May 01, 2017

EPA's Endangerment Finding for Aircraft Emissions: How Should the Airline Industry Respond

Brett A. Shanks

Reprinted with permission from The Air & Space Lawyer, Spring 2017 (30:1), at 1, 19–22. Copyright © 2017 American Bar Association. All rights reserved. This information or any or portion thereof may not be copied or disseminated in any form or by any means or stored in an electronic database or retrieval system without the express written consent of the American Bar Association.

The general aviation fleet in the United States includes more than 200,000 aircraft that flew over 23 million miles in 2015.1 Total mainline air carrier and regional enplanements exceeded 785 million that year, and the Federal Aviation Administration (FAA) forecasts that number will increase to 1.24 billion by 2036.2 Total air traffic worldwide produced 781 million tons of carbon dioxide (CO2) in 2015,3 and the FAA projects that aircraft greenhouse gas (GHG) emissions will increase by 60 percent by the year 2025.4 GHGs are linked to historical changes in the global atmosphere, which is commonly referred to as climate change or global warming.5

On August 15, 2016, in light of these statistics and the national focus on reducing GHGs, the Environmental Protection Agency (EPA) published its “Finding That Greenhouse Gas Emissions from Aircraft Cause or Contribute to Air Pollution That May Reasonably Be Anticipated to Endanger Public Health and Welfare.”6 The finding, commonly known as an “endangerment finding,” states that “six well-mixed GHGs from certain classes of engines used in certain aircraft cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.”7 The finding itself does not impose obligations on any party except the EPA, which, pursuant to the Clean Air Act (CAA), must now engage in formal rulemaking to control or reduce aircraft emissions. It is unclear what standards or obligations this rulemaking may seek to impose on aircraft manufacturers and other stakeholders.8

This article describes the EPA’s obligations following its endangerment finding, the international context in which the EPA reached its finding, and the ways in which the aviation industry may decide to respond.




The Clean Air Act and the EPA

The CAA establishes a statutory framework by which the EPA, using its rulemaking and enforcement authority, implements the CAA’s stated goals. These include: (1) controlling ambient levels of air pollutants across the United States, (2) limiting human exposure to hazardous air pollutants, (3) protecting and improving air visibility in “important natural areas,” (4) reducing emissions that cause or contribute to acid rain, and (5) stopping the use of chemicals that destroy stratospheric ozone.9

In the 1970 amendments to the CAA, Congress directed the EPA administrator to investigate aircraft emissions to determine “the extent to which such emissions affect air quality in air quality control regions throughout the United States, and . . . the technological feasibility of controlling such emissions.”10 The CAA requires the administrator “from time to time” to issue regulations governing aircraft emissions whenever, in the administrator’s judgment, such emissions “cause[], or contribute[] to, air pollution which may reasonably be anticipated to endanger public health or welfare.”11

From an environmental regulatory standpoint, aircraft emissions fall into a unique situation. On the one hand, because the FAA has authority to regulate aircraft in the national airspace, that agency’s Office of Environment and Energy has a role in the regulation of aircraft emissions.12 On the other hand, the EPA is tasked with issuing standards for pollutants emitted from aircraft engines.13 To alleviate issues that could be caused by this dual-agency authority, the CAA requires the EPA administrator to consult with the FAA administrator prior to promulgating aircraft emissions standards.14 Further, because of the emphasis placed on safety, the president may disapprove any aircraft emissions rule based on a finding by the secretary of transportation that the regulation would pose a hazard to public safety.15

By issuing this endangerment finding that the six well-mixed GHGs may reasonably be anticipated to endanger public health or welfare, the EPA, under the CAA, is now required to initiate a rulemaking to “issue proposed emission standards.” While that obligation may be clear, it remains uncertain what those standards will be and when they will be proposed and implemented.




The International Civil Aviation Organization (ICAO)

The EPA’s endangerment finding did not emerge in a vacuum, nor did it come as a surprise.16 As the EPA pointed out in the text of the endangerment finding, its decision to issue its finding was based, at least in part, on the ICAO’s decision to regulate CO2 emissions in international aviation.

