American Airlines buys in to Boom, despite significant uncertainties

On Monday afternoon, speaking to the Global Business Traveler Association, American Airlines CEO Robert Isom asserted, “The best thing we can do about sustainability is fly new aircraft.” On Tuesday morning the company announced a new aircraft order from Boom Supersonic that cannot deliver on that goal.

American Airlines is the second US carrier to sign with Boom Supersonic. The airline plans for 20 Overture deliveries, plus another 40 options. They do not specify a timeline for the delivery of the aircraft to American Airlines.

The companies are keen to point out that American’s order includes a “non-refundable deposit on the initial 20 aircraft.”

Looking to the future, supersonic travel will be an important part of our ability to deliver for our customers. We are excited about how Boom will shape the future of travel both for our company and our customers.

– Derek Kerr, American’s Chief Financial Officer

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Focusing on markets where American can benefit from the supersonic performance, the carrier highlights the potential to connect Miami to London in just under five hours and Los Angeles to Honolulu in three hours, among the possible opportunities. When accounting for fuel reserves and headwinds, the Miami-London route appears to be approaching the edge of the range Boom plans for Overture.

Boom is touting it as a “firm” order with options. But, as with the other orders Boom has announced, Overture “must meet industry-standard operating, performance and safety requirements” and airline qualifications before delivery, or even American filing SEC paperwork of a material event and logging the frames on its order book.

Getting to that point will be something of a miracle given the company’s current position in the development and manufacturing process.

Engine Issues for Boom Supersonic

Earlier this summer Boom announced the finalized design of its Overture supersonic jet. This includes a shift to four engines on each plane. But the company still does not have an engine manufacturer selected, and it expects to start test flights in three years.

Developing and certifying a new engine is a time-consuming and expensive process. Boom CEO Blake Scholl played down that challenge four years ago. At that time Scholl suggested the engine would be a relatively easy design shift from existing products, “It is not a new technology engine, it is a new design engine. You’ve got knobs on an engine like bypass ratio and pressure ratio and they’re set in certain places for the 787 and you want to set them in different places for this airplane.”

Since then, however, the company has little visible progress to show.

Boom hired Rolls-Royce to help develop engine concepts back in 2020. Both parties agree that work is now complete. But Rolls did not commit to further development the necessary engine presumably specified from the research without Boom (or someone else) footing the bill. No other companies appear to be stepping into that role, either.

Scholl only offers that “We’re looking at multiple different options,” when pressed on the status of this critical component.

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Supersonic is not a sustainable solution

On the sustainability front, Boom’s Overture presents myriad challenges.

The company focuses on it ability to fly on 100% sustainable aviation fuel (SAFs) as solving that problem. Putting aside that making such a claim prior to selecting the engines is a bit questionable, SAFs alone do not solve emissions issues in aviation.

Among the challenges, supersonic flight will burn roughly 4-6x the volume required for subsonic travel. And the subsonic operations continue to eke out additional efficiencies. Given a very limited supply of SAFs for at least the next decade, burning extra of it for supersonic travel would appear to be counter to the airlines’ stated environmental goals.

Moreover, an MIT/ICCT study suggests that, because of the way the SAFs burn and the higher altitude at which Overture would fly, “a small fleet of supersonic aircraft, providing between 0.1% and 0.6% of the total number of seat-km of the projected subsonic fleet, could cause ozone depletion equivalent to up to 8% of the total impact of CFC emissions” at their peak.

Or, as David W. Fahey, director of the Chemical Sciences Laboratory at the National Oceanic and Atmospheric Administration explains, “Getting a sustainable source of fuel doesn’t negate the effect that you are creating water vapor and nitric oxides… The nature of the environmental effects of supersonic aircraft are unchanged from the 1990s when they were last a major focus of the stratospheric science community.”

Boom has, to date, failed to address these concerns. Instead, the company continues to repeat that the not-yet-specified engines can run on 100% SAFs to address all sustainability issues.