[Federal Register Volume 85, Number 162 (Thursday, August 20, 2020)]
[Proposed Rules]
[Pages 51556-51594]
[FR Doc No: 2020-16271]

Vol. 85

Thursday,

No. 162

August 20, 2020

Part II

Environmental Protection Agency

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40 CFR Parts 87 and 1030

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

Federal Register / Vol. 85, No. 162 / Thursday, August 20, 2020 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 87 and 1030

[EPA-HQ-OAR-2018-0276; FRL-10010-88-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: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing
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 proposed
standards are equivalent to the airplane CO2 standards
adopted by the International Civil Aviation Organization (ICAO) in 2017
and would apply to both new type design airplanes and in-production
airplanes. The standards proposed in this rule are the equivalent of
the ICAO standards, consistent with U.S. efforts to secure the highest
practicable degree of uniformity in aviation regulations and standards.
The proposed standards would, if finalized, also meet the EPA's
obligation under section 231 of the Clean Air Act 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
proposing to use the fuel-efficiency-based metric established by ICAO,
which reasonably serves as a surrogate for controlling both the GHGs
emitted by airplane engines, CO2 and N2O.

DATES:
    Comments: Written comments on this proposal must be received on or
before October 19, 2020. Under the Paperwork Reduction Act (PRA),
comments on the information collection provisions are best assured of
consideration if the Office of Management and Budget (OMB) receives a
copy of your comments on or before September 21, 2020.
    Public Hearing: EPA will announce the public hearing date and
location for this proposal in a supplemental Federal Register document.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2018-0276, at http://www.regulations.gov (our preferred method), or
the other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. The EPA may
publish any comment received to its public docket. Do not submit to
EPA's docket at https://www.regulations.gov any information you
consider to be Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e. on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    EPA solicits comments on all aspects of the proposed standards.
However, we do not seek and do not intend to respond to comments on any
aspect of EPA's 2016 Findings.
    The EPA is temporarily suspending its Docket Center and Reading
Room for public visitors, with limited exceptions, to reduce the risk
of transmitting COVID-19. Our Docket Center staff will continue to
provide remote customer service via email, phone, and webform. We
encourage the public to submit comments via https://www.regulations.gov/ as there may be a delay in processing mail and
faxes. Hand deliveries or couriers will be received by scheduled
appointment only. For further information and updates on EPA Docket
Center services, please visit us online at https://www.epa.gov/dockets.
    The EPA continues to carefully and continuously monitor information
from the Centers for Disease Control and Prevention (CDC), local area
health departments, and our Federal partners so that we can respond
rapidly as conditions change regarding COVID-19.

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 proposed
rule?
    C. Executive Summary
II. Introduction: Overview and Context for This Proposed Action
    A. Summary of Proposed Rule
    B. EPA Statutory Authority and Responsibilities Under the Clean
Air Act
    C. Background Information Helpful to Understanding This Proposed
Action
    D. U.S. Airplane Regulations and the International Community
    E. Consideration of Whole Airplane Characteristics
III. Summary of the 2016 Findings
IV. Summary of Advance Notice of Proposed Rulemaking and Comments
Received
    A. Summary
V. Details for the Proposed Rule
    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 Proposed GHG Rules
    F. Application of Rules for New Version of an Existing GHG-
Certificated Airplane
    G. Annual Reporting Requirement
    H. Test and Measurement Procedures
    I. Controlling Two of the Six Well-Mixed GHGs
VI. 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 CO2 emissions?
    C. What are the projected effects in fuel burn and GHG
emissions?
VII. 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
VIII. Aircraft Engine Technical Amendments
IX. 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

I. General Information

A. Does this action apply to me?

    This proposed action would 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     potentially  affected
                                       code \a\          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 proposed
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 and are used as
appropriate throughout the new proposed regulation under 40 CFR part
1030.

B. Did EPA conduct a peer review before issuing this proposed rule?

    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 proposed action underwent peer review; a report detailing the
technologies likely to be used in compliance with the proposed
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. Executive Summary

