2136 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 87 and 1030 

[EPA–HQ–OAR–2018–0276; FRL–10018–45– 

OAR] 

RIN 2060–AT26 

Control of Air Pollution From Airplanes 

and Airplane Engines: GHG Emission 

Standards and Test Procedures 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is adopting greenhouse 

gas (GHG) emission standards 

applicable to certain classes of engines 

used by certain civil subsonic jet 

airplanes with a maximum takeoff mass 

greater than 5,700 kilograms and by 

certain civil larger subsonic propellerdriven airplanes with turboprop engines 

having a maximum takeoff mass greater 

than 8,618 kilograms. These standards 

are equivalent to the airplane carbon 

dioxide (CO2) standards adopted by the 

International Civil Aviation 

Organization (ICAO) in 2017 and apply 

to both new type design airplanes and 

in-production airplanes. The standards 

in this rule reflect U.S. efforts to secure 

the highest practicable degree of 

international uniformity in aviation 

regulations and standards. The 

standards also meet the EPA’s obligation 

under section 231 of the Clean Air Act 

(CAA) to adopt GHG standards for 

certain classes of airplanes as a result of 

the 2016 ‘‘Finding That Greenhouse Gas 

Emissions From Aircraft Cause or 

Contribute to Air Pollution That May 

Reasonably Be Anticipated To Endanger 

Public Health and Welfare’’ (hereinafter 

‘‘2016 Findings’’)—for six well-mixed 

GHGs emitted by certain classes of 

airplane engines. Airplane engines emit 

only two of the six well-mixed GHGs, 

CO2 and nitrous oxide (N2O). 

Accordingly, EPA is adopting the fuelefficiency-based metric established by 

ICAO, which will control both the GHGs 

emitted by airplane engines, CO2 and 

N2O. 

DATES: This final rule is effective on 

January 11, 2021. The incorporation by 

reference of certain publications listed 

in this regulation is approved by the 

Director of the Federal Register as of 

January 11, 2021. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2018–0276. All 

documents are listed on the http://

www.regulations.gov website. Although 

listed in the index, some information is 

not publicly available, e.g., confidential 

business information (CBI) or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the internet and will be 

publicly available only in hard copy 

form. Publicly available docket 

materials are available either 

electronically through http://

www.regulations.gov or in hard copy at 

Air and Radiation Docket and 

Information Center, EPA Docket Center, 

EPA/DC, EPA WJC West Building, 1301 

Constitution Ave. NW, Room 3334, 

Washington, DC. Note that the EPA 

Docket Center and Reading Room were 

closed to public visitors on March 31, 

2020, to reduce the risk of transmitting 

COVID–19. The Docket Center staff will 

continue to provide remote customer 

service via email, phone, and webform. 

The telephone number for the Public 

Reading Room is (202) 566–1744, and 

the telephone number for the Air Docket 

is (202) 566–1742. For further 

information on EPA Docket Center 

services and the current status, go to 

https://www.epa.gov/dockets. 

FOR FURTHER INFORMATION CONTACT: 

Bryan Manning, Office of 

Transportation and Air Quality, 

Assessment and Standards Division 

(ASD), Environmental Protection 

Agency, 2000 Traverwood Drive, Ann 

Arbor, MI 48105; telephone number: 

(734) 214–4832; email address: 

manning.bryan@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. General Information 

A. Does this action apply to me? 

B. Did EPA conduct a peer review before 

issuing this action? 

C. Basis for Immediate Effective Date 

D. Judicial Review and Adminstrative 

Reconsideration 

E. Executive Summary 

II. Introduction: Overview and Context for 

This Action 

A. Summary of Final Rule 

B. EPA Statutory Authority and 

Responsibilities Under the Clean Air Act 

C. Background Information Helpful to 

Understanding This Action 

D. U.S. Airplane Regulations and the 

International Community 

E. Consideration of Whole Airplane 

Characteristics 

III. Summary of the 2016 Findings 

IV. EPA’s Final GHG Standards for Covered 

Airplanes 

A. Airplane Fuel Efficiency Metric 

B. Covered Airplane Types and 

Applicability 

C. GHG Standard for New Type Designs 

D. GHG Standard for In-Production 

Airplane Types 

E. Exemptions From the GHG Standards 

F. Application of Rules for New Version of 

an Existing GHG-Certificated Airplane 

G. Test and Measurement Procedures 

H. Controlling Two of the Six Well-Mixed 

GHGs 

I. Response to Key Comments 

V. Aggregate GHG and Fuel Burn Methods 

and Results 

A. What methodologies did the EPA use for 

the emissions inventory assessment? 

B. What are the baseline GHG emissions? 

C. What are the projected effects in fuel 

burn and GHG emissions? 

VI. Technological Feasibility and Economic 

Impacts 

A. Market Considerations 

B. Conceptual Framework for Technology 

C. Technological Feasibility 

D. Costs Associated With the Program 

E. Summary of Benefits and Costs 

VII. Aircraft Engine Technical Amendments 

VIII. Statutory Authority and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

B. Executive Order 13771: Reducing 

Regulation and Controlling Regulatory 

Costs 

C. Paperwork Reduction Act (PRA) 

D. Regulatory Flexibility Act (RFA) 

E. Unfunded Mandates Reform Act 

(UMRA) 

F. Executive Order 13132: Federalism 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

H. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

I. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution or Use 

J. National Technology Transfer and 

Advancement Act (NTTAA) and 1 CFR 

Part 51 

K. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

L. Congressional Review Act 

I. General Information 

A. Does this action apply to me? 

This action will affect companies that 

manufacture civil subsonic jet airplanes 

that have a maximum takeoff mass 

(MTOM) of greater than 5,700 kilograms 

and civil subsonic propeller driven 

airplanes (e.g., turboprops) that have a 

MTOM greater than 8,618 kilograms, 

including the manufacturers of the 

engines used on these airplanes. 

Affected entities include the following: 

Category NAICS code a

Examples of 

potentially 

affected entities 

Industry 336412 Manufacturers of 

new aircraft engines. 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2137 

1OMB, 2004: Memorandum for Heads of 

Departments and Agencies, Final Information 

Quality Bulletin for Peer Review. Available at 

https://www.whitehouse.gov/sites/whitehouse.gov/ 

files/omb/memoranda/2005/m05-03.pdf. 

2 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

3U.S. EPA, 2020: Technical Report on Aircraft 

Emissions Inventory and Stringency Analysis, July 

2020, 52pp. 

4RTI International and EnDyna, Aircraft CO2 

Cost and Technology Refresh and Aerospace 

Industry Characterization: Peer Review, June 2018, 

114pp. 

5RTI International and EnDyna, EPA Technical 

Report on Aircraft Emissions Inventory and 

Stringency Analysis: Peer Review, July 2019, 157pp. 

Category NAICS code a

Examples of 

potentially 

affected entities 

Industry 336411 Manufacturers of 

new aircraft. 

a North American Industry Classification 

System (NAICS) 

This table lists the types of entities 

that EPA is now aware could potentially 

be affected by this action. Other types of 

entities not listed in the table might also 

be subject to these regulations. To 

determine whether your activities are 

regulated by this action, you should 

carefully examine the relevant 

applicability criteria in 40 CFR parts 87 

and 1030. If you have any questions 

regarding the applicability of this action 

to a particular entity, consult the person 

listed in the preceding FOR FURTHER

INFORMATION CONTACT section. 

For consistency purposes across the 

United States Code of Federal 

Regulations (CFR), the terms ‘‘airplane,’’ 

‘‘aircraft,’’ and ‘‘civil aircraft’’ have the 

meanings found in title 14 CFR 1.1 and 

are used as appropriate throughout the 

new regulation under 40 CFR part 1030. 

B. Did EPA conduct a peer review before 

issuing this action? 

This regulatory action is supported by 

influential scientific information. 

Therefore, the EPA conducted peer 

reviews consistent with the Office of 

Management and Budget’s (OMB’s) 

Final Information Quality Bulletin for 

Peer Review.1 Two different reports 

used in support of this action 

underwent peer review; a report 

detailing the technologies likely to be 

used in compliance with the standards 

and their associated costs 2 and a report 

detailing the methodology and results of 

the emissions inventory modeling.3

These reports were each peer-reviewed 

through external letter reviews by 

multiple independent subject matter 

experts (including experts from 

academia and other government 

agencies, as well as independent 

technical experts).4 5 The peer review 

reports and the Agency’s response to the 

peer review comments are available in 

Docket ID No. EPA–HQ–OAR–2018– 

0276. 

C. Basis for Immediate Effective Date 

This rule is subject to the rulemaking 

procedures in section 307(d) of the 

Clean Air Act (CAA). See CAA section 

307(d)(1)(F). Section 307(d)(1) of the 

CAA states that: ‘‘The provisions of 

section 553 through 557 * * * of Title 

5 shall not, except as expressly provided 

in this subsection, apply to actions to 

which this subsection applies.’’ Thus, 

section 553(d) of the Administrative 

Procedure Act (APA), which requires 

publication of a substantive rule to be 

made ‘‘not less than 30 days before its 

effective date’’ subject to limited 

exceptions, does not apply to this 

action. In the alternative, the EPA 

concludes that it is consistent with APA 

section 553(d) to make this action 

effective January 11, 2021. 

Section 553(d)(3) of the APA, 5 U.S.C. 

553(d)(3), provides that final rules shall 

not become effective until 30 days after 

publication in the Federal Register 

‘‘except . . . as otherwise provided by 

the agency for good cause found and 

published with the rule.’’ ‘‘In 

determining whether good cause exists, 

an agency should ‘balance the necessity 

for immediate implementation against 

principles of fundamental fairness 

which require that all affected persons 

be afforded a reasonable amount of time 

to prepare for the effective date of its 

ruling.’’ Omnipoint Corp. v. Fed. 

Commc’n Comm’n, 78 F.3d 620, 630 

(D.C. Cir. 1996) (quoting United States 

v. Gavrilovic, 551 F.2d 1099, 1105 (8th 

Cir. 1977)). The purpose of this 

provision is to ‘‘give affected parties a 

reasonable time to adjust their behavior 

before the final rule takes effect.’’ Id.; 

see also Gavrilovic, 551 F.2d at 1104 

(quoting legislative history). 

As discussed in the notice of 

proposed rulemaking, and below, the 

standards adopted here are meant to be 

technology following standards that 

align with international standards that 

were previously adopted in 2017 by 

ICAO. This means the rule reflects the 

performance and technology achieved 

by existing airplanes. Moreover, the 

EPA is not aware of any manufacturers 

who would seek certification of any new 

type design airplanes in the near future, 

such that making the rule effective 

immediately upon publication could 

disrupt their certification plans. The 

EPA is determining that in light of the 

nature of this action, good cause exists 

to make this final rule effective 

immediately because the Agency seeks 

to provide regulatory certainty as soon 

as possible and no party will be harmed 

by an immediate effective date since 

there is no need to provide a delay of 

30 days after publication for parties to 

adjust their behavior prior to the 

effective date. Accordingly, the EPA is 

making this rule effective immediately 

upon publication. 

D. Judicial Review and Administrative 

Reconsideration 

Under Clean Air Act (CAA) section 

307(b)(1), judicial review of this final 

action is available only by filing a 

petition for review in the United States 

Court of Appeals for the District of 

Columbia Circuit by March 12, 2021. 

Under CAA section 307(b)(2), the 

requirements established by this final 

rule may not be challenged separately in 

any civil or criminal proceedings 

brought by the EPA to enforce the 

requirements. 

Section 307(d)(7)(B) of the CAA 

further provides that only an objection 

to a rule or procedure which was raised 

with reasonable specificity during the 

period for public comment (including 

any public hearing) may be raised 

during judicial review. This section also 

provides a mechanism for the EPA to 

reconsider the rule if the person raising 

an objection can demonstrate to the 

Administrator that it was impracticable 

to raise such objection within the period 

for public comment or if the grounds for 

such objection arose after the period for 

public comment (but within the time 

specified for judicial review) and if such 

objection is of central relevance to the 

outcome of the rule. Any person seeking 

to make such a demonstration should 

submit a Petition for Reconsideration to 

the Office of the Administrator, U.S. 

EPA, Room 3000, WJC South Building, 

1200 Pennsylvania Ave. NW, 

Washington, DC 20460, with a copy to 

both the person(s) listed in the 

preceding FOR FURTHER INFORMATION

CONTACT section, and the Associate 

General Counsel for the Air and 

Radiation Law Office, Office of General 

Counsel (Mail Code 2344A), U.S. EPA, 

1200 Pennsylvania Ave. NW, 

Washington, DC 20460 

E. Executive Summary 

1. Purpose of This Regulatory Action 

One of the core functions of the 

International Civil Aviation 

Organization (ICAO) is to adopt 

Standards and Recommended Practices 

on a wide range of aviation-related 

matters, including aircraft emissions. As 


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2138 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

6 ICAO, 2006: Convention on International Civil 

Aviation, Ninth Edition, Document 7300/9, Article 

37, 114 pp. Available at: http://www.icao.int/ 

publications/Documents/7300_9ed.pdf (last 

accessed October 27, 2020). 

7U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

a member State of ICAO, the United 

States seeks to secure the highest 

practicable degree of international 

uniformity in aviation regulations and 

standards.6 ICAO adopted airplane CO2

standards in 2017. The adoption of 

these aviation standards into U.S. law 

will align with the ICAO standards. For 

reasons discussed herein, the EPA is 

adopting standards for GHG emissions 

from certain classes of engines used on 

covered airplanes (hereinafter ‘‘covered 

airplanes’’ or ‘‘airplanes’’) that are 

equivalent in scope, stringency and 

timing to the CO2 standards adopted by 

ICAO. 

These standards will ensure control of 

GHG emissions, maintain international 

uniformity of airplane standards, and 

allow U.S. manufacturers of covered 

airplanes to remain competitive in the 

global marketplace. In the absence of 

U.S. standards for implementing the 

ICAO Airplane CO2 Emission Standards, 

U.S. civil airplane manufacturers could 

be forced to seek CO2 emissions 

certification from an aviation 

certification authority of another 

country (not the Federal Aviation 

Administration (FAA)) in order to 

market and operate their airplanes 

internationally. We anticipate U.S. 

manufacturers would be at a significant 

disadvantage if the U.S. failed to adopt 

standards that are harmonized with the 

ICAO standards for CO2 emissions. The 

ICAO Airplane CO2 Emission Standards 

have been adopted by other ICAO 

member states that certify airplanes. The 

action to adopt in the U.S. GHG 

standards that match the ICAO Airplane 

CO2 Emission Standards will help 

ensure international consistency and 

acceptance of U.S. manufactured 

airplanes worldwide. 

In August 2016, the EPA issued two 

findings regarding GHG emissions from 

aircraft engines (the 2016 Findings).7

First, the EPA found that elevated 

concentrations of GHGs in the 

atmosphere endanger the public health 

and welfare of current and future 

generations within the meaning of 

section 231(a)(2)(A) of the CAA. Second, 

EPA found that emissions of GHGs from 

certain classes of engines used in certain 

aircraft are contributing to the air 

pollution that endangers public health 

and welfare under CAA section 

231(a)(2)(A). Additional details of the 

2016 Findings are described in Section 

III. As a result of the 2016 Findings, 

CAA sections 231(a)(2)(A) and (3) 

obligate the EPA to propose and adopt, 

respectively, GHG standards for these 

covered aircraft engines. 

2. Summary of the Major Provisions of 

This Regulatory Action 

The EPA is regulating GHG emissions 

from covered airplanes through the 

adoption of domestic GHG regulations 

that match international standards to 

control CO2 emissions. The GHG 

standards finalized in this action are 

equivalent to the CO2 standards adopted 

by ICAO and will be implemented and 

enforced in the U.S. The standards 

apply to covered airplanes: Civil 

subsonic jet airplanes (those powered by 

turbojet or turbofan engines and with a 

MTOM greater than 5,700 kilograms), as 

well as larger civil subsonic propellerdriven airplanes (those powered by 

turboprop engines and with a MTOM 

greater than 8,618 kilograms). The 

timing and stringencies of the standards 

differ depending on whether the 

covered airplane is a new type design 

(i.e., a design that has not previously 

been type certificated under title 14 

CFR) or an in-production model (i.e., an 

existing design that had been type 

certificated under title 14 CFR prior to 

the effective date of the GHG standards). 

The standards for new type designs 

apply to covered airplanes for which an 

application for certification is submitted 

to the FAA on or after January 11, 2021 

(January 1, 2023, for new type designs 

that have a maximum takeoff mass 

(MTOM) of 60,000 kilograms MTOM or 

less and have 19 passenger seats or 

fewer). The in-production standards 

apply to covered airplanes beginning 

January 1, 2028. Additionally, 

consistent with ICAO standards, before 

the in-production standards otherwise 

apply in 2028, certain modifications 

made to airplanes (i.e., changes that 

result in an increase in GHG emissions) 

will trigger a requirement to certify to 

the in-production regulation beginning 

January 1, 2023. Some minor technical 

corrections have been made to the 

proposed regulatory text in this action 

to further clarify that the standards do 

not apply to in-service airplanes or 

military airplanes. 

The EPA is adopting the ICAO CO2

metric, which measures fuel efficiency, 

for demonstrating compliance with the 

GHG emission standards. This metric is 

a mathematical function that 

incorporates the specific air range (SAR) 

of an airplane/engine combination (a 

traditional measure of airplane cruise 

performance in units of kilometer/ 

kilogram of fuel) and the reference 

geometric factor (RGF), a measure of 

fuselage size. The metric is further 

discussed in Section IV.A. 

To measure airplane fuel efficiency, 

the EPA is adopting the ICAO test 

procedures whereby the airplane/engine 

SAR value is measured at three specific 

operating test points, and a composite of 

those results is used in the metric to 

determine compliance with the GHG 

standards. The test procedures are 

discussed in Section IV.G. 

The EPA proposed an annual 

reporting provision which would have 

required manufacturers of covered 

airplanes to submit to the EPA 

information on airplane characteristics, 

emissions characteristics and 

production volumes. Commenters raised 

several issues such as duplicative 

reporting burdens with FAA and ICAO, 

risks to confidential business 

information, and higher costs associated 

with the reporting requirement than 

EPA projections. The Agency is not 

adopting the proposed annual reporting 

provisions. Further information on 

those comments and the EPA’s response 

can be found in the Response to 

Comments (RTC) document 

accompanying this action. Further 

information on all aspects of the GHG 

standards can be found in Section IV. 

Finally, as proposed, the EPA is 

updating the existing incorporation by 

reference of the ICAO test procedures 

for hydrocarbons (HC), carbon 

monoxide (CO), oxides of nitrogen 

(NOX) and smoke to reference the most 

recent edition of the ICAO procedures. 

This update will improve clarity in the 

existing test procedures and includes a 

minor change to the composition of the 

test fuel used for engine certification. 

Further details on this technical 

amendment can be found in Section VII. 

3. Costs and Benefits 

Given the significant international 

market pressures to continually improve 

the fuel efficiency of their airplanes, 

U.S. manufacturers have already 

developed or are developing 

technologies that will allow affected 

airplanes to comply with the ICAO 

standards, in advance of EPA’s adoption 

of standards. Many airplanes 

manufactured by U.S. manufacturers 

already met the ICAO standards at the 

time of their adoption and thus already 

meet the standards contained in this 

action. Furthermore, based on the 

manufacturers’ expectation that the 

ICAO standards will be implemented 

globally, the EPA anticipates nearly all 

affected airplanes to be compliant by the 

respective effective dates for new type 

designs and for in-production airplanes 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2139 

8 ICAO, 2006: Convention on International Civil 

Aviation, Ninth Edition, Document 7300/9, 114 pp. 

Available at: http://www.icao.int/publications/ 

Documents/7300_9ed.pdf (last accessed October 27, 

2020). 

9U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare and Advance 

Notice of Proposed Rulemaking; Final Rule, 81 FR 

54422 (August 15, 2016). 

10Covered airplanes are those airplanes to which 

the international CO2 standards and the GHG 

standards apply: subsonic jet airplanes with a 

maximum takeoff mass (MTOM) greater than 5,700 

kilograms and subsonic propeller-driven (e.g., 

turboprop) airplanes with a MTOM greater than 

8,618 kilograms. Section IV describes covered and 

non-covered airplanes in further detail. 

ICAO, 2016: Tenth Meeting Committee on 

Aviation Environmental Protection Report, Doc 

10069, CAEP/10, 432 pp, Available at: http://

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed October 27, 2020). The ICAO CAEP/ 

10 report is found on page 27 of the English Edition 

2020 catalog and is copyright protected; Order No. 

10069. 

11 ICAO’s certification standards and test 

procedures for airplane CO2 emissions are based on 

the consumption of fuel (or fuel burn) under 

prescribed conditions at optimum cruise altitude. 

ICAO uses the term, CO2, for its standards and 

procedures, but ICAO is actually regulating or 

measuring the rate of an airplane’s fuel burn (fuel 

efficiency). For jet fuel, the emissions index or 

emissions factor for CO2 is 3.16 kilograms of CO2

per kilogram of fuel burn (or 3,160 grams of CO2

per kilogram of fuel burn). Thus, to convert an 

airplane’s rate of fuel burn to a CO2 emissions rate, 

this emission index needs to be applied. 

12Previous EPA rulemakings for aircraft engine 

regulations are described later in section II.D.2. 

(see Section IV.I.2 for further 

information on affected airplanes). The 

EPA’s business as usual baseline 

projects that even independent of the 

ICAO standards, nearly all airplanes 

produced by U.S. manufacturers will 

meet the ICAO in-production standards 

in 2028. This result is not surprising, 

given the significant market pressure on 

airplane manufacturers to continually 

improve the fuel efficiency of aircraft, 

the significant annual research and 

development expenditures from the 

aircraft industry (much of which is 

focused on fuel efficiency), and the 

more than 50 year track record of the 

industry in developing and selling 

aircraft which have shown continuous 

improvement in fuel efficiency. EPA’s 

assessment includes the expectation 

that existing in-production airplanes 

that are non-compliant will either be 

modified and re-certificated as 

compliant, will likely go out of 

production before the production 

compliance date of January 1, 2028, or 

will seek exemptions from the GHG 

standard. For these reasons, the EPA is 

not projecting emission reductions 

associated with these GHG regulations. 

However, the EPA does note that 

consistency with the international 

standards will prevent backsliding by 

ensuring that all new type design and 

in-production airplanes are at least as 

efficient as today’s airplanes. For further 

details on the benefits and costs 

associated with these GHG standards, 

see Sections V and VI, respectively. 

II. Introduction: Overview and Context 

for this Action 

This section provides a summary of 

the final rule. This section describes the 

EPA’s statutory authority, the U.S. 

airplane engine regulations and the 

relationship with ICAO’s international 

standards, and consideration of the 

whole airplane in addressing airplane 

engine GHG emissions. 

A. Summary of Final Rule 

In February 2016, ICAO’s Committee 

on Aviation Environmental Protection 

(CAEP) agreed to international Airplane 

CO2 Emission Standards, which ICAO 

approved in 2017. The EPA is adopting 

GHG standards that are equivalent to the 

international Airplane CO2 Emission 

Standards promulgated by ICAO in 

Annex 16.8

As a result of the 2016 Findings,9 10

the EPA is obligated under section 

231(a) of the CAA to issue emission 

standards applicable to GHG emissions 

from the classes of engines used by 

covered aircraft included in the 2016 

Findings. As described later in further 

detail in Section III, we are regulating 

the air pollutant that is the aggregate of 

the six well-mixed GHGs. Only two of 

the six well-mixed GHGs—CO2 and N2O 

—have non-zero emissions for total civil 

subsonic airplanes and U.S. covered 

airplanes. CO2 represents 99 percent of 

all GHGs emitted from both total U.S. 

civil airplanes and U.S. covered 

airplanes, and N2O represents 1 percent 

of GHGs emitted from total airplanes 

and U.S. covered airplanes. 

Promulgation of the GHG emission 

standards for the certain classes of 

engines used by covered airplanes will 

fulfill EPA’s obligations under the CAA 

and is the next step for the United States 

in implementing the ICAO standards 

promulgated in Annex 16 under the 

Chicago Convention. We are issuing a 

new rule that controls aircraft engine 

GHG emissions through the use of the 

ICAO regulatory metric that quantifies 

airplane fuel efficiency. 

The rule will establish GHG standards 

applicable to U.S. airplane 

manufacturers that are no less stringent 

than the Airplane CO2 Emission 

Standards adopted by ICAO.11 This rule 

incorporates the same compliance 

schedule as the ICAO Airplane CO2

Emission Standards. The standards will 

apply to both new type designs and inproduction airplanes. The in-production 

standards have later applicability dates 

and different emission levels than do 

the standards for new type designs. The 

different emission levels for new type 

designs and in-production airplanes 

depend on the airplane size, weight, and 

availability of fuel efficiency 

technologies. 

Apart from the GHG requirements, we 

are updating the engine emissions 

testing and measurement procedures 

applicable to HC, NOX, CO, and smoke 

in current regulations. The updates will 

implement recent amendments to ICAO 

standards in Annex 16, Volume II, and 

these updates will be accomplished by 

incorporating provisions of the Annex 

by reference, as has historically been 

done in previous EPA rulemakings.12

B. EPA Statutory Authority and 

Responsibilities Under the Clean Air Act 

Section 231(a)(2)(A) of the CAA 

directs the Administrator of the EPA to, 

from time to time, propose aircraft 

engine emission standards applicable to 

the emission of any air pollutant from 

classes of aircraft engines which in the 

Administrator’s judgment causes or 

contributes to air pollution that may 

reasonably be anticipated to endanger 

public health or welfare. (See 42 U.S.C. 

7571(a)(2)(A)). Section 231(a)(2)(B) 

directs the EPA to consult with the 

Administrator of the FAA on such 

standards, and it prohibits the EPA from 

changing aircraft engine emission 

standards if such a change would 

significantly increase noise and 

adversely affect safety (see 42 U.S.C. 

7571(a)(2)(B)(i)–(ii)). Section 231(a)(3) 

provides that after we propose 

standards, the Administrator shall issue 

such standards ‘‘with such 

modifications as he deems appropriate.’’ 

(see 42 U.S.C. 7571(a)(3)). The U.S. 

Court of Appeals for the D.C. Circuit has 

held that this provision confers an 

unusually broad degree of discretion on 

the EPA to adopt aircraft engine 

emission standards that the Agency 

determines are reasonable. Nat’l Ass’n 

of Clean Air Agencies v. EPA, 489 F.3d 

1221, 1229–30 (D.C. Cir. 2007) 

(NACAA). 

In addition, under CAA section 231(b) 

the EPA is required to ensure, in 

consultation with the U.S. Department 

of Transportation (DOT), that the 

effective date of any standard provides 

the necessary time to permit the 

development and application of the 

requisite technology, giving appropriate 

consideration to the cost of compliance 


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2140 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

13 ICAO, 2006: Convention on International Civil 

Aviation, Ninth Edition, Document 7300/9, 114 pp. 

