FAA Proposes Replacing 53-Year Supersonic Flight Ban With New Noise Standard

For more than half a century, the United States has maintained a strict speed limit in the sky. Since 1973, federal law has explicitly prohibited commercial aircraft from flying faster than the speed of sound over domestic land, a blanket ban enacted to protect communities from the thunderous, window-rattling disruptions of sonic booms. Now, the Federal Aviation Administration is preparing to rewrite the rules of modern aviation. In a Notice of Proposed Rulemaking published this week, the agency outlined a plan to replace the 53-year-old speed restriction with a performance-based acoustic standard. Under the new framework, aerospace companies will be permitted to fly passenger jets at supersonic velocities over the continental United States, provided they can prove their aircraft will not subject the people below to disruptive noise. The shift marks a pivotal moment for a resurgent aerospace sector that has spent years developing technologies designed to silence the sonic boom.

The core of the FAA’s proposal represents a fundamental philosophical shift in how airspace is regulated. Rather than outlawing a specific velocity—Mach 1, or roughly 767 miles per hour depending on altitude and temperature—the agency is proposing a strict cap on the physical force of the sound waves allowed to reach the ground. Specifically, the draft rule states that overland supersonic flights will only be authorized if the aircraft’s sonic boom overpressure at the surface does not exceed 0.11 pounds per square foot (psf). If an operator can demonstrate through flight testing, atmospheric modeling, or aerodynamic design that their aircraft meets this threshold, they will be free to fly as fast as their engines allow. FAA Administrator Bryan Bedford noted that technological advances will effectively eliminate the traditional sonic boom, allowing the agency to repeal the 1970s-era ban while minimizing the impact on residential communities.[1]

To understand the significance of the 0.11 psf threshold, it is necessary to look back at the events that prompted the original 1973 ban. During the 1960s, as the aviation industry raced to develop the first supersonic transports, the U.S. government conducted a series of controversial tests over Oklahoma City. For six months, military jets flew over the area up to eight times a day, generating massive sonic booms that shattered windows, cracked plaster, and resulted in nearly 10,000 public complaints. A traditional sonic boom occurs when an aircraft moving faster than sound pushes air molecules aside, creating shock waves that merge into a massive pressure cone. When the trailing edge of that cone sweeps across the ground, it produces a violent, explosive noise. The public backlash from the Oklahoma City tests was so severe that the FAA instituted a categorical ban on the speed itself, effectively ensuring that commercial airliners like the Concorde were restricted to flying supersonically only over the open ocean.[4]

The 1973 regulation fundamentally altered the trajectory of commercial aviation. By outlawing the speed itself rather than the resulting noise, the Federal Aviation Administration effectively ensured that the Concorde—the world's only successful supersonic passenger jet—was restricted to flying its fastest routes exclusively over the open ocean. Because it was illegal to fly faster than Mach 1 over land regardless of how quiet an aircraft might theoretically be, aerospace manufacturers had zero financial incentive to invest in noise-mitigation technologies. For decades, passenger planes became safer, larger, and vastly more fuel-efficient, but they never grew any faster. The speed limit remained an immovable barrier, locking transcontinental and global flight times into the same subsonic schedules that existed in the 1970s.[4]

To understand how modern engineers are attempting to bypass this barrier, it is necessary to understand the physics of a sonic boom. As an aircraft moves through the sky, it pushes air molecules aside, creating pressure waves that travel outward at the speed of sound. When the aircraft accelerates past Mach 1, it outruns its own pressure waves. These waves compress and merge into a massive, continuous shock wave cone that trails behind the aircraft. When the edge of this high-pressure cone sweeps across the ground, the sudden spike in atmospheric pressure is perceived by the human ear as a violent, explosive boom. The goal of modern supersonic research is not to eliminate the shock waves—which is physically impossible—but to manipulate how they travel through the atmosphere.[4]

The first major approach to solving this problem involves radical aerodynamic shaping. For years, NASA has been developing the X-59 Quesst (Quiet SuperSonic Technology), an experimental aircraft designed to fundamentally alter the geometry of shock waves. Featuring a distinctively elongated, 30-foot needle-like nose and a meticulously sculpted fuselage, the X-59 is engineered to keep the shock waves generated at its nose, wings, and tail from coalescing into a single, powerful boom. Instead, the waves remain separated as they travel toward the ground. The result is a gentle "sonic thump" rather than a thunderous crack. NASA engineers compare the acoustic impact of the X-59 to the sound of a car door slamming shut approximately 20 feet away, a dramatic reduction that poses no threat to glass or plaster.[4]

The second methodology, which the FAA anticipates will be utilized by the first generation of new commercial supersonic jets, relies on atmospheric physics rather than extreme aircraft shaping. Known as "Mach cutoff," this flight technique leverages the fact that the speed of sound is not a constant; it fluctuates depending on air temperature and altitude. By flying at specific high altitudes and speeds under precise atmospheric conditions, pilots can cause the downward-traveling shock waves to refract, or bend, upward. The shock waves curve back into the upper atmosphere before they ever reach the surface. The FAA's draft rule explicitly acknowledges this technique, noting that successful Mach cutoff operations prevent the primary boom from striking the earth entirely.

