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United Airlines’ Supersonic Jet Is a Bad Idea

Like a lot of rich-people hobbies, bringing back really fast planes is dumb and helps wreck the planet.

A long plane with a pointy nose is depicted over clouds.
Copyright © 2021 Boom Supersonic
A creative rendering of the Boom Supersonic Overture aircraft that United intends to purchase

United Airlines announced this week that it will purchase at least 15 supersonic Overture jets, at $200 million a pop, from a startup called Boom, which—having yet to put a single one of its fast new planes in the sky—aims to start ferrying loads of up to 88 business-class passengers between major cities by the end of the decade. The International Council on Clean Transportation, or ICCT, estimates that supersonic jets are five to seven times as carbon-intensive as traditional planes. Improbably, Boom and United are each marketing this new era of supersonic travel as a climate innovation. They’ve pledged their planes will be “net-zero carbon from day one,” whatever that means.

On some level, Boom and United seem to recognize that they need to sell their shiny new jets as climate-friendly, even when the evidence suggests they will be anything but. Airlines publicly angsted about the rise of flight-shaming even before Covid-19 ground travel to a virtual standstill last year. As it picks back up, those worries haven’t gone away. Yet the question of how these companies plan to make good on their climate promises skirts past a more basic one: Why are they making these extra resource-intensive jets at all?

As part of its goal to be “100% green” by 2050, Boom reportedly plans to work with Prometheus Fuels to capture carbon and turn it into jet fuel, a process that is not currently feasible at any meaningful scale. Overture crafts plan to “accommodate” the use of so-called “sustainable aviation fuels,” or SAFs, an umbrella term referring to a number of jet fuels with lower carbon footprints. That does not mean they will actually run entirely on these fuels. As pointed out by Dan Rutherford of the ICCT, doing so would likely mean exhausting the available supplies of alternative fuels. In 2020, those accounted for just 0.05 percent of total supplies. United’s 15 supersonic jets could eat up the entirety of the EU’s synthetic fuel supply in 2030 twice over. The airline’s own use of SAFs, climate analyst Ketan Joshi notes, has fallen since 2016 from 0.031 percent to 0.028 percent as its emissions have ballooned. As Rutherford previously observed, the International Air Transport Association—a trade lobby—aimed to use 6 percent alternative jet fuels by 2020. The industry ended up using just 0.25 percent last year. What’s more, the noncarbon greenhouse gas emissions of supersonic flight could be enormous. Given the already monumental task of greening existing air travel, why add an even more polluting fleet to the mix?

Essentially, because some very rich people (read: Boom’s investors) think it would be cool. And they have more cash than ever to throw at shiny new toys. Who, after all, urgently needs to get from Newark to London in three and a half hours, if not a fabulously wealthy investment banker or pharmaceutical executive? Who can pay the roughly $6,000 per ticket needed to do so? Even that price seems optimistic: Tickets on the Concorde—the now-defunct supersonic jets that operated until 2003—ran at a cool $12,900 in 2020 dollars. And while it was a deadly crash that finally grounded those planes, aviation journalist Seth Miller writes that its operators had long had trouble coaxing enough corporations to pay for their employees to take faster, far costlier flights. Given the more widespread use of videoconferencing through the pandemic, filling up an entire supersonic cabin could be an even tougher sell now.

Like Tesla and the Concorde—both made possible by generous public sector support—Boom is best understood as a public-private partnership. The company’s board members, according to its fact sheet, include individuals from both major military contractors like Boeing and Lockheed Martin and the Department of Defense. Among its first major customers is the U.S. Air Force, with which it is “developing custom Overture configurations for government executive transport.” U.S. airlines received generous bailouts over the last year, all after having poured 96 percent of their free cash flow into stock buybacks that padded shareholder pockets: United alone got $7.7 billion. Thanks to diligent organizing by the Association of Flight Attendants-CWA, those bailouts were tied to ensuring that workers could stay on the payroll. Republicans struck down a union-backed proposal also to tie them to modest emissions reductions.

Government funds aren’t scarce, but it’s a pity to waste them on something as useless as supersonic jets. There is a plausible case to be made that selling Teslas as a high-performance luxury item helps to popularize the idea of electric vehicles by making them cool. Or that a hulking, Biden-approved 6,500 pound electric Ford F-150—whose internal combustion engine version is among the best-selling vehicles in the U.S.—can, however egregious its resource usage, help make the energy transition safe for American masculinity. The case for supposedly green supersonic travel is less compelling.

Beyond being a major source of local air pollution, aviation is responsible for roughly 3 percent of U.S. emissions and 9 percent of national transportation emissions. Like shipping, aviation emissions are not covered by the Paris Agreement. Climate rules for the industry are governed by the International Civil Aviation Organization. The United Nations body is, in broad strokes, similar to the International Maritime Organization, profiled at length this week in The New York Times for its intense secrecy, industry-heavy membership, and lax approach to emissions reduction. To become loosely Paris Agreement–aligned, the ICAO has leaned heavily on dubious carbon offsets. Airlines lobbied to further weaken already paltry climate rules amid the pandemic. This could mean airlines will get a free pass to pollute until 2024. Part of why Boom and United can move forward with an arguably unnecessary plan for supersonic air travel, then, is that it’s not clear who would tell them not to.

If the goal is to create a new class of theoretically zero-carbon toys for rich boys, then letting investor fantasies drive innovation may be the way to go. If the goal is to decarbonize transit and the world, then governments should play a more heavy-handed role, both restricting boondoggles like supersonic flight and investing in things that could actually make aviation sustainable. That’s not to say we can’t have cool things—or even planes! But the future should probably look a bit more like zero-carbon mass transit and ebikes for the many rather than supersonic jets for the few.