Available at: http://www.icao.int/publications/ 

Documents/7300_9ed.pdf (last accessed October 27, 

2020). 14Members of ICAO’s Assembly are generally 

termed member States or contracting States. These 

terms are used interchangeably throughout this 

preamble. 15There are currently 193 contracting states 

according to ICAO’s website: https://www.icao.int/ 

MemberStates/Member%20States.English.pdf (last 

accessed March 16, 2020). 

16 ICAO, 2006: Doc 7300-Convention on 

International Civil Aviation, Ninth Edition, 

Document 7300/9, 114 pp. Available at http://

www.icao.int/publications/Documents/7300_

9ed.pdf (last accessed October 27, 2020). 

17 ICAO, 2006: Convention on International Civil 

Aviation, Article 33, Ninth Edition, Document 

7300/9, 114 pp. Available at http://www.icao.int/ 

publications/Documents/7300_9ed.pdf(last 

accessed October 27, 2020). 

18 ICAO, 2006: Convention on International Civil 

Aviation, Article 33, Ninth Edition, Document 

7300/9, 114 pp. Available at http://www.icao.int/ 

publications/Documents/7300_9ed.pdf (last 

accessed October 27, 2020). 

(see 42 U.S.C. 7571(b)). Section 232 then 

directs the Secretary of Transportation 

to prescribe regulations to ensure 

compliance with the EPA’s standards 

(see 42 U.S.C. 7572). Finally, section 

233 of the CAA vests the authority to 

promulgate emission standards for 

aircraft engines only in the Federal 

Government. States are preempted from 

adopting or enforcing any standard 

respecting emissions from aircraft or 

aircraft engines unless such standard is 

identical to the EPA’s standards (see 42 

U.S.C. 7573). 

C. Background Information Helpful to 

Understanding This Action 

Civil airplanes and associated engines 

are international commodities that are 

manufactured and sold around the 

world. The member States of ICAO and 

the world’s airplane and airplane engine 

manufacturers participated in the 

deliberations leading up to ICAO’s 

adoption of the international Airplane 

CO2 Emission Standards. However, 

ICAO’s standards are not directly 

applicable to nor enforceable against 

member States’ airplane and engine 

manufacturers. Instead, after adoption of 

the standards by ICAO, a member State 

is required (as described later in Section 

II.D.1) to adopt domestic standards at 

least as stringent as ICAO standards and 

apply them, as applicable, to subject 

airplane and airplane engine 

manufacturers in order to ensure 

recognition of their airworthiness and 

type certificate by other member State’s 

civil aviation authorities. This 

rulemaking is a necessary step to meet 

this obligation for the United States. 

D. U.S. Airplane Regulations and the 

International Community 

The EPA and the FAA work within 

the standard-setting process of ICAO’s 

CAEP to help establish international 

emission standards and related 

requirements, which individual member 

States adopt into domestic law and 

regulations. Historically, under this 

approach, international emission 

standards have first been adopted by 

ICAO, and subsequently the EPA has 

initiated rulemakings under CAA 

section 231 to establish domestic 

standards that are harmonized with 

ICAO’s standards. After EPA 

promulgates aircraft engine emission 

standards, CAA section 232 requires the 

FAA to issue regulations to ensure 

compliance with the EPA aircraft engine 

emission standards when issuing 

airworthiness certificates pursuant to its 

authority under Title 49 of the United 

States Code. This rule continues this 

historical rulemaking approach. 

1. International Regulations and U.S. 

Obligations 

The EPA has worked with the FAA 

since 1973, and later with ICAO, to 

develop domestic and international 

standards and other recommended 

practices pertaining to aircraft engine 

emissions. The Convention on 

International Civil Aviation (commonly 

known as the ‘Chicago Convention’) was 

signed in 1944 at the Diplomatic 

Conference held in Chicago. The 

Chicago Convention establishes the 

legal framework for the development of 

international civil aviation. The primary 

objective is ‘‘that international civil 

aviation may be developed in a safe and 

orderly manner and that international 

air transport services may be established 

on the basis of equality of opportunity 

and operated soundly and 

economically.’’ 13 In 1947, ICAO was 

established, and later in that same year 

ICAO became a specialized agency of 

the United Nations (UN). ICAO sets 

international standards for aviation 

safety, security, efficiency, capacity, and 

environmental protection and serves as 

the forum for cooperation in all fields of 

international civil aviation. ICAO works 

with the Chicago Convention’s member 

States and global aviation organizations 

to develop international Standards and 

Recommended Practices (SARPs), 

which member States reference when 

developing their domestic civil aviation 

regulations. The United States is one of 

193 currently participating ICAO 

member States.14 15

In the interest of global harmonization 

and international air commerce, the 

Chicago Convention urges its member 

States to ‘‘collaborate in securing the 

highest practicable degree of uniformity 

in regulations, standards, procedures 

and organization in relation to aircraft, 

. . . in all matters which such 

uniformity will facilitate and improve 

air navigation.’’ The Chicago 

Convention also recognizes that member 

States may adopt national standards that 

are more or less stringent than those 

agreed upon by ICAO or standards that 

are different in character or that comply 

with the ICAO standards by other 

means. Any member State that finds it 

impracticable to comply in all respects 

with any international standard or 

procedure, or that determines it is 

necessary to adopt regulations or 

practices differing in any particular 

respect from those established by an 

international standard, is required to 

give notification to ICAO of the 

differences between its own practice 

and that established by the international 

standard.16

ICAO’s work on the environment 

focuses primarily on those problems 

that benefit most from a common and 

coordinated approach on a worldwide 

basis, namely aircraft noise and engine 

emissions. SARPs for the certification of 

aircraft noise and aircraft engine 

emissions are contained in Annex 16 to 

the Chicago Convention. To continue to 

address aviation environmental issues, 

in 2004, ICAO established three 

environmental goals: (1) Limit or reduce 

the number of people affected by 

significant aircraft noise; (2) limit or 

reduce the impact of aviation emissions 

on local air quality; and (3) limit or 

reduce the impact of aviation GHG 

emissions on the global climate. 

The Chicago Convention has a 

number of other features that govern 

international commerce. First, member 

States that wish to use aircraft in 

international transportation must adopt 

emission standards that are at least as 

stringent as ICAO’s standards if they 

want to ensure recognition of their 

airworthiness certificates. Member 

States may ban the use of any aircraft 

within their airspace that does not meet 

ICAO standards.17 Second, the Chicago 

Convention indicates that member 

States are required to recognize the 

airworthiness certificates issued or 

rendered valid by the contracting State 

in which the aircraft is registered 

provided the requirements under which 

the certificates were issued are equal to 

or above ICAO’s minimum standards.18

Third, to ensure that international 

commerce is not unreasonably 

constrained, a member State that cannot 

meet or deems it necessary to adopt 

regulations differing from the 

international standard is obligated to 

notify ICAO of the differences between 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2141 

19 ICAO, 2006: Convention on International Civil 

Aviation, Article 38, Ninth Edition, Document 

7300/9, 114 pp. Available at http://www.icao.int/ 

publications/Documents/7300_9ed.pdf (last 

accessed October 27, 2020). 

20 ICAO: CAEP Terms of Reference. Available at 

http://www.icao.int/environmental-protection/ 

Pages/Caep.aspx#ToR (last accessed March 16, 

2020). 

21 ICAO, 2017: Aircraft Engine Emissions, 

International Standards and Recommended 

Practices, Environmental Protection, Annex 16, 

Volume II, Fourth Edition, July 2017, 174 pp. 

Available at http://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). The ICAO Annex 16 Volume II is found on 

page 16 of the ICAO Products & Services English 

Edition of the 2020 catalog, and it is copyright 

protected; Order No. AN16–2. Also see: ICAO, 

2020: Supplement No.7, August 2020, Annex 16 

Environmental Protection—Volume II—Aircraft 

Engine Emissions, Amendment 10 (20/7/20).76pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup07_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume II, 

Amendment 10 is found on page 3 of Supplement 

No. 7—August 2020; English Edition, Order No. 

AN16–2/E/12. 

22CAEP develops new emission standards based 

on an assessment of the technical feasibility, cost, 

and environmental benefit of potential 

requirements. 

23 ICAO, 2017: Aircraft Engine Emissions: 

Foreword, International Standards and 

Recommended Practices, Environmental Protection, 

Annex 16, Volume II, Fourth Edition, July 2017, 

174pp. Available at https://www.icao.int/ 

publications/Pages/catalogue.aspx (last accessed 

March 16, 2020). The ICAO Annex 16 Volume II is 

found on page 16 of the ICAO Products & Services 

English Edition 2020 catalog and is copyright 

protected; Order No. AN16–2. Also see: ICAO, 

2020: Supplement No. 7, August 2020, Annex 16 

Environmental Protection-Volume II-Aircraft 

Engine Emissions, Amendment 10 (20/7/20).76pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup07_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume II, 

Amendment 10 is found on page 3 of Supplement 

No. 7—August 2020; English Edition, Order No. 

AN16–2/E/12. 

24CAEP conducts its work triennially. Each 

3-year work cycle is numbered sequentially and 

that identifier is used to differentiate the results 

from one CAEP meeting to another by convention. 

The first technical meeting on aircraft emission 

standards was CAEP’s predecessor, i.e., CAEE. The 

first meeting of CAEP, therefore, is referred to as 

CAEP/2. 

25CAEP/5 did not address new airplane engine 

emission standards. 

26 ICAO, 2017: Aircraft Engine Emissions, 

International Standards and Recommended 

Practices, Environmental Protection, Annex 

16,Volume II, Fourth Edition, July 2017, 174pp. 

Available at https://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). The ICAO Annex 16 Volume II is found on 

page 16 of the ICAO Products & Services English 

Edition of the 2020 catalog, and it is copyright 

protected; Order No. AN16–2. Also see: ICAO, 

2020: Supplement No. 7, August 2020, Annex 16 

Environmental Protection-Volume II-Aircraft Engine 

Emissions, Amendment 10 (20/7/20).76pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup07_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume II, 

Amendment 10 is found on page 3 of Supplement 

No. 7—August 2020; English Edition, Order No. 

AN16–2/E/12. 

27CAEP/7 did not address new aircraft engine 

emission standards. 

28 ICAO, 2010: Committee on Aviation 

Environmental Protection (CAEP), Report of the 

Eighth Meeting, Montreal, February 1–12, 2010, 

CAEP/8–WP/80 Available in Docket EPA–HQ– 

OAR–2010–0687. 

29 ICAO, 2017: Aircraft Engine Emissions, 

International Standards and Recommended 

Practices, Environmental Protection, Annex 16, 

Volume II, Fourth Edition, July 2017, Amendment 

9, 174 pp. CAEP/8 corresponds to Amendment 7 

effective on July 18, 2011. Available at https://

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed March 16, 2020). The ICAO Annex 16 

Volume II is found on page 16 of the ICAO Products 

& Services English Edition of the 2020 catalog, and 

it is copyright protected; Order No. AN16–2. Also 

see: ICAO, 2020: Supplement No. 7, August 2020, 

Annex 16 Environmental Protection—Volume II— 

Aircraft Engine Emissions, Amendment 10 (20/7/ 

20).76pp. Available at https://www.icao.int/ 

publications/catalogue/cat_2020_Sup07_en.pdf 

Continued 

its domestic regulations and ICAO 

standards.19

ICAO’s CAEP, which consists of 

members and observers from States, 

intergovernmental and nongovernmental organizations 

representing the aviation industry and 

environmental interests, undertakes 

ICAO’s technical work in the 

environmental field. The Committee is 

responsible for evaluating, researching, 

and recommending measures to the 

ICAO Council that address the 

environmental impacts of international 

civil aviation. CAEP’s terms of reference 

indicate that ‘‘CAEP’s assessments and 

proposals are pursued taking into 

account: Technical feasibility; 

environmental benefit; economic 

reasonableness; interdependencies of 

measures (for example, among others, 

measures taken to minimize noise and 

emissions); developments in other 

fields; and international and national 

programs.’’ 20 The ICAO Council 

reviews and adopts the 

recommendations made by CAEP. It 

then reports to the ICAO Assembly, the 

highest body of the organization, where 

the main policies on aviation 

environmental protection are adopted 

and translated into Assembly 

Resolutions. If ICAO adopts a CAEP 

proposal for a new environmental 

standard, it then becomes part of ICAO 

standards and recommended practices 

(Annex 16 to the Chicago 

Convention).21 22

The FAA plays an active role in 

ICAO/CAEP, including serving as the 

representative (member) of the United 

States at annual ICAO/CAEP Steering 

Group meetings, as well as the ICAO/ 

CAEP triennial meetings, and 

contributing technical expertise to 

CAEP’s working groups. The EPA serves 

as an advisor to the U.S. member at the 

annual ICAO/CAEP Steering Group and 

triennial ICAO/CAEP meetings, while 

also contributing technical expertise to 

CAEP’s working groups and assisting 

and advising the FAA on aviation 

emissions, technology, and 

environmental policy matters. In turn, 

the FAA assists and advises the EPA on 

aviation environmental issues, 

technology and airworthiness 

certification matters. 

CAEP’s predecessor at ICAO, the 

Committee on Aircraft Engine Emissions 

(CAEE), adopted the first international 

SARPs for aircraft engine emissions that 

were proposed in 1981.23 These 

standards limited aircraft engine 

emissions of hydrocarbons (HC), carbon 

monoxide (CO), and oxides of nitrogen 

(NOX). The 1981 standards applied to 

newly manufactured engines, which are 

those engines built after the effective 

date of the regulations—also referred to 

as in-production engines. In 1993, ICAO 

adopted a CAEP/2 proposal to tighten 

the original NOX standard by 20 percent 

and amend the test procedures.24 These 

1993 standards applied both to newly 

certificated turbofan engines (those 

engine models that received their initial 

type certificate after the effective date of 

the regulations, referred to as newly 

certificated engines or new type design 

engines) and to in-production engines; 

the standards had different effective 

dates for newly certificated engines and 

in-production engines. In 1995, CAEP/3 

recommended a further tightening of the 

NOX standards by 16 percent and 

additional test procedure amendments, 

but in 1997 the ICAO Council rejected 

this stringency proposal and approved 

only the test procedure amendments. At 

the CAEP/4 meeting in 1998, the 

Committee adopted a similar 16 percent 

NOX reduction proposal, which ICAO 

approved in 1998. Unlike the CAEP/2 

standards, the CAEP/4 standards 

applied only to new type design engines 

after December 31, 2003, and not to inproduction engines, leaving the CAEP/ 

2 standards applicable to in-production 

engines. In 2004, CAEP/6 recommended 

a 12 percent NOX reduction, which 

ICAO approved in 2005.25 26 The CAEP/ 

6 standards applied to new engine 

designs certificated after December 31, 

2007, again leaving the CAEP/2 

standards in place for in-production 

engines before January 1, 2013. In 2010, 

CAEP/8 recommended a further 

tightening of the NOX standards by 15 

percent for new engine designs 

certificated after December 31, 2013.27 28

The Committee also recommended that 

the CAEP/6 standards be applied to inproduction engines on or after January 

1, 2013, which cut off the production of 

CAEP/2 and CAEP/4 compliant engines 

with the exception of spare engines; 

ICAO adopted these as standards in 

2011.29


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2142 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

(last accessed October 27, 2020). The ICAO Annex 

16, Volume II, Amendment 10 is found on page 3 

of Supplement No. 7—August 2020; English 

Edition, Order No. AN16–2/E/12. 

30U.S. EPA, 1973: Emission Standards and Test 

Procedures for Aircraft; Final Rule, 38 FR 19088 

(July 17, 1973). 

31U.S. EPA, 1997: Control of Air Pollution from 

Aircraft and Aircraft Engines; Emission Standards 

and Test Procedures; Final Rule, 62 FR 25355 (May 

8, 1997). 

32The full CAEP membership meets every three 

years and each session is denoted by a numerical 

identifier. For example, the second meeting of 

CAEP is referred to as CAEP/2, and CAEP/2 

occurred in 1994. 

33This does not mean that in 1997 we 

promulgated requirements for the re-certification or 

retrofit of existing in-use engines. 

34Those engines built after the effective date of 

the regulations that were already certificated to preexisting standards are also referred to as inproduction engines. 

35 In the existing EPA regulations, 40 CFR part 87, 

newly certificated aircraft engines are described as 

engines of a type or model of which the date of 

manufacture of the first individual production 

model was after the implementation date. Newly 

manufactured aircraft engines are characterized as 

engines of a type or model for which the date of 

manufacturer of the individual engine was after the 

implementation date. 

36Those engine models that received their initial 

type certificate after the effective date of the 

regulations are also referred to as new engine 

designs. 

37U.S. EPA, 1997: Control of Air Pollution from 

Aircraft and Aircraft Engines; Emission Standards 

and Test Procedures; Final Rule, 62 FR 25355 (May 

8, 1997). 

38U.S. EPA, 2005: Control of Air Pollution from 

Aircraft and Aircraft Engines; Emission Standards 

and Test Procedures; Final Rule, 70 FR 69664 

(November 17, 2005). 

39U.S. EPA, 2012: Control of Air Pollution from 

Aircraft and Aircraft Engines; Emission Standards 

and Test Procedures; Final Rule, 77 FR 36342 (June 

18, 2012). 

40While ICAO’s standards were not limited to 

‘‘commercial’’ airplane engines, our 1997 standards 

were explicitly limited to commercial engines, as 

our finding that NOX and carbon monoxide 

emissions from airplane engines cause or contribute 

to air pollution which may reasonably be 

anticipated to endanger public health or welfare 

was so limited. See 62 FR 25358 (May 8, 1997). In 

the 2012 rulemaking, we expanded the scope of that 

finding and of our standards pursuant to CAA 

section 231(a)(2)(A) to include such emissions from 

both commercial and non-commercial airplane 

engines based on the physical and operational 

similarities between commercial and 

noncommercial civilian airplane and to bring our 

standards into full alignment with ICAO’s. 

41U.S. EPA, 2015: Proposed Finding that 

Greenhouse Gas Emissions from Aircraft Cause or 

Contribute to Air Pollution that May Reasonably Be 

Anticipated to Endanger Public Health and Welfare 

and Advance Notice of Proposed Rulemaking, 80 

FR 37758 (July 1, 2015). 

42 ICAO, 2016: Report of Tenth Meeting, 

Montreal, 1–12 February 2016, Committee on 

Aviation Environmental Protection, Document 

10069, 432pp. Available at: https://www.icao.int/ 

publications/Pages/catalogue.aspx (last accessed 

March 16, 2020). ICAO Document 10069 is found 

on page 27 of the ICAO Products & Services English 

Edition 2020 Catalog, and it is copyright protected; 

Order No. 10069. See Appendix C (starting on page 

5C–1) of this report. 

43 ICAO, Environmental Report 2010—Aviation 

and Climate Change, 2010, which is located at 

http://www.icao.int/environmental-protection/ 

Pages/EnvReport10.aspx (last accessed March 16, 

2020). 

44Although weight reducing technologies affect 

fuel burn, they do not affect the metric value for the 

GHG standard. The standard is a function of 

At the CAEP/10 meeting in 2016, the 

Committee agreed to the first airplane 

CO2 emission standards, which ICAO 

approved in 2017. The CAEP/10 CO2

standards apply to new type design 

airplanes for which the application for 

a type certificate will be submitted on 

or after January 1, 2020, some modified 

in-production airplanes on or after 

January 1, 2023, and all applicable inproduction airplanes built on or after 

January 1, 2028. 

2. EPA’s Regulation of Aircraft Engine 

Emissions and the Relationship to 

International Aircraft Standards 

As required by the CAA, the EPA has 

been engaged in reducing harmful air 

pollution from airplane engines for over 

40 years, regulating gaseous exhaust 

emissions, smoke, and fuel venting from 

engines.30 We have periodically revised 

these regulations. In a 1997 rulemaking, 

for example, we made our emission 

standards and test procedures more 

consistent with those of ICAO’s CAEP 

for turbofan engines used in commercial 

aviation with rated thrusts greater than 

26.7 kilonewtons.31 These ICAO 

requirements are generally referred to as 

CAEP/2 standards.32 The 1997 

rulemaking included new NOX emission 

standards for newly manufactured 

commercial turbofan engines 33 34 and 

for newly certificated commercial 

turbofan engines.35 36 It also included a 

CO emission standard for in-production 

commercial turbofan engines.37 In 2005, 

we promulgated more stringent NOX

emission standards for newly 

certificated commercial turbofan 

engines.38 That final rule brought the 

U.S. standards closer to alignment with 

ICAO CAEP/4 requirements that became 

effective in 2004. In 2012, we issued 

more stringent two-tiered NOX emission 

standards for newly certificated and inproduction commercial and noncommercial turbofan engines, and these 

NOX standards align with ICAO’s CAEP/ 

6 and CAEP/8 standards that became 

effective in 2013 and 2014, 

respectively.39 40 The EPA’s actions to 

regulate certain pollutants emitted from 

aircraft engines come directly from the 

authority in section 231 of the CAA, and 

we have aligned the U.S. emissions 

requirements with those promulgated by 

ICAO. All of these previous ICAO 

emission standards, and the EPA’s 

standards reflecting them, have 

generally been considered antibacksliding standards (most aircraft 

engines meet the standards), which are 

technology following. 

The EPA and the FAA worked from 

2009 to 2016 within the ICAO/CAEP 

standard-setting process on the 

development of the international 

Airplane CO2 Emission Standards. In 

this action, we are adopting GHG 

standards equivalent to the ICAO 

Airplane CO2 Emission Standards. As 

stated earlier in this Section II, the 

standards established in the United 

States need to be at least as stringent as 

the ICAO Airplane CO2 Emission 

Standards in order to ensure global 

acceptance of FAA airworthiness 

certification. Also, as a result of the 

2016 Findings, as described later in 

Section IV, the EPA is obligated under 

section 231 of the CAA to propose and 

issue emission standards applicable to 

GHG emissions from the classes of 

engines used by covered aircraft 

included in the 2016 Findings. 

When the EPA proposed the aircraft 

GHG findings in 2015, we included an 

aircraft GHG emission standards 

advance notice of proposed rulemaking 

(henceforth the ‘‘2015 ANPR’’) 41 that 

provided information on the 

international process for setting the 

ICAO Airplane CO2 Emission Standards. 

Also, the 2015 ANPR described and 

sought input on the potential use of 

section 231 of the CAA to adopt and 

implement the corresponding 

international Airplane CO2 Emission 

Standards domestically as a CAA 

section 231 GHG standard. 

E. Consideration of Whole Airplane 

Characteristics 

In addressing CO2 emissions, ICAO 

adopted an approach that measures the 

fuel efficiency from the perspective of 

whole airplane design—an airframe and 

engine combination. Specifically, ICAO 

adopted CO2 emissions test procedures 

based on measuring the performance of 

the whole airplane rather than the 

airplane engines alone.42 The ICAO 

standards account for three factors: 

Aerodynamics, airplane weight, and 

engine propulsion technologies. These 

airplane performance characteristics 

determine the overall CO2 emissions. 

Rather than measuring a single chemical 

compound, the ICAO CO2 emissions test 

procedures measure fuel efficiency 

based on how far an airplane can fly on 

a single unit of fuel at the optimum 

cruise altitude and speed. 

The three factors—and technology 

categories that improve these factors— 

are described as follows: 43

• Weight: Reducing basic airplane 

weight 44 via structural changes to 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2143 

maximum takeoff mass (MTOM). Reductions in 

airplane empty weight (excluding usable fuel and 

the payload) can be canceled out or diminished by 

a corresponding increase in payload, fuel, or both— 

when MTOM is kept constant. Section IV and VI 

provide a further description of the metric value 

and the effects of weight reducing technologies. 

45Fly-by-wire refers to a system which transmits 

signals from the cockpit to the airplane’s control 

surfaces electronically rather than mechanically. 

AirlineRatings.com, Available at https://

www.airlineratings.com/did-you-know/what-doesthe-term-fly-by-wire-mean/ (last accessed on March 

16, 2020). 

46U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

47U.S. EPA, 2009: Endangerment and Cause or 

Contribute Findings for Greenhouse Gases Under 

Section 202(a) of the Clean Air Act; Final Rule, 74 

FR 66496 (December 15, 2009). 

48Certain aircraft in this context are referred to 

interchangeably as ‘‘covered airplanes,’’ ‘‘US 

covered airplanes,’’ or airplanes throughout this 

rulemaking. 

49 81 FR 54423, August 15, 2016. 

50 In 2014, classes of engines used in U.S. covered 

airplanes contribute to domestic GHG inventories as 

follows: 10 percent of all U.S. transportation GHG 

emissions, representing 2.8 percent of total U.S. 

emissions. 

U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

U.S. EPA, 2016: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2014, 1,052 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

16–002, April 2016. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2014 

(last accessed March 16, 2020). 

ERG, 2015: U.S. Jet Fuel Use and CO2 Emissions 

Inventory for Aircraft Below ICAO CO2 Standard 

Thresholds, Final Report, EPA Contract Number 

EP–D–11–006, 38 pp. 

51 In 2010, classes of engines used in U.S. covered 

airplanes contribute to global GHG inventories as 

follows: 26 percent of total global airplane GHG 

emissions, representing 2.7 percent of total global 

transportation emissions and 0.4 percent of all 

global GHG emissions. 

U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

U.S. EPA, 2016: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2014, 1,052 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

16–002, April 2016. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2014 

(last accessed March 16, 2020). 

ERG, 2015: U.S. Jet Fuel Use and CO2 Emissions 

Inventory for Aircraft Below ICAO CO2 Standard 

Thresholds, Final Report, EPA Contract Number 

EP–D–11–006, 38 pp. 

IPCC, 2014: Climate Change 2014: Mitigation of 

Climate Change. Contribution of Working Group III 

to the Fifth Assessment Report of the 

Intergovernmental Panel on Climate Change 

[Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. 

Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, 

Continued 

increase the commercial payload or 

extend range for the same amount of 

thrust and fuel burn; 

• Propulsion (thermodynamic and 

propulsion efficiency): Advancing the 

overall specific performance of the 

engine, to reduce the fuel burn per unit 

of delivered thrust; and 

• Aerodynamic: Advancing the 

airplane aerodynamics to reduce drag 

and its associated impacts on thrust. 

As examples of technologies that 

support addressing aircraft engine CO2

emissions accounting for the airplane as 

a whole, manufacturers have already 

achieved significant weight reduction 

with the introduction of advanced 

alloys and composite materials and 

lighter weight control systems (e.g., flyby-wire) 45 and aerodynamic 

improvements with advanced wingtip 

devices such as winglets. 

The EPA agrees with ICAO’s approach 

to measure the fuel efficiency based on 

the performance of the whole airplane. 

Accordingly, under section 231 of the 

CAA, the EPA is adopting regulations 

that are consistent with this approach. 

We are also adopting GHG test 

procedures that are the same as the 

ICAO CO2 test procedures. (See Section 

IV.G for details on the test procedures.) 