The ICAO is a United Nations specialized agency created by the Convention on International Civil Aviation, which is a multilateral treaty commonly called the Chicago Convention.17 Its stated purpose is to develop international civil aviation in a safe and orderly manner “on the basis of equality of opportunity[,] operated soundly and economically.”18 Pursuant to the Chicago Convention, member states like the United States that participate in international civil aviation must comply with any standards agreed upon by the ICAO.

For many years, the ICAO has been considering aviation emissions issues, and made clear its intent to issue new standards.19 On October 6, 2016, the ICAO finally agreed to recommend adoption of its long-awaited Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).20 CORSIA is a global market-based measure whereby CO2 emissions that exceed prescribed limits for the aviation sector must be offset by reducing CO2 emissions in another sector.21

Environmental activists have criticized the new ICAO standards as “weak” and demanded that the EPA issue stricter standards.22 The EPA has indicated that the rulemaking it intends to promulgate will be “at least as stringent” as the ICAO standards, which some commentators have interpreted as reflecting an intent to issue stricter rules than CORSIA.23




Aviation Industry Options

Facing an apparently imminent rulemaking and a potential outcry from environmental advocacy groups, how should the aviation industry respond? The industry has three broad options: (1) do nothing and hope that the Trump administration, seemingly hostile to climate change regulation, will put a halt to any aircraft emissions rulemaking;24 (2) fight the rulemaking through litigation; or (3) work with the EPA and advocate for adoption of standards that are at least tolerable to the industry.

Based on the Trump administration’s anti-regulation agenda, some uncertainty exists about what will happen in the aftermath of the aircraft emission endangerment finding with a new presidential (and EPA) administration.25 Some speculate that the president could issue an executive order specifically directed at rolling back GHG emissions rules.26 Alternatively, with Republican majorities in both the U.S. House of Representatives and the Senate, the endangerment finding itself could be stricken pursuant to the Congressional Review Act, thereby eliminating the EPA’s obligation to initiate a rulemaking.27

However, contrary to this speculation, doing nothing is likely not an option because the CAA requires a formal rulemaking process now that the final endangerment finding has been published in the Federal Register. Even if President Trump were to instruct the EPA to do nothing, the CAA allows anyone to sue the EPA administrator “where there is alleged a failure of the Administrator to perform any act or duty under [the CAA] which is not discretionary.”28 So-called “citizen suits” are commonplace, and environmental activist groups like the Sierra Club are willing to sue the EPA to enforce the CAA.29 The EPA has an entire website devoted to citizen suits—more than 50 notices of intent to file suit were issued to the EPA under the CAA in 2016.30 In fact, a citizen suit was filed against the EPA in April 2016 for unreasonable delay in issuing the endangerment finding for aircraft emissions.31 Because a failure to issue any rule following the endangerment finding is contrary to the plain language of the statute, a citizen suit seems a likely response to any delay by the EPA in proceeding with a rulemaking. Furthermore, notwithstanding recent commentary about the Congressional Review Act, that statute has been rarely invoked.32

Second, choosing to fight any rule that the EPA may promulgate would involve considerable risk, time, and cost. Although the U.S. Supreme Court recently stayed implementation of the EPA’s Clean Power Plan pending judicial review, such a stay is unusual.33 Federal agencies enjoy deference in rulemaking actions, and vigorously defend themselves against legal challenges. Thus, if the aviation industry were to bring a court challenge to an aircraft emissions rule, the industry would spend years paying attorney fees for an uncertain result.

Perhaps more important than the above considerations is the practical concern that, regardless of U.S. law, aircraft manufacturers must comply with the ICAO standards in order for their new aircraft to operate internationally. Therefore, it is in the industry’s best interests for any EPA rule to correspond to the ICAO standards. Rather than hoping a Trump administration does something drastic or litigating this matter for years, the industry should urge the EPA to adopt the ICAO standards, as the industry will have to comply with them anyway.

