Tuesday morning at Mojave Air & Space Port in California, almost 80 years after U.S. Air Force ace Chuck Yeager first eclipsed the sound barrier in a Bell X-1, an independently built jet reached supersonic speeds for the first time.

Boom Supersonic’s XB-1 “Baby Boom,” a demonstrator designed as a prelude to Overture—the company’s concept for a supersonic airliner capable of flying anywhere in the world in four hours, for just $100—hit Mach 1.1, or about 750 mph, during its 12th test flight. The feat marks a historic moment for civil aviation, which until now has leaned on outside help to develop supersonic aircraft.

“A small band of talented and dedicated engineers has accomplished what previously took governments and billions of dollars,” said Blake Scholl, founder and CEO of Boom, in a postflight update. “Next, we are scaling up the technology on XB-1 for the Overture supersonic airliner.”

Tristan “Geppetto” Brandenburg, Boom’s chief test pilot, flew the Baby Boom to an altitude of about 35,290 feet before breaking the sound barrier. The flight also served to validate some of the technologies that will appear on Overture, which Boom says will be the first supersonic commercial airliner since its ancestor, Concorde, was retired more than two decades ago. It would be the first American-made civil supersonic jet.

“There we are! XB-1 is supersonic, faster than the speed of sound,” said Mike Bannister, former chief Concorde pilot for British Airways, during the flight, which was streamed live using a chase aircraft and SpaceX Starlink satellites.

Boom in November told FLYING that the XB-1 will be retired after completing a handful of supersonic test flights, and Scholl on Tuesday predicted its swan song will come in February. The campaign kicked off in March, with each flight inching closer to the speed of sound.

“Our discipline and methodical approach to this flight test program created the safety culture that made a safe and successful first supersonic flight possible,” said Brandenburg.

The Baby Boom is only about one-third the size of Overture, which is being developed to carry 64-80 passengers at Mach 1.7—about twice the speed of commercial airliners. But the two share some key similarities: carbon fiber composites, special supersonic intakes, optimized aerodynamics, and augmented reality vision systems to help pilots “see” the landing area.

As the XB-1 test campaign progressed, Boom made key changes to Overture’s design, such as doubling its seating capacity.

“Some ask: ‘what’s the point of the prototype, if the production aircraft design is different?’” Scholl said Sunday in a post on X. “This perspective overlooks learning. If the production design hadn’t changed, it would imply we’d learned nothing from XB-1!”

Overture won’t quite reach Concorde’s speeds but is expected to have a range of 4,250 nm and cruise at about 60,000 feet—high enough to see the curvature of the Earth. Its Symphony engines are designed to run on 100 percent sustainable aviation fuel (SAF). The aircraft’s flight deck is designed around Honeywell’s Anthem avionics suite, and its cockpit will be the first to include sticks that physically respond to aircraft movements and copilot or autopilot inputs.

Boom’s goal is to fly Overture by 2026 and certify it with the FAA as a transport category airplane with special requirements by 2029. That would enable deliveries to customers—such as United Airlines and American Airlines—which have placed a combined 130 orders and preorders, Boom said Tuesday.

The firm still has a long way to go before it reintroduces supersonic commercial flight to the world. But Tuesday marked its biggest achievement yet.

“Beginning in 1905, the National Aeronautic Association [NAA] recognized aviation’s most historic events, including breaking the sound barrier in 1947 and the moon landing in 1969,” said Amy Marino Spowart, president and CEO of the NAA. “XB-1 has continued to prove that [Boom’s] dream is in line with the achievements that have come before.”

Editor’s Note: This story first appeared on FlyingMag.com.