There’s finally movement to bring back supersonic passenger planes, which have been off the table since Concorde which was never a commercial success. Boeing never produced its government-funded SST jet. The Soviet Tupolov Tu-144 nicknamed Konkordski crashed at the Paris Air Show in 1973. Supposedly the plane was built based on stolen plans from the French and Americans but they had been fed fake plans.

Boom Supersonic recently raised $100 million in a ‘down round’ to fund engine development though an engine is likely to cost much more than this.

Two weeks ago, Boom’s XB-1 test plane broke the sound barrier. The plane is about 30% of the size of their planned passenger jet. This is a long way off from having a passenger plane with engines certified and legally allowed to fly in a manner that’s useful to commercial airlines.

Ultimately, though, there’s no technical reason that supersonic passenger flight can’t happen. And it should be far quieter and more fuel efficient than Concorde, whose first flight was in March 1969.

Trump Administration May Legalize Supersonic Flight

Late in the last Trump administration, the FAA proposed loosening rules on supersonic flight which make operating sonic boom aircraft illegal. Elon Musk says this will finally happen.

This administration will get rid of all regulations that make no sense, like this one

— Elon Musk (@elonmusk) February 10, 2025

Prediction markets give legalizing supersonic a 27% chance of happening this year.

Meanwhile, Boom Supersonic says they can achieve supersonic speed without the sonic boom reaching earth.

Boom! We cracked it! Today we are introducing Boomless Cruise—supersonic flights up to 50% faster with no audible sonic boom.

We quietly (har har) demo'd this on XB-1's first supersonic flight—three times actually. pic.twitter.com/oe0VHJqNit

— Blake Scholl (@bscholl) February 10, 2025

Will Boom Supersonic Have An Engine?

Engines can cost billions of dollars to design and tens of millions of dollars apiece to purchase. It’s a huge bet for an engine manufacture, which $100 million doesn’t fund. They will need to sell large numbers of engines just to break even. If a manufacturer can’t sell several hundred engines they won’t recoup their development cost, after recouping production costs, let alone turn the project profitable.

Boom’s need to self-fund is as much about skepticism of the market as skepticism of the plane, or put another way, to the extent that it’s about the plane it’s not whether the plane is possible, or an engineering marvel, but whether the plane will be good enough, to be so compelling, that airlines cannot turn down placing orders and taking actual delivery in large numbers.

Most people in aviation think that the plane will never be built because it has a very limited market, relatively short flying range (for an initial plane, at least) and an expected need to fly overwater due to noise – likely still true even with quieter technology and regulatory changes. And so there’s limited willingness to invest.

Will Airlines Buy A Supersonic Plane?

Paul Graham, who invested in Boom’s latest $100 million raise, argues that the economics of the new plane will work because of densification of the passenger cabin while maintaining current pricing.

If business class travelers have a choice of a 10 hour subsonic flight from Seattle to Tokyo or a 5 hour supersonic one at the same price, they're all going to take the 5 hour one. Which means all the business class travelers switch to supersonic.

— Paul Graham (@paulg) January 29, 2025

And, he says, this means that all airlines flying long haul premium cabins will be forced to become buyers.

Credit: Boom Supersonic

In 2021, United Airlines placed an order for Boom Aerospace’s promised Supersonic jets.

Credit: Boom Supersonic

Then in 2022 American Airlines followed suit. Japan Airlines is an investor in the company. However these aren’t exactly ‘firm’ orders.

What most people don't realize about Boom is that if they ship an airliner at all, every airline that flies internationally will have to buy it or be converted against their will into a discount airline, flying tourists subsonically.

— Paul Graham (@paulg) January 29, 2025

On the other hand,

• No U.S. airline ever purchased a Concorde, though orders were placed by Pan Am, Continental, TWA, American Airlines, Eastern, United and Braniff.

• There were also orders from Qantas, Air India, Sabena, Air Canada, Lufthansa, and even Middle East Airlines and others which never came to fruition.

• Only British Airways and Air France took actual deliveries of new aircraft.

• The only other committed order came from Iran Air, and that was cancelled after the Iranian revolution.

Oddly Braniff did briefly own Concordes for a few hours at a time. They operated service between Dallas and Washington Dulles in conjunction with Air France and British Airways, but to do so they were required to take ownership of the plane for the flight segment in order to operate under their own certificate of airworthiness.

As well as changing flight crews the US approved documentation and procedures had to be present on the flight deck, which meant that the UK/French documentation had to be stored in the forward toilet.

There also had to be a change in the aircraft registration, while being flow on the Dallas – Washington – Dallas routes the “G” or “F” was covered up with white tape. On landing at Washington the ground staff would pull work ladders up to the tail and peel of the F- or G- registration numbers and changed them to an “N” with two letters and the numbers “94″ after that. This was repeated every time the Concordes landed in the US from Europe.

But This Could Still Succeed!

If operating economics are good enough, supersonic is a huge marketing advantage. The market between East Coast and London and Paris and maybe Frankfurt and Zurich may be robust enough to support customers paying a sufficient premium for supersonic, and competition for these customers is fierce. Once an airline takes the plunge, others may as well.

Of course short east coast transatlantics don’t offer as much of a time advantage as East Coast – Asia or Europe – Asia but those involve greater travel over land and greater regulatory skepticism. Existing airlines, even that have placed orders for these planes, may lobby against it preferring a status quo to one where they have to make huge capital investments that will be matched by other carriers.

Then again, 3-4 hours flights to London and Paris allow for morning departures that land in time for dinner, and after work departures from Europe that allow passengers to make it home for dinner as well.

The best-positioned carriers in the world to execute on this would be British Airways and American Airlines, with their diverse slot portfolio at London Heathrow – and the ability to finally make good on American’s slots at New York JFK. The shorter flight times would play havoc with slot usage, a modern day Boeing Boeing.

In that French play-turned-1965 film starring Tony Curtis and Jerry Lewis, a cad who liked flight attendants so much he was dating three of them (for Air France, Lufthansa, and British United Airways) and their international routes never had them in town at the same time.

All of the cabin crew live with him whenever they’re in Paris, with photos and personal touches swapped out to match each one’s arrival. But then the jet age meant faster planes, screwing up their schedules, and bringing them back to him all at the same time. Hijinks ensue. And so would it happen with slots.

Delta, with its 49% stake in Virgin Atlantic, could probably manage this as well but their slots aren’t nearly as diverse as BA’s. (Indeed, Virgin can’t really operate connecting banks with their slots today.)

There are always airlines that have come along and said ‘the transatlantic market is so robust, we only need to capture 1% of it to profit’ but never offer a compelling reason why they would capture that 1%. In fact, without the sales teams and corporate contracts, frequent flyer programs and robust frequencies they never do. Airlines like Eos and Maxjet never made it.

But supersonic would be a difference-maker, at least until other carriers pulled the trigger, too. And they wouldn’t just share shift business travelers on premium fares (though often at lower, more deeply discounted fares than you’d expect) but they would shift frequent flyer program preference and therefore credit card co-brand revenue as well.

Also think that many business travelers would switch loyalty programs over it, which is a threat out of proportion to the number of transoceanic flights. It might be the only product innovation in decades that has threatened that.

— Patrick McKenzie (@patio11) January 29, 2025

If regulations are changed to allow for supersonic flight over land while controlling for noise, then there will be technological development and we’ll eventually see commercial flight at faster speeds. It’s unclear whether Boom Supersonic in particular gets there. But ultimately the technology is possible – and needs to advance enough so that the economics supports it.