1. Purpose of the Proposed Regulatory Action
    One of the core functions of ICAO is to adopt Standards and
Recommended Practices on a wide range of aviation-related matters,
including aircraft emissions. As a member State of the ICAO, the United
States seeks to secure the highest practicable degree of 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 proposing to adopt 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 March 16, 2020).
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    These proposed standards would 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. U.S. manufacturers would be presumed to be
at a significant disadvantage if the U.S. fails to adopt standards that
are at least as stringent as 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 Clean Air Act (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 the Proposed Regulatory Action
    The EPA is proposing to regulate GHG emissions from covered
airplanes through the adoption of domestic GHG regulations that match
international standards to control CO2 emissions. The
proposed GHG standards are equivalent to the CO2 standards
adopted by ICAO and will be implemented and enforced in the U.S. The
proposed standards would 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 would 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 would apply to covered airplanes for which an
application for certification is submitted to the FAA on or after
January 1, 2020 (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 would apply
to covered airplanes beginning January 1, 2028. Additionally,
consistent with ICAO standards, the EPA is proposing that, 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) would trigger a requirement to certify to the in-production
regulation beginning January 1, 2023.
    The EPA is proposing to adopt 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 V.A.
    To measure airplane fuel efficiency, the EPA is proposing to adopt
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
proposed GHG standards. The test procedures are discussed in Section
V.H.
    Consistent with the current annual reporting requirement for engine
emissions, the EPA is proposing to require the annual reporting of the
number of airplanes produced, airplane characteristics, and test
parameters. Further information on all aspects of the proposed GHG
standards can be found in Section V.
    Finally, the EPA is proposing to update 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
would 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 VIII.
3. Cost and Benefits
    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. 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. This includes the expectation that
existing in-production airplanes that are non-compliant will either be
modified and re-certificated as compliant or will likely go out of
production before the production compliance date of January 1, 2028.
For these reasons, the EPA is not projecting emission reductions
associated with these proposed GHG regulations. We do, however, project
a small cost associated with the proposed annual reporting requirement.
For further details on the benefits and costs associated with these
proposed GHG standards, see Sections VI and VII, respectively.

II. Introduction: Overview and Context for This Proposed Action

    This section provides a summary of the proposed 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 Proposed 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 proposing
to adopt 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
March 16, 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 propose and 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 proposing to regulate 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 proposed GHG
emission standards for the certain classes of engines used by covered
airplanes would 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 proposing
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 proposed GHG
standards would 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 V 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 March
16, 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 proposed rule would establish GHG standards applicable to U.S.
airplane manufacturers that are no less stringent than the ICAO
Airplane CO2 Emission Standards adopted by ICAO.\11\ This
proposed rule incorporates the same compliance schedule as the ICAO

Airplane CO2 Emission Standards. The proposed standards
would apply to both new type designs and in-production airplanes. The
in-production standards would have later applicability dates and
different emission levels than for 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 proposed GHG requirements, we are also proposing to
update the engine emissions testing and measurement procedures
applicable to HC, NOX, CO, and smoke in current regulations.
The updates would implement recent amendments to ICAO standards in
Annex 16, Volume II, and these updates would be accomplished by
incorporating provisions of the Annex by reference, as has historically
been done.

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 as the Agency
determines are reasonable. Nat'l Ass'n of Clean Air Agencies v. EPA,
489 F.3d 1221, 1229-30 (D.C. Cir. 2007) (NACAA).
    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 Proposed 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 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 and 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 engine manufacturers in order to ensure
recognition of their airworthiness and type certificate by other civil
aviation authorities. This proposed 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 at least as stringent as 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 proposed 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.'' \12\ 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.13 14
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    \12\ 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
March 16, 2020).
    \13\ Members of ICAO's Assembly are generally termed member
States or contracting States. These terms are used interchangeably
throughout this preamble.
    \14\ 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 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.\15\
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    \15\ 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 March 16, 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.\16\ 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.\17\ 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.\18\
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    \16\ 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).
    \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 March 16, 2020).
    \18\ 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).
---------------------------------------------------------------------------

    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.'' \19\ 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).20 21
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    \19\ ICAO: CAEP Terms of Reference. Available at http://www.icao.int/environmental-protection/Pages/Caep.aspx#ToR (last
accessed March 16, 2020).
    \20\ 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 2020 catalog and is
copyright protected; Order No. AN16-2.
    \21\ 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 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.\22\ 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.\23\ 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. In 2004, CAEP/6 recommended a 12 percent NOX
reduction, which ICAO approved in 2005.24 25 The CAEP/6
standards applied

to new engine designs certificated after December 31, 2007. In 2010,
CAEP/8 recommended a further tightening of the NOX standards
by 15 percent for new engine designs certificated after December 31,
2013.26 27 The Committee also recommended that the CAEP/6
standards be applied to in-production engines, which cut off the
production of CAEP/4 compliant engines with the exception of spare
engines; ICAO adopted these as standards in 2011.\28\
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    \22\ 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.
    \23\ 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.
    \24\ CAEP/5 did not address new airplane engine emission
standards.
    \25\ 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 2020 catalog and is
copyright protected; Order No. AN16-2.
    \26\ CAEP/7 did not address new aircraft engine emission
standards.
    \27\ 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.
    \28\ 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
2020 catalog and is copyright protected; Order No. AN16-2.
---------------------------------------------------------------------------