As stated earlier in Section II, section 

231(a)(2)(A) of the CAA directs the 

Administrator of the EPA to, from time 

to time, propose aircraft engine 

emission standards applicable to the 

emission of any air pollutant from 

classes of aircraft engines which in the 

Administrator’s judgment causes or 

contributes to air pollution that may 

reasonably be anticipated to endanger 

public health or welfare. For a standard 

promulgated under CAA section 

231(a)(2)(A) to be ‘‘applicable to’’ 

emissions of air pollutants from aircraft 

engines, it could take many forms and 

include multiple elements in addition to 

a numeric permissible engine exhaust 

rate. For example, EPA rules adopted 

pursuant to CAA section 231 have 

addressed fuel venting to prevent the 

discharge of raw fuel from the engine 

and have adopted test procedures for 

exhaust emission standards. See 40 CFR 

part 87, subparts B and G. 

Given both the absence of a statutory 

directive on what form a CAA section 

231 standard must take (in contrast to, 

for example, CAA section 129(a)(4), 

which requires numerical emissions 

limitations for emissions of certain 

pollutants from solid waste incinerators) 

and the D.C. Circuit’s 2007 NACAA 

ruling that section 231 of the CAA 

confers an unusually broad degree of 

discretion on the EPA in establishing 

airplane engine emission standards, the 

EPA is controlling GHG emissions in a 

manner identical to how ICAO’s 

standards control CO2 emissions—with 

a fuel efficiency standard based on the 

characteristics of the whole airplane. 

While this standard incorporates 

characteristics of airplane design as 

adopted by ICAO, the EPA is not 

asserting independent regulatory 

authority over airplane design. 

III. Summary of the 2016 Findings 

On August 15, 2016,46 the EPA issued 

two findings regarding GHG emissions 

from aircraft engines. First, the EPA 

found that elevated concentrations of 

GHGs in the atmosphere endanger the 

public health and welfare of current and 

future generations within the meaning 

of section 231(a)(2)(A) of the CAA. The 

EPA made this finding specifically with 

respect to the same six well-mixed 

GHGs—CO2, methane, N2O, 

hydrofluorocarbons, perfluorocarbons, 

and sulfur hexafluoride—that together 

were defined as the air pollution in the 

2009 Endangerment Finding 47 under 

section 202(a) of the CAA and that 

together were found to constitute the 

primary cause of climate change. 

Second, the EPA found that emissions 

of those six well-mixed GHGs from 

certain classes of engines used in certain 

aircraft 48 cause or contribute to the air 

pollution—the aggregate group of the 

same six GHGs—that endangers public 

health and welfare under CAA section 

231(a)(2)(A). 

The EPA identified U.S. covered 

aircraft as subsonic jet aircraft with a 

maximum takeoff mass (MTOM) greater 

than 5,700 kilograms and subsonic 

propeller-driven (e.g., turboprop) 

aircraft with a MTOM greater than 8,618 

kilograms. See Section IV of this final 

rulemaking for examples of airplanes 

that correspond to the U.S. covered 

aircraft identified in the 2016 

Findings.49 The EPA did not at that time 

make findings regarding whether other 

substances emitted from aircraft engines 

cause or contribute to air pollution 

which may reasonably be anticipated to 

endanger public health or welfare. The 

EPA also did not make a cause or 

contribute finding regarding GHG 

emissions from engines not used in U.S. 

covered aircraft (i.e., those used in 

smaller turboprops, smaller jet aircraft, 

piston-engine aircraft, helicopters and 

military aircraft). Consequently, the 

2016 Findings did not trigger the EPA’s 

authority or duty under the CAA to 

regulate these other substances or 

aircraft types. 

The EPA explained that the collective 

GHG emissions from the classes of 

engines used in U.S. covered aircraft 

contribute to the national GHG emission 

inventories 50 and estimated global GHG 

emissions.51 52 53 54 The 2016 Findings 


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2144 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

S. Brunner, P. Eickemeier, B. Kriemann, J. 

Savolainen, S. Schlo ̈mer, C. von Stechow, T. 

Zwickel and J.C. Minx (eds.)]. Cambridge University 

Press, 1435 pp. 

52U.S. EPA, 2016: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2014, 1,052 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

16–002, April 2016. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2014 

(last accessed March 16, 2020). 

53 IPCC, 2014: Climate Change 2014: Mitigation of 

Climate Change. Contribution of Working Group III 

to the Fifth Assessment Report of the 

Intergovernmental Panel on Climate Change 

[Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. 

Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, 

S. Brunner, P. Eickemeier, B. Kriemann, J. 

Savolainen, S. Schlo ̈mer, C. von Stechow, T. 

Zwickel and J.C. Minx (eds.)]. Cambridge University 

Press, 1435 pp. 

54The domestic inventory comparisons are for 

the year 2014, and global inventory comparisons are 

for the year 2010. The rationale for the different 

years is described in section IV.B.4 of the 2016 

Findings, 81 FR 54422 (August 15, 2016). 

55Covered U.S. aircraft GHG emissions in the 

2016 Findings were from airplanes that operate in 

and from the U.S. and thus contribute to emissions 

in the U.S. This includes emissions from U.S. 

domestic flights, and emissions from U.S. 

international bunker flights (emissions from the 

combustion of fuel used by airplanes departing the 

U.S., regardless of whether they are a U.S. flagged 

carrier—also described as emissions from 

combustion of U.S. international bunker fuels). For 

example, a flight departing Los Angeles and 

arriving in Tokyo, regardless of whether it is a U.S. 

flagged carrier, is considered a U.S. international 

bunker flight. A flight from London to Hong Kong 

is not. 

56U.S. EPA, 2016: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2014, 1,052 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

16–002, April 2016. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2014 

(last accessed March 16, 2020). 

57U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

58U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

U.S. EPA, 2016: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2014, 1,052 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

16–002, April 2016. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2014 

(last accessed March 16, 2020). 

ERG, 2015: U.S. Jet Fuel Use and CO2 Emissions 

Inventory for Aircraft Below ICAO CO2 Standard 

Thresholds, Final Report, EPA Contract Number 

EP–D–11–006, 38 pp. 

59Methane emissions are no longer considered to 

be emitted from aircraft gas turbine engines burning 

jet fuel A at higher power settings. Modern aircraft 

jet engines are typically net consumers of methane 

(Santoni et al. 2011). Methane is emitted at low 

power and idle operation, but at higher power 

modes aircraft engines consume methane. Over the 

range of engine operating modes, aircraft engines 

are net consumers of methane on average. 

60U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

61 ICAO, 2006: Convention on International Civil 

Aviation, Article 38, Ninth Edition, Document 7300/ 

9, 114 pp. Available at http://www.icao.int/ 

publications/Documents/7300_9ed.pdf (last 

accessed March 16, 2020). 

62U.S. EPA, 2015: Proposed Finding That 

Greenhouse Gas Emissions From Aircraft Cause or 

Contribute to Air Pollution That May Reasonably Be 

Anticipated To Endanger Public Health and 

Welfare and Advance Notice of Proposed 

Rulemaking; Proposed Rule, 80 FR 37758 (July 1, 

2015). 

63 ICAO, 2006: Convention on International Civil 

Aviation, Article 33, Ninth Edition, Document 7300/ 

9, 114 pp. Available at http://www.icao.int/ 

publications/Documents/7300_9ed.pdf (last 

accessed March 16, 2020). 

accounted for the majority (89 percent) 

of total U.S. aircraft GHG emissions.55 56

As explained in the 2016 Findings,57

only two of the six well-mixed GHGs, 

CO2 and N2O, are emitted from covered 

aircraft. CO2 represents 99 percent of all 

GHGs emitted from both total U.S. 

aircraft and U.S. covered aircraft, and 

N2O represents 1 percent of GHGs 

emitted from total U.S. aircraft and U.S. 

covered aircraft.58 Modern aircraft are 

overall consumers of methane.59

Hydrofluorocarbons, perfluorocarbons, 

and sulfur hexafluoride are not products 

of aircraft engine fuel combustion. 

(Section IV.H discusses controlling two 

of the six well-mixed GHGs—CO2 and 

N2O— in the context of the details of 

this rule.) 

IV. EPA’s Final GHG Standards for 

Covered Airplanes 

This section describes the fuel 

efficiency metric that will be used as a 

measure of airplane GHG emissions, the 

size and types of airplanes that will be 

affected, the emissions levels, and the 

applicable test procedures. As explained 

earlier in Section III and in the 2016 

Findings,60 only two of the six wellmixed GHGs—CO2 and N2O—are 

emitted from covered aircraft. Both CO2

and N2O emissions scale with fuel burn, 

thus allowing them to be controlled 

through fuel efficiency. 

The GHG emission regulations for this 

rule are being specified in a new part in 

title 40 of the CFR—40 CFR part 1030. 

The existing aircraft engine regulations 

applicable to HC, NOX, CO, and smoke 

remain in 40 CFR part 87. 

In order to promote international 

harmonization of aviation standards and 

to avoid placing U.S. manufacturers at 

a competitive disadvantage that would 

result if EPA were to adopt standards 

different from the standards adopted by 

ICAO, the EPA is adopting standards for 

GHG emissions from certain classes of 

engines used on airplanes that match 

the scope, stringency, and timing of the 

CO2 standards adopted by ICAO. The 

EPA and the FAA worked within ICAO 

to help establish the international CO2

emission standards, which under the 

Chicago Convention individual member 

States then adopt into domestic law and 

regulations in order to implement and 

enforce them against subject 

manufacturers. A member State that 

adopts domestic regulations differing 

from the international standard—in 

either scope, stringency or timing—is 

obligated to notify ICAO of the 

differences between its domestic 

regulations and the ICAO standards.61

Under the longstanding EPA and FAA 

rulemaking approach to regulate 

airplane emissions (as described earlier 

in Section II.D), international emission 

standards have been adopted by ICAO, 

with significant involvement from the 

FAA and the EPA, and subsequently the 

EPA has undertaken rulemakings under 

CAA section 231 to establish domestic 

standards that are harmonized with 

ICAO’s standards. Then, CAA section 

232 requires the FAA to issue 

regulations to ensure compliance with 

the EPA standards. In 2015, EPA issued 

an advance notice of proposed 

rulemaking 62 which noted EPA and 

FAA’s engagement in ICAO to establish 

an international CO2 emissions standard 

and EPA’s potential use of section 231 

to adopt corresponding airplane GHG 

emissions standards domestically. This 

rulemaking continues this statutory 

paradigm. 

The rule will facilitate the acceptance 

of U.S. manufactured airplanes and 

airplane engines by member States and 

airlines around the world. We anticipate 

that U.S. manufacturers would be at a 

significant competitive disadvantage if 

the U.S. failed to adopt standards that 

are aligned with the ICAO standards for 

CO2 emissions. Member States may ban 

the use of any airplane within their 

airspace that does not meet ICAO 

standards.63 If the EPA were to adopt no 

standards or standards that were not as 

stringent as ICAO’s standards, U.S. civil 

airplane manufacturers could be forced 

to seek CO2 emissions certification from 

an aviation certification authority of 

another country (other than the FAA) in 

order to market their airplanes for 

international operation. 

Having invested significant effort and 

resources, working with FAA and the 

Department of State, to gain 

international consensus to adopt the 

first-ever CO2 standards for airplanes, 

the EPA believes that meeting the 

United States’ obligations under the 

Chicago Convention by aligning 

domestic standards with the ICAO 

standards, rather than adopting more 

stringent standards, will have 

substantial benefits for future 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2145 

64Payload is the weight of passengers, baggage, 

and cargo. FAA Airplane Weight & Balance 

Handbook (Chapter 9, page 9–10, file page 82) 

https://www.faa.gov/regulations_policies/ 

handbooks_manuals/aviation/media/FAA-H-8083- 

1.pdf (x)(last accessed on March 16, 2020). 

65 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

66Annex 16 Volume III Part II Chapter 2 sec. 2.2. 

ICAO, 2017: Annex 16 Volume III—Environmental 

Protection—Aeroplane CO2 Emissions, First 

Edition, 40 pp. Available at: http://www.icao.int/ 

publications/Pages/catalogue.aspx (last accessed 

July 15, 2020). The ICAO Annex 16 Volume III is 

found on page 16 of the English Edition of the 2020 

catalog, and it is copyright protected; Order No. AN 

16–3. Also see: ICAO, 2020, Supplement No. 6— 

July 2020, Annex 16 Environmental ProtectionVolume III-Aeroplane CO2 Emissions, Amendment 

1 (20/7/20). 22pp. Available at https://

www.icao.int/publications/catalogue/cat_2020_

Sup06_en.pdf (last accessed October 27, 2020). The 

ICAO Annex 16, Volume III, Amendment 1 is found 

on page 2 of Supplement No. 6—July 2020, English 

Edition, Order No. AN16–3/E/01. 

67 ICAO, 2016: Tenth Meeting Committee on 

Aviation Environmental Protection Report, Doc 

10069, CAEP/10, 432 pp, AN/192, Available at: 

https://www.icao.int/publications/Pages/ 

catalogue.aspx (last accessed March 16, 2020). The 

ICAO Report of the Tenth Meeting report is found 

on page 27 of the ICAO Products & Services English 

Edition 2020 catalog and is copyright protected; 

Order No. 10069. 

68Avg means average. 

69Annex 16 Vol. III Part II Chapter 2 sec. 2.3. 

ICAO, 2017: Annex 16 Volume III—Environmental 

Protection—Aeroplane CO2 Emissions, First 

Edition, 40 pp. Available at: http://www.icao.int/ 

publications/Pages/catalogue.aspx (last accessed 

July 15, 2020). The ICAO Annex 16 Volume III is 

found on page 16 of the English Edition of the 2020 

catalog, and it is copyright protected; Order No. AN 

16–3. Also see: ICAO, 2020, Supplement No. 6— 

July 2020, Annex 16 Environmental ProtectionVolume III-Aeroplane CO2 Emissions, Amendment 

1 (20/7/20). 22pp. Available at https://

www.icao.int/publications/catalogue/cat_2020_

Sup06_en.pdf (last accessed October 27, 2020). The 

ICAO Annex 16, Volume III, Amendment 1 is found 

on page 2 of Supplement No. 6—July 2020, English 

Edition, Order No. AN16–3/E/01. 

70The fuselage is an aircraft’s main body section. 

It holds crew, passengers, and cargo. 

international cooperation on airplane 

emission standards, and such 

cooperation is the key for achieving 

worldwide emission reductions. 

Nonetheless, the EPA also analyzed the 

impacts of two more stringent 

alternatives, and the results of our 

analyses are described in chapters 4, 5, 

and 6 of the Technical Support 

Document (TSD) which can be found in 

the docket for this rulemaking. The 

analyses show that one alternative 

would result in limited additional costs, 

but no additional costs or GHG emission 

reductions compared to the final 

standards. The other alternative would 

have further limited additional costs 

and some additional GHG emission 

reductions compared to the final 

standards, but the additional emission 

reductions are relatively small from this 

alternative and do not justify deviating 

from the international standards and 

disrupting international harmonization. 

ICAO intentionally established its 

standards at a level which is technology 

following to adhere to its definition of 

technical feasibility that is meant to 

consider the emissions performance of 

in-production and in-development 

airplanes, including types that would 

first enter into service by about 2020. 

Thus, the additional emission 

reductions associated with the more 

stringent alternatives are relatively 

small because all but one of the affected 

airplanes either meet the stringency 

levels or are expected to go out of 

production by the effective dates. In 

addition, requiring U.S. manufacturers 

to certify to a different standard than 

has been adopted internationally (even 

one more stringent) could have 

disruptive effects on manufacturers’ 

ability to market planes for international 

operation. Consequently, the EPA did 

not choose to finalize either of these 

alternatives. 

A. Airplane Fuel Efficiency Metric 

For the international Airplane CO2

Emission Standards, ICAO developed a 

metric system to allow the comparison 

of a wide range of subsonic airplane 

types, designs, technology, and uses. 

While ICAO calls this a CO2 emissions 

metric, it is a measure of fuel efficiency, 

which is directly related to CO2 emitted 

by aircraft engines. The ICAO metric 

system was designed to differentiate 

between fuel-efficiency technologies of 

airplanes and to equitably capture 

improvements in propulsive and 

aerodynamic technologies that 

contribute to a reduction in the airplane 

CO2 emissions. In addition, the ICAO 

metric system accommodates a wide 

range of technologies and designs that 

manufacturers may choose to 

implement to reduce CO2 emissions 

from their airplanes. However, because 

of an inability to define a standardized 

empty weight across manufacturers and 

types of airplanes, the ICAO CO2

emissions metric is based on the MTOM 

of the airplane. This metric does not 

directly reward weight reduction 

technologies because the MTOM of an 

airplane will not be reduced when 

weight reduction technologies are 

applied so that cargo carrying capacity 

or range can be increased. Further, 

while weight reduction technologies can 

be used to improve airplane fuel 

efficiency, they may also be used to 

allow increases in payload,64

equipment, and fuel load.65 Thus, even 

though weight reducing technologies 

increase the airplane fuel efficiency, this 

improvement in efficiency may not be 

reflected in operation. 

The ICAO metric system consists of a 

CO2 emissions metric (Equation IV–1) 

and a correlating parameter.66

The ICAO CO2 emissions metric uses 

an average of three Specific Air Range 

(SAR) test points that is normalized by 

a geometric factor representing the 

physical size of an airplane. SAR is a 

measure of airplane cruise performance, 

which measures the distance an 

airplane can travel on a unit of fuel. 

Here the inverse of SAR is used (1/ 

SAR), which has the units of kilograms 

of fuel burned per kilometer of flight; 

therefore, a lower metric value 

represents a lower level of airplane CO2

emissions (i.e., better fuel efficiency). 

The SAR data are measured at three 

gross weight points used to represent a 

range of day-to-day airplane operations 

(at cruise).67 For the ICAO CO2

emissions metric, (1/SAR)avg 68 is 

calculated at 3 gross weight fractions of 

Maximum Takeoff Mass (MTOM): 69

• High gross mass: 92% MTOM. 

• Mid gross mass: Average of high 

gross mass and low gross mass. 

• Low gross mass: (0.45 * MTOM) + 

(0.63 * (MTOM∧0.924)). 

The Reference Geometric Factor (RGF) 

is a non-dimensional measure of the 

fuselage 70 size of an airplane 


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2146 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

71Annex 16 Vol. III Appendix 2. ICAO, 2017: 

Annex 16 Volume III—Environmental Protection— 

Aeroplane CO2 Emissions, First Edition, 40 pp. 

Available at: http://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed July 15, 2020). 

The ICAO Annex 16 Volume III is found on page 

16 of the English Edition 2020 catalog, and it is 

copyright protected; Order No. AN 16–3. Also see: 

ICAO, 2020, Supplement No. 6—July 2020, Annex 

16 Environmental Protection-Volume III-Aeroplane 

CO2 Emissions, Amendment 1 (20/7/20). 22pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup06_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume III, 

Amendment 1 is found on page 2 of Supplement 

No. 6—July 2020, English Edition, Order No. 

AN16–3/E/01. 

72Currently, civilian supersonic airplanes are not 

in operation. The international standard did not 

consider the inclusion of supersonic airplanes in 

the standard. More recently, there has been 

renewed interest in the development of civilian 

supersonic airplanes. This has caused ICAO to 

begin considering how existing emission standards 

should be revised for new supersonic airplanes. The 

US is involved in these discussions and at this 

point plans to work with ICAO to develop emission 

standards on the international stage prior to 

adopting them domestically. 

73This was previously owned by Bombardier and 

was sold to Viking in 2018, November 8, 2018 

(Forbes). 

74 It should be noted that there are no US 

domestic manufacturers that produce turboprops 

that meet the MTOM thresholds. These airplanes 

are given as examples but will be expected to be 

certificated by their national aviation certification 

authority. 

75RGF refers to the pressurized compartment of 

an airplane, generally meant for passengers and/or 

cargo. If an airplane is unpressurized, the calculated 

RGF of the airplane is zero (0). These airplanes are 

very rare, and the few that are in service are used 

for special missions. An example is Boeing’s 

Dreamlifter. 

76This is not expected to include freight versions 

of passenger airplanes such as the Boeing 767F, 

Boeing 747–8F, or Airbus A330F. Rather, this is 

intended to except airplanes such as the Lockheed 

L–100 which is a civilian variant of the military C– 

130. 

77For example, the NASA SOFIA airborne 

astronomical observatory. 

normalized by 1 square meter, generally 

considered to be the shadow area of the 

airplane’s pressurized passenger 

compartment.71

When the ICAO CO2 emissions metric 

is correlated against MTOM, it has a 

positive slope. The international 

Airplane CO2 Emission Standards use 

the MTOM of the airplane as an already 

certificated reference point to compare 

airplanes. In this action, we are 

adopting MTOM as the correlating 

parameter as well. 

We are adopting ICAO’s airplane CO2

emissions metric (shown in Equation 

IV–1) as the measure of airplane fuel 

efficiency as a surrogate for GHG 

emissions from covered airplanes 

(hereafter known as the ‘‘fuel efficiency 

metric’’ or ‘‘fuel burn metric’’). This is 

because the fuel efficiency metric 

controls emissions of both CO2 and N2O, 

the only two GHG emitted by airplane 

engines (see Section IV.H for further 

information). Consistent with ICAO, we 

are also adopting MTOM as the 

correlating parameter to be used when 

setting emissions limits. 

B. Covered Airplane Types and 

Applicability 

1. Maximum Takeoff Mass Thresholds 

This GHG rule applies to civil 

subsonic jet airplanes (turbojet or 

turbofan airplanes) with certificated 

MTOM over 5,700 kg (12,566 lbs.) and 

propeller-driven civil airplanes 

(turboprop airplanes) over 8,618 kg 

(19,000 lbs.). These applicability criteria 

are the same as those in the ICAO 

Airplane CO2 Emission Standards and 

correspond to the scope of the 2016 

Findings. The applicability of this rule 

is limited to civil subsonic airplanes 

and does not extend to civil supersonic 

airplanes.72 Through this action, as 

described earlier in Section II, the EPA 

is fully discharging its obligations under 

the CAA that were triggered by the 2016 

Findings. Once the EPA and the FAA 

fully promulgate the airplane GHG 

emission standards and regulations for 

their implementation and enforcement 

domestically, the United States 

regulations will align with ICAO Annex 

16 standards. 

Examples of covered airplanes under 

this GHG rule include smaller civil jet 

airplanes such as the Cessna Citation 

CJ3+, up to and including the largest 

commercial jet airplanes—the Boeing 

777 and the Boeing 747. Other examples 

of covered airplanes include larger civil 

turboprop airplanes, such as the ATR 72 

and the Viking Q400.73 74 The GHG rule 

does not apply to smaller civil jet 

airplanes (e.g., Cessna Citation M2), 

smaller civil turboprop airplanes (e.g., 

Beechcraft King Air 350i), piston-engine 

airplanes, helicopters, and military 

airplanes. 

2. Applicability 

The rule applies to all covered 

airplanes, in-production, and new type 

designs produced after the respective 

effective dates of the standards except as 

provided in IV.B.3. There are different 

regulatory emissions levels and/or 

applicability dates depending on 

whether the covered airplane is inproduction before the applicability date 

or is a new type design. 

The in-production standards are only 

applicable to previously type 

certificated airplanes, newly-built on or 

after the applicability date (described in 

IV.D.1), and do not apply retroactively 

to airplanes that are already in-service. 

For example, converting a passenger 

airplane built prior to the 2028 inproduction (and/or after 2023 if 

applicable) applicability date into a 

freight airplane would not trigger the 

change criteria described later in section 

IV.D.1.i (Changes for non-GHG 

Certificated Airplane Types), which 

apply only to newly produced airplanes 

(airplanes receiving their first 

airworthiness certificate) incorporating 

such modifications. 

3. Exceptions 

Consistent with the applicability of 

the ICAO standards, the EPA is adopting 

applicability language that excepts the 

following airplanes from the scope of 

the standards: Amphibious airplanes, 

airplanes initially designed or modified 

and used for specialized operational 

requirements, airplanes designed with 

an RGF of zero,75 and those airplanes 

specifically designed or modified and 

used for fire-fighting purposes. 

Airplanes in these excepted categories 

are generally designed or modified in 

such a way that their designs are well 

outside of the design space of typical 

passenger or freight carrying airplanes. 

For example, amphibious airplanes are, 

by necessity, designed with fuselages 

that resemble boats as much as 

airplanes. As such, their aerodynamic 

efficiency characteristics fall well 

outside of the range of airplanes used in 

developing the ICAO Airplane CO2

Emission Standards and our GHG rules. 

Airplanes designed or modified for 

specialized operational requirements 

could include a wide range of activities, 

but many are outside the scope of the 

2017 ICAO Airplane CO2 standards. 

Airplanes that may be out of scope 

could include: 

• Airplanes that require capacity to 

carry cargo that is not possible by using 

less specialized airplanes (e.g. civil 

variants of military transports); 76

• Airplanes that require capacity for 

very short or vertical takeoffs and 

landings; 

• Airplanes that require capacity to 

conduct scientific, 77 research, or 

humanitarian missions exclusive of 

commercial service; or 

• Airplanes that require similar 

factors. 

The EPA is finalizing the exceptions 

to the rule as proposed. Comments on 

this issue and our responses can be 

found in the RTC document included in 

the docket for this rulemaking. 

4. New Airplane Types and InProduction Airplane Designations 

The final rule recognizes differences 

between previously type certificated 


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78A type certificate is a design approval whereby 

the FAA ensures that the manufacturer’s designs 

meet the minimum requirements for airplane safety 

and environmental regulations. According to ICAO 

Cir 337, a type certificate is ‘‘[a] document issued 

by a Contracting State to define the design of an 

airplane type and to certify that this design meets 

the appropriate airworthiness requirements of that 

State.’’ A type certificate is issued once for each 

new type design airplane and modified as an 

airplane design is changed over the course of its 

production life. 

79 ICAO, 2016: Tenth Meeting Committee on 

Aviation Environmental Protection Report, Doc 

10069, CAEP/10, 432 pp, AN/192, Available at: 

http://www.icao.int/publications/Pages/ 

catalogue.aspx (last accessed March 16, 2020). The 

ICAO Report of the Tenth Meeting report is found 

on page 27 of the ICAO Products & Services English 

Edition 2020 catalog and is copyright protected; 

Order No. 10069. 

80 In existing U.S. aviation emissions regulations, 

in-production means newly-manufactured or built 

after the effective date of the regulations—and 

already certificated to pre-existing rules. This is 

similar to the current ICAO definition for inproduction airplane types for purposes of the 

international CO2 standard. 81 ICF International, 2015: CO2 Analysis of CO2- 

Reducing Technologies for Airplane, Final Report, 

EPA Contract Number EP–C–12–011, March 17, 

2015. 

82 Insofar as we are going through a wave of major 

redesign and service entry now, prospects for 

further step-function improvements will be low in 

the coming 10–15 years. (ICF International, CO2

Analysis of CO2-Reducing Technologies for 

Airplane, Final Report, EPA Contract Number EP– 

C–12–011, March 17, 2015.) 

83 ICF International, 2015: CO2 Analysis of CO2- 

Reducing Technologies for Airplane, Final Report, 

EPA Contract Number EP–C–12–011, March 17, 

2015. 

84The Airbus A350 was announced in 2006 and 

received its type certification in 2014. The first 

model, the A350–900 entered service with Qatar 

Airways in 2015. 

85The Bombardier C-series was announced in 

2005 and received its type certification in 2015. The 

first model, the C100 entered service with Swiss 

Global Air Lines in 2016. 

