[Federal Register Volume 86, Number 6 (Monday, January 11, 2021)]
[Rules and Regulations]
[Pages 2136-2174]
[FR Doc No: 2020-28882]

Vol. 86

Monday,

No. 6

January 11, 2021

Part IV

 Environmental Protection Agency

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40 CFR Parts 87 and 1030

Control of Air Pollution From Airplanes and Airplane Engines: GHG
Emission Standards and Test Procedures; Final Rule

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

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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.

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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 propeller-driven 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 fuel-efficiency-
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<PHONE_NUMBER>, and the telephone
number for the Air Docket is<PHONE_NUMBER>. 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:<PHONE_NUMBER>; email address:
<EMAIL_ADDRESS>
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:

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                                                         Examples of
             Category               NAICS code \a\       potentially
                                                      affected entities
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Industry..........................          336412  Manufacturers of new
                                                     aircraft engines.

Industry..........................          336411  Manufacturers of new
                                                     aircraft.
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\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.
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    \1\ OMB, 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.
    \3\ U.S. EPA, 2020: Technical Report on Aircraft Emissions
Inventory and Stringency Analysis, July 2020, 52pp.
    \4\ RTI International and EnDyna, Aircraft CO2 Cost and
Technology Refresh and Aerospace Industry Characterization: Peer
Review, June 2018, 114pp.
    \5\ RTI International and EnDyna, EPA Technical Report on
Aircraft Emissions Inventory and Stringency Analysis: Peer Review,
July 2019, 157pp.
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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

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.
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    \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).
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    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.
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    \7\ 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).
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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 propeller-
driven 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

(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\
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    \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).
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    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.
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    \9\ 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 and Advance Notice
of Proposed Rulemaking; Final Rule, 81 FR 54422 (August 15, 2016).
    \10\ Covered 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.
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    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 in-production 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.
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    \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.
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    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\
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    \12\ Previous EPA rulemakings for aircraft engine regulations
are described later in section II.D.2.
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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

(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
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    \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).
    \14\ Members of ICAO's Assembly are generally termed member
States or contracting States. These terms are used interchangeably
throughout this preamble.
    \15\ There are currently 193 contracting states according to
ICAO's website: https://www.icao.int/MemberStates/Member%20States.English.pdf (last accessed March 16, 2020).
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    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\
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    \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).
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    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

its domestic regulations and ICAO standards.\19\
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    \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).
    \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).
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    ICAO's CAEP, which consists of members and observers from States,
intergovernmental and non-governmental 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
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    \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.
    \22\ CAEP develops new emission standards based on an assessment
of the technical feasibility, cost, and environmental benefit of
potential requirements.
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    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 in-production 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 in-production 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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    \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.
    \24\ CAEP 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.
    \25\ CAEP/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.
    \27\ CAEP/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 (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.

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    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 in-production
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 in-
production commercial and non-commercial 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 anti-
backsliding standards (most aircraft engines meet the standards), which
are technology following.
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    \30\ U.S. EPA, 1973: Emission Standards and Test Procedures for
Aircraft; Final Rule, 38 FR 19088 (July 17, 1973).
    \31\ U.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).
    \32\ The 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.
    \33\ This does not mean that in 1997 we promulgated requirements
for the re-certification or retrofit of existing in-use engines.
    \34\ Those engines built after the effective date of the
regulations that were already certificated to pre-existing standards
are also referred to as in-production 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.
    \36\ Those engine models that received their initial type
certificate after the effective date of the regulations are also
referred to as new engine designs.
    \37\ U.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).
    \38\ U.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).
    \39\ U.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).
    \40\ While 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.
---------------------------------------------------------------------------

    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.
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    \41\ U.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).
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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.
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    \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.
---------------------------------------------------------------------------

    The three factors--and technology categories that improve these
factors--are described as follows: \43\
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

     Weight: Reducing basic airplane weight \44\ via structural
changes to

increase the commercial payload or extend range for the same amount of
thrust and fuel burn;
---------------------------------------------------------------------------

    \44\ Although weight reducing technologies affect fuel burn,
they do not affect the metric value for the GHG standard. The
standard is a function of 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.
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     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., fly-by-wire) \45\ and aerodynamic
improvements with advanced wingtip devices such as winglets.
---------------------------------------------------------------------------

    \45\ Fly-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-does-the-term-fly-by-wire-mean/ (last accessed on March 16, 2020).
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    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).
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    \46\ 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).
    \47\ U.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).
    \48\ Certain aircraft in this context are referred to
interchangeably as ``covered airplanes,'' ``US covered airplanes,''
or airplanes throughout this rulemaking.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \49\ 81 FR 54423, August 15, 2016.
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    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

accounted for the majority (89 percent) of total U.S. aircraft GHG
emissions.55 56
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    \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-us-greenhouse-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-us-greenhouse-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, S. Brunner, P. Eickemeier, B. Kriemann, J.
Savolainen, S. Schl[ouml]mer, C. von Stechow, T. Zwickel and J.C.
Minx (eds.)]. Cambridge University Press, 1435 pp.
    \52\ 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-us-greenhouse-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. Schl[ouml]mer, C. von Stechow, T. Zwickel and J.C.
Minx (eds.)]. Cambridge University Press, 1435 pp.
    \54\ The 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).
    \55\ Covered 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.
    \56\ 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-us-greenhouse-gas-emissions-and-sinks-1990-2014 (last accessed March 16, 2020).
---------------------------------------------------------------------------