A recent example of an industry working with the EPA to reach a mutually satisfactory outcome is the EPA’s GHG rule for commercial trucks.34 As with aircraft emissions, the commercial truck rulemaking began with the EPA issuing an endangerment finding.35 The commercial trucking industry, labor unions, and other interested stakeholders then worked with the EPA to agree on emissions standards and a timeline for implementation.36

The same process could work here, particularly in a new political environment in which the EPA under the new presidential administration may be more sympathetic to the industry’s perspective and concerns.37 Further, the EPA already has a set of standards on which to base its rulemaking in the form of the ICAO’s CORSIA agreement.





The EPA’s recent endangerment finding regarding aircraft GHG emissions obligates the agency to promulgate rules restricting those emissions. If Congress or the Trump administration does not reverse the finding, the aviation industry will have to decide whether to ignore the EPA’s proposed regulatory action and hope for the best, litigate to obstruct it at significant expense, or, as this author advocates, work with the EPA and encourage it to adopt the same standards as the ICAO.





1. Fact Sheet—FAA Forecast Fact Sheet—Fiscal Years 2016–2036, FAA (Mar. 24, 2016),

2. Id.

3. Facts & Figures, Air Transport Action Group (May 2016),

4. Office Of Env’t & Energy, FAA, Aviation & Emissions: A Primer 10 (2005).

5. See, e.g., Gabriele C. Hegerl & Ulrich Cubasch, Greenhouse Gas Induced Climate Change, 3 Envtl. Sci. & Pollution Res. 99 (1996). Climate change is also frequently associated with predicted future events that are of near-apocalyptic proportions. See, e.g., EPA Ruling on Aircraft Emissions Paves Way for New Regulations, Guardian, July 26, 2016, (“Public health will suffer as heatwaves become more frequent and intense, rising seas inundate coastal cities, extreme storms lead to more deaths and catastrophic wildfires burn more forests and reduce air quality.”).

6. 81 Fed. Reg. 54,422 (Aug. 15, 2016).

7. Id. at 54,423. “Well-mixed” refers to how these particular chemicals have long lifetimes and mix with the global atmosphere, as compared to chemicals that only create an increase in local concentrations. Kassie Siegel et al., Strong Law, Timid Implementation: How the EPA Can Apply the Full Force of the Clean Air Act to Address the Climate Crisis, 30 UCLA J. Envtl. L. & Pol’y 185, 216 (2012).

8. The endangerment finding exempts turboprops, piston-engine aircraft, helicopters, and military aircraft. 81 Fed. Reg. at 54,461. The deadlines to judicially or administratively challenge the endangerment finding have expired. The only known challenge came from a group called Biogenic CO2 Coalition, which filed both a judicial and an administrative challenge on October 14, 2016. Abby Smith, Agricultural Groups Challenge EPA Aircraft GHG Finding, Seeking Exclusion, InsideEPA/climate (Oct. 20, 2016), The coalition asked that the EPA “categorically exclude . . . emissions resulting from the combustion of biofuels derived from annual herbaceous crops.” The judicial challenge was stayed on November 16, 2016, to allow the parties to negotiate outside of court how best to handle the biofuel issue. Biogenic CO2 Coalition v. EPA, No. 16-1358 (D.C. Cir. Nov. 16, 2016). The EPA denied the coalition’s petition for reconsideration on December 21, 2016. Reconsideration of Finding That Greenhouse Gas Emissions from Aircraft Cause or Contribute to Air Pollution That May Reasonably Be Anticipated to Endanger Public Health and Welfare, 81 Fed. Reg. 96,413 (Dec. 30, 2016) (Docket ID No. EPA-HQ-OAR-2014-0828).

9. McCoy & Assocs., Inc., McCoy’s CAA Unraveled 3–4 (2009).

10. 42 U.S.C. § 7571.                                                   

11. Id. § 7571(a)(2)(A).

12. Kathryn Kisska-Schulze & Gregory P. Tapis, Projections for Reducing Aircraft Emissions, 77 J. Air L. & Com. 701, 710 (2012).

13. 42 U.S.C. § 7571(a)(2)(A).