86Boeing, 2011: Boeing Unveils First 787 to Enter 

Service for Japan Airlines, December 14. Available 

at http://boeing.mediaroom.com/2011-12-14- 

Boeing-Unveils-First-787-to-Enter-Service-for-JapanAirlines (last accessed March 16, 2020). 

87 ICF International, 2015: CO2 Analysis of CO2- 

Reducing Technologies for Airplane, Final Report, 

EPA Contract Number EP–C–12–011, March 17, 

2015. 

88 Ibid. 

89Analysts estimate a new single aisle airplane 

would have cost $10–12 billion to develop. The 

A380 and 787 are estimated to each have cost 

around $20 billion to develop; the A350 is 

estimated to have cost $15 billion, excluding engine 

development. Due to the large development cost of 

a totally new airplane design, manufacturers are 

opting to re-wing or re-engine their airplane. Boeing 

is said to have budgeted $5 billion for the re-wing 

of the 777, and Airbus and Boeing have budgeted 

$1–2 billion each for the re-engine of the A320 and 

the 737, respectively (excluding engine 

development costs). Embraer has publicly stated 

that it will need to spend $1–2 billion to re-wing 

the EMB–175 and variants. (ICF International, CO2

Analysis of CO2-Reducing Technologies for 

Airplane, Final Report, EPA Contract Number EP– 

C–12–011, March 17, 2015.) 

90 ICAO policy is that the compliance date of an 

emissions standard must be at least 3 years after it 

has been agreed to by CAEP. Adding in the 5-year 

certification window, this means that the level of 

the standard can be known 8 years prior to entry 

into service date for a new type design. 

Manufacturers also have significant involvement in 

the standard development process at ICAO, which 

begins at least 3 years before any new standard is 

agreed to. 

airplanes that are in production and 

new type designs presented for original 

certification. 

• In-production airplanes: Those 

airplane types which have already 

received a type certificate 78 from the 

FAA, and for which manufacturers 

either have existing undelivered sales 

orders or would be willing and able to 

accept new sales orders. The term can 

also apply to the individual airplane 

manufactured according to the approved 

design type certificate, and for which an 

Airworthiness Certificate is required 

before the airplane is permitted to 

operate.79 80

• New type designs: Airplane types 

for which original certification is 

applied for on or after the compliance 

date of a rule, and which have never 

been manufactured prior to the 

compliance date of a rule. 

Certificated designs may subsequently 

undergo design changes such as new 

wings, engines, or other modifications 

that would require changes to the type 

certificated design. These modifications 

happen more frequently than 

applications for a new type design. For 

example, a number of airplanes have 

undergone significant design changes 

(including the Boeing 747–8, Boeing 737 

Max, Airbus 320 Neo, Airbus A330 Neo, 

and Boeing 777–X). As with a previous 

series of redesigns from 1996–2006, 

which included the Boeing 777–200LR 

in 2004, Boeing 777–300ER in 2006, 

Airbus 319 in 1996, and Airbus 330–200 

in 1998, incremental improvements are 

expected to continue to be more 

frequent than major design changes over 

the next decade—following these more 

recent major programs (or more recent 

significant design changes).81 82

New type designs are infrequent, and 

it is not unusual for new type designs 

to take 8–10 years to develop, from 

preliminary design to entry into 

service.83 The most recent new type 

designs introduced in service were the 

Airbus A350 in 2015, 84 the Airbus A220 

(formerly known as the Bombardier CSeries) in 2016, 85 and the Boeing 787 in 

2011.86, 87 However, it is unlikely more 

than one new type design will be 

presented for certification in the next 

ten years.88 New type designs (and some 

redesigns) typically yield large fuel burn 

reductions—10 percent to 20 percent— 

over the prior generation they replace 

(considered a step-change in fuel burn 

improvement). As one might expect, 

these significant fuel burn reductions do 

not happen frequently. Also, airplane 

development programs are expensive.89

At ICAO, the difference between inproduction airplanes and new type 

designs has been used to differentiate 

two different pathways by which fuel 

efficiency technologies can be 

introduced into civil airplane designs. 

When a new requirement is applied to 

an in-production airplane, there may be 

a real and immediate effect on the 

manufacturer’s ability to continue to 

build and deliver it in its certificated 

design configuration and to make 

business decisions regarding future 

production of that design configuration. 

Manufacturers need sufficient notice to 

make design modifications that allow 

for compliance to the new standards 

and to have those modifications 

certificated by their certification 

authorities. In the United States, 

applying a new requirement to an inproduction airplane means that a newly 

produced airplane subject to this rule 

that does not meet the GHG standards 

would likely be denied an airworthiness 

certificate after January 1, 2028. As 

noted above in IV.B.2, in-service 

airplanes are not subject to the ICAO 

CO2 standards and likewise are not 

subject to these GHG standards. 

For new type designs, this rule has no 

immediate effect on airplane production 

or certification for the manufacturer. 

The standards that a new type design 

must meet are those in effect when the 

manufacturer applies for type 

certification. The applicable design 

standards at the time of application 

remain frozen over the typical 5-year 

time frame provided by certification 

authorities for completing the type 

certification process. Because of the 

investments and resources necessary to 

develop a new type design, 

manufacturers have indicated that it is 

important to have knowledge of the 

level of future standards at least 8 years 

in advance of any new type design 

entering service.90 Because standards 

are known early in the design and 

certification process, there is more 

flexibility in how and what technology 

can be incorporated into a new type 

design. (See Section VI describing the 

Technology Response for more 

information on this). 

To set standards at levels that 

appropriately reflect the feasibility to 

incorporate technology and lead time, 

the level and timing of the standards are 

different for in-production airplanes and 

new type designs. This is discussed 

further in Sections IV.C and IV.D below, 

describing standards for new type 

designs and in-production airplanes, 


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91Annex 16 Vol. III Part II Chapter 2 sec. 2.4.2 

(a), (b), and (c). ICAO, 2017: Annex 16 Volume III— 

Environmental Protection—Aeroplane CO2

Emissions, First Edition, 40 pp. Available at: http:// 

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed July 15, 2020). The ICAO Annex 16 

Volume III is found on page 16 of the English 

Edition of the 2020 catalog and it is copyright 

protected; Order No. AN 16–3. Also see: ICAO, 

2020, Supplement No.6—July 2020, Annex 16 

Environmental Protection-Volume III-Aeroplane 

CO2 Emissions, Amendment 1 (20/7/20). 22pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup06_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume III, 

Amendment 1 is found on page 2 of Supplement 

No. 6—July 2020, English Edition, Order No. 

AN16–3/E/01. 

and Section VI, discussing the 

technology response. 

C. GHG Standard for New Type Designs 

1. Applicability Dates for New Type 

Designs 

The EPA is adopting GHG standards 

that apply to civil airplanes within the 

scope of the international standards 

adopted by ICAO in 2017 that meet 

maximum takeoff weight thresholds, 

passenger capacity, and dates of 

applications for original type 

certificates. In this way, EPA’s standards 

align with ICAO’s in defining those 

airplanes that are now subject to the 

standards finalized in this action. 

Consequently, for subsonic jet airplanes 

over 5,700 kg MTOM and certificated 

with more than 19 passenger seats, and 

for turboprop airplanes over 8,618 kg 

MTOM, the regulations apply to all 

airplanes for which application for an 

original type certificate is made to the 

FAA as the first certificating authority 

on or after January 11, 2021. For 

subsonic jet airplanes over 5,700 kg 

MTOM and less than 60,000 kg MTOM 

and a type certificated maximum 

passenger seating capacity of 19 seats or 

fewer, the regulations apply to all 

airplanes for which an original type 

certification application was made to 

the FAA as the first certificating 

authority on or after January 1, 2023. 

Consistency with international 

standards is important for 

manufacturers, as they noted in 

comments to our ANPR in 2015 and in 

their comments to this rulemaking. 

Airplane manufacturers and engine 

manufacturers would have been 

surprised if the EPA had adopted 

criteria to identify airplanes covered by 

our GHG standards that resulted in 

different coverage than that of ICAO’s 

standards—either in terms of maximum 

takeoff mass, passenger capacity, or 

dates of applications for new original 

type certificates. Additionally, if the 

EPA diverged from ICAO’s criteria for 

CO2 standards applicability, it would 

have introduced unnecessary 

uncertainty into the airplane type 

certification process. Also, as described 

earlier for the 2016 Findings, covered 

airplanes accounted for the majority (89 

percent) of total U.S. aircraft GHG 

emissions. 

In order to harmonize with the ICAO 

standards to the maximum extent 

possible, the EPA proposed the same 

effective date as ICAO, January 1, 2020, 

for defining those type certification 

applications subject to the standards, 

noting in the NPRM that it was a date 

that had already passed. However, to 

avoid potential concerns raised by 

commenters and because it does not 

affect harmonization with ICAO 

standards, we are adopting standards 

that are effective upon the effective date 

of this rule January 11, 2021. No 

airplane manufacturer has in fact yet 

submitted an application for a new type 

design certification since January 1, 

2020, no manufacturer will currently 

need to amend any already submitted 

application to address the GHG 

standards. Further, neither the EPA nor 

the FAA is aware of any anticipated 

original new type design application to 

be submitted before the EPA’s standards 

are promulgated and effective. Thus, 

there is no practical impact of changing 

the effective date for the new type 

design standards from January 1, 2020, 

as proposed, to the effective date of this 

rule January 11, 2021. 

The EPA recognizes that new 

regulatory requirements have differing 

impacts on items that are already in 

production and those yet to be built. 

Airplane designs that have yet to 

undergo original type certification can 

more easily be adapted for new 

regulatory requirements, compared with 

airplanes already being produced 

subject to older, existing design 

standards. The agency has experience 

adopting regulations that acknowledge 

these differences, such as in issuing 

emission standards for stationary 

sources of hazardous air pollutants 

(which often impose more stringent 

standards for new sources, defined 

based on dates that precede dates of 

final rule promulgation, than for 

existing sources). See, e.g., 42 U.S.C. 

7412(a)(4), defining ‘‘new source’’ to 

mean a stationary source the 

construction or reconstruction of which 

is commenced after the EPA proposes 

regulations establishing an emission 

standard. 

2. Regulatory limit for New Type 

Designs 

The EPA is adopting the GHG 

emissions limit for new type designs 

that is a function of the airplane 

certificated MTOM and consists of three 

levels described below in Equation 

IV–2, Equation IV–3, and Equation 

IV–4.91


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Figure IV–1 and Figure IV–2 show the 

numerical limits of the adopted new 

type design rules and how the airplane 

types analyzed in Sections V and VI 

relate to this limit. Figure IV–2 shows 

only the lower MTOM range of Figure 

IV–1 to better show the first two 

segments of the limit line. These plots 

below show the airplane fuel efficiency 

metric values as they were modeled. 

This includes all anticipated/modeled 

technology responses, improvements, 

and production assumptions in 

response to the market and this rule. 

(See Section V and VI for more 

information about this.) These final 

GHG emission limits are the same as the 

limits of the ICAO Airplane CO2

Emission Standards. 


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92 In this rulemaking, 60 tons means 60 metric 

tons (or tonnes), which is equal to 60,000 kilograms 

(kg). 1 ton means 1 metric ton (or tonne), which is 

equal to 1,000 kg. 

93 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

94U.S., United States Position on the ICAO 

Aeroplane CO2 Emissions Standard, Montre ́al, 

Canada, CAEP10 Meeting, February 1–12, 2016, 

Presented by United States, CAEP/10–WP/59. 

Available in the docket for this rulemaking, Docket 

EPA–HQ–OAR–2018–0276. 

95 Initial data that were reviewed at ICAO did not 

include data on the Bombardier C-Series (now the 

Airbus A220) airplane. Once data were provided for 

this airplane, it was determined by ICAO that while 

the airplane did cross the 60 tons kink point, this 

did not pose a problem for analyzing stringency 

options, because the airplane passes all options 

considered. 

96 In-development airplanes are airplanes that 

were in-development when setting the standard at 

ICAO but will be in production by the applicability 

dates. These could be new type designs (e.g. Airbus 

A350) or redesigned airplanes (e.g. Boeing 737Max). 

97Note: Figure IV–1 and Figure IV–2 show the 

metric values used in the EPA modeling for this 

action. These values differ from those used at ICAO. 

The rationale for this difference is discussed below 

in section VI of this rule, and in chapter 2 of the 

TSD. 

After analyzing potential levels of the 

standard, ICAO determined, based on 

assessment of available data, that there 

were significant performance 

differences between large and small 

airplanes. Jet airplanes with an MTOM 

less than 60 tons 92 are either business 

jets or regional jets. The physical size of 

smaller airplanes presents scaling 

challenges that limit technology 

improvements that can readily be made 

on larger airplanes.93 This leads to 

requiring higher capital costs to 

implement the technology relative to the 

sale price of the airplanes.94 Business 

jets (generally less than 60 tons MTOM) 

tend to operate at higher altitudes and 

faster speeds than larger commercial 

traffic. 

Based on these considerations, when 

developing potential levels for the 

international standards, ICAO further 

realized that curve shapes of the data 

differed for large and small airplanes 

(on MTOM versus metric value plots). 

Looking at the dataset, there was 

originally a gap in the data at 60 tons.95

This natural gap allowed a ‘‘kink’’ point 

(i.e., change in the slope of the standard) 

to be established between larger 

commercial airplanes and smaller 

business jets and regional jets. The 

identification of this kink point 

provided flexibility at ICAO to consider 

standards at appropriate levels for 

airplanes above and below 60 tons. 

The level adopted for new type 

designs was set to reflect the 

performance for the latest generation of 

airplanes. The CO2 emission standards 

agreed to at ICAO, and the GHG 

standards adopted here, are meant to be 

technology following standards. This 

means the rule reflects the performance 

and technology achieved by existing 

airplanes (in-production and indevelopment airplanes 96).97

Airplanes of less than 60 tons with 19 

or fewer passenger seats have additional 

economic challenges to technology 

development compared with similarly 

sized commercial airplanes. ICAO 

sought to reduce the burden on 

manufacturers of airplanes with 19 or 

fewer seats, and thus ICAO agreed to 

delay the applicability of the new type 

designs for 3 years. In maintaining 

consistency with the international 

decision, the applicability dates adopted 

in this rule reflect this difference 

determined by ICAO (see Section VI for 

further information). 

As described earlier in Section II, 

consistency with the international 

standards will facilitate the acceptance 

of U.S. airplanes by member States and 

airlines around the world, and it will 

help to ensure that U.S. manufacturers 


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98Note that IV.D.1.i, Changes for non-GHG 

certified Airplane Types, is different than the No 

GHG Change Threshold described in IV.F.1 below. 

IV.F.1 applies only to airplanes that have previously 

been certificated to a GHG rule. IV.D.1.i only 

applies only to airplane types that have not been 

certificated for GHG. 

99Annex 16 Vol. III Part II Chapter 2 sec. 2.4.2(d), 

(e), and (f). ICAO, 2017: Annex 16 Volume III— 

Environmental Protection—Aeroplane CO2

Emissions, First Edition, 40 pp. Available at: http:// 

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed July 15, 2020). The ICAO Annex 16 

Volume III is found on page 16 of the English 

Edition of the 2020 catalog, and it is copyright 

protected; Order No. AN 16–3. Also see: ICAO, 

2020, Supplement No. 6—July 2020, Annex 16 

Environmental Protection-Volume III-Aeroplane 

CO2 Emissions, Amendment 1 (20/7/20). 22 pp. 

Available at https://www.icao.int/publications/ 

catalogue/cat_2020_Sup06_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume III, 

Amendment 1 is found on page 2 of Supplement 

No. 6—July 2020, English Edition, Order No. 

AN16–3/E/01. 

will not be at a competitive 

disadvantage compared with their 

international competitors. Consistency 

with the international standards will 

also prevent backsliding by ensuring 

that all new type design airplanes are at 

least as efficient as today’s airplanes. 

D. GHG Standard for In-Production 

Airplane Types 

1. Applicability Dates for In-Production 

Airplane Types 

The EPA is adopting the same 

compliance dates for the GHG rule as 

those adopted by ICAO for its CO2

emission standards. Section IV.D.2 

below describes the rationale for these 

dates and the time provided to inproduction types. 

All airplanes type certificated prior to 

January 11, 2021, and receiving its first 

certificate of airworthiness after January 

1, 2028, will be required to comply with 

the in-production standards. This GHG 

regulation will function as a production 

cutoff for airplanes that do not meet the 

fuel efficiency levels described below. 

i. Changes for Non-GHG Certificated 

Airplane Types 

After January 1, 2023, and until 

January 1, 2028, an applicant that 

submits a modification to the type 

design of a non-GHG certificated 

airplane that increases the Metric Value 

of the airplane type by greater than 

1.5% 98 will be required to demonstrate 

that newly produced airplanes comply 

with the in-production standard. This 

earlier applicability date for inproduction airplanes, January 1, 2023, is 

the same as that adopted by ICAO and 

is similarly designed to capture 

modifications to the type design of nonGHG certificated airplanes newly 

manufactured (initial airworthiness 

certificate) prior to the January 1, 2028, 

production cut-off date. The January 1, 

2028 production cut-off date was 

introduced by ICAO as an antibacksliding measure that gives notice to 

manufacturers that non-compliant 

airplanes will not receive airworthiness 

certification after this date. 

An application for certification of a 

modified airplane type on or after 

January 1, 2023, will trigger compliance 

with the in-production GHG emissions 

limit provided that the airplane’s GHG 

emissions metric value for the modified 

version to be produced thereafter 

increases by more than 1.5 percent from 

the prior version of the airplane type. As 

with changes to GHG certificated 

airplane types, introduction of a 

modification that does not adversely 

affect the airplane fuel efficiency Metric 

Value will not require demonstration of 

compliance with the in-production GHG 

standards at the time of that change. 

Manufacturers may seek to certificate 

any airplane type to this standard, even 

if the criteria do not require compliance. 

As an example, if a manufacturer 

chooses to shorten the fuselage of a type 

certificated airplane, such action will 

not automatically trigger the 

requirement to certify to the inproduction GHG rule. The fuselage 

shortening of a certificated type design 

would not be expected to adversely 

affect the metric value, nor would it be 

expected to increase the certificated 

MTOM. Manufacturers noted that ICAO 

included criteria that would require 

manufactures to recertify if they made 

‘‘significant’’ changes to their airplane. 

ICAO did not define a ‘‘significant 

change’’ to a type design. The EPA did 

not include this requirement because 

‘‘significant change’’ is not a defined 

term in the certification process. 

However, it is expected that 

manufacturers will likely volunteer to 

certify to the in-production rule when 

applying to the FAA for these types of 

changes, in order to maximize 

efficiencies in overall airworthiness 

certification processes (i.e., avoid the 

need for iterative rounds of 

certification). This earlier effective date 

for in-production airplane types is 

expected to help encourage some earlier 

compliance for new airplanes. 

2. Regulatory Limit for In-Production 

Type Designs 

The EPA is adopting an emissions 

limit for in-production airplanes that is 

a function of airplane certificated 

MTOM and consists of three MTOM 

ranges as described below in Equation 

IV–5, Equation IV–6, and Equation IV– 

7.99


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Figure IV–3 and Figure IV–4 show the 

numerical limits of the adopted inproduction rules and the relationship of 

the airplane types analyzed in Sections 

V and VI to this limit. Figure IV–4 

shows only the lower MTOM range of 

Figure IV–3 to better show the first two 

segments of the limit line. These plots 

below show the airplane CO2 metric 

values as they were modeled. This 

includes all anticipated/modeled 

technology responses, improvements, 

and production assumptions in 

response to the market and the final 

rule. (See Sections V and VI for more 

information about this.) These GHG 

emission limits are the same as the 

limits of the ICAO Airplane CO2

Emission Standards. 


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100Title 49 of the United States Code, sec. 

44701(f), vests power in the FAA Administrator to 

issue exemptions as long as the public interest 

condition is met, and, pursuant to sec. 232(a) of the 

CAA, the Administrator may use that power ‘‘in the 

execution of all powers and duties vested in him 

under this section’’ ‘‘to insure compliance’’ with 

emission standards. 

As discussed in Section IV.C above, 

the kink point was included in the 

ICAO Aircraft CO2 standards at 60 tons 

to account for a change in slope that is 

observed between large and small 

airplanes. The flat section starting at 60 

tons is used as a transition to connect 

the curves for larger and smaller 

airplanes. 

While the same technology is 

considered for both new type design 

and in-production airplanes, there will 

be a practical difference in compliance 

for in-production airplanes. 

Manufacturers will need to test and 

certify each type design to the GHG 

standard prior to January 1, 2028, or else 

newly produced airplanes will likely be 

denied an airworthiness certificate. In 

contrast, new type design airplanes have 

yet to go into production, but these 

airplanes will need to be designed to 

comply with the standards for new type 

designs (for an application for a new 

type design certificate on or after 

January 11, 2021). This poses a 

challenge for setting the level of the inproduction standard because sufficient 

time needs to be provided to allow for 

the GHG certification process and the 

engineering and airworthiness 

certifications needed for improvements. 

The more stringent the in-production 

standard is, the more time that is 

necessary to provide manufacturers to 

modify production of their airplanes. 

ICAO determined that while the 

technology to meet the in-production 

level is available in 2020 (the ICAO 

standards new type design applicability 

date), additional time beyond the new 

type design applicability date was 

necessary to provide sufficient time for 

manufacturers to certify all of their 

products. The EPA agrees that 

additional time for in-production 

airplanes beyond the new type design 

applicability date is necessary to allow 

sufficient time to certify airplanes to the 

GHG standards. 

Section VI describes the analysis that 

the EPA conducted to determine the 

cost and benefits of adopting this 

standard. Consistent with the ICAO 

standard, this rule applies to all inproduction airplanes built on or after 

January 1, 2028, and to all in-production 

airplanes that have any modification 

that trigger the change criteria after 

January 1, 2023. 

The levels of the in-production GHG 

standards are the same as ICAO’s CO2

standards, and they reflect the emission 

performance of current in-production 

and in-development airplanes. As 

discussed in Section IV.B.4 above and 

in Section VI, the regulations reflect 

differences in economic feasibility for 

introducing modifications to inproduction airplanes and new type 

designs. The standards adopted by 

ICAO, and here, for in-production 

airplanes were developed to reflect 

these differences. 

E. Exemptions From the GHG Standards 

On occasion, manufacturers may need 

additional time to comply with a 

standard. The reasons for needing a 

temporary exemption from regulatory 

requirements vary and may include 

circumstances beyond the control of the 

manufacturer. The FAA is familiar with 

these actions, as it has handled the 

similar engine emission standards under 

its CAA authority to enforce the 

standards adopted by the EPA. The FAA 

has considerable authority under its 

authorizing legislation and its 

regulations to deal with these events.100

Since requests for exemptions are 

requests for relief from the enforcement 


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101A fairing is ‘‘a structure on the exterior of an 

aircraft or boat, for reducing drag.’’ https://

www.dictionary.com/browse/fairing (last accessed 

November 30, 2020). 

102Annex 16, Volume III, Part 1, Chapter 1. ICAO, 

2017: Annex 16 Volume III—Environmental 

Protection—Aeroplane CO2 Emissions, First 

Edition, 40 pp. Available at: http://www.icao.int/ 

publications/Pages/catalogue.aspx (last accessed 

July 15, 2020). The ICAO Annex 16 Volume III is 

found on page 16 of the English Edition of the 2020 

catalog, and it is copyright protected; Order No. AN 

16–3. Also see: ICAO, 2020. Supplement No. 6— 

July 2020, Annex 16 Environmental Protection— 

Volume III—Aeroplane CO2 Emissions, Amendment 

1 (20/7/20). 22 pp. Available at https://

www.icao.int/publications/catalogue/CAT_2020_

Sup06_en.pdf (last accessed October 28, 2020). The 

ICAO Annex 16, Volume III, Amendment 1 is found 

on page 2 of Supplement No. 6—July 2020; English 

Edition, Order No. AN 16–3/E/01. 

of these standards (as opposed to a 

request to comply with a different 

standard than set by the EPA), this rule 

will continue the relationship between 

the agencies by directing any request for 

exemption be filed with the FAA under 

its established regulatory paradigm. The 

instructions for submitting a petition for 

exemption to the FAA can be found in 

14 CFR part 11, specifically § 11.63. 

Section 11.87 lists the information that 

must be filed in a petition, including a 

reason ‘‘why granting your petition is in 

the public interest.’’ Any request for 

exemption will need to cite the 

regulation that the FAA will adopt to 

carry out its duty of enforcing the 

standard set by the EPA. A list of 

requests for exemption received by the 

FAA is routinely published in the 

Federal Register. 

The primary criterion for any 

exemption filed with the FAA is 

whether a grant of exemption will be in 

the public interest. The FAA will 

continue to consult with the EPA on all 

petitions for exemption that the FAA 

receives regarding the enforcement of 

aircraft engine and emission standards 

adopted under the CAA. 

F. Application of Rules for New Version 

of an Existing GHG-Certificated 

Airplane 

Under the international Airplane CO2

Emission Standards, a new version of an 

existing CO2-certificated airplane is one 

that incorporates modifications to the 

type design that increase the MTOM or 

increase its CO2 Metric Value more than 

the No-CO2-Change Threshold 

(described in IV.F.1 below). ICAO’s 

standards provide that once an airplane 

is CO2 certificated, all subsequent 

changes to that airplane must meet at 

least the CO2 emissions regulatory level 

(or CO2 emissions standard) of the 

parent airplane. For example, if the 

parent airplane is certificated to the inproduction CO2 emissions level, then all 

subsequent versions must also meet the 

in-production CO2 emissions level. This 

would also apply to voluntary 

certifications under ICAO’s standards. If 

a manufacturer seeks to certificate an inproduction airplane type to the level 

applicable to a new type design, then 

future versions of that airplane must 

also meet the new type regulatory level. 

Once certificated, subsequent versions 

of the airplane may not fall back to a 

less stringent regulatory CO2 level. 

To comport with ICAO’s approach, if 

the FAA finds that a new original type 

certificate is required for any reason, the 

airplane will need to comply with the 

regulatory level applicable to a new type 

design. 

In this action, the EPA is adopting 

provisions for new versions of existing 

GHG-certificated airplanes that are the 

same as the ICAO requirements for the 

international Airplane CO2 Emission 

Standards. These provisions will reduce 

the certification burden on 

manufacturers by clearly defining when 

a new GHG metric value must be 

established for the airplane. 

1. No Fuel Efficiency Change Threshold 

for GHG-Certificated Airplanes 

There are many types of modifications 

that could be introduced on an airplane 

design that could cause slight changes 

in GHG emissions (e.g. changing the 

fairing on a light,101 adding or changing 

an external antenna, changing the 

emergency exit door configuration, etc.). 

To reduce burden on both certification 

authorities and manufacturers, a set of 

no CO2 emissions change thresholds 

was developed for the ICAO Airplane 

CO2 Emission Standards as to when new 

metric values will need to be 

certificated for changes. The EPA is 

adopting these same thresholds in its 

GHG rules. 

