WORKING PAPER 2019-02 Noise and climate impacts of an unconstrained commercial supersonic network Authors: Dan Rutherford, Ph.D.; Brandon Graver, Ph.D.; Chen Chen Date: 30 January 2019 Keywords: supersonic, aviation, noise, CO2 SUMMARY Los Angeles, Singapore, San Francisco, and climate impacts of commercial New York-JFK, Frankfurt, and Bangkok. SSTs. Aspiring manufacturers could Three U.S.-based startups, strongly The aircraft could double the area boost the public acceptability of their supported by the current U.S. admin- around airports exposed to substantial designs by committing to meet existing istration, are working to develop new noise pollution compared to existing environmental standards for subsonic commercial supersonic transport subsonic aircraft of the same size. aircraft and by supporting new en route (SST) aircraft. This paper estimates the noise standards that would mandate environmental impacts of reintroduc- Substantial parts of the world would low-boom technology. ing commercial SSTs at scale into the experience disruptive sonic booms from global aviation fleet. Using an open the new SST aircraft. Canada, Germany, source emissions model developed Iraq, Ireland, Israel, Romania, Turkey, INTRODUCTION at Stanford University, we model the and parts of the United States would In this paper, we analyze the LTO landing and takeoff (LTO) noise, sonic experience frequent sonic booms; the noise, sonic boom, and CO implica- boom, and carbon dioxide (CO ) emis- most heavily impacted regions could be 2 2 tions of manufacturer goals to sell sions from a new, unconstrained SST exposed to between 150 and 200 inci- 2,000 new commercial SST aircraft network of 2,000 aircraft linking 500 dents per day, or up to one boom every serving 500 city-city pairs in 2035. We city-city pairs in 2035. five minutes over a hypothetical 16-hour start by introducing recent efforts to flight day. The SST fleet would emit an revive supersonic flight along with the Reintroducing SSTs at this scale would estimated 96 (88 to 114) million metric existing noise and climate impacts of have substantial noise and climate tons (MMT) of CO per year, roughly 2 commercial aviation. Next, we describe impacts. This fleet would support the combined emissions of American, the methodology we used to identify approximately 5,000 flights per day Delta, and Southwest Airlines in 2017, future commercial SST routes, map the at 160 airports located predominately and an additional 1.6 to 2.4 gigatonnes in Europe, North America, the Middle of CO over their 25-year lifetime. That associated sonic booms, and model 2 the fuel burn and CO of that network. East, Asia, and Oceana. Of these would consume about one-fifth of the 2 flights, 87% are expected to be inter- entire carbon budget afforded inter- Then, we identify the markets, airports, national, with one-third (33%) being national aviation under a 1.5°C climate and countries that would be most transoceanic. The two busiest airports, trajectory, assuming that aviation main- affected by noise pollution from these Dubai and London Heathrow, could tains its current share of emissions. aircraft and their annual and lifetime each see more than 300 operations CO2 emissions. Finally, we close with per day. Other airports that could see The findings highlight the need for some policy implications and areas of 100 or more daily SST LTOs include robust standards to manage the noise future research. Acknowledgements: We thank Anastasia Kharina and Tim MacDonald for help with sonic boom mapping and fuel burn modeling for this paper. Tim Johnson, Vera Pardee, Clare Lakewood, Ben Rubin, Dale Hall, Andrew Murphy, Darren Rhodes, Bryan Comer, Amy Smorodin, and Joe Schultz provided constructive input and feedback on an initial draft. Airline Data Inc kindly provided the dataset used to identify future SST routes. The research was generously funded through the support of the ClimateWorks Foundation. © INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION, 2019 WWW.THEICCT.ORG NOISE AND CLIMATE IMPACTS OF AN UNCONSTRAINED COMMERCIAL SUPERSONIC NETWORK BACKGROUND changes in flight paths under the FAA’s States in 1973, to ban commercial NextGen program (Aratani, 2018). aircraft from operating at supersonic Greenhouse gas emissions and air pollu- speeds over land. tion from commercial aircraft are rapidly Three U.S.