    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.\29\ 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.\30\ These ICAO requirements are generally referred to
as CAEP/2 standards.\31\ The 1997 rulemaking included new
NOX emission standards for newly manufactured commercial
turbofan engines 32 33 and for newly certificated commercial
turbofan engines.34 35 It also included a CO emission
standard for in-production commercial turbofan engines.\36\ In 2005, we
promulgated more stringent NOX emission standards for newly
certificated commercial turbofan engines.\37\ 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.38 39
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 emission standards have generally been
considered anti-backsliding standards (most aircraft engines meet the
standards), which are technology following.
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    \29\ U.S. EPA, 1973: Emission Standards and Test Procedures for
Aircraft; Final Rule, 38 FR 19088 (July 17, 1973).
    \30\ 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).
    \31\ 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.
    \32\ This does not mean that in 1997 we promulgated requirements
for the re-certification or retrofit of existing in-use engines.
    \33\ 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.
    \34\ 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.
    \35\ Those engine models that received their initial type
certificate after the effective date of the regulations are also
referred to as new engine designs.
    \36\ 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).
    \37\ 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).
    \38\ 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).
    \39\ 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 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
proposing to adopt 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
V, 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 greenhouse gas emission standards advance notice
of proposed rulemaking (henceforth the ``2015 ANPR'') \40\ 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. Section IV provides a summary of the ANPR comments that we
received.
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    \40\ 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.\41\ 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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    \41\ 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.
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    The three factors--and technology categories that improve these
factors--are described as follows: \42\
---------------------------------------------------------------------------

    \42\ 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 \43\ via structural
changes to increase the commercial payload or extend range for the same
amount of thrust and fuel burn;
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    \43\ Although weight reducing technologies affect fuel burn,
they do not affect the metric value for the proposed 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 V and VII 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) \44\ and aerodynamic
improvements with advanced wingtip devices such as winglets.
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    \44\ 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 proposing regulations that are
consistent with this approach. We are proposing GHG test procedures
that are the same as the ICAO CO2 test procedures. (See
Section V.H for details on the proposed 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 proposes to control 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 proposed 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,\45\ 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 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 \46\ 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).
---------------------------------------------------------------------------

    \45\ 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).
    \46\ Certain aircraft in this context are referred to
interchangeably as ``covered airplanes,'' ``US covered airplanes,''
or airplanes throughout this notice of proposed 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 V of this proposed rule for
examples of airplanes that correspond to the U.S. covered aircraft
identified in the 2016 Findings.\47\ 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).
---------------------------------------------------------------------------

    \47\ 81 FR 54423, August 15, 2016.
---------------------------------------------------------------------------

    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 \48\ and estimated global GHG

emissions.49 50 51 52 The 2016 Findings accounted for the
majority (89 percent) of total U.S. aircraft GHG
emissions.53 54
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    \48\ 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.
    \49\ 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.
    \50\ 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).
    \51\ 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\ 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 V.B.4 of
the 2016 Findings, 81 FR 54422 (August 15, 2016).
    \53\ 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.
    \54\ 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,\55\ 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.\56\ Modern aircraft are overall consumers of
methane.\57\ Hydrofluorocarbons, perfluorocarbons, and sulfur
hexafluoride are not products of aircraft engine fuel combustion.
(Section V.I discusses controlling two of the six well-mixed GHGs--
CO2 and N2O-- in the context of the details of
the proposed rule.)
---------------------------------------------------------------------------

    \55\ 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).
    \56\ 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.
    \57\ 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.
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IV. Summary of Advance Notice of Proposed Rulemaking and Comments
Received

A. Summary

    As described earlier in Section II, the 2015 ANPR \58\ discussed
the issues arising from the ICAO/CAEP proceedings for the international
Airplane CO2 Emission Standards. The ANPR requested public
comment on a variety of issues to help ensure transparency and to
obtain views on airplane engine GHG emission standards that the EPA
might potentially adopt under the CAA section 231. This section
provides a summary of the ANPR comments that the EPA received in 2015.
---------------------------------------------------------------------------

    \58\ 80 FR 37758 (July 1, 2015).
---------------------------------------------------------------------------