Under this rule, an airplane is 

considered a modified version of an 

existing GHG certificated airplane, and 

therefore must recertify, if it 

incorporates a change in the type design 

that either (a) increases its maximum 

takeoff mass, or (b) increases its GHG 

emissions evaluation metric value by 

more than the no-fuel efficiency change 

threshold percentages described below 

and in Figure IV–5: 102

• For airplanes with a MTOM greater 

than or equal to 5,700 kg, the threshold 

value decreases linearly from 1.35 to 

0.75 percent for an airplane with a 

MTOM of 60,000 kg. 

• For airplanes with a MTOM greater 

than or equal to 60,000 kg, the threshold 

value decreases linearly from 0.75 to 

0.70 percent for airplanes with a MTOM 

of 600,000 kg. 

• For airplanes with a MTOM greater 

than or equal to 600,000 kg, the 

threshold value is 0.70 percent. 


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103ETM Vol. III sec. 2.2.3. ICAO, 2018: 

Environmental Technical Manual Volume III— 

Procedures for the CO2 Emissions Certification of 

Aeroplanes, First Edition, Doc 9501, 64 pp. 

Available at: http://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed July 15, 2020). 

The ICAO Environmental Technical Manual 

Volume III is found on page 77 of the English 

Edition of the 2020 catalog, and it is copyright 

protected; Order No. 9501–3. Also see: ICAO, 2020: 

Doc 9501—Environmental Technical Manual 

Volume III—Procedures for the CO2 Emissions 

Certification of Aeroplanes, 2nd Edition, 2020. 90 

pp. Available at https://www.icao.int/publications/ 

catalogue/cat_2020_sup06_en.pdf (last accessed 

October 28, 2020). The ICAO Environmental 

Technical Manual Volume III, 2nd Edition is found 

on page 3 of Supplement No. 6—July 2020, English 

Edition, Order No. 9501–3. 

The threshold is dependent on 

airplane size because the potential fuel 

efficiency changes to an airplane are not 

constant across all airplanes. For 

example, a change to the fairing 

surrounding a wing light, or the 

addition of an antenna to a small 

business jet, may have greater impacts 

on the airplane’s metric value than a 

similar change would on a large twin 

aisle airplane. 

These GHG changes will be assessed 

on a before-change and after-change 

basis. If there is a flight test as part of 

the certification, the metric value (MV) 

change will be assessed based on the 

change in calculated metric value of 

flights with and without the change. 

A modified version of an existing 

GHG certificated airplane will be subject 

to the same regulatory level as the 

airplane from which it was modified. A 

manufacturer may also choose to 

voluntarily comply with a later or more 

stringent standard.103

Under this rule, when a change is 

made to an airplane type that does not 

exceed the no-change threshold, the fuel 

efficiency metric value will not change. 

There will be no method to track these 

changes to airplane types over time. If 

an airplane type has, for example, a 10 

percent compliance margin under the 

rule, then a small adverse change less 

than the threshold may not require the 

re-evaluation of the airplane metric 

value. However, if the compliance 

margin for a type design is less than the 

No Fuel Efficiency Change threshold 

and the proposed modification results 

in a change to the metric value that is 

less than the no fuel efficiency change 

threshold, then the airplane retains its 

original metric value, and the 

compliance margin to the regulatory 

limit remains the same. The proposal 

stated that if the margin to the standard 

was less than the No Fuel Efficiency 

Change Threshold that the plane would 

still be required to demonstrate 

compliance with the standard. Some 

commenters pointed out that this 

language was different than the 

description adopted by ICAO. To be 

consistent with ICAO, this language has 

been corrected. 

Under this rule, a manufacturer that 

introduces modifications that reduce 

GHG emissions can request voluntary 

recertification from the FAA. There will 

be no required tracking or accounting of 

GHG emissions reductions made to an 

airplane unless it is voluntarily recertificated. 

The EPA is adopting, as part of the 

GHG rules, the no-change thresholds for 

modifications to airplanes discussed 

above, which are the same as the 

provisions in the international standard. 

We believe that these thresholds will 

maintain the effectiveness of the rule 

while limiting the burden on 

manufacturers to comply. The 

regulations reference specific test and 

other criteria that were adopted 

internationally in the ICAO standards 

setting process. 

G. Test and Measurement Procedures 

The international certification test 

procedures have been developed based 

upon industry’s current best practices 

for establishing the cruise performance 

of their airplanes and on input from 


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104 It is expected that manufacturers will choose 

conditions that result in the highest SAR value for 

a given certification mass. Manufacturers may 

choose other than optimum conditions to determine 

SAR; however, doing so will be at their detriment. 

105Annex 16, Vol. III, sec. 2.5. ICAO, 2017: 

Annex 16 Volume III—Environmental Protection— 

Aeroplane CO2 Emissions, First Edition, 40 pp. 

Available at: http://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed July 15, 2020). 

The ICAO Annex 16 Volume III is found on page 

16 of English Edition 2020 catalog and is copyright 

protected; Order No. AN 16–3. Also see: ICAO, 

2020, Supplement No. 6—July 2020, Annex 16 

Environmental Protection—Volume III—Aeroplane 

CO2 Emissions, Amendment 1 (20/7/20) 22 pp. 

Available at http://www.icao.int/publications/ 

catalogue/cat_2020_sup06_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume III, 

Amendment 1, is found on page 2 of Supplement 

No. 6—July 2020, English Edition, Order No. AN 

16–3/E/01. 

106Annex 16, Vol. III, Appendix 1. ICAO, 2017: 

Annex 16 Volume III—Environmental Protection— 

Aeroplane CO2 Emissions, First Edition, 40 pp. 

Available at: http://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed July 15, 2020). 

The ICAO Annex 16 Volume III is found on page 

16 of English Edition 2020 catalog and is copyright 

protected; Order No. AN 16–3. Also see: ICAO, 

2020, Supplement No. 6—July 2020, Annex 16 

Environmental Protection—Volume III—Aeroplane 

CO2 Emissions, Amendment 1 (20/7/20) 22 pp. 

Available at http://www.icao.int/publications/ 

catalogue/cat_2020_sup06_en.pdf (last accessed 

October 27, 2020). The ICAO Annex 16, Volume III, 

Amendment 1, is found on page 2 of Supplement 

No. 6—July 2020, English Edition, Order No. AN 

16–3/E/01. 

107 ICAO’s certification standards and procedures 

for airplane CO2 emissions are based on the 

consumption of fuel (or fuel burn). ICAO uses the 

term CO2 for its standards and procedures, but 

ICAO is actually regulating or measuring the rate of 

an airplane’s fuel burn (or fuel efficiency). As 

described earlier, to convert an airplane’s rate of 

fuel burn (for jet fuel) to a CO2 emissions rate, a 3.16 

kilograms of CO2 per kilogram of fuel burn emission 

index needs to be applied. 

108U.S. EPA, 2016: Finding That Greenhouse Gas 

Emissions From Aircraft Cause or Contribute To Air 

Pollution That May Reasonably Be Anticipated To 

Endanger Public Health and Welfare; Final Rule, 81 

FR 54422 (August 15, 2016). 

109For jet fuel, the emissions index or emissions 

factor for CO2 is 3.16 kilograms of CO2 per kilogram 

of fuel burn (or 3,160 grams of CO2 per kilogram 

of fuel burn). For jet fuel, the emissions index for 

nitrous oxide is 0.1 grams of nitrous oxide per 

kilogram of fuel burn (which is significantly less 

than the emissions index for CO2). Since CO2 and 

nitrous oxide emissions are indexed to fuel burn, 

they are both directly tied to fuel burn. Controlling 

CO2 emissions means controlling fuel burn, and in 

turn this leads to limiting nitrous oxide emissions. 

Thus, controlling CO2 emissions scales with 

limiting nitrous oxide emissions. 

SAE, 2009, Procedure for the Calculation of 

Airplane Emissions, Aerospace Information Report, 

AIR5715, 2009–07 (pages 45–46). The nitrous oxide 

emissions index is from this report. 

ICAO, 2016: ICAO Environmental Report 2016, 

Aviation and Climate Change, 250 pp. The CO2

emissions index is from this report. Available at 

https://www.icao.int/environmental-protection/ 

Documents/ICAO%20Environmental%20Report

%202016.pdf (last accessed March 16, 2020). 

110See section II.E (Consideration of Whole 

Airplane Characteristics) of this rule for a 

discussion on regulating emissions from the whole 

airplane. 111Although compliance with the final GHG 

standard will be measured in terms of fuel 

efficiency, the EPA considers the six well-mixed 

GHGs to be the regulated pollutant for the purposes 

of the final standard. 

certification authorities. These 

procedures include specifications for 

airplane conformity, weighing, fuel 

specifications, test condition stability 

criteria, required confidence intervals, 

measurement instrumentation required, 

and corrections to reference conditions. 

In this action, we are incorporating by 

reference the test procedures for the 

ICAO Airplane CO2 Emission Standards. 

Adoption of these test procedures will 

maintain consistency among all ICAO 

member States. 

Airplane flight tests, or FAA approved 

performance models, will be used to 

determine SAR values that form the 

basis of the GHG metric value. Under 

the adopted rule, flight testing to 

determine SAR values shall be 

conducted within the approved normal 

operating envelope of the airplane, 

when the airplane is steady, straight, 

level, and trim, at manufacturer-selected 

speed and altitude.104 The rule will 

provide that flight testing must be 

conducted at the ICAO-defined 

reference conditions where possible,105

and that when testing does not align 

with the reference conditions, 

corrections for the differences between 

test and reference conditions shall be 

applied.106

We are incorporating by reference, in 

40 CFR 1030.23(d), certain procedures 

found in ICAO Annex 16, Volume III. 

H. Controlling Two of the Six WellMixed GHGs 

As described earlier in Section IV.A 

and IV.G, we are adopting the ICAO test 

procedures and fuel efficiency 

metric.107 The ICAO test procedures for 

the international Airplane CO2 Emission 

Standards measure fuel efficiency (or 

fuel burn), and ICAO uses fuel 

efficiency in the metric (or equation) for 

determining compliance. As explained 

earlier in Section III and in the 2016 

Findings,108 only two of the six wellmixed GHGs—CO2 and N2O—are 

emitted from covered aircraft. Although 

there is not a standardized test 

procedure for directly measuring 

airplane CO2 or N2O emissions, the test 

procedure for fuel efficiency scales with 

the limiting of both CO2 and N2O 

emissions, as they both can be indexed 

on a per-unit-of-fuel-burn basis. 

Therefore, both CO2 and N2O emissions 

are controlled as airplane fuel burn is 

limited.109 Since limiting fuel burn is 

the only means by which airplanes 

control their GHG emissions, the fuelburn-based metric (or fuel-efficiencybased metric) reasonably serves as a 

means for controlling both CO2 and 

N2O. 

Since CO2 emissions represent nearly 

all GHG emissions from airplanes and 

ICAO’s CO2 test procedures measure 

fuel efficiency by using a fuelefficiency-based metric, we are adopting 

rules that harmonize with the ICAO CO2

standard—by adopting an aircraft 

engine GHG 110 standard that employs a 

fuel efficiency metric that will also scale 

with both CO2 and N2O emissions. The 

aircraft engine GHG standard will 

control both CO2 and N2O emissions, 

without the need for adoption of engine 

exhaust emissions rates for either CO2 or 

N2O. However, the air pollutant 

regulated by these standards will remain 

the aggregate of the six well-mixed 

GHGs.111

I. Response to Key Comments 

The EPA received numerous 

comments on the proposed rulemaking 

which are presented in the Response to 

Comments document along with the 

EPA’s responses to those comments. 

Below is a brief discussion of some of 

the key comments received. 

1. Stringency of the Standards 

Several commenters stated that the 

proposed rulemaking satisfies the 

requirements in the CAA, is consistent 

with the precedent for setting airplane 

emission standards in coordination with 

ICAO, and is supported by the 

administrative record for this 

rulemaking. The establishment of 

aircraft engine GHG standards that 

match the ICAO airplane CO2 standards 

into U.S. law is consistent with the 

authority given to the EPA under 

section 231 of the CAA, and it clearly 

meets the criteria for adoption of aircraft 

engine standards specified in section 

231. In addition, the proposed GHG 

standards align with the following 

CAEP terms of reference (described 

earlier in section II.D.1) that were 

assessed for the international airplane 

CO2 standards: Technical feasibility, 

environmental benefit, economic 

reasonableness, and interdependencies 

of measures (i.e., measures taken to 

minimize noise and emissions). These 

CAEP terms of reference are consistent 

with the criteria the EPA must adhere to 

under section 231(b) of the CAA that 

requires the EPA to allow enough lead 

time ‘‘to permit the development and 

application of the requisite technology, 

giving appropriate consideration to the 

cost of compliance within such 

period’’—when adopting aircraft engine 

emission standards. 

In addition, these commenters 

expressed that the EPA adopting 


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112U.S. EPA, 2005: Control of Air Pollution from 

Aircraft and Aircraft Engines; Emission Standards 

and Test Procedures; Final Rule, 70 FR 69664 

(November 17, 2005). See page 69676 of this 

Federal Register notice. 

standards that match ICAO standards is 

vital to competitiveness of the U.S. 

industry and certainty in the regulatory 

landscape. This approach provides 

international harmonization regulatory 

uniformity throughout the world. 

Adopting ICAO standards will protect 

U.S. jobs and strengthen the American 

aviation industry by ensuring the 

worldwide acceptance of U.S. 

manufactured airplanes. Adopting more 

stringent standards would place U.S. 

airplane manufacturers at a competitive 

disadvantage compared to their 

international competitors. Reciprocity 

and consistency are essential, 

specifically the worldwide mutual 

recognition of the sufficiency of ICAO’s 

standards and the avoidance of any 

unnecessary difference from those 

standards in each Member State’s law. 

Aviation is a global industry, and 

airplanes are assets that can fly 

anywhere in the world and cross 

international borders. Within this 

context, alignment of domestic and 

international standards levels the 

playing field for the aviation industry, 

and it makes sure that financial 

resources can be focused on 

improvement for the benefit of the 

environment (including investments 

creating CO2 emissions reductions via 

carrying out the non-airplanetechnology elements of ICAO’s basket of 

measures). In addition, reciprocity and 

consistency of international standards 

decrease administrative complexity for 

airplane manufacturers and air carriers. 

Some commenters stated that aligning 

with ICAO standards ensures that U.S. 

manufacturers’ airplanes are available to 

U.S. air carriers, while encouraging 

global competition and enabling U.S. air 

carriers to obtain airplanes and airplane 

engines at competitive prices. 

In contrast, several commenters stated 

that the EPA’s lack of consideration of 

feasible standards that result in GHG 

emission reductions is unlawful and 

arbitrary, and that the EPA should adopt 

more stringent standards. Under the 

authority that the EPA is provided in 

Clean Air Act section 231, the EPA is 

obligated to account for the danger to 

public health and welfare of the 

pollutant and the technological 

feasibility to control the pollutant. All 

in-production and new type design 

airplanes will meet the standards 

because existing non-compliant 

airplanes are anticipated to end 

production by 2028, the applicability 

date for in-production airplanes. More 

stringent standards are feasible for inproduction and new type design 

airplanes, and the EPA should adopt 

technology-forcing instead of 

technology following standards to make 

sure the rulemaking will result in 

needed reductions in GHG emissions. 

In response to these comments, we 

refer to Section II.B and the introductory 

paragraphs of Section IV which present 

our reasons for finalizing GHG 

standards that are aligned with the 

international CO2 standards. Section 

231(a)(2)(A) of the CAA directs the 

Administrator of the EPA to, from time 

to time, propose aircraft engine 

emission standards applicable to the 

emission of any air pollutant from 

classes of aircraft engines which in the 

Administrator’s judgment causes or 

contributes to air pollution that may 

reasonably be anticipated to endanger 

public health or welfare. Section 

231(a)(3) provides that after we propose 

standards, the Administrator shall issue 

such standards ‘‘with such 

modifications as he deems appropriate.’’ 

Section 231(b) requires that any 

emission standards ‘‘take effect after 

such period as the Administrator finds 

necessary . . . to permit the 

development and application of the 

requisite technology, giving appropriate 

consideration to the cost of compliance 

during such period.’’ The U.S. Court of 

Appeals for the D.C. Circuit has held 

that these provisions confer an 

unusually broad degree of discretion on 

the EPA to adopt aircraft engine 

emission standards as the Agency 

determines are reasonable. Nat’l Ass’n 

of Clean Air Agencies v. EPA, 489 F.3d 

1221, 1229–30 (D.C. Cir. 2007) 

(NACAA). As described in the 2005 EPA 

rule on aircraft engine NOx standards,112

while the statutory language of section 

231 is not identical to other provisions 

in title II of the CAA that direct the EPA 

to establish technology-based standards 

for various types of engines, the EPA 

interprets its authority under section 

231 to be somewhat similar to those 

provisions that require us to identify a 

reasonable balance of specified 

emissions reduction, cost, safety, noise, 

and other factors. See, e.g., Husqvarna 

AB v. EPA, 254 F.3d 195 (D.C. Cir. 2001) 

(upholding the EPA’s promulgation of 

technology-based standards for small 

non-road engines under section 

213(a)(3) of the CAA). However, we are 

not compelled under section 231 to 

obtain the ‘‘greatest degree of emission 

reduction achievable’’ as per sections 

213 and 202(a)(3)(A) of the CAA, and so 

the EPA does not interpret the Act as 

requiring the agency to give subordinate 

status to factors such as cost, safety, and 

noise in determining what standards are 

reasonable for aircraft engines. Rather, 

the EPA has greater flexibility under 

section 231 in determining what 

standard is most reasonable for aircraft 

engines, and the EPA is not required to 

achieve a technology-forcing result. 

Moreover, in light of the United States’ 

ratification of the Chicago Convention, 

EPA has historically given significant 

weight to uniformity with international 

requirements as a factor in setting 

aircraft engine standards. The fact that 

most airplanes already meet the 

standards does not in itself mean that 

the standards are inappropriate, 

provided the agency has a reasonable 

basis after considering all the relevant 

factors for setting the standards at a 

level that results in no actual emission 

reductions. By the same token, the EPA 

believes a technology-forcing standard 

would not be precluded by section 231, 

in light of section 231(b)’s forwardlooking language. However, the EPA 

would, after consultation with the 

Secretary of Transportation, need to 

provide manufacturers sufficient lead 

time to develop and implement 

requisite technology. Also, there is an 

added emphasis on the consideration of 

safety in section 231 (see, e.g., sections 

231(a)(2)(B)(ii) (‘‘The Administrator 

shall not change the aircraft engine 

emission standards if such change 

would [* * *] adversely affect safety’’), 

42 U.S.C. 7571(a)(2)(B)(ii), and 231(c) 

(‘‘Any regulations in effect under this 

section [* * *] shall not apply if 

disapproved by the President, after 

notice and opportunity for public 

hearing, on the basis of a finding by the 

Secretary of Transportation that any 

such regulation would create a hazard to 

aircraft safety’’), 42 U.S.C. 7571(c). 

Thus, it is reasonable for the EPA to give 

greater weight to considerations of 

safety in this context than it might in 

balancing emissions reduction, cost, and 

energy factors under other title II 

provisions. 

In order to promote international 

cooperation on GHG emissions 

regulation and international 

harmonization of aviation standards and 

to avoid placing U.S. manufacturers at 

a competitive disadvantage that likely 

would result if the EPA were to adopt 

standards different from the standards 

adopted by ICAO, as discussed further 

above, the EPA is adopting standards for 

GHG emissions from certain classes of 

engines used on airplanes that match 

the stringency of the CO2 standards 

adopted by ICAO. This rule will 

facilitate the acceptance of U.S. 

manufactured airplanes and airplane 


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113Boeing stated that the EPA granted 

exemptions, but the FAA granted the exemptions 

after consultation with the EPA, as EPA is not 

authorized under the CAA to grant exemptions. 

engines by member States and airlines 

around the world. In addition, requiring 

U.S. manufacturers to certify to different 

or more stringent standards than have 

been adopted internationally could have 

disruptive effects on manufacturers’ 

ability to market planes for international 

operation. Having invested significant 

effort and resources, working with the 

FAA and the Department of State, to 

gain international consensus within 

ICAO to adopt the first-ever 

international CO2 standards for 

airplanes, the EPA believes that meeting 

the United States’ obligations under the 

Chicago Convention by aligning 

domestic standards with the ICAO 

standards, rather than adopting more 

stringent standards, will have 

substantial benefits for future 

international cooperation on airplane 

emission standards, and such 

cooperation is the key for achieving 

worldwide emission reductions. This 

EPA rule to promulgate airplane GHG 

standards equivalent to international 

standards is consistent with U.S. 

obligations under ICAO. By issuing 

standards that meet or exceed the 

minimum stringency levels of ICAO 

standards, we satisfy these obligations. 

Also, these final standards are the 

first-ever airplane GHG standards and 

test procedures for U.S. manufacturers, 

and international regulatory uniformity 

and certainty are key elements for these 

manufacturers as they become familiar 

with adhering to these standards and 

test procedures. Consistency with the 

international standards will prevent 

backsliding by ensuring that all new 

type design and in-production airplanes 

are at least as efficient as today’s 

airplanes. CAEP meets triennially, and 

in the future, we anticipate ICAO/CAEP 

considering more stringent airplane CO2

standards. The U.S. Interagency Group 

on International Aviation (IGIA) 

facilitates coordinated 

recommendations to the Secretary of 

State on issues pertaining to 

international aviation (and ICAO/ 

CAEP), and the FAA is the chair of 

IGIA. Representatives of domestic states, 

NGOs, and industry can participate in 

IGIA to provide input into future 

standards for ICAO/CAEP. U.S. 

manufacturers will be prepared for any 

future standard change due to their 

experience with the first-ever standards. 

Moreover, the manufacturers 

anticipation of future ICAO standards 

will be another factor for them to 

consider in continually improving the 

fuel efficiency of their airplanes in 

addition to the business-as-usual market 

forces (i.e., in addition to business-asusual continually improving fuel 

efficiency for airplanes), as described 

later in section V. 

2. Timing of the Standard—Extension of 

In Production Applicability Date for 

Some Freight Airplanes 

Some commenters requested that the 

EPA deviate from the ICAO standards 

(and the EPA proposed implementation 

dates) and delay the 2028 in-production 

applicability date for a class of 

widebody purpose-built (or dedicated) 

freighters such as the Boeing 767F and 

Airbus A330–220F. These commenters 

requested that the in-production 

applicability date for purpose-built 

freight airplanes with MTOMs between 

180,000 kg and 240,000 kg be extended 

by 10 years, from January 1, 2028 to 

January 1, 2038. 

Boeing argued that significant 

unexpected economic factors arising 

after the ICAO CO2 standard was 

established, including the COVID–19 

pandemic, have affected and continue to 

severely affect Boeing, its supply chain, 

and its customers, and warrant 

additional time for Boeing to upgrade or 

replace the 767F in a practicable and 

economically feasible manner, 

consistent with the ICAO terms of 

reference and the mandatory factors in 

CAA section 231(b). Additional details 

on these comments can be found in the 

Response to Comments document under 

section 6.2.1. 

The EPA recognizes the significant 

financial hardships the aviation 

industry is experiencing as a result of 

the COVID–19 pandemic. The 

challenges the industry now faces were 

not anticipated when the standards 

were agreed by ICAO in 2017. However, 

ICAO recognized that unexpected 

hardships may arise in the future and 

included language to allow certification 

authorities to grant exemptions when it 

may be appropriate to provide relief 

from the standards. 

Consistent with ICAO, the EPA 

proposed to include exemption 

provisions (40 CFR 1030.10 of the 

regulations) by pointing to the FAA’s 

existing exemption process to provide 

relief when unforeseen circumstances or 

hardships result in the need for 

additional time to comply with the GHG 

standards. These provisions are similar 

to those exemption provisions that have 

been in 40 CFR part 87 of the 

regulations for decades. Manufacturers 

will be able to apply to the FAA for 

exemptions in accordance with the 

regulations of 14 CFR part 11, and the 

FAA will consult with the EPA on each 

exemption application prior to granting 

relief from certification to the GHG 

standards. 

Boeing provided a list of historical 

examples where they say the EPA 

delayed aircraft engine emission 

standards, adopted standards after ICAO 

implementation dates, or granted 

exemptions.113 Boeing characterizes the 

examples of exemptions as the most 

relevant to their current situation with 

the 767F. However, neither Boeing nor 

other commenters provided any 

information or rationale to justify why 

the exemption provisions proposed in 

part 1030.10, which point to the FAA’s 

existing exemption process, would be 

insufficient to resolve their concerns. 

Thus, there is not a sufficient basis for 

the EPA to conclude that the exemption 

provisions would not resolve this issue 

for the commenters. 

As we noted at the beginning of 

Section IV and above in IV.J.1, there are 

significant benefits to industry and 

future international cooperation to 

adopting standards that to the highest 

practicable degree match ICAO 

standards, in terms of scope, timing, 

stringency, etc. If less stringent or 

delayed standards were adopted, it 

would have a disruptive impact on the 

manufacturers’ ability to market their 

airplanes internationally. Boeing 

recognized this disruption in their 

proposed addition to the regulatory text, 

1030.1(a)(8)(ii), where they stated the 

airworthiness certificate would be 

limited to U.S. domestic operation. 

Commenters did not provide any 

rationale, or make any statements, about 

this suggested revision to limit the 

operation of these freighters to the U.S., 

nor did they state why such an 

operational requirement would be in 

EPA’s purview. To include limits as this 

on an airworthiness certificate would 

seem to impose operational restrictions 

on air carriers. Imposing a restriction 

such as that suggested by Boeing would 

be unprecedented for the EPA, and it is 

not clear how it could be accomplished. 

Further, such a significant change was 

not proposed for comment by interested 

parties. Operational restrictions would 

typically be the purview of the FAA 

under its enabling legislation. 

Finally, although Boeing’s request 

purported to also cover an Airbus 

airplane of the same weight class, the 

EPA received no comments from Airbus 

seconding the request, and therefore it 

does not appear that the problem 

identified by Boeing is universal to all 

airplanes of the same class that may be 

put into freighter service. 


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114 ICAO, 2016: Doc 10069—Report of the Tenth 

Meeting, Montreal,1–12 February 2016, Committee 

on Aviation Environmental Protection, CAEP 10, 

432 pp., pages 271 to 308, is found on page 27 of 

the ICAO Products & Services English Edition 2020 

Catalog and is copyright protected. For purchase 

available at: https://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). The summary of technological feasibility and 

cost information is located in Appendix C (starting 

on page 5C–1) of this report. 

115U.S. EPA, 2020: Technical Report on Aircraft 

Emissions Inventory and Stringency Analysis, July 

2020, 52 pp. 

116RTI International and EnDyna, EPA Technical 

Report on Aircraft Emissions Inventory and 

Stringency Analysis: Peer Review, July 2019, 157 

pp. 

Given that no information was 

provided to show why the proposed 

exemptions would be insufficient, that 

the would-be affected airplane 

manufacturers do not seem to be 

universally in favor of or need a 10-year 

compliance extension, and that 

significant challenges and adverse 

impacts would arise if timely 

harmonization with international 

standards did not occur, the EPA is 

finalizing the standards and timing 

proposed in the NPRM. The EPA, in 

consultation with the FAA, believes that 

the exemption process should provide 

an appropriate avenue for 

manufacturers to seek relief. 

