Seven miles above the Mojave Desert, a spindly white aircraft made history. Flanked by the snow-capped Tehachapi Mountains, the jet barreled through California’s supersonic corridor and, at a carefully chosen moment, nudged its way past the sound barrier.

Curious things happen at this speed. Beyond Mach 1, a jet travels faster than the Earth rotates, and the sun can appear to rise from the west. The supersonic object — in this instance, a civilian jet made by the Denver aerospace firm Boom — displaces sound waves so quickly that they compress into a single, thunderous clap, forming the so-called sonic boom.

No scientific frontiers were crossed on this morning. Boom’s XB-1 aircraft was barreling through the same corridor where, nearly eight decades ago, Chuck Yeager became the first man to go supersonic.

Still, standing with the small crowd on a frigid stretch of tarmac, it was hard not to marvel at the spectacle. The group cheered as a livestream from a chase craft announced that XB-1 had reached Mach 1.12, becoming the first U.S. civilian craft to break the sound barrier. Twenty minutes later, the jet landed safely on the runway, to applause and Champagne fanfare.

“It’s time to bring supersonic flight back,” Boom Supersonic CEO Blake Scholl told the crowd. “Let’s make America boom again.”

As historical milestones go, the test Tuesday morning was barely a footnote. Several countries developed civil supersonic craft decades ago, and the U.S. Navy’s pilots break the sound barrier nearly as easily as they breathe.

But Boom says it was a crucial proof of concept. The single-seater XB-1 is a scaled-down version of the Overture, an 80-seat supersonic commercial airliner that the company aspires to produce. Boom, which has amassed an all-star roster of Silicon Valley investors, is promising to revive civil supersonic travel after a decades-long hiatus — and deliver it to the masses.

The technology is tantalizing. The company says its yet-to-be-built Overture jet will ferry passengers from SFO to Tokyo in just six hours, making the 5,100-mile journey roughly equivalent to driving from San Francisco to Los Angeles on a good traffic day. Today, the flight is an 11-hour sufferfest. 

On the East Coast, an ambitious New Yorker could fly to London for afternoon meetings, sit for an early dinner, then return that same evening on a roughly 3.5-hour flight. Boom says it’ll make supersonic travel “mainstream.” It’ll be fast. Sustainable. Affordable, even. 

But pragmatically, the Silicon Valley-backed firm faces a mammoth set of technical, environmental, and regulatory hurdles that could foil its efforts before the first jet ever leaves the tarmac. And in spite of Boom’s democratic parlance, commercial supersonic flight — done before on the legendary Concorde — has only ever served the world’s elite.

To put it lightly, Scholl and his team face extraordinary turbulence. And they’ll have to navigate the graveyard of supersonic dreamers who’ve come before them.

Boom is not inventing the wheel. 

The Concorde burst onto the scene in 1976 amid the technological cage match of the Cold War. The French-British product wasn’t the world’s first supersonic passenger airliner; the Soviets tested the Tupolev Tu-144 in 1968. It was, however, the first such aircraft to enter commercial service. 

Cue the celebrity decadence. Paul McCartney, a frequent Concorde flyer, reportedly hosted impromptu singalongs between Champagne toasts and caviar. Michael Jackson said he wrote music on a Concorde, and Phil Collins famously boarded the jet to rock both stages at Live Aid — not to mention rides by the Queen and the Pope.

But it was not sustainable. Just 14 of the aircraft entered commercial service, and roundtrip flights cost roughly $20,000, adjusted for inflation. French and British taxpayers underwrote at least $2 billion in production costs, and airlines fielded the jets at a loss for the first six years.

It did not help that the Concorde was a gas-guzzling beast. To fly from New York to Paris, the plane required four times as much fuel as a Boeing 747, to transport one-fourth as many passengers. 

Aviator Charles Lindbergh advocated for an outright ban of the aircraft, writing in The New York Times that “it is essential for us to reduce such pollution.”

And then there was the noise. The Concorde’s sonic boom had a nasty habit of rattling windows and startling groundlings, which led several countries, including the U.S., to ban civilian craft from flying supersonic speeds over land to this day. It was not uncommon to find Anti-Concorde Project demonstrators rallying on the tarmac, and New York Gov. Hugh Carey once suggested the federal government would have to send in “the 82d Airborne” to make him accept the airliners at Kennedy International Airport.

The Concorde flew its last flight Nov. 26, 2003.

“We are living in the dark ages of flight,” said Scholl, who founded Boom in 2014 in his Oakland basement. “We had a technology in Concorde that we never took mainstream. We shut it down with no plan to replace it.”

Scholl’s promise is not just to revitalize the Concorde but to bring supersonic travel to the masses. It is a lofty aspiration that has attracted a who’s who of Silicon Valley investors, including Sam Altman, Reid Hoffman, Paul Graham, Y Combinator, Emerson Collective, and Michael Moritz, who is the chairman of The Standard.

Boom has raised more than $600 million from those investors. More than any of its competitors — which include the startups Hermeus and Spike Aerospace — Boom has couched itself in the language of techno-optimism.