14. Id. § 7571(a)(2)(B).

15. Id. § 7571(c).

16.   Jad Mouawad & Coral Davenport, E.P.A. Takes Step to Cut Emissions from Planes, N.Y. Times, June 10, 2015,

17. Convention on International Civil Aviation, Dec. 7, 1944, ICAO Doc. No. 7300/9, 15 U.N.T.S. 295. The United States is a signatory party to this multilateral treaty.

18. Id. at pmbl.

19. Intergovernmental Panel on Climate Change [IPCC], Aviation and the Global Atmosphere (1999),

20. Press Release, ICAO, Historic Agreement Reached to Mitigate International Aviation Emissions (Oct. 6, 2016),

21. What Is CORSIA and How Does It Work?, ICAO, (last visited April 10, 2017).

22. Abby Smith & Doug Obey, EPA Eyes Options on Aircraft GHG Rule as Industry Pushes ICAO Standard, InsideEPA/climate (Oct. 19, 2016),

23. See, e.g., id. (“EPA is reiterating its stance that it has the option to issue domestic standards for new and in-production aircraft that are stronger than global limits for such sources, despite adamant arguments from industry groups that the agency should simply translate the international standards into domestic law.”).

24. Even before President Trump took office, airline trade associations were urging the adoption of the ICAO standards without modification. Letter from Nicholas E. Calio, President & CEO, Airlines for America, et al., to Gina McCarthy, Adm’r, EPA & Michael P. Huerta, Adm’r, FAA (Feb. 6, 2015), Generally speaking, the largest industry groups (like the International Air Transport Association (IATA)) support the ICAO’s CORSIA standards. See, e.g., Press Release, IATA, Airlines Support ICAO on Cusp of Historic Emissions Agreement (Sept. 27, 2016),

25. Ira Kasdan & Mindy Pava, Option for Deregulation under the Trump Administration: Agency Non-Enforcement, Hill ( Jan. 4, 2017),; see also Memorandum for the Heads of Executive Departments and Agencies; Regulatory Freeze Pending Review, 82 Fed. Reg. 8346 (Jan. 24, 2017).

26. Jim Park, Could New Administration, Congress Scuttle GHG Phase 2 Rule?, Truckinginfo ( Jan. 6, 2017),

27. 5 U.S.C. §§ 801–808. Indeed, the Atlantic has cited several Republican-linked sources, including a direct quote from Sen. John Cornyn, asserting that the Congressional Review Act may be used to roll back Obama administration rules. Michelle Cottle, How Republicans Plan to Roll Back Obama-Era Regulations, Atlantic (Jan. 6, 2017),

28. 42 U.S.C. § 7604.

29. Eugene C. McCall & Ryan W. Trail, Citizen Suits to Enforce Federal Environmental Laws, S.C. Law., July 2011, at 35.

30. Notices of Intent to Sue the U.S. Environmental Protection Agency Documents, EPA, (last updated Mar. 20, 2017).

31. Ctr. for Biological Diversity v. EPA, No. 1:16-cv-00681, 2016 WL 7157051 (D.D.C. Sept. 9, 2016). This case was resolved when the EPA issued the endangerment finding in August 2016.

32. Stuart Shapiro, The Congressional Review Act, Rarely Used and (Almost Always) Unsuccessful, Hill (Apr. 17, 2015),

33. Lyle Denniston, Carbon Pollution Controls Put on Hold, SCOTUSblog (Feb. 9, 2016),

34. Greenhouse Gas Emissions and Fuel Efficiency Standards for Mediumand Heavy-Duty Engines and Vehicles—Phase 2, 81 Fed. Reg. 73,478 (Oct. 25, 2016).

35. Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496 (Dec. 15, 2009).

36. Press Release, EPA, EPA and DOT Finalize Greenhouse Gas and Fuel Efficiency Standards for Heavy-Duty Trucks (Aug. 18, 2016),

37. S.A. Miller, Open for Business: Trump Creating Commerce-Friendly White House, Wash. Times, Nov. 30, 2016,


Brett A. Shanks



Brett A. Shanks is an attorney at Stinson Leonard Street LLP in the firm’s Kansas City office. His practice focuses on aviation defense, environmental compliance, and environmental litigation matters. He may be reached at