V. Aggregate GHG and Fuel Burn 

Methods and Results 

This section describes the EPA’s 

emission impacts analysis for the final 

standards. This section also describes 

the assumptions and data sources used 

to develop the baseline GHG emissions 

inventories and the potential 

consequences of the final standards on 

aviation emissions. Consistent with 

Executive Order 12866, we analyzed the 

impacts of alternatives (using similar 

methodologies), and the results for these 

alternatives are described in chapters 4 

and 5 of the Technical Support 

Document (TSD). 

As described earlier in Section II, the 

manufacturers of affected airplanes and 

engines have already developed or are 

developing technologies that meet the 

2017 ICAO Airplane CO2 Emission 

Standards. The EPA expects that the 

manufacturers will comply with the 

ICAO Airplane CO2 Emission Standards 

even in advance of member States’ 

adoption into domestic regulations. 

Therefore, the EPA expects that the final 

GHG standards will not impose an 

additional burden on manufacturers. In 

keeping with the ICAO/CAEP need to 

consider technical feasibility in 

standard setting, the ICAO Airplane CO2

Emission Standards reflect 

demonstrated technology that will be 

available in 2020. 

As described below, the analysis for 

the final GHG standards considered 

individual airplane types and market 

forces. We have assessed GHG emission 

reductions needed for airplane types (or 

airplane models) to meet the final GHG 

standards compared to the 

improvements that are driven by market 

competition and are expected to occur 

in the absence of any standard (business 

as usual improvements). A summary of 

these results is described later in this 

section. Additional details can be found 

in chapter 5 of the accompanying TSD 

for the final standards. 

A. What methodologies did the EPA use 

for the emissions inventory assessment? 

The EPA participated in ICAO/ 

CAEP’s standard-setting process for the 

international Airplane CO2 Emission 

Standards. CAEP provided a summary 

of the results from this analysis in the 

report of its tenth meeting,114 which 

occurred in February 2016. However, 

due to the commercial sensitivity of the 

data used in the analysis, much of the 

underlying information is not available 

to the public. For the U.S. domestic 

GHG standards, however, we are making 

our analysis, data sources, and model 

assumptions transparent to the public so 

all stakeholders affected by the final 

standards can understand how the 

agency derives its decisions. Thus, the 

EPA has conducted an independent 

impact analysis based solely on publicly 

available information and data sources. 

An EPA report detailing the 

methodology and results of the 

emissions inventory analysis 115 was 

peer-reviewed by multiple independent 

subject matter experts, including experts 

from academia and other government 

agencies, as well as independent 

technical experts.116

The methodologies the EPA uses to 

assess the impacts of the final GHG 

standards are summarized in a flow 

chart shown in Figure V–1. This section 

describes the impacts of the final GHG 

standards. Essentially, the approach is 

to compare the GHG emissions of the 

business as usual baseline in the 

absence of standards with those 

emissions under the final GHG 

standards. 


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117To convert fuel burn to CO2 emissions, we 

used the conversion factor of 3.16 kg/kg fuel for CO2

emissions, and to convert to the six well-mixed 

GHG emissions, we used 3.19 kg/kg fuel for CO2

equivalent emissions. Our method for calculating 

CO2 equivalent emissions is based on SAE AIR 

5715, 2009: Procedures for the Calculation of 

Aircraft Emissions and the EPA publication: 

Emissions Factors for Greenhouse Gas Inventories, 

EPA, last modified 4, April 2014, https://

www.epa.gov/sites/production/files/2015-07/ 

documents/emission-factors_2014.pdf (last 

accessed March 16, 2020). 

118PIANO is the Aircraft Design and Analysis 

Software by Dr. Dimitri Simos, Lissys Limited, UK, 

1990–present; Available at www.piano.aero (last 

accessed March 16, 2020). PIANO is a commercially 

available airplane design and performance software 

suite used across the industry and academia. 

119FAA 2015–2040 Terminal Area Forecast, the 

Terminal Area Forecast (TAF) is the official FAA 

forecast of aviation activity for U.S. airports. It 

contains active airports in the National Plan of 

Integrated Airport Systems (NPIAS) including FAAtowered airports, Federal contract-towered airports, 

non-Federal towered airports, and non-towered 

airports. Forecasts are prepared for major users of 

the National Airspace System including air carrier, 

air taxi/commuter, general aviation, and military. 

The forecasts are prepared to meet the budget and 

planning needs of the FAA and provide information 

for use by state and local authorities, the aviation 

industry, and the public. 

120FlightGlobal Fleets Analyzer is a subscription 

based online data platform providing 

comprehensive and authoritative source of global 

airplane fleet data (also known as ASCEND 

database) for manufacturers, suppliers and 

Maintenance, Repair, Overhaul (MRO) providers. 

https://signin.cirium.com (last accessed December 

16, 2019). 

121For example, in the absence of exact airplane 

match, the aggregated growth rate of airplane 

category is used; in case of no exact OD-pair match, 

the growth rate of route group is used. Outside the 

U.S. the non-US flights were modelled with global 

average growth rates from ICAO for passenger and 

freighter operations and from the Bombardier 

forecast for business jets. See chapter 5 of the TSD 

for details. 

The first step of the EPA analysis is 

to create a baseline, which is 

constructed from the unique airport 

origin-destination (OD) pairs and 

airplane combinations in the 2015 base 

year. As described further in the next 

section, these base year operations are 

then evolved to future year operations, 

2016–2040, by emulating the market 

driven fleet renewal process to define 

the baseline (without the final GHG 

regulatory requirements). The same 

method then is applied to define the 

fleet evolution under the final GHG 

standards, except that different potential 

technology responses are defined for the 

airplanes impacted by the final GHG 

standards. Specifically, they are either 

modified to meet the standards or 

removed from production. Once the 

flight activities for all analysis scenarios 

are defined by the fleet evolution 

module, then fuel burn and GHG 117

emissions are modelled for all the 

scenarios with a physics-based airplane 

performance model known as 

PIANO.118 A brief account of the 

methods, assumptions, and data sources 

used is given below, and more details 

can be found in chapter 4 of the TSD. 

1. Fleet Evolution Module 

To develop the baseline, the EPA used 

FAA 2015 operations data as the basis 

from which to project future fleet 

operations out to 2040. The year-to-year 

activity growth rate was determined by 

the FAA 2015–2040 Terminal Area 

Forecast 119 (TAF) based on airport ODpairs, route groups (domestic or 

international), and airplane types. The 

retirement rate of a specific airplane is 

determined by the age of the airplane 

and the retirement curve of its 

associated airplane type. Retirement 

curves of major airplane types are 

derived statistically based on data from 

the FlightGlobal Fleets Analyzer 

database 120 (also known as ASCEND 

Online Fleets Database—hereinafter 

‘‘ASCEND’’). 

The EPA then linked the 2015 FAA 

operations data to the TAF and 

ASCEND-based growth and retirement 

rates by matching the airport and 

airplane parameters. Where the OD-pair 

and airplane match between the 

operations data and the TAF, then the 

exact TAF year-on-year growth rates 

were applied to grow 2015 base year 

activities to future years. For cases 

without exact matches, growth rates 

from progressively more aggregated 

levels were used to grow the future year 

activities.121

The retirement rate was based on the 

exact age of the airplane from ASCEND 

for airplanes with a known tail number. 

When the airplane tail number was not 

known, the aggregated retirement rate of 

the next level matching fleet (e.g., 

airplane type or category as defined by 


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122The airplane G&R database contains all the 

EPA-known in-production and in-development 

airplanes that are projected to grow and replace the 

global base-year fleet over the 2015–2040 analysis 

period. This airplane G&R database, the annual 

continuous improvements, and the technology 

responses are available in the 2018 ICF Report. 

123The EPA uses equal product market share (for 

all airplane present in the G&R database), but 

attention has been paid to make sure that competing 

manufacturers have reasonable representative 

products in the G&R database. 

124 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

125 ICAO, 2016: Doc 10069—Report of the Tenth 

Meeting, Montreal,1–12 February 2016, Committee 

on Aviation Environmental Protection, CAEP 10, 

432 pp., pages 271 to 308, is found on page 27 of 

the ICAO Products & Services English Edition 2020 

Catalog and is copyright protected. For purchase 

available at: https://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). The summary of technological feasibility and 

cost information is located in Appendix C (starting 

on page 5C–1) of this report. In particular, see 

paragraph 2.3 for the caveats, limitations and 

context of the ICAO analysis. 

126U.S. EPA, 2018: Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2016, 1,184 pp., 

U.S. EPA Office of Air and Radiation, EPA 430–R– 

18–003, April 2018. Available at: https://

www.epa.gov/ghgemissions/inventory-usgreenhouse-gas-emissions-and-sinks-1990-2016 

(last accessed March 16, 2020). 

127 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

128For typical medium/long-haul airplanes, the 

default reserve settings are 200 NM diversion, 30 

minutes hold, plus 5% contingency on mission 

fuel. Depending on airplane types, other reserve 

rules such as U.S. short-haul, European short-haul, 

National Business Aviation Association— 

Instrument Flight Rules (NBAA–IFR) or Douglas 

rules are used as well. 

ASCEND) was used to calculate the 

retirement rates for future years. 

Combining the growth and retirement 

rates together, we calculate the future 

year growth and replacement (G&R) 

market demands. These future year G&R 

market demands are aligned to each 

base year flight, and the future year 

flights are allocated with available G&R 

airplanes 122 using an equal-product 

market-share selection process.123 The 

market demand allocation is made 

based on ASK (Available Seat 

Kilometer) for passenger operations, 

ATK (Available Tonne Kilometer) for 

freighter operations, and number of 

operations for business jets. 

For the 2015 base-year analysis, the 

baseline (no regulation) modelling 

includes continuous (2016–2040) 

annual fuel efficiency improvements. 

The modelling tracks the year airplanes 

enter the fleet and applies the typespecific fuel efficiency improvement 124

via an annual adjustment factor based 

on the makeup of the fleet in a 

particular year. Since there is 

uncertainty associated with the fuelefficiency improvement assumption, the 

analysis also includes a sensitivity 

scenario without this assumption in the 

baseline. This sensitivity scenario 

applied the ICAO Constant Technology 

Assumption to the baseline, which 

meant that no technology improvements 

were projected beyond what was known 

in 2016. Specifically, current airplane 

types were assumed to have the same 

metric value in 2040 as they did in 

2016. ICAO used this simplifying 

assumption because they conducted 

their stringency analysis on comparative 

basis and did not attempt to include 

future emission trends in their 

stringency analysis. ICAO stated that its 

analysis was ‘‘. . .not suitable for 

application to any other purpose of any 

kind, and any attempt at such 

application would be in error.’’ 125 In 

contrast to how ICAO used the Constant 

Technology Assumption, as a 

simplification, the EPA is using this as 

a worst case scenario in our sensitivity 

studies to provide an estimate of the 

range of uncertainty to our main 

analysis in extreme cases. 

The EPA fleet evolution model 

focuses on U.S. aviation, including both 

domestic and international flights (with 

U.S. international flights defined as 

flights departing from the U.S. but 

landing outside the U.S.). This is the 

same scope of operations used for the 

EPA Inventory of U.S. Greenhouse Gas 

Emissions and Sinks.126 However, 

because aviation is an international 

industry and manufacturers of covered 

airplanes sell their products globally, 

the analysis also covers the global fleet 

evolution and emissions inventories for 

reference (but at a much less detailed 

level for traffic growth and fleet 

evolution outside of the U.S.). 

The fleet evolution modelling for the 

final regulatory scenarios defines 

available G&R airplanes for various 

market segments based on the 

technology responses identified by ICF, 

a contractor for the EPA, as described 

later in Section VI.127

2. Full Flight Simulation Module 

PIANO version 5.4 was used for all 

the emissions modelling. PIANO v5.4 

(2017 build) has 591 airplane models 

(including many project airplanes still 

under development, e.g., the B777–9X) 

and 56 engine types in its airplane and 

engine databases. PIANO is a physicsbased airplane performance model used 

widely by industry, research institutes, 

non-governmental organizations and 

government agencies to model airplane 

performance metrics such as fuel 

consumption and emissions 

characteristics based on specific 

airplane and engine types. We use it to 

model airplane performance for all 

phases of flight from gate to gate 

including taxi-out, takeoff, climb, 

cruise, descent, approach, landing, and 

taxi-in in this analysis. 

To simplify the computation, we 

made the following modeling 

assumptions: (1) Assume airplanes fly 

great circle distance (which is the 

shortest distance along the surface of the 

earth between two airports) for each 

origin-destination (OD) pair. (2) Assume 

still air flights and ignore weather or jet 

stream effects. (3) Assume no delays in 

takeoff, landing, en route, and other 

flight-related operations. (4) Assume a 

load factor of 75 percent maximum 

payload capacity for all flights except 

for business jet where 50 percent is 

assumed. (5) Use the PIANO default 

reserve fuel rule 128 for a given airplane 

type. (6) Assume a one-to-one 

relationship between metric value 

improvement and fuel burn 

improvement for airplanes with better 

fuel-efficiency technology insertions (or 

technology responses). 

Given the flight activities defined by 

the fleet evolution module in the 

previous section, we generated a unit 

flight matrix to summarize all the 

PIANO outputs of fuel burn, flight 

distance, flight time, emissions, etc. for 

all flights uniquely defined by a 

combination of departure and arrival 

airports (OD-pairs), airplane types, and 

engine types. This matrix includes 

millions of flights and forms the basis 

for our analysis (including the 

sensitivity studies). 

3. Emissions Module 

The GHG emissions calculation 

involves summing the outputs from the 

first two modules for every flight in the 

database. This is done globally, and 

then the U.S. portion is segregated from 

the global dataset. The same calculation 

is done for the baseline and the final 

GHG standard. When a surrogate 

airplane is used to model an airplane 

that is not in the PIANO database, or 

when a technology response is required 

for an airplane to pass a standard level, 

an adjustment factor is also applied to 

model the expected performance of the 

intended airplane and technology 

responses. 

The differences between the final 

GHG standards and the baseline provide 

quantitative measures to assess the 

emissions impacts of the final GHG 

standards. A brief summary of these 

results is described in the next two 

sections. More details can be found in 

chapter 5 of the TSD. 


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129U.S. EPA, 2016: Regulatory Impact Analysis: 

Greenhouse Gas Emissions and Fuel Efficiency 

Standards for Medium- and Heavy-Duty Engines 

and Vehicles—Phase 2, EPA–420–R–16–900, 

August 2016. 

130U.S. EPA, 2009: Regulatory Impact Analysis: 

Control of Emissions of Air Pollution from Category 

3 Marine Diesel Engines, EPA–420–R–09–019, 

December 2009. 

131A comparison of the EPA and ICAO modeling 

approaches and results is available in chapter 5 and 

6 of the TSD. 

132To convert fuel burn to CO2 emissions, we 

used the conversion factor of 3.16 kg/kg fuel for CO2

emissions, and to convert to the six well-mixed 

GHG emissions, we used 3.19 kg/kg fuel for CO2

equivalent emissions. Our method for calculating 

CO2 equivalent emissions is based on SAE AIR 

5715, 2009: Procedures for the Calculation of 

Aircraft Emissions and the EPA publication: 

Emissions Factors for Greenhouse Gas Inventories, 

EPA, last modified 4, April 2014. https://

www.epa.gov/sites/production/files/2015-07/ 

documents/emission-factors_2014.pdf (last 

accessed March 16, 2020). 

B. What are the baseline GHG 

emissions? 

The commercial aviation marketplace 

is continually changing, with new 

origin-destination markets and new, 

more fuel-efficient airplanes growing in 

number and replacing existing airplanes 

in air carrier (or airline) fleets. This 

behavior introduces uncertainty to the 

future implications of this rulemaking. 

Since there is uncertainty, multiple 

baseline/scenarios may be analyzed to 

explore a possible range of implications 

of the rule. 

For the analysis in this rulemaking 

and consistent with our regulatory 

impact analyses for many other mobile 

source sectors,129,130 the EPA is 

analyzing additional baseline/scenarios 

that reflect a business-as-usual 

continually improving baseline with 

respect to fleet fuel efficiency. We also 

evaluated a baseline scenario that is 

fixed to reflect 2016 technology levels 

(i.e., no continual improvement in fuelefficient technology), and this baseline 

scenario is consistent with the approach 

used by ICAO.131

For the EPA analysis, the baseline 

GHG emissions are assessed for 2015, 

2020, 2023, 2025, 2028, 2030, 2035, and 

2040. The projected baseline GHG 

emissions for all U.S. flights (domestic 

and international) are shown in Figure 

V–2 and Figure V–3, both with and 

without the continuous (2016–2040) 

fuel-efficiency improvement 

assumption. More detailed breakdowns 

for the passenger, freighter, and 

business market segments can be found 

in chapter 5 of the TSD. It is worth 

noting that the U.S. domestic market is 

relatively mature, with a lower growth 

rate than those for most international 

markets. The forecasted growth rate for 

the U.S. domestic market combined 

with the Continuous Improvement 

Assumption results in a low GHG 

emissions growth rate in 2040 for the 

U.S. domestic market. However, it 

should be noted that this is one set of 

assumptions combined with a market 

forecast. Actual air traffic and emissions 

growth may vary as a result of a variety 

of factors. 

BILLING CODE 6560–50–P 


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133 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

134 ICAO, 2016: Doc 10069—Report of the Tenth 

Meeting, Montreal,1–12 February 2016, Committee 

on Aviation Environmental Protection, CAEP 10, 

432pp., pages 271 to 308, is found on page 27 of 

the ICAO Products & Services English Edition 2020 

Catalog and is copyright protected. For purchase 

available at: https://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). The summary of technological feasibility and 

cost information is located in Appendix C (starting 

on page 5C–1) of this report. In particular, see 

paragraph 2.3 for the caveats, limitations and 

context of the ICAO analysis. 

Conceptually, the difference between 

the EPA and ICAO analysis baselines is 

illustrated in Figure V–4. The solid line 

represents the historical growth of 

emissions from the dawn of the jet age 

in 1960s to the present (2016). In this 

time, air traffic and operations have 

increased and offset the technology 

improvements. The long-dashed line 

(l l) and dot-dash-dot (l . l) lines 

represent different assumptions used by 

the EPA and ICAO to create baseline 

future inventories to compare the 

benefits of potential standards. The two 

baselines start in 2016, but their 

different assumptions lead to very 

different long-term forecasts. The EPA 

method (long dash) uses the input from 

an independent analysis conducted by 

ICF 133 to develop a Projected 

Continuous Improvement baseline to 

model future improvements similar to 

historical trends. The ICAO method 

creates a baseline using a Constant 

Technology Assumption that freezes the 

airplane technology going forward. This 

means that the in-production airplanes 

after that date will be built with no 

changes indefinitely into the future, i.e. 

the baseline assumes airplanes will have 

the same metric value in 2040 as they 

did in 2016. The dot-dot-dash 

(l . l) line compares this Constant 

Technology Assumption to the solid 

historical emissions growth. ICAO used 

this simplifying assumption because 

they conducted their stringency analysis 

on comparative basis and did not 

attempt to include future emission 

trends in their stringency analysis. 

Comparative basis means ICAO looked 

at the difference in emission reductions 

between stringency options in isolation 

and did not attempt to factor in future 

business as usual improvements or fleet 

changes. The projected benefits of any 

standards will be different depending 

upon the baseline that is assumed. Note 

that ICAO stated that its analysis was 

‘‘. . . not suitable for application to any 

other purpose of any kind, and any 

attempt at such application would be in 

error.’’ 134 To understand the true 

meaning of the analysis and make wellinformed policy decisions, one must 

consider the underlying assumptions 

carefully. For example, if the EPA were 

to use the ICAO Constant Technology 

Assumption in our main analysis, the 

impact of the rulemaking would be 

overestimated, i.e., these results would 

not be able to differentiate the effect of 

the standards from the expected 

business as usual improvements. 


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135 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

136The differences in the analyses include 

different assumptions. Our analysis assumes 

continuous improvement and ICAO’s analysis does 

not. Also, we make different projections about the 

end of production of the A380 and 767 compared 

to ICAO. 137On February 14, 2019, Airbus made an 

announcement to end A380 production by 2021 

after Emirates airlines reduced its A380 order by 39 

and replaced them with A330 and A350. (The 

Airbus press release is available at: https://

www.airbus.com/newsroom/press-releases/en/2019/ 

02/airbus-and-emirates-reach-agreement-on-a380- 

fleet-sign-new-widebody-orders.html, last accessed 

on February 10, 2020). EPA’s analysis was 

conducted prior to Airbus’s announcement, so the 

analysis does not consider the impact of the A380 

BILLING CODE 6560–50–C 

C. What are the projected effects in fuel 

burn and GHG emissions? 

EPA’s analysis projects that the final 

GHG standards will not result in 

reductions in fuel burn and GHG 

emissions beyond the baseline. This 

result makes sense because all of the 

airplanes in the G&R fleet either will 

meet the standard level associated with 

the final GHG standards or are expected 

to be out of production by the time the 

standards take effect, according to our 

technology responses.135 In other words, 

the existing or expected fuel efficiency 

technologies from airplane and engine 

manufacturers that were the basis of the 

ICAO standards, which match the final 

standards, demonstrate technological 

feasibility. Thus, we do not project a 

cost or benefit for the final GHG 

standards (further discussion on the 

rationale for no expected reductions and 

no costs is provided later in this section 

and Section VI). 

The EPA projected reduction in GHG 

emissions is different from the results of 

the ICAO analysis mentioned in V.A, 

which bounds the range of analysis 

exploration given the uncertainties 

involved with predicting the 

implications of this rule. The agency has 

conducted sensitivity studies around 

our main analysis to understand the 

differences 136 between our analysis and 

ICAO’s (further detail on the differences 

in the analyses and the sensitivity 

studies is provided in the TSD). These 

sensitivity studies show that the no 

cost-no benefit conclusion is quite 

robust. For example, even if we assume 

no continuous improvement, the 

projected GHG emissions reductions for 

the final standards will still be zero 

since all the non-compliant airplanes 

(A380 137 and 767 freighters) are 


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ending production in 2021. The early exit of A380, 

compared to the modeled scenarios, fits the general 

trend of reduced demands for large quad engine 

airplanes projected by the ICF technology responses 

and is consistent with our conclusion of no cost and 

no benefit for this rule. 

138As described later in section VI.B for 

Technology Readiness Level 8 (TRL8), this refers to 

having been proven to be ‘‘actual system completed 

and ‘flight qualified’ through test and 

demonstration.’’ 

139 ICAO, 2016: Report of Tenth Meeting, 

Montreal, 1–12 February 2016, Committee on 

Aviation Environmental Protection, Document 

10069, CAEP/10, 432pp, is found on page 27 of the 

English Edition of the ICAO Products & Services 

2020 Catalog and is copyright protected; Order No. 

10069. For purchase available at: https://

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed March 16, 2020). The summary of 

technological feasibility and cost information is 

located in Appendix C (starting on page 5C–1) of 

this report. 

140 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

141 ICF International, 2015: CO2 Analysis of CO2- 

Reducing Technologies for Aircraft, Final Report, 

EPA Contract Number EP–C–12–011, March 17, 

2015. 

projected to be out of production by 

2028 (according to ICF analysis), the 

final standard effective year. We note 

that in their public comments on the 

proposal Boeing, along with Fedex, GE, 

and the Cargo Airline Association, 

expressed that there would continue to 

be a low volume demand for the B767 

freighter beyond January 1, 2028. These 

commenters did not indicate the 

number of 767F’s that would be 

produced after 2028. The EPA did not 

change the analysis to adjust the 

baseline to include continued 

production of the 767F beyond 2028 

because insufficient information to 

characterize this scenario was provided. 

Furthermore, we analyzed a 

sensitivity case where A380 and 767 

freighters comply with the standards in 

2028 and continue production until 

2030 and not make any improvement 

between 2015 and 2027, the GHG 

emissions reductions will still be an 

order of magnitude lower than the ICAO 

results since all emissions reductions 

will come from just 3 years’ worth of 

production (2028 to 2030) of A380 and 

767 freighters. Considering that both 

airplanes are close to the end of their 

production life cycle by 2028 and low 

market demands for them, these limited 

emissions reductions may not be 

realized if the manufacturers are granted 

exemptions. Thus, the agency analysis 

results in a no cost-no benefit 

conclusion that is reasonable for the 

final GHG standards. 

In summary, the ICAO Airplane CO2

Emission Standards, which match the 

final EPA GHG standards, were 

predicated on technologies that 

manufacturers of affected airplanes and 

engines had already demonstrated to be 

safe and airworthy to the advanced 

technology readiness level 8 138 when 

they were adopted in 2017. The EPA 

expects that the manufacturers will 

comply with the ICAO Airplane CO2

Emission Standards even before member 

States’ adoption into domestic 

regulations. Therefore, the EPA expects 

that the final airplane GHG standards 

will not impose an additional burden on 

manufacturers. 

VI. Technological Feasibility and 

Economic Impacts 

This section describes the 

technological feasibility and costs of the 

airplane GHG rule. This section 

describes the agency’s methodologies 

for assessing technological feasibility 

and estimated costs of the final 

standards. Consistent with Executive 

Order 12866, we analyzed the 

technological feasibility and costs of 

alternatives (using similar 

methodologies), and the results for these 

alternatives are described in chapter 6 of 

the TSD. 

The EPA and the FAA participated in 

the ICAO analysis that informed the 

adoption of the international Airplane 

CO2 Emission Standards. A summary of 

that analysis was published in the 

report of ICAO/CAEP’s tenth 

meeting,139 which occurred in February 

2016. However, due to the commercial 

sensitivity of much of the underlying 

data used in the ICAO analysis, the 

ICAO-published report (which is 

publicly available) provides only 

limited supporting data for the ICAO 

analysis. The EPA TSD for this 

rulemaking compares the ICAO analysis 

to the EPA analysis. 

For the purposes of evaluating the 

final GHG regulations based on publicly 

available and independent data, the 

EPA had an analysis conducted of the 

technological feasibility and costs of the 

international Airplane CO2 Emission 

Standards through a contractor (ICF) 

study.140 141 The results, developed by 

the contractor, include estimates of 

technology responses and non-recurring 

costs for the domestic GHG standards, 

which are equivalent to the 

international Airplane CO2 Emission 

Standards. Technologies and costs 

needed for airplane types to meet the 

final GHG regulations were analyzed 

and compared to the improvements that 

are anticipated to occur in the absence 

of regulation. The methods used in and 

the results from the analysis are 

described in the following paragraphs— 

and in further detail in chapter 2 of the 

TSD for this rulemaking. 

A. Market Considerations 

Prior to describing our technological 

feasibility and cost analysis, potential 

market impacts of the final GHG 

regulations are discussed in this section. 

As described earlier, airplanes and 

airplane engines are sold around the 

world, and international airplane 

emission standards help ensure the 

worldwide acceptability of these 

products. Airplane and airplane engine 

manufacturers make business decisions 

and respond to the international market 

by designing and building products that 

conform to ICAO’s international 

standards. However, ICAO’s standards 

need to be implemented domestically 

for products to prove such conformity. 