When an aircraft successfully executes a Mach cutoff maneuver, the ground below is not subjected to a traditional sonic boom. Instead, the refraction process leaves behind what physicists call "evanescent waves." These low-level pressure fluctuations reach the surface as a faint, distant rumble. NASA has extensively measured these evanescent waves and found them to be roughly equivalent to the volume of standard background street noise. Under the FAA’s newly proposed framework, these evanescent waves would be legally permissible, provided their physical force remains strictly below the 0.11 pounds per square foot overpressure limit. If an operator can prove their aircraft will not exceed this threshold, they will be granted the freedom to operate supersonically over domestic airspace.[2]

The push to modernize these regulations was formally catalyzed by the White House. In June 2025, President Donald Trump signed Executive Order 14304, directing the Department of Transportation and the FAA to repeal the overland prohibition and establish an interim noise-based certification standard. The directive argued that the existing speed-based rules were outdated and actively hindering the advancement of American aerospace technology. The resulting 63-page draft rule published this week is the direct regulatory response to that mandate. It establishes a clear, measurable target for private aviation companies like Boom Supersonic, which is currently developing a commercial airliner dubbed the Overture. Boom has already demonstrated the viability of the Mach cutoff technique during a successful test flight of its XB-1 demonstrator aircraft earlier this year.[1]

While the aerospace industry has welcomed the Notice of Proposed Rulemaking, the regulatory framework is not yet complete. The current proposal exclusively addresses en-route cruise noise—the sound generated while the aircraft is flying at high altitudes between destinations. It does not set acceptable noise limits for the massive engines required to propel these aircraft during takeoff and landing. Because supersonic jets require narrow, low-drag wings to operate efficiently at high speeds, they typically need immense thrust to get off the runway, making them exceptionally loud in the vicinity of airports. The FAA has stated that this week's proposal is merely the first step in a multi-step regulatory process. The agency plans to publish a second rule later this year that will establish strict landing and takeoff noise standards, ensuring that communities near major international hubs are not subjected to deafening engine roar.

Even as the regulatory hurdles begin to clear, the return of commercial supersonic flight faces skepticism from the scientific community. Several acoustic researchers have cautioned that the FAA's chosen metric—a simple pressure limit of 0.11 psf—does not perfectly correlate with human annoyance. William Crossley, a professor of aeronautics and astronautics at Purdue University, noted that raw overpressure measurements fail to account for how different frequencies and environmental factors influence the way people perceive sound. A sudden, unexpected thump can startle residents and trigger complaints even if the physical pressure wave is relatively weak. While experts acknowledge that the 0.11 psf limit is a vast improvement over the unregulated booms of the 1960s, they emphasize that the FAA will need to closely monitor public reaction as NASA begins flying the X-59 over select U.S. communities to gather real-world perception data.

Beyond the acoustic challenges, the next generation of supersonic airliners must also navigate daunting economic and environmental realities. The Concorde ultimately failed as a commercial enterprise because its massive fuel consumption made ticket prices prohibitively expensive for all but the wealthiest travelers. Modern supersonic designs are significantly more fuel-efficient, but pushing an aircraft through the sound barrier still requires exponentially more energy than cruising at subsonic speeds. In an era where the global aviation industry is under intense pressure to decarbonize, the reintroduction of fuel-heavy supersonic jets has raised concerns among environmental advocates. Companies like Boom Supersonic have pledged to operate their fleets entirely on sustainable aviation fuel to mitigate their carbon footprint, but the global supply of that specialized fuel remains severely constrained.[2][3]

Despite these challenges, the allure of cutting global travel times in half remains a powerful incentive for both manufacturers and airlines. If the FAA's proposed framework is finalized and adopted internationally, it could fundamentally reshape long-haul travel. A nonstop flight from Los Angeles to New York, which currently takes roughly six hours, could be reduced to just three. Transatlantic and transpacific routes would see similar dramatic reductions, allowing business travelers to cross oceans and return in a single day. The FAA's proposal is now open for a 45-day public comment period, during which industry stakeholders, acoustic experts, and local communities will weigh in on the 0.11 psf standard. While passengers are unlikely to board a commercial supersonic flight before the end of the decade, the United States has officially taken the first step toward breaking the sound barrier over land once again.[3]