    All major stakeholders (airplane manufacturers, engine
manufacturers, airlines, states, and environmental organizations)
expressed their support for the United States' efforts in ICAO/CAEP for
the adoption of the international Airplane CO2 Emission
Standards, as well as the subsequent EPA adoption of a domestic GHG
standard.
    The states and environmental organizations commented that the U.S.
aircraft sector is the single largest GHG emissions source yet to be
regulated among the domestic transportation sectors. They indicated
that the EPA should adopt airplane GHG emission standards that
materially reduce GHG emissions from the U.S. airplane sector in the
near- to mid-term, beyond the expected ``business-as-usual''
improvement absent GHG emission standards. These commenters stated that
the airplane GHG emission standards should be technology-forcing
standards.
    The airplane manufacturers, aircraft engine manufacturers, and
airlines commented that the U.S. should adopt airplane GHG emission
standards that are equivalent to ICAO/CAEP's standards. These
commenters indicated that aviation is a global industry which requires
common, world-wide standards. Airplanes are uniquely mobile assets that
are designed to fly anywhere in the world, and consistency amongst
national rules makes sure there is a level playing field globally for
the aviation industry. In addition, they asserted that the CAEP terms
of reference for adopting airplane emission standards (which include
technical feasibility, environmental benefit, and economic
reasonableness \59\), as described earlier in Section II.D.1, line up
with the criteria for adopting such standards under section 231 of the
CAA. Therefore, the U.S. should align with those terms and criteria in
continuing their efforts in the ICAO/CAEP proceedings and in
subsequently adopting the ICAO/CAEP Airplane CO2 Emission
Standards domestically.
---------------------------------------------------------------------------

    \59\ 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.'' ICAO: CAEP Terms
of Reference. Available at http://www.icao.int/environmental-protection/Pages/Caep.aspx#ToR (last accessed March 16, 2020).
---------------------------------------------------------------------------

    All of the comments received on the 2015 ANPR are located in the
docket for the 2016 Findings under Docket ID No. EPA-HQ-OAR-2014-0828.
See the ANPR phase of that docket.

V. Details for the Proposed Rule

    For the proposed rule, this section describes the fuel efficiency
metric that would be used as a measure of airplane GHG emissions, the
size and types of airplanes that would be affected, the emissions
levels, the applicable test procedures, and the associated reporting
requirements. 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.
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    \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).
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    We are proposing that the GHG emission regulations for this
proposed rule would be 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 would 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 likely would result if EPA were to adopt standards
different from the standards adopted by ICAO, the EPA is proposing to
adopt 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\
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    \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, 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 the same as or at least as
stringent as 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 standard and EPA's potential use of section 231 to adopt
corresponding airplane GHG emissions standards domestically. This
proposed rulemaking continues this statutory paradigm.
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    \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).
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    The proposed rule, if adopted, would facilitate the acceptance of
U.S. manufactured airplanes and airplane engines by member States and
airlines around the world. We anticipate U.S. manufacturers would be at
a significant competitive disadvantage if the U.S. fails 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 Draft 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 GHG emission reductions compared to
the proposed standards. The other alternative would have further
limited additional costs and some additional GHG emission reductions
compared to the proposed standards, but the additional emission
reductions are relatively small from this alternative and do not
justify differentiating 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 is not proposing 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 international 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 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\ equipage, and fuel load.\65\ Thus, even though weight
reducing technologies increase the airplane fuel efficiency, this
improvement in efficiency frequently would not be reflected in
operation.
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    \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 V-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 English Edition 2020
catalog and is copyright protected; Order No. AN 16-3.
[GRAPHIC] [TIFF OMITTED] TP20AU20.000

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

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

    (1/SAR)avg \68\ is calculated at 3 gross weight
fractions of Maximum Take Off Mass (MTOM): \69\
---------------------------------------------------------------------------

    \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
English Edition 2020 catalog and is copyright protected; Order No.
AN 16-3.
---------------------------------------------------------------------------

     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[supcaret]0.924))
    The Reference Geometric Factor (RGF) is a non-dimensional measure
of the fuselage size of an airplane normalized by 1 square meter,
generally considered to be the shadow area of the airplane's
pressurized passenger compartment.\70\
---------------------------------------------------------------------------

    \70\ 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 English Edition 2020 catalog
and is copyright protected; Order No. AN 16-3.
---------------------------------------------------------------------------

    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 propose to use MTOM as the correlating parameter as well.
    We are proposing to adopt ICAO's airplane CO2 emissions
metric (shown in Equation V-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 V.I for further information).
Consistent with ICAO, we are also proposing to adopt MTOM as a
correlating parameter to be used when setting emissions limits.

B. Covered Airplane Types and Applicability

1. Maximum Takeoff Mass Thresholds
    The proposed GHG rule would apply 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 the proposed rule is limited to civil subsonic
airplanes and does not extend to civil supersonic airplanes.\71\
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 EPA and FAA fully promulgate the airplane GHG
emission standards domestically, the United States regulations will
align with ICAO Annex 16 standards.
---------------------------------------------------------------------------

    \71\ 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 the proposed GHG rules 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
Q400.72 73 The proposed GHG rules would 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.
---------------------------------------------------------------------------

