The world's largest jet engine maker confirms it won't develop supersonic engines for Boom, leaving the startup with few options

• CFM International told media on Sunday that the company has no plans to build a supersonic engine for Boom.
• Boom is developing an ultra-fast jet that it says could fly from New York to London in less than four hours.

The revival of supersonic travel may still be decades away as the most promising company just lost another engine option.

Colorado-based startup Boom Supersonic is developing an ultra-high-speed jet, known as Overture, that could catapult travelers from New York to London in less than four hours.

So far, two of the largest US carriers United Airlines and American Airlines have ordered the aircraft, with an expected entry to service in 2029. But, there is one problem — no engine makers want to help Boom create a supersonic engine.

President and CEO Gaël Méheust of CFM International told media at an industry forum on Sunday that the company doesn't "see a significant market for an engine that targets a very small potential niche," Aviacionline reported.

Rather, he said CFM wants to put its time and resources into developing an engine "that improves emissions and performance compared to current engines."

The move comes after the joint venture's parent companies, GE Aviation and Safran Aircraft Engines, already said no to Boom in September.

"As a practice, we avoid commenting on any ongoing and confidential negotiation with our suppliers, until both sides are ready to announce jointly," Boom told Insider in a statement. "However, we can reconfirm our intention to announce Boom's selected engine partner and transformational approach for reliable, cost-effective, and sustainable supersonic flight, later this year."

Without CFM as an option, Boom is left with no major manufacturers that could help it develop a supersonic engine, shining doubt on its 2029 timeline.

Engine maker Rolls-Royce was at one point a contender, having signed an "engagement agreement" with Boom in 2020 to look into a supersonic engine. But, it has since pulled out of the project.

The company told AIN Online in September that it has "determined that the commercial aviation supersonic market is not currently a priority for us and, therefore, will not pursue further work on the program at this time."

Shortly thereafter, several other major manufacturers, including Safran, GE, and Honeywell, all told FlightGlobal that they do not have an interest in helping Boom at this time.

Meanwhile, Pratt & Whitney chief sustainability officer Graham Webb told the outlet that supersonic travel is "tangential."

Even before CFM announced its hesitancy to develop a supersonic engine, Henry Harteveldt, travel analyst and president of Atmosphere Research Group, told Insider in September that Boom may have to make its own.

"Boom has stated it wants its aircraft to be as environmentally responsible as it can be, which is a noble and critically important objective, but it is already hard enough and expensive enough for Boom to build the airplane," he explained. "So, if they were to also take on the engine, then it will be a big challenge."

However, if Boom is able to pull off creating a supersonic engine, it could give the company a big advantage in the industry.

Harteveldt said the success could make Boom an "attractive acquisition target" for corporations like Boeing, or the company could sell its engine design to "not only recoup its cost but also possibly make a profit off of it."