“When we fly twice as fast, cities rarely visited become major travel destinations,” Boom’s marketing materials say. “We can attend meetings in far-off places and return for evenings with loved ones. Global leaders can solve crises in-person and children grow up in a world where nothing is foreign.”

Boom says its Overture airliner could start operating commercially within five years. That’s a daunting task, given that the plane hasn’t been built yet. But Scholl — an aviation nut who has worked software jobs at Amazon and Groupon — says his team is the one to do it.

“Boom is a Silicon Valley company that happens to be based in Colorado,” Scholl said, adding that the company’s “small, mighty, vertically integrated teams” are far more nimble than those of traditional industry giants. That belief extends to the rank-and-file engineers.

“There is a clear sense of urgency,” said a Boom engineer who asked to remain anonymous because he wasn’t authorized to speak to the press. “The faster you move, the less money you burn.”

It is not uncommon to work 12-hour days, six days a week, he said, adding that he and other staffers truly buy into the company’s mission.

“There’s no science that needs to be done for this,” he said. “It’s an engineering problem. We just need to go and do it.”

Overture is slated to carry between 64 and 80 passengers in an experience akin to today’s business class travel. The company most often highlights potential cross-ocean routes, where its aircraft won’t have to contend with overland supersonic bans.

Still, Boom says, even without surpassing Mach 1, Overture will travel 20% faster than subsonic airliners over land; this would save a little over an hour flying from SFO to New York. It’s unclear how much tickets will cost, but Scholl said Boom is engineering the Overture to have a “break-even fare” of $3,500 for a roundtrip, trans-Atlantic flight. Ultimately, though, the airlines will set prices.

Boom frequently touts that it has “secured 130 Overture orders and pre-orders with global airlines.” But of the three airlines that have inked deals with Boom, only American has put down a nonrefundable deposit for 20 planes. A United Airlines spokesperson said the company has agreed to a “nonbinding purchase agreement” for 15 Overtures. A Japan Airlines representative said, “We haven’t made final decisions,” but the company has “the option to purchase up to 20 Boom aircraft through a preorder arrangement.” 

The remaining 75 planes are an “option” for American and United to purchase, if their initial orders and preorders go through.

“The airlines that have placed orders are trying to create a perception in the market of how advanced they are,” said Brian Foley, an aviation industry analyst. “But in my mind, there’s no intention of taking any of these things.”

If Boom were to abruptly fail, it would not be the first aerospace startup to do so.

For years, the Nevada-based Aerion Corporation was seen as a frontrunner in the race to assume the Concorde’s mantle. The company raised more than half a billion dollars and, in 2018, said it expected to field its first supersonic business jet in five years.

That wouldn’t have been a bad bet. Aerion assembled a set of established industry backers like Boeing, GE Aviation, and Honeywell and broke ground on a behemoth $300 million research and design complex in Florida. Crucially, Aerion focused initially on “ultra-luxury” business jets, targeting a more specific market segment than that of Boom.

None of it panned out. By the summer of 2021, Aerion had burned through its capital and couldn’t find an outside lifeline. It ceased operations.

“These programs tend to go at the speed of cash,” Foley said. “It’s very difficult to succeed with something new in aviation because of the costs.”

Far-out timelines — Boom took 10 years to build XB-1 using technology that already existed — and the uncertainty of Federal Aviation Administration certification can spook investors, Foley said. 

“They’re moving the football down the field, but it’s in no way a done deal,” Foley said. “It’s a low-probability effort.”

Scholl remains defiant.

“If we gather just the very best people in the world, we can do it,” he told the crowd after Tuesday’s XB-1 flight demonstration. “We just need to keep going. There are always going to be naysayers, but they don’t make the future.”

Boom’s contention, in so many words, is that it will engineer its way out of the problems that doomed the Concorde.

“Concorde was built on 1960s technology,” Scholl said, when asked how Boom plans to make its jets affordable. “You couldn’t build an iPhone out of 1960s technology. So what if we build a supersonic jet out of 2020s technology?”

The first version of the Overture will be 75% less expensive to fly than the Concorde, Scholl promised. As for environmental concerns: The company says Overture will be “optimized” to run on “100% sustainable aviation fuel.” The emerging class of fuel is an alternative that relies on biomass and waste resources that can dramatically reduce a jet’s carbon footprint. But today, because of a lack of scale, sustainable fuel is exorbitant compared with traditional options.

“I believe in a future where more people can go more places more often,” Scholl said, noting that aviation accounts for roughly 2% of the world’s carbon emissions.

After Tuesday’s test flight, XB-1 taxied down the tarmac. A support crew jogged to the jet as it parked at its carefully staged mark in front of the crowd. 

The cockpit lifted, and out came Tristan “Geppetto” Brandenburg, a Navy veteran and graduate of the mythic TOPGUN flight school. He descended from the cockpit and flashed a smile at the cheering spectators.

Scholl met him at the bottom of the ramp. The two shook hands, exchanged a hug, then took curt sips from Champagne flutes. Perhaps aware of the daunting obstacles to come, they made no ostentatious display. Instead, Scholl took the mic.

“This afternoon, we celebrate,” he said. “Tomorrow, we’re back to work.”