    \72\ This was previously owned by Bombardier and was sold to
Viking in 2018, November 8, 2018 (Forbes).
    \73\ 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 proposed rule would apply to all covered airplanes, in-
production and new type designs, produced after the respective
effective dates of the standards except as provided in V.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 proposed in-production standards would only be applicable to
previously type certificated airplanes, newly-built on or after the
applicability date (described in V.D.1), and would not apply
retroactively to airplanes that are already in-service.
3. Exceptions
    Consistent with the applicability of the ICAO standards, the EPA is
proposing applicability language that excepts the following airplanes:
Amphibious airplanes, airplanes initially designed or modified and used
for specialized operational requirements, airplanes designed with an
RGF of zero,\74\ and those airplanes specifically designed or modified
and used for fire-fighting purposes. Airplanes in these categories
proposed to be excepted 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
proposed GHG rules.
---------------------------------------------------------------------------

    \74\ 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 would be 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 all of them
require performance that was outside of the scope considered during the
development of the ICAO standards. Such airplanes could include
     airplanes that required capacity to carry cargo that is
not possible by using less specialized airplanes (e.g. civil variants
of military transports); \75\
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    \75\ 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.
---------------------------------------------------------------------------

     airplanes that required capacity for very short or
vertical take-offs and landings;
     airplanes that required capacity to conduct
scientific,\76\ research, or humanitarian missions exclusive of
commercial service; or
---------------------------------------------------------------------------

    \76\ For example, the NASA SOFIA airborne astronomical
observatory.
---------------------------------------------------------------------------

     airplanes that required similar factors.
    The EPA requests comments on proposed exceptions for specialized
operational requirements. Some exceptions are based on the use of the
airplane after civil certification (e.g., use for firefighting). The
EPA requests comment on the proposed definitions of these excepted
airplanes.
4. New Airplane Types and In-Production Airplane Designations
    The proposed 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 \77\ 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.78 79
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    \77\ 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.
    \78\ 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.
    \79\ 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 (to the FAA) 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 the application 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, which included the Boeing 777-200LR in 2004, 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.80 81
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    \80\ ICF International, 2015: CO2 Analysis of CO2-Reducing
Technologies for Airplane, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
    \81\ 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.\82\ The most recent new type designs introduced in
service were the Airbus A350 in 2015,\83\ the Airbus A220 (formerly
known as the Bombardier C-Series) in 2016,\84\ and the Boeing 787 in
2011.85 86 However, it is unlikely more than one new type
design will be presented for certification in the next ten years.\87\
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.\88\
---------------------------------------------------------------------------

    \82\ ICF International, 2015: CO2 Analysis of CO2-Reducing
Technologies for Airplane, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
    \83\ 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.
    \84\ 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.
    \85\ 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).
    \86\ ICF International, 2015: CO2 Analysis of CO2-Reducing
Technologies for Airplane, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
    \87\ Ibid.
    \88\ 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 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
V.B.2, in-service airplanes are not subject to the ICAO CO2
standards and likewise would not be subject to these proposed GHG
standards.
    For new type designs, this proposed rule would have 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 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.\89\ 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 VII describing the Technology Response for
more information on this).
---------------------------------------------------------------------------

    \89\ 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 proposed standards would be different for in-production
airplanes and new type designs. This is discussed further in Sections
V.C and V.D below, describing standards for new type designs and in-
production airplanes, and Section VII, discussing the technology
response.

C. GHG Standard for New Type Designs

1. Applicability Dates for New Type Designs
    The EPA is proposing that the GHG standards would apply to the same
airplanes as those identified as within the scope of the international
standards adopted by ICAO in 2017, in terms of maximum take-off weight
thresholds, passenger capacity, and reference to dates of applications
for original type certificates. In this way, EPA's standards would
align with ICAO's in defining those airplanes that will become subject
to our standards. 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 proposed regulations would
apply to all airplanes for which application for an original type
certificate is made to the FAA on or after January 1, 2020. For
subsonic jet airplanes over 5,700 kg MTOM with 19 passenger seats or
fewer, the proposed regulations would apply to all airplanes for which
an original type certification application was made to the FAA on or
after January 1, 2023.
    Consistency with international standards is important for
manufacturers, as they noted in comments to our ANPR in 2017, and to
propose criteria to identify those airplanes to be covered by our
standards that differ from those covered by ICAO's standards--either in
terms of maximum take-off mass, passenger capacity, or dates of
applications for new original type certificates--would not be expected
by airplane manufacturers and engine manufacturers, and would introduce
unnecessary uncertainty into the airplane type certification process.
    The EPA understands that by adopting the same effective date as
ICAO, January 1, 2020, for defining those type certification
applications subject to the standards, we are employing a date that has
already passed. Since no airplane manufacturer has in fact yet
submitted an application for a new type design certification since
January 1, 2020, no manufacturer would currently need to amend any
already submitted application to address the GHG standards. Neither the
EPA nor the FAA is aware of any anticipated original new type design
application expected to be submitted before the EPA's standards are
promulgated and effective that would need amendment to reflect the GHG
standards. Therefore, no airplane manufacturer is expected to be
adversely affected by adoption of the same applicability dates as
ICAO's applicability dates for new type design certification
applications, including the January 1, 2020, date.
    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. In addition, the EPA has previously, for the Tier
4 NOX aircraft engine standards, defined the scope of
aircraft engines that were to become subject to the standards based on
a date that preceded the effective date of the final standards, while
at the same time providing that the standards applied as prescribed
after the effective date of the rule. See, e.g., 40 CFR 87.23(d)(1)(vi)
and (vii).
    Here, the U.S. airplane manufacturers that would be subject to
these GHG standards participated in the development of them at ICAO and
have been aware of and supported ICAO's use of the January 1, 2020,
date for new type design certificate applications as triggering
applicability of the international standards, knowing for several years
that any as-yet undetermined new designs would have to comply with the
international standards in order to be marketable internationally.
Consequently, EPA proposes that adoption of the January 1, 2020, date
to define which future new type design certification applications