Domestic action through EPA 

rulemaking and subsequent FAA 

rulemaking enables U.S. manufacturers 

to obtain internationally recognized 

FAA certification, which for the 

adopted GHG standards will ensure type 

certification consistent with the 

requirements of the international 

Airplane CO2 Emission Standards. This 

is important, as compliance with the 

international standards (via FAA type 

certification) is a critical consideration 

in airlines’ purchasing decisions. By 

implementing the requirements that 

conform to ICAO requirements in the 

United States, we will remove any 

question regarding the compliance of 

airplanes certificated in the United 

States. The rule will facilitate the 

acceptance of U.S. airplanes and 

airplane engines by member States and 

airlines around the world. Conversely, 

U.S. manufacturers will be at a 

competitive disadvantage compared 

with their international competitors 

without this domestic action. 

In considering the aviation market, it 

is important to understand that the 

international Airplane CO2 Emission 

Standards were predicated on 

demonstrating technological feasibility; 

i.e., that manufacturers have already 

developed or are developing improved 

technology that meets the 2017 ICAO 

CO2 standards, and that the new 

technology will be integrated in 

airplanes throughout the fleet in the 

time frame provided before the 

implementation of the standards’ 

effective date. Therefore, as described in 

Section V.C, the EPA projects that these 

final standards will impose no 

additional burden on manufacturers. 

While recognizing that the 

international agreement was predicated 

on demonstrated technological 

feasibility, without access to the 


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142 ICF International, 2015: CO2 Analysis of CO2- 

Reducing Technologies for Aircraft, Final Report, 

EPA Contract Number EP–C–12–011, March 17, 

2015. 

143 ICF, 2018: Aircraft CO2 Cost and Technology 

Refresh and Industry Characterization, Final 

Report, EPA Contract Number EP–C–16–020, 

September 30, 2018. 

144As described earlier in section IV, the ICAO 

test procedures for the international airplane CO2

standards measure fuel efficiency (or fuel burn). 

Only two of the six well-mixed GHGs—CO2 and 

N2O are emitted from airplanes. The test procedures 

for fuel efficiency scale with the limiting of both 

CO2 and N2O emissions, as they both can be 

indexed on a per-unit-of-fuel-burn basis. Therefore, 

both CO2 and N2O emissions can be controlled as 

airplane fuel burn is limited. Since limiting fuel 

burn is the only means by which airplanes control 

their GHG emissions, the fuel burn (or fuel 

efficiency) reasonably serves as a surrogate for 

controlling both CO2 and N2O. 

145TRL is a measure of Technology Readiness 

Level. CAEP has defined TRL8 as the ‘‘actual 

system completed and ‘flight qualified’ through test 

and demonstration.’’ TRL is a scale from 1 to 9, 

TRL1 is the conceptual principle, and TRL9 is the 

‘‘actual system ‘flight proven’ on operational 

flight.’’ The TRL scale was originally developed by 

NASA. ICF International, CO2 Analysis of CO2- 

Reducing Technologies for Aircraft, Final Report, 

EPA Contract Number EP–C–12–011, see page 40, 

March 17, 2015. 

146 ICAO, 2016: Report of the Tenth Meeting, 

Montreal, 1–12 February 2016, Committee on 

Aviation Environmental Protection, Document 

10069, CAEP10, 432pp, is found on page 27 of the 

English Edition of the ICAO Products & Services 

2020 Catalog and is copyright protected: Order No. 

10069. For purchase available at: https://

www.icao.int/publications/Pages/catalogue.aspx 

(last accessed March 16, 2020). The statement on 

technological feasibility is located in Appendix C 

(page 5C–15, paragraph 6.2.1) of this report. 

147Aircraft that are currently in-development but 

were anticipated to be in production by about 2020. 

148To generate metric values, the 2015 ICF 

analysis and 2018 ICF updated analysis used 

PIANO (Project Interactive Analysis and 

Optimization) data so that their analyses results can 

be shared publicly. Metric values developed 

utilizing PIANO data are similar to ICAO metric 

values. PIANO is the Aircraft Design and Analysis 

Software by Dr. Dimitri Simos, Lissys Limited, UK, 

1990-present; Available at www.piano.aero (last 

accessed March 16, 2020). PIANO is a commercially 

available aircraft design and performance software 

suite used across the industry and academia. 

149Also referred to as the constant annual 

improvement in CO2 metric value. 

underlying ICAO/CAEP data it is 

informative to evaluate individual 

airplane models relative to the 

equivalent U.S. regulations. Therefore, 

the technologies and costs needed for 

airplane types to meet the rule were 

compared to the improvements that are 

expected to occur in the absence of 

standards (business as usual 

improvements). A summary of these 

results is described later in this section. 

B. Conceptual Framework for 

Technology 

As described in the 2015 ANPR, the 

EPA contracted with ICF to develop 

estimates of technology improvements 

and responses needed to modify inproduction airplanes to comply with the 

international Airplane CO2 Emission 

Standards. ICF conducted a detailed 

literature search, performed a number of 

interviews with industry leaders, and 

did its own modeling to estimate the 

cost of making modifications to inproduction airplanes.142 Subsequently, 

for this rulemaking, the EPA contracted 

with ICF to update its analysis (herein 

referred to as the ‘‘2018 ICF updated 

analysis’’).143 It had been three years 

since the initial 2015 ICF analysis was 

completed, and the EPA had ICF update 

the assessment to ensure that the 

analysis included in this rulemaking 

reflects the current status of airplane 

GHG technology improvements. 

Therefore, ICF’s assessment of 

technology improvements was updated 

since the 2015 ANPR was issued.144

The long-established ICAO/CAEP 

terms of reference were taken into 

account when deciding the international 

Airplane CO2 Emission Standards, 

principal among these being technical 

feasibility. For the ICAO CO2

certification standard setting, technical 

feasibility refers to any technology 

expected to be demonstrated to be safe 

and airworthy proven to Technology 

Readiness Level 145 (TRL) 8 by 2016 or 

shortly thereafter (per CAEP member 

guidance; approximately 2017), and 

expected to be available for application 

in the short term (approximately 2020) 

over a sufficient range of newly 

certificated airplanes.146 This means 

that the analysis that informed the 

international standard considered the 

emissions performance of in-production 

and on-order or in-development 147

airplanes, including types that first 

enter into service by about 2020. (ICAO/ 

CAEP’s analysis was completed in 2015 

for the February 2016 ICAO/CAEP 

meeting.) 

In assessing the airplane GHG rule, 

the 2018 ICF updated analysis, which 

was completed a few years after the 

ICAO analysis, was able to use a 

different approach for technology 

responses. ICF based these responses on 

technology available at TRL8 by 2017 

and projected continuous improvement 

of CO2 metric values for in-production 

and in-development (or on-order) 

airplanes from 2010 to 2040 based on 

the incorporation of these technologies 

onto these airplanes over this same 

timeframe. Also, ICF considered the end 

of production of airplanes based on the 

expected business-as-usual status of 

airplanes (with the continuous 

improvement assumptions). This 

approach is described in further detail 

later in Section VI.C. The ICF approach 

differed from ICAO’s analysis for years 

2016 to 2020 and diverged even more 

for years 2021 and after. Since ICF was 

able to use the final effective dates in 

their analysis of the final airplane GHG 

standard (for new type design airplanes 

2020, or 2023 for airplanes with less 

than 19 seats, and for in-production 

airplanes 2028), ICF was able to 

differentiate between airplane GHG 

technology improvements that would 

occur in the absence of the final 

standard (business as usual 

improvements) compared against 

technology improvements/responses 

needed to comply with the final 

standard. ICF’s approach is appropriate 

for the EPA-final GHG standard because 

it is based on more up-to-date inputs 

and assumptions. 

C. Technological Feasibility 

1. Technology Principles and 

Application 

i. Short- and Mid-Term Methodology 

ICF analyzed the feasible 

technological improvements to new inproduction airplanes and the potential 

GHG emission reductions they could 

generate. For this analysis, ICF created 

a methodological framework to assess 

the potential impact of technology 

introduction on airplane GHG emissions 

for the years 2015–2029 (upcoming 

short and mid-term). This framework 

included five steps to estimate annual 

metric value (baseline metric values 

were generated using PIANO data 148) 

improvements for technologies that are 

being or will be applied to inproduction airplanes. First, ICF 

identified the technologies that could 

reduce GHG emissions of new inproduction airplanes. Second, ICF 

evaluated each technology for the 

amount of potential GHG reduction and 

the mechanisms by which this 

reduction could be achieved. These first 

two steps were analyzed by airplane 

category. Third and fourth, the 

technologies were passed through 

technical success probability and 

commercial success probability 

screenings, respectively. Finally, 

individual airplane differences were 

assessed within each airplane category 

to generate GHG emission reduction 

projections by technology by airplane 

model—at the airplane family level (e.g., 

737 family). ICF refers to their 

methodological framework for 

projection of the metric value 

improvement or reduction as the 

expected value methodology. The 

expected value methodology is a 

projection of the annual fuel efficiency 

metric value improvement 149 from 


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150The fuel burn reduction prospect index is a 

projected ranking of the feasibility and readiness of 

technologies (for reducing fuel burn) to be 

implemented for 2030 and later. There are three 

main steps to determine the fuel burn reduction 

prospect index. First, the technology factors that 

mainly contribute to fuel burn were identified. 

These factors included the following engine and 

airframe technologies as described below: (Engine) 

sealing, propulsive efficiency, thermal efficiency, 

reduced cooling, and reduced power extraction and 

(Airframe) induced drag reduction and friction drag 

reduction. Second, each of the technology factors 

were scored on the following three scoring 

dimensions that will drive the overall fuel burn 

reduction effectiveness in the outbound forecast 

years: Effectiveness of technology in reducing fuel 

burn, likelihood of technology implementation, and 

level of research effort required. Third, the scoring 

of each of the technical factors on the three 

dimensions were averaged to derive an overall fuel 

burn reduction prospect index. 

151The metric value does not directly reward 

weight reduction technologies because such 

technologies are also used to allow for increases in 

payload, equipage and fuel load. Thus, reductions 

in empty weight can be canceled out or diminished 

by increases in payload, fuel, or both; and, this 

varies by operation. Empty weight refers to 

operating empty weight. It is the basic weight of an 

airplane including the crew, all fluids necessary for 

operation such as engine oil, engine coolant, water, 

unusable fuel and all operator items and equipment 

required for flight, but excluding usable fuel and 

the payload. 

152Airplanes that are currently in-development 

but will be in production by the applicability dates. 

These could be new type designs or redesigned 

airplanes. 

2015–2029 for all the technologies that 

would be applied to each airplane (or 

business as usual improvement in the 

absence of a standard). 

As a modification to the 2015 ICF 

analysis, the 2018 ICF updated analysis 

extended the metric value 

improvements at the airplane family 

level (e.g., 737 family) to the more 

specific airplane variant level (e.g., 737– 

700, 737–800, etc.). Thus, to estimate 

whether each airplane variant complied 

with the final GHG standard, ICF 

projected airplane family metric value 

reductions to a baseline (or base year) 

metric value of each airplane variant. 

ICF used this approach to estimate 

metric values for 125 airplane models 

allowing for a comparison of the 

estimated metric value for each airplane 

model to the level of the final GHG 

standard at the time the standard goes 

into effect. 

In addition, ICF projected which 

airplane models will end their 

production runs (or production cycle) 

prior to the effective date of the final 

GHG standard. These estimates of 

production status, at the time the 

standard will go into effect, further 

informed the projected response of 

airplane models to the final standard. 

Further details of the short- and midterm methodology are provided in 

chapter 2 of the TSD. 

ii. Long-Term Methodology 

To project metric value improvements 

for the long-term, years 2030–2040, ICF 

generated a different methodology 

compared with the short- and mid-term 

methodology. The short- and mid-term 

methodology is based on forecasting 

metric value improvements contributed 

by specific existing technologies that are 

implemented, and ICF projects that 

about the 2030 timeframe a new round 

of technology implementation will 

begin that leads to developing a 

different method for predicting metric 

value improvements for the long term. 

For 2030 or later, ICF used a parametric 

approach to project annual metric value 

improvements. This approach included 

three steps. First, for each airplane type, 

technical factors were identified that 

drive fuel burn and metric value 

improvements in the long-term (i.e., 

propulsive efficiency, friction drag 

reduction), and the fuel burn reduction 

prospect index 150 was estimated on a 

scale of 1 to 5 for each technical factor 

(chapter 2 of the TSD describes these 

technical factors in detail). Second, a 

long-term market prospect index was 

generated on a scale of 1 to 5 based on 

estimates of the amount of potential 

research and development (R&D) put 

into various technologies for each 

airplane type. Third, the long-term 

market prospect index for each airplane 

type was combined with its respective 

fuel burn reduction prospect index to 

generate an overall index score for its 

metric value improvements. A low 

overall index score indicates that the 

airplane type will have a reduced 

annual metric value reduction (the 

metric value decreases yearly at a 

slower rate relative to an extrapolated 

short- and mid-term annual metric value 

improvement), and a high overall index 

score indicates an accelerated annual 

metric value improvement (the metric 

value decreases yearly at a quicker rate 

relative to an extrapolated short- and 

mid-term annual metric value 

improvement). Further details of the 

long-term methodology are provided in 

chapter 2 of the TSD. 

2. What technologies did the EPA 

consider to reduce GHG emissions? 

ICF identified and analyzed seventy 

different aerodynamic, weight, and 

engine (or propulsion) technologies for 

fuel burn reductions. Although weightreducing technologies affect fuel burn, 

they do not affect the metric value for 

the GHG rule.151 Thus, ICF’s assessment 

of weight-reducing technologies was not 

included in this rule, which excluded 

about one-third of the technologies 

evaluated by ICF for fuel burn 

reductions. In addition, based on the 

methodology described earlier in 

Section VI.C, ICF utilized a subset of the 

about fifty aerodynamic and engine 

technologies they evaluated to account 

for the improvements to the metric 

value for the final standard (for inproduction and in-development 

airplanes 152). 

A short list of the aerodynamic and 

engine technologies that were 

considered to improve the metric value 

of the rule is provided below. Chapter 

2 of the TSD provides a more detailed 

description of these technologies. 

• Aerodynamic technologies: The 

airframe technologies that accounted for 

the improvements to the metric values 

from airplanes included aerodynamic 

technologies that reduce drag. These 

technologies included advance wingtip 

devices, adaptive trailing edge, laminar 

flow control, and riblet coatings. 

• Engine technologies: The engine 

technologies that accounted for 

reductions to the metric values from 

airplanes included architecture and 

cooling technologies. Architecture 

technologies included ultra-high bypass 

engines and the fan drive gear, and 

cooling technologies included 

compressor airfoil coating and turbine 

air cooling. 

3. Technology Response and 

Implications of the Final Standard 

The EPA does not project that the 

GHG rule will cause manufacturers to 

make technical improvements to their 

airplanes that would not have occurred 

in the absence of the rule. The EPA 

projects that the manufacturers will 

meet the standards independent of the 

EPA standards, for the following reasons 

(as was described earlier in Section 

VI.A): 

• Manufacturers have already 

developed or are developing improved 

technology in response to the ICAO 

standards that match the final GHG 

regulations; 

• ICAO decided on the international 

Airplane CO2 Emission Standards, 

which are equivalent to the final GHG 

standards, based on proven technology 

by 2016/2017 that was expected to be 

available over a sufficient range of inproduction and on-order airplanes by 

approximately 2020. Thus, most or 

nearly all in-production and on-order 

airplanes already meet the levels of the 

final standards; 

• Those few in-production airplane 

models that do not meet the levels of the 

final GHG standards are at the end of 

their production life and are expected to 

go out of production in the near term or 


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153As described earlier, this result is different 

from the ICAO analysis, which did not use 

continuous improvement CO2 metric values nor 

production end dates for products. 

154Engineering and Integration includes the 

engineering and Research & Development (R&D) 

needed to progress a technology from its current 

level to a level where it can be integrated onto a 

production airframe. It also includes all airframe 

and technology integration costs. 

155For the incremental technology category of an 

engine minor PIP, 35 percent of NRC is for 

engineering of integration costs, 50 percent is for 

testing, and 15 percent is for tooling, capital 

equipment, and infrastructure. For the category of 

a large incremental upgrade, 55 percent of NRC is 

for engineering of integration costs, 40 percent is for 

testing, and 5 percent is for tooling, capital 

equipment, and infrastructure. 

156Engineering and integration costs and tooling, 

capital equipment, and infrastructure costs were 

scaled by airplane realized sale price from the 

single-aisle airplane category to the other airplane 

categories. Testing costs were scaled by average 

airplane operating costs. 

157 In addition, European authorities charge fees 

to airplane manufacturers for the certification of 

their airplanes, but FAA does not charge fees for 

certification. 

seek an exemption from the final 

standards; and 

• These few in-production airplane 

models anticipated to go out of 

production are being replaced or are 

expected to be replaced by indevelopment airplane models (airplane 

models that have recently entered 

service or will in the next few years) in 

the near term—and these indevelopment models have much 

improved metric values compared to the 

in-production airplane model they are 

replacing. 

Based on the approach described 

above in Sections VI.C.1 and VI.C.2, ICF 

assessed the need for manufacturers to 

develop technology responses for inproduction and in-development 

airplane models to meet the final GHG 

standards (for airplane models that were 

projected to be in production by the 

effective dates of the final standards and 

would be modified to meet these 

standards, instead of going out of 

production). After analyzing the results 

of the approach/methodology, ICF 

estimated that all airplane models (inproduction and in-development 

airplane models) will meet the levels of 

the final standard or be out of 

production by the time the standard 

became effective. Thus, a technology 

response is not necessary for airplane 

models to meet the final rule. This 

result confirms that the international 

Airplane CO2 Emission Standards are 

technology following standards, and 

that the EPA’s final GHG standards as 

they will apply to in-production and indevelopment airplane models will also 

be technology following.153

For the same reasons, a technology 

response is not necessary for new type 

design airplanes to meet the GHG rule. 

The EPA is currently not aware of a 

specific model of a new type design 

airplane that is expected to enter service 

after 2020. Additionally, any new type 

design airplanes introduced in the 

future will have an economic incentive 

to improve their fuel burn or metric 

value at the level of or less than the rule. 

D. Costs Associated With the Program 

This section provides the elements of 

the cost analysis for technology 

improvements, including certification 

costs, and recurring costs. As described, 

above, the EPA does not anticipate new 

technology costs due to the GHG rule. 

While recognizing that the GHG rule 

does not have non-recurring costs 

(NRC), certification costs, or recurring 

costs, it is informative to describe the 

elements of these costs. 

1. Non-Recurring Costs 

Non-recurring cost (NRC) consists of 

the cost of engineering and 

integration,154 testing (flight and ground 

testing) and tooling, capital equipment, 

and infrastructure. As described earlier 

for the technology improvements and 

responses, ICF conducted a detailed 

literature search, conducted a number of 

interviews with industry leaders, and 

did its own modeling to estimate the 

NRC of making modifications to inproduction airplanes. The EPA used the 

information gathered by ICF for 

assessing the cost of individual 

technologies, which were used to build 

up NRC for incremental improvements 

(a bottom-up approach). These 

improvements are for 0 to 10 percent 

improvements in the airplane CO2

metric value, and this magnitude of 

improvements is typical for inproduction airplanes (the focus of our 

analysis). In the initial 2015 ICF 

analysis, ICF developed NRC estimates 

for technology improvements to inproduction airplanes, and in the 2018 

ICF updated analysis these estimates 

have been brought up to date. The 

technologies available to make 

improvements to airplanes are briefly 

listed earlier in Section VI.C.2. 

The methodology for the development 

of the NRC for in-production airplanes 

consisted of six steps. First, 

technologies were categorized either as 

minor performance improvement 

packages (PIPs) with 0 to 2 percent (or 

less than 2 percent) fuel burn 

improvements or as larger incremental 

updates with 2 to 10 percent 

improvements. Second, the elements of 

non-recurring cost were identified (e.g., 

engineering and integration costs), as 

described earlier. Third, these elements 

of non-recurring cost are apportioned by 

incremental technology category for 

single-aisle airplanes (e.g., for the 

category of an airframe minor PIP, 85 

percent of NRC is for engineering of 

integration costs, 10 percent is for 

testing, and 5 percent is for tooling, 

capital equipment, and 

infrastructure). 155 Fourth, the NRC 

elements were scaled to the other 

airplane size categories (from the 

baseline single-aisle airplane category). 

Fifth, we estimated the NRC costs for 

single-aisle airplane and applied the 

scaled costs to the other airplane size 

categories.156 Sixth, we compiled 

technology supply curves by airplane 

model, which enabled us to rank 

incremental technologies from most cost 

effective to the least cost effective. For 

determining technical responses by 

these supply curves, it was assumed 

that the manufacturer invests in and 

incorporates the most cost-effective 

technologies first and go on to the next 

most cost-effective technology to attain 

the metric value improvements needed 

to meet the standard. Chapter 2 of the 

TSD provides a more detailed 

description of this NRC methodology for 

technology improvements and results. 

2. Certification Costs 

Following this final rulemaking for 

the GHG standards, the FAA will issue 

a rulemaking to enforce compliance to 

these standards, and any potential 

certification costs for the GHG standards 

will be estimated by FAA and attributed 

to the FAA rulemaking. However, it is 

informative to discuss certification 

costs. 

As described earlier, manufacturers 

have already developed or are 

developing technologies to respond to 

ICAO standards that are equivalent to 

the final standards, and they will 

comply with the ICAO standards in the 

absence of U.S. regulations. Also, this 

rulemaking will potentially provide for 

a cost savings to U.S. manufacturers 

since it will enable them to domestically 

certify their airplane (via subsequent 

FAA rulemaking) instead of having to 

certify with foreign certification 

authorities (which will occur without 

this EPA rulemaking). If the final GHG 

standards, which match the ICAO 

standards, are not adopted in the U.S., 

the U.S. civil airplane manufacturers 

will have to certify to the ICAO 

standards at higher costs because they 

will have to move their entire 

certification program(s) to a non-U.S. 

certification authority.157 Thus, there 

are no new certification costs for the 

rule. However, it is informative to 


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Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 2169 

158 ICAO, 2016: Report of Tenth Meeting, 

Montreal, 1–12 February 2016, Committee on 

Aviation Environmental Protection, Document 

10069, CAEP/10, 432pp, is found on page 27 of the 

English Edition of the ICAO Products & Services 

2020 Catalog and is copyright protected; Order No. 

10069. See Appendix C of this report. For purchase 

available at: https://www.icao.int/publications/ 

Pages/catalogue.aspx (last accessed March 16, 

2020). 

159ATAG, 2020: Tracking Aviation Efficiency, 

How is the aviation sector performing in its drive 

to improve fuel efficiency, in line with its short-term 

goal? Fact Sheet #3, January 2020. Available at 

https://aviationbenefits.org/downloads/fact-sheet-3- 

tracking-aviation-efficiency/ . 

describe the elements of the certification 

cost, which include obtaining an 

airplane, preparing an airplane, 

performing the flight tests, and 

processing the data to generate a 

certification test report (i.e., test 

instrumentation, infrastructure, and 

program management). 

The ICAO certification test 

procedures to demonstrate compliance 

with the international Airplane CO2

Emission Standards—incorporated by 

reference in this rulemaking—were 

based on the existing practices of 

airplane manufacturers to measure 

airplane fuel burn (and to measure highspeed cruise performance).158 Therefore, 

some manufacturers already have or 

will have airplane test data (or data from 

high-speed cruise performance 

modelling) to certify their airplane to 

the standard, and they will not need to 

conduct flight testing for certification to 

the standard. Also, these data will 

already be part of the manufacturers’ 

fuel burn or high-speed performance 

models, which they can use to 

demonstrate compliance with the 

international Airplane CO2 Emission 

Standards. In the absence of the 

standard, the relevant CO2 or fuel burn 

data will be gathered during the typical 

or usual airplane testing that the 

manufacturer regularly conducts for 

non-GHG standard purposes (e.g., for 

the overall development of the airplane 

and to demonstrate its airworthiness). In 

addition, such data for new type design 

airplanes (where data has not been 

collected yet) will be gathered in the 

absence of a standard. Also, the EPA is 

not making any attempt to quantify the 

costs associated with certification by the 

FAA. 

3. Recurring Operating Costs 

For the same reasons there are no 

NRC and certification costs for the rule 

as discussed earlier, there will be no 

recurring costs (recurring operating and 

maintenance costs) for the rule; 

however, it is informative to describe 

elements of recurring costs. The 

elements of recurring costs for 

incorporating fuel saving technologies 

will include additional maintenance, 

material, labor, and tooling costs. Our 

analysis shows that airplane fuel 

efficiency improvements typically result 

in net cost savings through the 

reduction in the amount of fuel 

consumed. If technologies add 

significant recurring costs to an 

airplane, operators (e.g., airlines) will 

likely reject these technologies. 

E. Summary of Benefits and Costs 

ICAO intentionally established its 

standards, which match the final 

standards, at a level which is technology 

following to adhere to its definition of 

technical feasibility that is meant to 

consider the emissions performance of 

in-production and in-development 

airplanes, including types that would 

first enter into service by about 2020. 

Independent of the ICAO standards 

nearly all airplanes produced by U.S. 

manufacturers will meet the ICAO inproduction standards in 2028 due to 

business-as-usual market forces on 

continually improving fuel efficiency. 

The cumulative fuel efficiency 

improvement of the global airplane fleet 

was 54 percent between 1990 and 2019, 

and over 21 percent from 2009 to 2019, 

which was an average annual rate of 2 

percent.159 Business-as-usual 

improvements are expected to continue 

in the future. The manufacturers 

anticipation of future ICAO standards 

will be another factor for them to 

consider in continually improving the 

fuel efficiency of their airplanes. Thus, 

all airplanes either meet the stringency 

levels, are expected to go out of 

production by the effective dates or will 

seek exemptions from the GHG 

standard. Therefore, there will be no 

costs and no additional benefits from 

complying with these final standards— 

beyond the benefits from maintaining 

consistency or harmonizing with the 

international standards and preventing 

backsliding by ensuring that all new 

type design and in-production airplanes 

are at least as fuel efficient as today’s 

airplanes. 

VII. Aircraft Engine Technical 

Amendments 

The EPA, through the incorporation 

by reference of ICAO Annex 16, Volume 

II, Third Edition (July 2008), requires 

the same test and measurement 

procedures as ICAO for emissions from 

aircraft engines. See our regulations at 

40 CFR 87.8(b)(1). At the CAEP/10 

meeting in February 2016, several minor 

technical updates and corrections to the 

test and measurement procedures were 

approved and ultimately included in a 

Fourth Edition of ICAO Annex 16, 

Volume II (July 2017). Further technical 

updates and corrections were approved 

at the CAEP/11 meeting in February 

2019 and included in Amendment 10 

(July 20, 2020). The EPA played an 

active role in the CAEP process during 

the development of these revisions and 

concurred with their adoption. Thus, we 

are updating the incorporation by 

reference in § 87.8(b) of our regulations 

to refer to the new Fourth Edition of 

ICAO Annex 16, Volume II (July 2017), 

Amendment 10 (July 20, 2020), 

replacing the older Third Edition. 

