”
The space agency’s 2012 research found that Mach cutoff abates sonic booms when they produce less than 0.11 psf. But that limit could change.
The NPRM notes that NASA is exploring supersonic noise reduction through its Quiet SuperSonic Technology (Quesst) project. Its experimental, needle-nosed X-59 broke the sound barrier in June and could soon fly over communities nationwide, allowing researchers to collect data from people below its trajectory.
The X-59 is designed to reduce the volume of a sonic boom to a quieter “thump” by breaking up sound waves, unlike Mach cutoff, which prevents sound waves from reaching the ground. If NASA can prove the aircraft’s capabilities, the FAA could raise the 0.11 psf limit.
The agency over the next 45 days is seeking comment on alternative restrictions.
The FAA will also need to approve the methods that operators use to show compliance with the 0.11 psf figure. Fortunately for them, these would not be limited to methods contained in Part 36 noise regulations. The proposed rule is prescriptive, meaning developers could propose an array of different designs to meet the criteria.
More Work To Do
The White House’s June 2025 executive order calls for the FAA to produce final noise certification standards by June 2027. It also directs the regulator to create a final standard for supersonic aircraft noise certification under Part 36.
The NPRM would only partially fulfill that mandate. It addresses en-route supersonic noise profiles but does not set acceptable noise limits for takeoff and landing. The FAA later this year plans to publish a second proposal that would do just that, describing this week’s proposal as the “first step of a multi-step regulatory process.”
The agency aims to finalize both rules by mid-2027.
In the meantime, if a manufacturer were to apply for type certification of a supersonic model, the agency would establish takeoff and landing noise standards for that particular aircraft.
The June 2025 White House order further calls for the FAA to create safety agreements with other regulators, opening up international supersonic flights. Per the NPRM, the International Civil Aviation Organization (ICAO) is developing noise standards for en-route supersonic transport, but the FAA does not expect that effort to conclude until 2031.