    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.)
---------------------------------------------------------------------------

    \57\ 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).
    \58\ 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-us-greenhouse-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.
    \59\ Methane 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.
---------------------------------------------------------------------------

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 well-mixed 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.
---------------------------------------------------------------------------

    \60\ 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).
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \62\ U.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).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    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

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.
---------------------------------------------------------------------------

    \64\ Payload 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.
---------------------------------------------------------------------------

    The ICAO metric system consists of a CO2 emissions
metric (Equation IV-1) and a correlating parameter.\66\
---------------------------------------------------------------------------

    \66\ Annex 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 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.
[GRAPHIC] [TIFF OMITTED] TR11JA21.001

    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\
---------------------------------------------------------------------------

    \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.
    \68\ Avg means average.
    \69\ Annex 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 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.
---------------------------------------------------------------------------

     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[caret]0.924)).
    The Reference Geometric Factor (RGF) is a non-dimensional measure
of the fuselage \70\ size of an airplane

normalized by 1 square meter, generally considered to be the shadow
area of the airplane's pressurized passenger compartment.\71\
---------------------------------------------------------------------------

    \70\ The fuselage is an aircraft's main body section. It holds
crew, passengers, and cargo.
    \71\ Annex 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.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \72\ Currently, 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.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \73\ This 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.
---------------------------------------------------------------------------

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 in-production 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 in-production (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.
---------------------------------------------------------------------------

    \75\ RGF 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.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \76\ This 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.
---------------------------------------------------------------------------

     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
---------------------------------------------------------------------------

    \77\ For example, the NASA SOFIA airborne astronomical
observatory.
---------------------------------------------------------------------------

     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 In-Production Airplane Designations
    The final rule recognizes differences between previously type
certificated

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
---------------------------------------------------------------------------

    \78\ A 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 in-
production airplane types for purposes of the international
CO2 standard.
---------------------------------------------------------------------------

     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
---------------------------------------------------------------------------

    \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.)
---------------------------------------------------------------------------

    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 C-Series) 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\
---------------------------------------------------------------------------

    \83\ ICF International, 2015: CO2 Analysis of CO2-
Reducing Technologies for Airplane, Final Report, EPA Contract
Number EP-C-12-011, March 17, 2015.
    \84\ The 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.
    \85\ The 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.
    \86\ Boeing, 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-Japan-Airlines (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.
    \89\ Analysts 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.)
---------------------------------------------------------------------------

    At ICAO, the difference between in-production 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 in-production 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).
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    \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.
---------------------------------------------------------------------------

    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,

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\
---------------------------------------------------------------------------

    \91\ Annex 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.
[GRAPHIC] [TIFF OMITTED] TR11JA21.002

[GRAPHIC] [TIFF OMITTED] TR11JA21.003

[GRAPHIC] [TIFF OMITTED] TR11JA21.004

    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.
[GRAPHIC] [TIFF OMITTED] TR11JA21.005

[GRAPHIC] [TIFF OMITTED] TR11JA21.006

    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.
---------------------------------------------------------------------------

    \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.
    \94\ U.S., United States Position on the ICAO Aeroplane
CO2 Emissions Standard, Montr[eacute]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.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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 in-development airplanes \96\).\97\
---------------------------------------------------------------------------

    \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).
    \97\ Note: 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.
---------------------------------------------------------------------------

    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

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 in-production 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 in-production airplanes, January 1, 2023, is the
same as that adopted by ICAO and is similarly designed to capture
modifications to the type design of non-GHG 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 anti-backsliding
measure that gives notice to manufacturers that non-compliant airplanes
will not receive airworthiness certification after this date.
---------------------------------------------------------------------------

    \98\ Note 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.
---------------------------------------------------------------------------

    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 in-production 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\
---------------------------------------------------------------------------

    \99\ Annex 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.
[GRAPHIC] [TIFF OMITTED] TR11JA21.007

[GRAPHIC] [TIFF OMITTED] TR11JA21.008

[GRAPHIC] [TIFF OMITTED] TR11JA21.009

    Figure IV-3 and Figure IV-4 show the numerical limits of the
adopted in-production 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.
[GRAPHIC] [TIFF OMITTED] TR11JA21.010

[GRAPHIC] [TIFF OMITTED] TR11JA21.011

    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 in-production 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 in-production
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 in-production 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\
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    \100\ Title 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.
---------------------------------------------------------------------------

    Since requests for exemptions are requests for relief from the
enforcement

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 Sec.  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 in-production 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 in-production 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