Enabling Supersonic Flight Over Land: Will Performance-Based Standards Meet the Challenge?

The Federal Aviation Administration (FAA) published a notice of proposed rulemaking (NPRM) on July 2, 2026, to enable supersonic flight over land as long as the operation does not exceed a certain noise standard. The NPRM is a significant development showing the agency's current mindset when it comes to rulemaking. The FAA ensured news of the proposed rule, "Enabling Supersonic Overland Flight," was available in time for the 250th anniversary of the U.S. Declaration of Independence and articulates a candid commitment to fulfilling President Donald Trump's mandate that was established in Executive Order (EO) 14304.

Noise-Based Standard

The proposed rule would replace the long-standing prohibition on civil operations of aircraft that exceed Mach 1 over land with a noise-based standard.¹ In particular, the proposed rule includes the following new definitions:

• Sonic boom is the acoustic event on the earth's surface that is a manifestation of the shock wave system an aircraft generates when it proceeds at a speed greater than the local speed of sound. The definition further states the "resulting surface impacts" of the sonic boom "have been studied and labelled as primary or secondary sonic boom(s)."
• Primary sonic boom is "the sonic boom that travels directly from the supersonic aircraft to the surface."
• Secondary sonic boom is the sonic boom that is refracted or reflected to travel farther and may eventually reach the surface, given certain conditions in the atmosphere. The definition goes on to clarify that direct secondary sonic boom travels from the aircraft upward and refracts through the "upper atmosphere" to the surface, whereas indirect secondary sonic boom travels down from the aircraft to the surface in a manner that results in the boom reflecting or refracting. The definition further states that refracting can occur upward based on atmospheric characteristics, or it might occur downward through the upper atmosphere and back to the surface.

Based on the above definitions, the proposed rule would amend 14 C.F.R. § 91.817 considerably. At present, Section 91.817 prohibits flight operations that exceed Mach 1. Under the proposed rule, Mach 1 is no longer the standard: Instead, the proposed rule would limit supersonic flight over land such that it may occur at a speed that exceeds Mach 1 if the aircraft is operated such that sonic boom overpressure at the surface does not exceed 0.11 pound per square foot (psf). In addition, such operations may occur only after the FAA determines that the operator has shown, through "measurement, modeling, or other methods," that primary and secondary (direct and indirect) sonic boom overpressure at the surface does not exceed 0.11 psf during operations. Lastly, all such operations may occur only in compliance with conditions and limitations the FAA might establish for each operation. The FAA bases its standard largely on data collected and manufacturers' statements, some of which indicate that it may be possible with avionics technologies to use Mach cutoff operations (MCO) to operate at supersonic speeds and abate sonic booms at the surface. 

The proposed rule is a direct response to EO 14304, which required the FAA to 1) "repeal the prohibition on supersonic overland flight," 2) establish interim and final noise-based standards (takeoff, landing and en route) for supersonic aircraft, 3) coordinate with other executive branch agencies to advance supersonic research and development, and 4) promote international engagement and harmonization on civil supersonic flight regulations. The EO also directed the FAA to take steps immediately to repeal 14 C.F.R. §§ 91.819 and 91.821, which the FAA states are regulations promulgated in the 1970s to address noise issues related to the Concorde aircraft. The FAA stated it intends to repeal these provisions in a future rulemaking.

Members of the U.S. Congress have also taken initiative by submitting amendments to the fiscal year 2027 National Defense Authorization Act (NDAA) that would direct the FAA to revise its regulations governing supersonic operations under 14 C.F.R. § 91.817 to be consistent with the EO's requirements. Such continued interest from Congress is not surprising, as Rep. Troy Nehls (R-Texas) and Sen. Ted Budd (R-N.C.) spearheaded the introduction of the Supersonic Aviation Modernization Act in 2025, which would permit operators to operate aircraft at supersonic speeds within the national airspace system as long as no sonic boom reaches the ground. The bill passed the U.S. House of Representatives by voice vote and is scheduled to be marked up by the U.S. Senate Committee on Commerce by the end of this month.

Performance-Based Rules

Perhaps the most noteworthy observation about the proposed rule is that it serves as confirmation of the FAA's commitment to promulgating performance-based standards. The agency has promulgated such rules with regard to aircraft certification, operational restrictions or criteria, and noise standards.² In contrast to the approach of prior years – which involved setting specific measurements and standards and dictating how a regulated entity must comply with such standards – new FAA rules often include performance standards and do not specify the means by which an entity must comply. Such rules or policies are known as performance-based rather than "prescriptive."

Consistent with other performance-based rules in recent years, operators subject to the rule would need to submit a means of compliance establishing that they fulfill the performance-based standard for FAA acceptance. With such proposed rules, operators that seek to take advantage of the rule are well advised to review the proposed FAA Advisory Circular that often accompanies the proposed rule, as it contains a pre-accepted means of compliance. The FAA stated in the preamble for the supersonic proposed rule that it will include a copy of the Advisory Circular in the public docket for the rulemaking. Each FAA Advisory Circular contains the standard language that the document is guidance, not regulation, and presents one, but not the only, way of compliance.

Looking Forward

The evolution of the FAA's regulatory philosophy is significant, as it will allow regulated entities flexibility to demonstrate compliance through their own manner of compliance. Such an approach, promulgated carefully and subject to appropriate levels of oversight, can strike a necessary balance that ensures the FAA does not compromise on its statutory responsibility of ensuring safety while enabling innovative approaches.

Operators or other regulated entities that seek acceptance of a means of compliance for the new supersonic standard will benefit from such an approach, given its lack of specificity and technology-agnostic framework. At the same time, those subject to the regulations might become frustrated if the agency does not immediately accept a proposed means of compliance but rather seeks varying iterations based on the original approach presented.

The FAA will likely receive hundreds of comments in response to its proposed rule. Stakeholders have the opportunity to submit comments to address whether the FAA should remain flexible or instead opt for prescriptive standards in certain situations. But for now, industry stakeholders engaged or interested in supersonic flights should look forward to a new framework that will no longer require obtaining special flight authorizations, which the FAA has issued only for individual aircraft and operation within a specific, limited operational area for aircraft research and testing.

Holland & Knight's Aviation Policy Team is monitoring developments and will provide additional analysis and guidance as needed. If you have any questions about the potential impact to your business, contact the authors.

Notes

¹ The proposed rule would significantly revise 14 C.F.R. 91.817, which was enacted in 1973 and prohibits any person from operating a civil aircraft in the U.S. at a true flight Mach number greater than one.

² The FAA used a performance-based framework for aircraft certification and noise standards in its July 2025 MOSAIC rule, described in Holland & Knight's previous alert, "A MOSAIC of Changes: Recent FAA Actions Promote Advanced Air Mobility," August 5, 2025. Other examples include aspects of the FAA's August 2025 proposed rule to address operations of unmanned aircraft systems beyond visual line of sight, the FAA's 2021 rule addressing operations of unmanned aircraft systems over people and the FAA's 2021 remote identification rule that requires remote identification of unmanned aircraft systems. Perhaps the most notable rule that indicated the FAA's commencement of an approach favoring use of performance-based standards was the agency's 2016 rulemaking to update the airworthiness standards that apply to certain types of airplanes under 14 C.F.R. Part 23.

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