would need to meet the GHG standards is reasonable and in harmony with
the 2017 ICAO Airplane CO2 Emission Standards. Adoption of the same
dates for new type design certification applications, as well as for
maximum take-off mass thresholds and passenger capacity cutoffs, will
also prevent any need for the United States to file a difference with
ICAO as would be required under the Chicago Convention.
2. Regulatory Limit for New Type Designs
    The EPA proposes that the GHG emissions limit for new type designs
would be a function of the airplane certificated MTOM and consist of
three levels described below in Equation V-2, Equation V-3, and
Equation V-4.\90\
---------------------------------------------------------------------------

    \90\ 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
English Edition 2020 catalog and is copyright protected; Order No.
AN 16-3.
[GRAPHIC] [TIFF OMITTED] TP20AU20.001

    Figure V-1 and Figure V-2 show the numerical limits of the proposed
new type design rules and how the airplane types analyzed in Sections
VI and VII relate to this limit. Figure V-2 shows only the lower MTOM
range of Figure V-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 the proposed rules. (See Section VI and VII for more
information about this.) These proposed GHG emission limits are the
same as the limits of the ICAO Airplane CO2 Emission
Standards.

[GRAPHIC] [TIFF OMITTED] TP20AU20.002

[GRAPHIC] [TIFF OMITTED] TP20AU20.003

    When 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. Airplanes
with an MTOM less than 60 tons \91\ 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.\92\ This leads to requiring higher capital costs
to implement the technology relative to the sale price of the
airplanes.\93\ Business jets (generally less than 60 tons MTOM) tend to
operate at higher altitudes and faster speeds than larger commercial
traffic.
---------------------------------------------------------------------------

    \91\ 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.
    \92\ ICF, 2018: Aircraft CO2 Cost and Technology Refresh and
Industry Characterization, Final Report, EPA Contract Number EP-C-
16-020, September 30, 2018.
    \93\ 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 proposed 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.\94\ This natural gap allowed a ``kink'' point (i.e.,
change in the slope of the proposed standard) to be established between
larger commercial airplanes and smaller business jets and regional
jets. The introduction of this kink point provided flexibility at ICAO
to consider standards at appropriate levels for airplanes above and
below 60 tons.
---------------------------------------------------------------------------

    \94\ Initial data that were reviewed at ICAO did not include
data on the Bombardier C-Series 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 proposed to apply to 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 proposed 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 \95\).\96\
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    \95\ 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).
    \96\ Note: Figure V-1 and Figure V-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 VII of this proposed rule, and in chapter 2 of the Draft
TSD.
---------------------------------------------------------------------------

    Airplanes of less than 60 tons with 19 passenger seats or fewer
have additional economic challenges to technology development compared
with similar sized commercial airplanes. ICAO sought to reduce the
burden on manufacturers of airplanes with 19 seats or fewer, 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 in this proposed rule reflect this difference
determined by ICAO (see Section VII for further information).
    As described earlier in Section II, consistency with the
international standards would facilitate the acceptance of U.S.
airplanes by member States and airlines around the world, and it would
ensure that U.S.

manufacturers would not be at a competitive disadvantage compared with
their international competitors. Consistency with the international
standards would also place an anti-backsliding cap on future emissions
of airplanes by ensuring that all new type design airplanes are at
least as efficient as today's airplanes.
    The EPA requests comment on all aspects of the proposed new type
design rule, including the level of the standard, timing, and
differentiation between airplane categories.