-based startups are working to increasing. If the global aviation sector develop new SST aircraft. One aspiring The development effortsof emerging was treated as a country, it would have manufacturer, Boom Supersonic, is SST manufacturers are strongly sup- been the sixth largest source of CO2 from working to bring a 55-seat commercial ported by the Trump administration, energy use in 2015, emitting more than jet dubbed “Overture” into service by which is advocating for permissive Germany (Air Transport Action Group, 2025.1 Boom aims to sell up to 2,000 international environmental standards 2017; Olivier, Janssens-Maenhout, jets serving a network of 500 city-city for SSTs (Lampert & Freed, 2018). Since Muntean & Peters, 2016). If current pairs (Morris, 2018; Bellamy, 2018). If 2016, advocates of supersonic flight trends hold, CO emissions from interna- 2 successful, Boom’s aircraft would be have pushed to lift existing bans on tional aviation are expected to approx- the first commercial supersonic jet overland flight in the United States imately triple by 2050 (International since the Concorde and the Tu-144, (Weigel, 2016; Hammond, 2017b; Civil Aviation Organization [ICAO], developed by Aerospatiale/BAC and Snead, 2018). These advocates won 2013), potentially accounting for 18% of Tupolev, respectively. Only Concorde a partial victory in October 2018 global anthropogenic emissions if the reached commercial service; it flew its when Trump signed the 2018 FAA rest of the world decarbonizes consis- first scheduled supersonic passenger Reauthorization Act into law. The act tent with a 1.5°C emissions trajectory service in 1976 and was retired in 2003. includes several provisions related to (International Coalition for Sustainable U.S. domestic standard setting, includ- Aviation, 2019). Concorde was powered by turbojet ing a periodic review of whether the engines with afterburners, which led overland flight ban can be lifted, but Low fuel prices have accelerated to high fuel burn and takeoff noise. increases in air travel. CO emissions it did not clarify the exact environ- 2 Concorde failed commercially due to from U.S. domestic aviation increased mental standards that new SSTs would its high operational costs and operat- need to meet (Rutherford, 2018b). By 7% from 2014 to 2016 in response to ing restrictions linked to its explosive low fuel prices and increased demand 2025, the International Civil Aviation sonic boom, which could reach up to Organization (ICAO), the specialized (Olmer & Rutherford, 2017), and hit an 2 109 perceived level decibels (PLdB). United Nations agency that regulates all-time peak of 162 MMT in 2017 (Graver Sonic boom, which propagates for tens international aviation, could develop a & Rutherford, 2018). Similar increases of miles on either side of a supersonic are observed globally, with CO emis- full set of environmental standards for 2 flight path, is an explosive, double-tap sions increasing to 859 MMT in 2017, SSTs, including for en route noise (sonic shock wave that follows an aircraft up 10% from 2015 levels (Air Transport boom) and cruise CO2. whenever it flies faster than the speed Action Group, 2017; International Air of sound. Sonic boom was linked to Because emerging SSTs are still under Transport Association, 2018). significant community disturbance in development, relatively little is known Aircraft noise—which is mainly associ- testing over Oklahoma City in 1964 about their likely environmental per- ated with LTO today but will include (Borsky, 1965), along with a success- formance. Kharina, McDonnell, and sonic booms over most of the flight ful class action lawsuit against the U.S. Rutherford (2018) assessed the aircraft- path if SSTs are reintroduced—poses a government over the testing. This led level environmental performance of serious risk to public health. Exposure many countries, including the United emerging SSTs using Boom’s design as to aircraft noise has been linked a reference point. That work concluded to sleep disturbance, learning delay 1 See boomsupersonic.com. Two other that emerging commercial SSTs could manufacturers—Aerion (https://www. in children, mental health problems, aerionsupersonic.com) and Spike (www. emit 5 to 7 times as much CO2 per pas- heart disease, and annoyance (World spikeaerospace.com)—are aiming to produce senger as comparable subsonic aircraft Health Organization, 2018; Aviation supersonic business jets. These are expected on equivalent routes, while failing all to be less noisy, have fewer deliveries, and be Environment Federation, 2016). operated fewer hours than commercial SSTs, applicable environmental standards for Evidence suggest that the public is and so are beyond the scope of this analysis. new subsonic jets. Subsequent analysis increasingly sensitive to airport noise 2 See Nickol (2018). Another way of expressing concluded that new SSTs are unlikely sonic boom intensities is via the metric of (UK Civil Aviation Authority, 2017). For atmospheric overpressure measured in to achieve fuel burn parity compared example, Washington, D.C., metro area pounds per square foot (psf). Relative to a with current subsonic business class airport noise complaints