MILAN – Eco-sustainability must be considered every time an aviation player makes a choice, but it risks becoming a toxic mantra advocated at all costs, even when there’s a clear incompatibility.
A case that stands out is the U.S. major airline United which is assiduously following the eco-sustainability trend, despite forcing the company to conform to a model that doesn’t belong to its roots.
On Tuesday, United officially revealed it has invested in the start-up Heart Aerospace and it has conditionally agreed to purchase 100 ES-19 turboprop aircraft with 19 seats that would be operated by the regional airline Mesa (United, 2021).

Small aircraft, which United has replaced with larger jets, such as the Embraer E145. United Express’s last flight with a turboprop was in January 2018 with a 37-seat Dash 8 Q200 operated by CommutAir (Roman, 2018).
In July of the same year, American Eagle made its last flight with a Dash 8 Q300 operated by Piedmont Air (Mutzbaugh, 2018). Both regional airlines then transitioned to an all-jet fleet chasing the increased demand for domestic flights.
To mark the occasion, Bloomberg published an article on the Dash 8’s retirement, headlining “The Airline Propeller Era Is Coming to an End.” (Bachman, 2018). To date, few U.S. carriers still fly turboprops, the primary user is Air Horizon, which operates on behalf of Alaska, and the small Florida-based Silver Air.
Despite United aims at lighting the way for sustainable travel, its latest announcement contradicts the direction taken a few years ago. In 2026, when the introduction of the ES-19 is expected, there would be a return to the past that United had legitimately greeted. It’s not the electric, it’s the airplane type.

Clarity is mandatory, especially on this point. Among Heart Aerospace’s investors, the European Commission (Heart Aerospace, 2021) has recently drafted plans to set an EU-wide minimum tax rate for polluting aviation fuels (Abnett, 2021).
An electric aircraft could become a bestseller in the near future, but is ES-19 the right product for United?
A conditional agreement for a 19-seat aircraft would have come naturally for a commuter airline like Cape Air which ordered 100 9-seat Tecnam P2012s to replace its old Cessna 402s. It’s hard to believe that United and its subsidiaries could fly a fleet of light aircraft (less than 10,000kg).
But there’s a worse chapter. Earlier this year, United announced an agreement with America’s Boom Technology for the purchase of 15 Overture supersonic jets that will be deployed on transoceanic routes.
The aircraft, currently under development, would fly at Mach 1.7 (Concorde flew at Mach 2) burning Sustainable Aviation Fuel (SAF). It could carry 65 to 88 passengers, considerably less capacity than the smaller planes in United’s fleet, the A319 and 737-700 in a 126-seat configuration.

If, and only if, the supersonic airliner meets United’s demanding safety, operating, and sustainability requirements, from 2029 it will operate passenger flights from Newark to London in just three and a half hours, Newark to Frankfurt in four hours, and San Francisco to Tokyo in just six hours.
We need to go fast!
According to aviation journalist Andreas Spaeth, “the airliner would emit three to five times more CO2 than a subsonic flight on the same route.” Spaeth also pointed out that “there is a severe shortage of SAF, and production is currently far more expensive than that of kerosene” (Spaeth, 2021).
As confirmed by Kate Aronoff at The New Republic, “United’s 15 supersonic jets could eat up the entirety of the EU’S synthetic fuel supply in 2030 twice over” (Aronoff, 2021).
United’s orders are out of the airline’s frame of reference. The ES-19 would operate very short-haul regional flights for a few passengers, the second would be reserved for very rich customers willing to pay thousands of dollars for a flight (current estimates say around $5,000 per passenger, more than a corporate flight!).

It’s not the United world. Moreover, the small electric plane and the supersonic are the polar opposite. On the one hand, there is environmental sustainability. On the other hand, the desire for futurism, speed, courage, audacity, but which doesn’t seem to be a climate-friendly solution.
By contrast, Delta is following a more realistic path with a fleet renewal that lives up to expectations. The airline plans to add 29 used Boeing 737-900ERs and lease seven used Airbus A350-900s. The A350s will be leased through AerCap and the 737-900ERs will be purchased from funds managed by Castlelake (Delta, 2021).
At present, unfortunately, United’s sensational announcements risk not meeting the expectations of even the most loyal customers and aviation geeks. However, United has an explicit commitment to environmental sustainability and this is a view embodied by modern society.
References:
- Abnett, K. (2021). Draft shows EU to propose aviation fuel tax in green policy push. Reuters. https://www.reuters.com/business/sustainable-business/draft-shows-eu-propose-aviation-fuel-tax-green-policy-push-2021-07-04/
- Aronoff, K. (2021). United Airlines’ Supersonic Jet Is a Bad Idea. The New Republic. https://newrepublic.com/article/162650/united-airlines-boom-supersonic-bad-idea-climate
- Bachman, J. (2018). The Airline Propeller Era Is Coming to an End. https://www.bloomberg.com/news/articles/2018-07-05/the-airline-propeller-era-is-coming-to-an-end
- Delta. (2021). Delta to add Airbus, Boeing aircraft to fleet amid travel demand recovery. Press release. https://news.delta.com/delta-add-airbus-boeing-aircraft-fleet-amid-travel-demand-recovery
- Hawkins, A. (2021). United Airlines is buying 15 supersonic aircraft from Boom Supersonic. The Verge. https://www.theverge.com/2021/6/3/22497462/united-airlines-boom-supersonic-deal-overture-jets
- Heart Aerospace. (2021). Official website. https://heartaerospace.com
- McKibben, B. (2021). We Don’t Need Supersonic Travel—in the “New Normal,” We Should Slow Down. The New Yorker. https://www.newyorker.com/news/annals-of-a-warming-planet/we-dont-need-supersonic-travel-in-the-new-normal-we-should-slow-down
- Mutzbaugh, B. (2018). End of an era: American ends turboprop flying with Dash 8 retirement. USA Today. https://eu.usatoday.com/story/travel/flights/todayinthesky/2018/07/09/american-ends-turboprop-flying-dash-8-retirement/768834002/
- Roman, G. (2018). Farewell to United Express turboprop flights. CommutAir. https://www.flycommutair.com/farewell-to-united-express-turboprop-flights/
- Spaeth, A. (2021). Supersonic flights: Empty promises or the start of a new era? DW. https://www.dw.com/en/supersonic-flights-empty-promises-or-the-start-of-a-new-era/a-57860579
- United. (2021). Electric Aircraft Set to Take Flight by 2026 Under New Agreements with United Airlines Ventures, Breakthrough Energy Ventures, Mesa Airlines, Heart Aerospace. Press release. https://hub.united.com/electric-aircraft-set-to-take-flight-by-2026-under-new-agreements-with-united-airlines-ventures-breakthrough-energy-ventures-mesa-airlines-heart-aerospace-2653765004.html