Ars Technica has a more detailed article [1]. Here are some excerpts:

> The newly proposed rule would replace the 53-year prohibition with an interim “noise-based” certification standard requiring any sonic boom overpressure at the surface to be kept below 0.11 pounds per square foot. That proposed standard is based on the Colorado-based startup Boom Supersonic having demonstrated quiet Mach cutoff flights with its XB-1 aircraft—harnessing specific atmospheric conditions while flying just beyond supersonic speeds at higher altitudes so that the aircraft’s shockwaves are refracted upward into the atmosphere rather than traveling to the ground

I've got a question about that approach. It depends on temperature gradients in the atmosphere to refract the boom away from the ground. In their test flights that demonstrated that this worked they depended on being able to predict when and where the atmospheric conditions would be right for this.

Are such conditions common enough and stable enough both in time and space so that this could actually work in regular scheduled commercial service?

There has been some criticism of basing the standard on overpressure:

> However, not everyone is sold on this proposed standard for allowing overland supersonic flights. Dan Rutherford, senior director at the nonprofit International Council on Clean Transportation, told Aviation Week that the overpressure metric was previously discarded by United Nations experts in 2014 because “it doesn’t actually measure loudness or annoyance.”

NASA's work on this has been using perceived sound levels to evaluate annoyance on the ground instead of overpressure:

> Meanwhile, NASA has been testing a different approach to quieter supersonic flight with the Lockheed Martin X-59 Quesst—a needle-nosed experimental aircraft with an airframe designed to reduce the typical sonic boom to a sonic thump. NASA has relied on perceived levels of decibels (PldB) to evaluate sound levels, with the goal of consistently demonstrating sonic thumps around 75 PldB that would sound like a car door slamming about 20 feet away.

There is a bill [2] in Congress that has passed the House:

> US lawmakers in Congress have also been pushing forward the Supersonic Aviation Modernization Act. That would require the FAA to allow for overland supersonic flights “so long as the aircraft is operated in such a manner that no sonic boom reaches the ground in the United States.” The bill passed the House on March 24, 2026, and is still awaiting a vote in the Senate.

The bill is short (3 paragraphs) and doesn't say what it means for no sonic boom to reach the ground. The Boom approach of making use of the Mach cutoff would almost surely qualify. Would the X-59 approach where it is a "sonic thump" rather than a "sonic boom" qualify?

[1] https://arstechnica.com/gadgets/2026/07/faa-proposal-superso...

[2] https://www.congress.gov/bill/119th-congress/house-bill/3410...

Supersonic flight returning to US after half-century ban