Most of these ICAO Annex 16 updates 

and corrections to the test and 

measurement procedures were editorial 

in nature and merely served to clarify 

the procedures rather than change them 

in any substantive manner. 

Additionally, some updates served to 

correct typographical errors and 

incorrect formula formatting. However, 

there is one change contained in these 

ICAO Annex 16 updates that warrants 

additional discussion here: a change to 

the certification test fuel specifications. 

Fuel specification bodies establish 

limits on jet fuels properties for 

commercial use so that aircraft are safe 

and environmentally acceptable in 

operation. For engine emissions 

certification testing, the ICAO fuel 

specification prior to CAEP10 was a 

minimum 1 percent volume of 

naphthalene content and a maximum 

content of 3.5 percent (1.0–3.5%). 

However, the ASTM International 

specification is 0.0–3.0 percent 

naphthalene, and an investigation found 

that it is challenging to source fuels for 

engine emissions certification testing 

that meet the minimum 1% naphthalene 

level. In many cases, engine 

manufacturers were forced to have fuels 

custom blended for certification testing 

purposes at a cost premium well above 

that of commercial jet fuel. 

Additionally, such custom blended 

fuels needed to be ordered well in 

advance and shipped by rail or truck to 

the testing facility. In order to 

potentially alleviate the cost and 

logistical burden that the naphthalene 

specification of certification fuel 

presented, CAEP undertook an effort to 

analyze and consider whether it would 

be appropriate to align the ICAO Annex 

16 naphthalene specification for 

certification fuel with that of in-use 

commercial fuel. 

Prior to the CAEP10 meeting, 

technical experts (including the EPA) 

reviewed potential consequences of a 

test fuel specification change and 

concluded that there would be no effect 

on gaseous emissions levels and a 

negligible effect on the ‘Smoke Number’ 

(SN) level as long as the aromatic and 


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hydrogen content remains within the 

current emissions test fuel specification 

limits. ICAO subsequently adopted the 

ASTM International specification of 

0.0–3.0 percent naphthalene for the 

engine emissions test fuel specification 

and no change to the aromatic and 

hydrogen limits, which was 

incorporated into the Fourth Edition of 

ICAO Annex 16, Volume II, (July 2017). 

The EPA is adopting, through the 

incorporation of the Annex revisions in 

40 CFR 87.8(b), the new naphthalene 

specification for certification testing 

into U.S. regulations. This change will 

have the benefit of more closely aligning 

the certification fuel specification for 

naphthalene with actual in-use 

commercial fuel properties while 

reducing the cost and logistical burden 

associated with certification fuel 

procurement for engine manufacturers. 

As previously mentioned, all the other 

changes associated with updating the 

incorporation by reference of ICAO 

Annex 16, Volume II, are editorial or 

typographical in nature and merely 

intended to clarify the requirements or 

correct mistakes and typographical 

errors in the Annex. 

VIII. Statutory Authority and Executive 

Order Reviews 

Additional information about these 

statutes and Executive orders can be 

found at http://www2.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

This action is a significant regulatory 

action that was submitted to the Office 

of Management and Budget (OMB) for 

review. The OMB has determined that 

this action raises ‘‘. . . novel legal or 

policy issues arising out of legal 

mandates, the President’s priorities, or 

the principles set forth in this Executive 

Order.’’ This action addresses novel 

policy issues due to it being the first 

ever GHG standards promulgated for 

airplanes and airplane engines. 

Accordingly, the EPA submitted this 

action to the OMB for review under E.O. 

12866 and E.O. 13563. Any changes 

made in response to OMB 

recommendations have been 

documented in the docket. Sections 

I.C.3 and VI.E of this preamble 

summarize the cost and benefits of this 

action. The supporting information is 

available in the docket. 

B. Executive Order 13771: Reducing 

Regulation and Controlling Regulatory 

Costs 

This action is expected to be an 

Executive Order 13771 regulatory 

action. Sections I.C.3. and VI.E. of this 

preamble summarize the cost and 

benefits of this action. The supporting 

information is available in the Final 

Technical Support Document and the 

docket. 

C. Paperwork Reduction Act (PRA) 

The EPA proposed a reporting 

requirement, along with an associated 

Information Collection Request (ICR), in 

the NPRM. However, the EPA is not 

adopting the proposed reporting 

requirement, and therefore not 

submitting a final ICR to OMB for 

approval. Thus, this action does not 

impose any new information collection 

burden under the PRA. 

D. Regulatory Flexibility Act (RFA) 

I certify that this action will not have 

a significant economic impact on a 

substantial number of small entities 

under the RFA. In making this 

determination, the impact of concern is 

any significant adverse economic 

impact on small entities. An agency may 

certify that a rule will not have a 

significant economic impact on a 

substantial number of small entities if 

the rule relieves regulatory burden, has 

no net burden or otherwise has a 

positive economic effect on the small 

entities subject to the rule. Among the 

potentially affected entities 

(manufacturers of covered airplanes and 

engines for those airplanes), there is one 

small business potentially affected by 

this action. This one small business is 

a manufacturer of aircraft engines. 

However, we did not project any costs 

associated with this action. We have 

therefore concluded that this action will 

have no net regulatory burden for all 

directly regulated small entities. 

E. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain an 

unfunded mandate of $100 million or 

more as described in UMRA, 2 U.S.C. 

1531–1538, and does not significantly or 

uniquely affect small governments. The 

action imposes no enforceable duty on 

any state, local or tribal governments or 

the private sector. 

F. Executive Order 13132: Federalism 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the states, on the 

relationship between the National 

Government and the states, or on the 

distribution of power and 

responsibilities among the various 

levels of government. 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have tribal 

implications as specified in Executive 

Order 13175. This action regulates the 

manufacturers of airplanes and aircraft 

engines and will not have substantial 

direct effects on one or more Indian 

tribes, on the relationship between the 

Federal Government and Indian tribes, 

or on the distribution of power and 

responsibilities between the Federal 

Government and Indian tribes. Thus, 

Executive Order 13175 does not apply 

to this action. 

H. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This action is not subject to Executive 

Order 13045 because it is not 

economically significant as defined in 

Executive Order 12866, and because the 

EPA does not believe the environmental 

health or safety risks addressed by this 

action present a disproportionate risk to 

children. 

I. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution or Use 

This action is not a ‘‘significant 

energy action’’ because it is not likely to 

have a significant adverse effect on the 

supply, distribution or use of energy 

and has not otherwise been designated 

by OIRA as a significant energy action. 

These airplane GHG regulations are not 

expected to result in any changes to 

airplane fuel consumption beyond what 

would have otherwise occurred in the 

absence of this rule, as discussed in 

Section V.C. 

J. National Technology Transfer and 

Advancement Act (NTTAA) and 1 CFR 

Part 51 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (‘‘NTTAA’’), Public Law 

104–113, 12(d) (15 U.S.C. 272 note) 

directs EPA to use voluntary consensus 

standards in its regulatory activities 

unless to do so would be inconsistent 

with applicable law or otherwise 

impractical. Voluntary consensus 

standards are technical standards (e.g., 

materials specifications, test methods, 

sampling procedures, and business 

practices) that are developed or adopted 

by voluntary consensus standards 

bodies. NTTAA directs agencies to 

provide Congress, through OMB, 

explanations when the Agency decides 


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not to use available and applicable 

voluntary consensus standards. This 

action involves technical standards. 

In accordance with the requirements 

of 1 CFR 51.5, we are incorporating by 

reference the use of test procedures 

contained in ICAO’s International 

Standards and Recommended Practices 

Environmental Protection, Annex 16, 

Volumes II and III, along with the 

modifications contained in this 

rulemaking. This includes the following 

standards and test methods: 

Standard or test method Regulation Summary 

ICAO 2017, Aircraft Engine Emissions, Annex 

16, Volume II, Fourth Edition, July 2017, as 

amended by Amendment 10, July 20, 2020.

40 CFR 87.1, 40 CFR 87.42(c), and 40 CFR 

87.60(a) and (b).

Test method describes how to measure gaseous and smoke emissions from airplane 

engines. 

ICAO 2017, Aeroplane CO2 Emissions, Annex 16, 

Volume III, First Edition, July 2017, as 

amended by Amendment 1, July 20, 2020.

40 CFR 1030.23(d), 40 CFR 1030.25(d), 40 

CFR 1030.90(d), and 40 CFR 1030.105.

Test method describes how to measure the 

fuel efficiency of airplanes. 

The material from the ICAO Annex 

16, Volume II is an updated version of 

the document that is already 

incorporated by reference in 40 CFR 

87.1, 40 CFR 87.42(c), and 40 CFR 

87.60(a) and (b). 

The referenced standards and test 

methods may be obtained through the 

International Civil Aviation 

Organization, Document Sales Unit, 999 

University Street, Montreal, Quebec, 

Canada H3C 5H7, (514) 954–8022, 

www.icao.int, or sales@icao.int. 

K. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

The EPA believes that this action does 

not have disproportionately high and 

adverse human health or environmental 

effects on minority populations, lowincome populations and/or indigenous 

peoples, as specified in Executive Order 

12898 (59 FR 7629, February 16, 1994). 

It provides similar levels of 

environmental protection for all affected 

populations without having any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority or low-income population. 

L. Congressional Review Act 

This action is subject to the CRA, and 

the EPA will submit a rule report to 

each House of the Congress and to the 

Comptroller General of the United 

States. This action is not a ‘‘major rule’’ 

as defined by 5 U.S.C. 804(2). 

List of Subjects 

40 CFR Part 87 

Environmental protection, Air 

pollution control, Aircraft, 

Incorporation by reference. 

40 CFR Part 1030 

Environmental protection, Air 

pollution control, Aircraft, Greenhouse 

gases, Incorporation by reference. 

Andrew Wheeler, 

Administrator. 

For the reasons set forth in the 

preamble, EPA amends 40 CFR chapter 

I as follows: 

PART 87—CONTROL OF AIR 

POLLUTION FROM AIRCRAFT AND 

AIRCRAFT ENGINES 

■ 1. The authority citation for part 87 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

■ 2. Section 87.8 is amended by revising 

paragraphs (a) and (b)(1) to read as 

follows: 

§ 87.8 Incorporation by reference. 

(a) Certain material is incorporated by 

reference into this part with the 

approval of the Director of the Federal 

Register under 5 U.S.C. 552(a) and 1 

CFR part 51. To enforce any edition 

other than that specified in this section, 

the Environmental Protection Agency 

must publish a document in the Federal 

Register and the material must be 

available to the public. All approved 

material is available for inspection at 

U.S. EPA, Air and Radiation Docket 

Center, WJC West Building, Room 3334, 

1301 Constitution Ave. NW, 

Washington, DC 20004, www.epa.gov/ 

dockets, (202) 202–1744, and is 

available from the sources listed in this 

section. It is also available for 

inspection at the National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at NARA, email fedreg.legal@

nara.gov or go to www.archives.gov/ 

federal-register/cfr/ibr-locations.html. 

(b) * * * 

(1) Annex 16 to the Convention on 

International Civil Aviation, 

Environmental Protection, as follows: 

(i) Volume II—Aircraft Engine 

Emissions, Fourth Edition, July 2017. 

IBR approved for §§ 87.1, 87.42(c), and 

87.60(a) and (b). 

(ii) Amendment 10 to Annex 16, 

Volume II, to the Convention on 

International Civil Aviation, effective 

July 20, 2020 (ICAO Annex 16, Volume 

II). IBR approved for §§ 87.1, 87.42(c), 

and 87.60(a) and (b). 

* * * * * 

■ 3. Add part 1030 to read as follows: 

PART 1030—CONTROL OF 

GREENHOUSE GAS EMISSIONS FROM 

ENGINES INSTALLED ON AIRPLANES 

Scope and Applicability 

1030.1 Applicability. 

1030.5 State standards and controls. 

1030.10 Exemptions. 

Subsonic Airplane Emission Standards and 

Measurement Procedures 

1030.20 Fuel efficiency metric. 

1030.23 Specific air range (SAR). 

1030.25 Reference geometric factor (RGF). 

1030.30 GHG emission standards. 

1030.35 Change criteria. 

1030.98 Confidential business information. 

Reference Information 

1030.100 Abbreviations. 

1030.105 Definitions. 

1030.110 Incorporation by reference. 

Authority: 42 U.S.C. 7401–7671q. 

Scope and Applicability 

§ 1030.1 Applicability. 

(a) Except as provided in paragraph 

(c) of this section, when an aircraft 

engine subject to 40 CFR part 87 is 

installed on an airplane that is 

described in this section and subject to 

title 14 of the Code of Federal 

Regulations, the airplane may not 

exceed the Greenhouse Gas (GHG) 

standards of this part when original 

civil certification under title 14 is 

sought. 

(1) A subsonic jet airplane that has— 

(i) A type certificated maximum 

passenger seating capacity of 20 seats or 

more; 

(ii) A maximum takeoff mass (MTOM) 

greater than 5,700 kg; and 


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(iii) An application for original type 

certification that is submitted on or after 

January 11, 2021. 

(2) A subsonic jet airplane that has— 

(i) A type certificated maximum 

passenger seating capacity of 19 seats or 

fewer; 

(ii) A MTOM greater than 5,700 kg, 

but not greater than 60,000 kg; and 

(iii) An application for original type 

certification that is submitted on or after 

January 1, 2023. 

(3) A propeller-driven airplane that 

has— 

(i) A MTOM greater than 8,618 kg; 

and 

(ii) An application for original type 

certification that is submitted on or after 

January 1, 2020. 

(4) A subsonic jet airplane— 

(i) That is a modified version of an 

airplane whose original type certificated 

version was not required to have GHG 

emissions certification under this part; 

(ii) That has a MTOM greater than 

5,700 kg; 

(iii) For which an application for the 

modification in type design is submitted 

on or after January 1, 2023; and 

(iv) For which the first certificate of 

airworthiness is issued for an airplane 

built with the modified design. 

(5) A propeller-driven airplane— 

(i) That is a modified version of an 

airplane whose original type certificated 

version was not required to have GHG 

emissions certification under this part; 

(ii) That has a MTOM greater than 

8,618 kg; 

(iii) For which an application for 

certification that is submitted on or after 

January 1, 2023; and 

(iv) For which the first certificate of 

airworthiness is issued for an airplane 

built with the modified design. 

(6) A subsonic jet airplane that has— 

(i) A MTOM greater than 5,700 kg; 

and 

(ii) Its first certificate of airworthiness 

issued on or after January 1, 2028. 

(7) A propeller-driven airplane that 

has— 

(i) A MTOM greater than 8,618 kg; 

and 

(ii) Its first certificate of airworthiness 

issued on or after January 1, 2028. 

(b) An airplane that incorporates 

modifications that change the fuel 

efficiency metric value of a prior version 

of airplane may not exceed the GHG 

standards of this part when certification 

under 14 CFR is sought. The criteria for 

modified airplanes are described in 

§ 1030.35. A modified airplane may not 

exceed the metric value limit of the 

prior version under § 1030.30. 

(c) The requirements of this part do 

not apply to: 

(1) Subsonic jet airplanes having a 

MTOM at or below 5,700 kg. 

(2) Propeller-driven airplanes having 

a MTOM at or below 8,618 kg. 

(3) Amphibious airplanes. 

(4) Airplanes initially designed, or 

modified and used, for specialized 

operations. These airplane designs may 

include characteristics or configurations 

necessary to conduct specialized 

operations that the EPA and the FAA 

have determined may cause a significant 

increase in the fuel efficiency metric 

value. 

(5) Airplanes designed with a 

reference geometric factor of zero. 

(6) Airplanes designed for, or 

modified and used for, firefighting. 

(7) Airplanes powered by piston 

engines 

§ 1030.5 State standards and controls. 

No State or political subdivision of a 

State may adopt or attempt to enforce 

any airplane or aircraft engine standard 

with respect to emissions unless the 

standard is identical to a standard that 

applies to airplanes under this part. 

§ 1030.10 Exemptions. 

Each person seeking relief from 

compliance with this part at the time of 

certification must submit an application 

for exemption to the FAA in accordance 

with the regulations of 14 CFR parts 11 

and 38. The FAA will consult with the 

EPA on each exemption application 

request before the FAA takes action. 

Subsonic Airplane Emission Standards 

and Measurement Procedures 

§ 1030.20 Fuel efficiency metric. 

For each airplane subject to this part, 

including an airplane subject to the 

change criteria of § 1030.35, a fuel 

efficiency metric value must be 

calculated in units of kilograms of fuel 

consumed per kilometer using the 

following equation, rounded to three 

decimal places: 

Where: 

SAR = specific air range, determined in 

accordance with § 1030.23. 

RGF = reference geometric factor, determined 

in accordance with § 1030.25. 

§ 1030.23 Specific air range (SAR). 

(a) For each airplane subject to this 

part the SAR of an airplane must be 

determined by either: 

(1) Direct flight test measurements; or 

(2) Using a performance model that is: 

(i) Validated by actual SAR flight test 

data; and 

(ii) Approved by the FAA before any 

SAR calculations are made. 

(b) For each airplane model, establish 

a 1/SAR value at each of the following 

reference airplane masses: 

(1) High gross mass: 92 percent 

maximum takeoff mass (MTOM). 

(2) Low gross mass: (0.45 * MTOM) + 

(0.63 * (MTOM¥0.924)). 

(3) Mid gross mass: Simple arithmetic 

average of high gross mass and low 

gross mass. 

(c) Calculate the average of the three 

1/SAR values described in paragraph (b) 

of this section to calculate the fuel 

efficiency metric value in § 1030.20. Do 

not include auxiliary power units in any 

1/SAR calculation. 

(d) All determinations under this 

section must be made according to the 

procedures applicable to SAR in 

Paragraphs 2.5 and 2.6 of ICAO Annex 

16, Volume III and Appendix 1 of ICAO 

Annex 16, Volume III (incorporated by 

reference in § 1030.110). 

§ 1030.25 Reference geometric factor 

(RGF). 

For each airplane subject to this part, 

determine the airplane’s 

nondimensional reference geometric 

factor (RGF) for the fuselage size of each 

airplane model, calculated as follows: 

(a) For an airplane with a single deck, 

determine the area of a surface 

(expressed in m∧2) bounded by the 

maximum width of the fuselage outer 

mold line projected to a flat plane 

parallel with the main deck floor and 

the forward and aft pressure bulkheads 

except for the crew cockpit zone. 

(b) For an airplane with more than 

one deck, determine the sum of the 

areas (expressed in m∧2) as follows: 

(1) The maximum width of the 

fuselage outer mold line, projected to a 

flat plane parallel with the main deck 


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floor by the forward and aft pressure 

bulkheads except for any crew cockpit 

zone. 

(2) The maximum width of the 

fuselage outer mold line at or above 

each other deck floor, projected to a flat 

plane parallel with the additional deck 

floor by the forward and aft pressure 

bulkheads except for any crew cockpit 

zone. 

(c) Determine the non-dimensional 

RGF by dividing the area defined in 

paragraph (a) or (b) of this section by 1 

m∧2. 

(d) All measurements and 

calculations used to determine the RGF 

of an airplane must be made according 

to the procedures for determining RGF 

in Appendix 2 of ICAO Annex 16, 

Volume III (incorporated by reference in 

§ 1030.110). 

§ 1030.30 GHG emission standards. 

(a) The greenhouse gas emission 

standards in this section are expressed 

as maximum permitted values fuel 

efficiency metric values, as calculated 

under § 1030.20. 

(b) The fuel efficiency metric value 

may not exceed the following, rounded 

to three decimal places: 

For airplanes defined in . . . with MTOM . . . the standard is . . . 

(1) Section 1030.1(a)(1) and (2) ................ 5,700 < MTOM < 60,000 kg ..................... 10(¥2.73780 + (0.681310 * log10(MTOM))

+ (¥0.0277861 * (log10(MTOM))∧2))

(2) Section 1030.1(a)(3) ............................. 8,618 < MTOM < 60,000 kg ..................... 10(¥2.73780 + (0.681310 * log10(MTOM))

+ (¥0.0277861 * (log10(MTOM))∧2))

(3) Section 1030.1(a)(1) and (3) ................ 60,000 < MTOM < 70,395 kg ................... 0.764 

(4) Section 1030.1(a)(1) and (3) ................ MTOM > 70,395 kg .................................. 10(¥1.412742 + (¥0.020517 * log10(MTOM))

+ (0.0593831 * (log10(MTOM))∧2))

(5) Section 1030.1(a)(4) and (6) ................ 5,700 < MTOM < 60,000 kg ..................... 10(¥2.57535 + (0.609766 * log10(MTOM))

+ (¥0.0191302 * (log10(MTOM))∧2))

(6) Section 1030.1(a)(5) and (7) ................ 8,618 < MTOM < 60,000 kg ..................... 10(¥2.57535 + (0.609766 * log10(MTOM))

+ (¥0.0191302 * (log10(MTOM))∧2))

(7) Section 1030.1(a)(4) through (7) .......... 60,000 < MTOM < 70,107 kg ................... 0.797 

(8) Section 1030.1(a)(4) through (7) .......... MTOM > 70,107 kg .................................. 10(¥1.39353 + (-0.020517 * log10(MTOM))

+ (0.0593831 * (log10(MTOM))∧2))

§ 1030.35 Change criteria. 

(a) For an airplane that has 

demonstrated compliance with 

§ 1030.30, any subsequent version of 

that airplane must demonstrate 

compliance with § 1030.30 if the 

subsequent version incorporates a 

modification that either increases— 

(1) The maximum takeoff mass; or 

(2) The fuel efficiency metric value by 

more than: 

(i) For airplanes with a MTOM greater 

than or equal to 5,700 kg, the value 

decreases linearly from 1.35 to 0.75 

percent for an airplane with a MTOM of 

60,000 kg. 

(ii) For airplanes with a MTOM 

greater than or equal to 60,000 kg, the 

value decreases linearly from 0.75 to 

0.70 percent for airplanes with a MTOM 

of 600,000 kg. 

(iii) For airplanes with a MTOM 

greater than or equal to 600,000 kg, the 

value is 0.70 percent. 

(b) For an airplane that has 

demonstrated compliance with 

§ 1030.30, any subsequent version of 

that airplane that incorporates 

modifications that do not increase the 

MTOM or the fuel efficiency metric 

value in excess of the levels shown in 

paragraph (a) of this section, the fuel 

efficiency metric value of the modified 

airplane may be reported to be the same 

as the value of the prior version. 

(c) For an airplane that meets the 

criteria of § 1030.1(a)(4) or (5), after 

January 1, 2023 and until January 1, 

2028, the airplane must demonstrate 

compliance with § 1030.30 if it 

incorporates any modification that 

increases the fuel efficiency metric 

value by more than 1.5 per cent from the 

prior version of the airplane. 

§ 1030.98 Confidential business 

information. 

The provisions of 40 CFR 1068.10 

apply for information you consider 

confidential. 

Reference Information 

§ 1030.100 Abbreviations. 

The abbreviations used in this part 

have the following meanings: 

TABLE 1 TO § 1030.100 

EPA ......... U.S. Environmental Protection Agency. 

FAA ......... U.S. Federal Aviation Administration. 

GHG ........ greenhouse gas. 

IBR .......... incorporation by reference. 

ICAO ....... International Civil Aviation Organization. 

MTOM ..... maximum takeoff mass. 

RGF ........ reference geometric factor. 

SAR ........ specific air range. 

§ 1030.105 Definitions. 

The following definitions in this 

section apply to this part. Any terms not 

defined in this section have the meaning 

given in the Clean Air Act. The 

definitions follow: 

Aircraft has the meaning given in 14 

CFR 1.1, a device that is used or 

intended to be used for flight in the air. 

Aircraft engine means a propulsion 

engine that is installed on or that is 

manufactured for installation on an 

airplane for which certification under 

14 CFR is sought. 

Airplane has the meaning given in 14 

CFR 1.1, an engine-driven fixed-wing 

aircraft heavier than air, that is 

supported in flight by the dynamic 

reaction of the air against its wings. 

Exempt means to allow, through a 

formal case-by-case process, an airplane 

to be certificated and operated that does 

not meet the applicable standards of this 

part. 

Greenhouse Gas (GHG) means an air 

pollutant that is the aggregate group of 

six greenhouse gases: carbon dioxide, 

nitrous oxide, methane, 

hydrofluorocarbons, perfluorocarbons, 

and sulfur hexafluoride. 

ICAO Annex 16, Volume III means 

Volume III of Annex 16 to the 

Convention on International Civil 

Aviation (see § 1030.110). 

Maximum takeoff mass (MTOM) is 

the maximum allowable takeoff mass as 

stated in the approved certification basis 

for an airplane type design. Maximum 

takeoff mass is expressed in kilograms. 

Performance model is an analytical 

tool (or a method) validated using 

corrected flight test data that can be 

used to determine the specific air range 

values for calculating the fuel efficiency 

metric value. 

Reference geometric factor is a nondimensional number derived from a 

two-dimensional projection of the 

fuselage. 

Round has the meaning given in 40 

CFR 1065.1001. 

Specific air range is the distance an 

airplane travels per unit of fuel 

consumed. Specific air range is 


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2174 Federal Register / Vol. 86, No. 6 / Monday, January 11, 2021 / Rules and Regulations 

expressed in kilometers per kilogram of 

fuel. 

Subsonic means an airplane that has 

not been certificated under 14 CFR to 

exceed Mach 1 in normal operation. 

Type certificated maximum passenger 

seating capacity means the maximum 

number of passenger seats that may be 

installed on an airplane as listed on its 

type certificate data sheet, regardless of 

the actual number of seats installed on 

an individual airplane. 

§ 1030.110 Incorporation by reference. 

(a) Certain material is incorporated by 

reference into this part with the 

approval of the Director of the Federal 

Register under 5 U.S.C. 552(a) and 1 

CFR part 51. To enforce any edition 

other than that specified in this section, 

the Environmental Protection Agency 

must publish a document in the Federal 

Register and the material must be 

available to the public. All approved 

material is available for inspection at 

EPA Docket Center, WJC West Building, 

Room 3334, 1301 Constitution Ave. NW, 

Washington, DC 20004, www.epa.gov/ 

dockets, (202) 202–1744, and is 

available from the sources listed in this 

section. It is also available for 

inspection at the National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at NARA, email fedreg.legal@

nara.gov or go to: www.archives.gov/ 

federal-register/cfr/ibr-locations.html. 

(b) International Civil Aviation 

Organization, Document Sales Unit, 999 

University Street, Montreal, Quebec, 

Canada H3C 5H7, (514) 954–8022, 

www.icao.int, or sales@icao.int. 

(1) ICAO Annex 16, Volume III, 

Annex 16 to the Convention on 

International Civil Aviation, 

Environmental Protection, Volume III— 

Aeroplane CO2 Emissions, as follows: 

(i) First Edition, July 2017. IBR 

approved for §§ 1030.23(d) and 

1030.25(d). 

(ii) Amendment 1, July 20, 2020. IBR 

approved for §§ 1030.23(d) and 

1030.25(d). 

(2) [Reserved] 

[FR Doc. 2020–28882 Filed 1–8–21; 8:45 am] 

BILLING CODE 6560–50–P 


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