Turbulence ahead for supersonic passenger aircraft, predicts ICCT, as ICAO declines to establish new international noise standard
Aerion says its Mach 1.4 business jet will comply with existing international environmental standards
Thu 21 Feb 2019 – In the light of high-profile projects in the United States to develop new supersonic passenger aircraft, there was an expectation ICAO’s Committee on Aviation Environmental Protection (CAEP) could agree to start work on establishing a specific international supersonic landing and take-off (LTO) noise standard at its triennial meeting (CAEP/11) that concluded last week. CAEP “considered the progress” of supersonic transport (SST) operations but decided instead to undertake an exploratory study during its next three-year work cycle. Dan Rutherford of the US-based International Council on Clean Transportation (ICCT) believes this is a blow in particular to the ambitions of Boom’s 55-seat Mach 2.2 airliner. Two other supersonic business aviation projects, Aerion and Spike, have said they intend complying with today’s ICAO LTO noise standard applying to subsonic aircraft.
Despite an existing regulation that prohibits civilian flights in excess of Mach 1 over land and to a distance offshore where a sonic boom may be heard on land, the United States government is supporting the development of viable civil supersonic aircraft. According to a Supersonic Flight Fact Sheet published last October, the FAA is initiating two rulemaking activities that propose rules for noise certification of supersonic aircraft and to streamline and clarify the procedures to obtain special flight authorisation for conducting flight testing in the United States.
The agency said it anticipates issuing the proposed rules in 2019 and opening them for public review and comment. However, it added, the rulemaking would not rescind the Mach 1 prohibition, although it also stated there is a procedure that allows supersonic operation under certain conditions granted on an individual basis. “The FAA is working within the existing statutory and regulatory authority to consider the range of permissible supersonic operations,” it said.
As it expects any new supersonic aircraft to operate internationally, the FAA said it is collaborating with other national aviation authorities and working within CAEP “to develop international noise and emissions standards appropriate for future supersonic aircraft and the engines that power them.”
ICCT’s Rutherford said the CAEP meeting had decided not to set weaker international environmental rules for supersonic aircraft. “It’s now up to the United States to figure out how to set a domestic LTO noise standard for SSTs on its own, as required under the 2018 FAA Reauthorization Act,” he said in a blog posted on the ICCT website.
However, he said, it was doubtful that demand for US domestic flights alone will be enough to finance the re-introduction of SSTs that don’t comply with ICAO’s Chapter 14 international noise standard. “Due to a ban on supersonic operations of civil aircraft over land in most parts of the world, the vast majority of flights for the foreseeable future will be overwater and therefore international,” he added.
Boom’s goal, said Rutherford, was 2,000 SSTs operating 5,000 flights linking 500 airport pairs by 2035. However, ICCT had assessed only 650 of those flights would be domestic, with 590 of them within the US but subject to the current overland speed ban. “So the market for a commercial supersonic that cannot operate internationally, nor fly overland, might be in the order of several aircraft, not 2,000,” he argued.
Rutherford suggests Boom has two possible approaches: convince an engine manufacturer to develop a new, more expensive, advanced clean-sheet engine with lower noise or significantly reduce the design speed of its aircraft and so reduce its LTO noise footprint. Aerion has already made the latter choice but this would require a change to Boom’s business model, he believes.
“Either tactic will make Boom’s goal of providing fast, cheap supersonic service to the masses that much harder to achieve,” he predicted.
The Boom website says the US supersonic overland ban should be reversed and replaced with a “commonsense” noise standard that promoted “efficient, affordable supersonic flight while disallowing nuisance.” In the meantime, it continues, the company would focus on routes, estimated at around 500, that were primarily over water, such as New York to London or San Francisco to Tokyo, and flying subsonically when over land. Boom claims that because noise limits are based on aircraft weight, its smaller-size aircraft relative to the current fleet of long-haul commercial airplanes will be quieter on take-off than many planes flying today.
Eli Dourado, Head of Global Policy & Communications at Boom, told GreenAir: “CAEP standards have always been based on high-quality data and analysis that takes into account several factors, including economic reasonableness, technical feasibility and environmental benefit. Boom is pleased with the outcome of the CAEP meeting, and we look forward to supporting the study in any way we can.”
Earlier this month, Boeing announced it would be making a significant investment in Aerion, which is developing a 12-passenger, Mach 1.4 business jet slated for first flight in 2023 and entry into service in 2026. The AS2 will have the ability to fly up to 70% faster than today’s business jets, says the company, saving around three hours on a transatlantic flight “while meeting environmental performance requirements.” It unveiled the AS2’s GE Affinity engine design last year.
Boeing will provide engineering, manufacturing and flight test resources to the project. “This is a strategic and disciplined leading-edge investment in further maturing supersonic technology,” commented Steve Nordlund, VP & GM of Boeing NeXt. “Through this partnership that combines Aerion’s supersonic expertise with Boeing’s global industrial scale and commercial aviation experience, we have the right team to build the future of sustainable supersonic flight.”