D. GHG Standard for In-Production Airplane Types

1. Applicability Dates for In-Production Airplane Types
    The EPA is proposing the same compliance dates for the proposed GHG
rule as those adopted by ICAO for its CO2 emission
standards. Section V.D.2 below describes the rationale for these
proposed dates and the time provided to in-production types.
    All airplanes type certificated prior to January 1, 2020, and newly
built after January 1, 2028, would be required to comply with the
proposed in-production rule. This proposed GHG regulation would
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 \97\ would be
required to demonstrate compliance with the in-production rule. This
proposed earlier applicability date for in-production airplanes, of
January 1, 2023, is the same as that adopted by ICAO and is similarly
designed to capture modifications to the type design of a non-GHG
certificated airplanes newly manufactured 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.
---------------------------------------------------------------------------

    \97\ Note that V.D.1.i, Changes for non-GHG certified Airplane
Types, is different than the No GHG Change Threshold described in
V.F.1 below. V.F.1 applies only to airplanes that have previously
been certificated to a GHG rule. V.D.1.i only applies only to
airplane types that have not been certificated for GHG.
---------------------------------------------------------------------------

    An application for certification of a modified airplane on or after
January 1, 2023, would trigger compliance with the in-production GHG
emissions limit provided that the airplane's GHG emissions metric value
for the modified version increases by more than 1.5 percent from the
prior version of the airplane. As with changes to GHG certificated
airplanes, introduction of a modification that does not adversely
affect the airplane fuel efficiency Metric Value would not be required
to comply with this GHG rule at the time of that change. Manufacturers
may seek to certificate any airplane 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 would 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. Again, a manufacturer may choose to
recertificate this change in type design for GHG compliance.
    This earlier effective date for in-production airplanes is expected
to help encourage some earlier compliance for new airplanes. However,
it is expected that manufacturers would likely volunteer to certify to
the in-production rule when applying to the FAA for these types of
changes.
2. Regulatory Limit for In-Production Type Designs
    The EPA proposes that the emissions limit for in-production
airplanes be a function of airplane certificated MTOM and consist of
three MTOM ranges as described below in Equation V-5, Equation V-6, and
Equation V-7.\98\
---------------------------------------------------------------------------

    \98\ 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
English Edition 2020 catalog and is copyright protected; Order No.
AN 16-3.
[GRAPHIC] [TIFF OMITTED] TP20AU20.004

    Figure V-3 and Figure V-4 show the numerical limits of the proposed
in-production rules and the relationship of the airplane types analyzed
in Sections VI and VII to this limit. Figure V-4 shows only the lower
MTOM range of

Figure V-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 proposed rules. (See Sections VI and VII for more
information about this.) These proposed GHG emission limits are the
same as the limits of the ICAO Airplane CO2 Emission
Standards.
[GRAPHIC] [TIFF OMITTED] TP20AU20.005

[GRAPHIC] [TIFF OMITTED] TP20AU20.006

    As discussed in Section V.C above, a kink point was added at 60
tons to accommodate a change in slope 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 would be a practical difference in
compliance for in-production airplanes. Manufacturers would need to
test and certify each type design to the GHG standard prior to January
1, 2028, or else newly produced airplanes would likely be denied an
airworthiness certificate. In contrast, new type design airplanes have
yet to go into production, but these airplanes would 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 1,
2020). 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
proposed in-production level is available in 2020 (the 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 is appropriate.
    Section VII describes the analysis that the EPA conducted to
determine the cost and benefits of adopting this standard. Consistent
with the ICAO standard, this proposed rule would apply 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 proposed 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 V.B.4 above and in Section VII, the regulations
reflect differences in economic feasibility for introducing
modifications to in-production airplanes and new type designs. The
standards adopted by ICAO, and proposed here, for in-production
airplanes were developed to reflect these differences.
    The EPA requests comment on all aspects of the proposed in-
production rule, including the level, timing, and differentiation
between airplane categories.

E. Exemptions From the Proposed GHG Rules

    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.\99\
---------------------------------------------------------------------------

    \99\ 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 would continue the
relationship between the agencies by proposing that any request for
exemption be filed with the FAA under its established regulatory
paradigm. The instructions for a 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 would 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 would be in the public interest. The FAA
will continue to consult with 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 V.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
regulatory level of the parent airplane. For example, if the parent
airplane is certificated to the in-production level, then all
subsequent versions must also meet the in-production 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 same regulatory level. Once certificated,
subsequent versions of the airplane may not fall back to a less
stringent regulatory GHG level.
    If the FAA finds that a new original type certificate is required
for any reason, the airplane would need to comply with the regulatory
level applicable to a new type design.
    The EPA is proposing provisions for versions of existing GHG-
certificated airplanes that are the same as the ICAO requirements for
the international Airplane CO2 Emission Standards. These
provisions would reduce the certification burden on manufacturers by
clearly defining when a new metric value must be established for the
airplane.
1. No Fuel Efficiency Change Threshold for GHG-Certificated Airplanes
    There are many types of modifications that could be introduced on
an airplane design that could cause slight changes in GHG emissions
(e.g. changing the fairing on a light,\100\ adding or changing an
external antenna, changing the emergency exit door configuration,
etc.). To reduce burden on both certification authorities and
manufacturers, a set of no CO2 emissions change thresholds
was developed for the ICAO Airplane CO2 Emission Standards
as to when new metric values would need to be certificated for changes.
The EPA proposes to adopt these same thresholds in its GHG rules.
---------------------------------------------------------------------------

    \100\ A fairing is ``a structure on the exterior of an aircraft
or boat, for reducing drag.'' https://www.dictionary.com/browse/fairing.
---------------------------------------------------------------------------

    Under this proposal, an airplane would be considered a modified
version of an existing GHG certificated airplane, and therefore have to
recertify, if it incorporates a change in the type design that either
(a) increases its maximum take-off mass, or (b) increases its GHG
emissions evaluation metric value by more than the no-fuel efficiency
change threshold percentages described below and in Figure V-5: \101\
---------------------------------------------------------------------------

    \101\ Annex 16, Volume III, Part 1, Chapter 1. ICAO, 2017: Annex
16 Volume III--Environmental Protection--Aeroplane CO2 Emissions,
First Edition, 40 pp. Available at: http://www.icao.int/publications/Pages/catalogue.aspx (last accessed July 15, 2020). The
ICAO Annex 16 Volume III is found on page 16 of English Edition 2020
catalog and is copyright protected; Order No. AN 16-3.
---------------------------------------------------------------------------

     For airplanes with a MTOM greater than or equal to 5,700
kg, the threshold value decreases linearly from 1.35 to 0.75 percent
for an airplane with a MTOM of 60,000 kg.
     For airplanes with a MTOM greater than or equal to 60,000
kg, the threshold value decreases linearly from 0.75 to 0.70 percent
for airplanes with a MTOM of 600,000 kg.
     For airplanes with a MTOM greater than or equal to 600,000
kg, the threshold value is 0.70 percent.

[GRAPHIC] [TIFF OMITTED] TP20AU20.007

    The threshold is dependent on airplane size, because the potential
fuel efficiency changes to an airplane are not constant across all
airplanes. For example, a change to the fairing surrounding a wing
light, or the addition of an antenna to a small business jet, may have
greater impacts on the airplane's metric value than a similar change
would on a large twin aisle airplane.
    These GHG changes would be assessed on a before-change and after-
change basis. If there is a flight test as part of the certification,
the metric value (MV) change could be assessed based on the change in
calculated metric value of flights with and without the change.
    A modified version of an existing GHG certificated airplane would
be subject to the same regulatory level as the airplane from which it
was modified. A manufacturer may also choose to voluntarily comply with
a later or more stringent standard.\102\
---------------------------------------------------------------------------

    \102\ ETM Vol. III sec. 2.2.3. ICAO, 2018: Environmental
Technical Manual Volume III--Procedures for the CO2 Emissions
Certification of Aeroplanes, First Edition, Doc 9501, 64 pp.
Available at: http://www.icao.int/publications/Pages/catalogue.aspx
(last accessed July 15, 2020). The ICAO Environmental Technical
Manual Volume III is found on page 77 of the English Edition 2020
catalog and is copyright protected; Order No. 9501-3.
---------------------------------------------------------------------------

    Under this proposed rule, when a change is made to an airplane type
that does not exceed the no-change threshold, the fuel efficiency
metric value would not change. There would be no method to track these
changes to airplane types over time. This feature of the proposed rule
would not remove the requirement for a manufacturer to demonstrate that
the airplane type would still meet the rule after a given change. If an
airplane type has, for example, a 10 percent compliance margin under
the rule, then a small adverse change less than the threshold may not
require the re-evaluation of the airplane metric value. However, if the
compliance margin for a type design is less than the no GHG change
criteria, a manufacturer would be required to prove that it meets the
rule to certify the adverse change.
    Under the proposed rule, a manufacturer that introduces
modifications that reduce GHG emissions can request voluntary
recertification from the FAA. There would be no required tracking or
accounting of GHG emissions reductions made to an airplane unless it is
voluntarily re-certificated.
    The EPA proposes to adopt as part of the GHG rules the no-change
thresholds for modifications to airplanes discussed above, which are
the same as the provisions in the international standard. We believe
that these thresholds would maintain the effectiveness of the rule
while limiting the burden on manufacturers to comply. The proposed
regulations reference specific test and other criteria that were
adopted internationally in the ICAO standards setting process.

G. Annual Reporting Requirement

    As described later in this section, the EPA proposes to collect
information about airplane GHG emissions and related parameters to help
inform the development of future policy, assessments of emissions
inventories, and specific technologies.