For example, one recent study has indicated that modern aircraft jet
engines operating at higher power modes consume rather than emit
methane (Santoni et al., 2011: Aircraft Emissions of Methane and
Nitrous Oxide during the Alternative Aviation Fuel Experiment,
Environ. Sci. Technol., 45, pp. 7075-7082).

                     Table V.1--Comparisons of U.S. Aircraft GHG Emissions to Total U.S. Transportation and Total U.S. GHG Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   1990         2000         2005         2010         2011         2012         2013
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total U.S. Aircraft GHG emissions (Tg CO2eq).................          228          262          254          216          215          212          216
Share of U.S. Transportation.................................          14%          13%          12%          11%          11%          11%          11%
Share of total U.S. Inventory................................         3.6%         3.6%         3.4%         3.1%         3.1%         3.2%         3.2%
U.S. Covered Aircraft GHG emissions (Tg CO2eq)...............          169          223          217          190          193          190          195
Share of U.S. aircraft GHG emissions.........................          74%          85%          85%          88%          90%          90%          90%
Share of U.S. Transportation.................................          10%          11%          10%         9.7%          10%         9.9%          10%
Share of total U.S. Inventory................................         2.6%           3%         2.9%         2.7%         2.8%         2.9%         2.9%
Transportation Sector emissions (Tg CO2eq)...................        1,659        2,044        2,137        1,966        1,932        1,907        1,911
Share of total U.S. Inventory................................          26%          28%          29%          28%          28%          29%          28%
    Total U.S. GHG emissions.................................        6,406        7,315        7,464        7,017        6,889        6,652        6,744
--------------------------------------------------------------------------------------------------------------------------------------------------------

b. U.S. Aircraft GHG Emissions Relative to Global Aircraft GHG
Inventory and the Total Global GHG Inventory
    For background information and context, we first provide
information on the contribution of GHG emissions from global aircraft
and the global transportation sector to total global GHG emissions, and
describe how this compares to the emissions from aircraft that would be
covered by the anticipated ICAO CO2 standard. We then
compare U.S. aircraft GHG emissions to the global aircraft sector, to
the global transport sector, and to total global GHG emissions as an
indication of the role this source plays in the total global
contribution to the air pollution that is causing climate change. As in
the preceding section, we present comparisons from both total U.S.
aircraft and U.S. covered aircraft.
    According to IPCC AR5, global aircraft GHG emissions in 2010 were
11 percent of global transport GHG emissions and 2 percent of total
global GHG emissions. Data from ICAO's 2013 Environmental Report
indicate that the vast majority of global emissions from the aircraft
sector are emitted by the types of aircraft that would be covered by
the anticipated ICAO CO2 standard (``ICAO covered
aircraft'').\177\ When compared to global data from IPCC AR5, worldwide
GHG emissions from ICAO covered aircraft represented about 93 percent
(688 Tg CO2eq) of global aircraft GHG emissions,\178\ 10
percent of global transport GHG emissions, and 1.5 percent of total
global GHG emissions in 2010.
---------------------------------------------------------------------------

    \177\ ICAO CAEP, 2013: ICAO Environmental Report 2013, Aviation
and Climate Change, 224 pp. Available at http://cfapp.icao.int/Environmental-Report-2013/ (last accessed May 12, 2015).
    \178\ Worldwide GHG emissions from ICAO covered aircraft include
emissions from both international and domestic aircraft operations
around the world.
---------------------------------------------------------------------------

    Comparing data from the U.S. Inventory to IPCC AR5, we find that
total U.S. aircraft GHG emissions represented about 29 percent of
global aircraft GHG emissions, about 3.1 percent of global transport
GHG emissions, and about 0.5 percent of total global GHG emissions in
2010 (see Table V.2). For U.S. covered aircraft in 2010 GHG emissions
represented about 26 percent of global aircraft GHG emissions, 2.7
percent of global transport GHG emissions, and 0.5 percent of total
global GHG emissions (see Table V.2). Because 2010 is the most recent
year for which IPCC emissions data are available, we also made
comparisons using 2011 estimates from WRI/CAIT and the International
Energy Agency (IEA) \179\ and found that they yield very similar
results.\180\
---------------------------------------------------------------------------

    \179\ International Energy Agency, Data Services. Available at
http://data.iea.org (last accessed May 12, 2015).
    \180\ Data from WRI/CAIT and IEA show that, in 2011, total U.S.
aircraft emissions represented about 28 percent of global aircraft
GHG emissions, about 3.7 percent of global transport GHG emissions,
and about 0.5 percent of total global GHG emissions. U.S. covered
aircraft represented about 25 percent of global aircraft GHG
emissions, 3.3 percent of global transport GHG emissions, and 0.5
percent of total global GHG emissions in 2011.

     Table V.2--Comparisons of U.S. Aircraft GHG Emissions to Total Global Greenhouse Gas Emissions in 2010
----------------------------------------------------------------------------------------------------------------
                                                                          Total U.S.  U.S. Covered     Global
                                                              2010 (Tg     Aircraft     Aircraft      Aircraft
                                                              CO2 eq)     Share (%)     Share (%)     Share (%)
----------------------------------------------------------------------------------------------------------------
Global Aircraft GHG emissions.............................          743           29          26    ............
Global Transport GHG emissions............................        7,000          3.1           2.7          11
Total Global GHG emissions................................       49,000          0.5           0.5           2
----------------------------------------------------------------------------------------------------------------

    For additional background information and context, we used 2011
WRI/CAIT and IEA data to make comparisons between the aircraft sector
and the emissions inventories of entire countries and regions. When
compared to entire countries, total global aircraft GHG emissions in
2011 ranked 9th overall, behind only China, United States, India,
Russian Federation, Japan, Brazil, Germany, and Indonesia, and ahead of
about 175 other countries. Total U.S. aircraft GHG emissions have
historically been and continue to be by far the largest contributor to
global aircraft GHG emissions. Total U.S. aircraft GHG emissions are
about 7 times higher than aircraft GHG emissions from China, which
globally is the second ranked country for aircraft GHG emissions, and
about 5 times higher than aircraft GHG emissions from all of Asia. U.S.
covered aircraft GHG emissions are about 6 times more than aircraft GHG
emissions from China, and about 4 times more than aircraft GHG
emissions from all of Asia. If U.S.

covered aircraft emissions of GHGs were ranked against total GHG
emissions for entire countries, these covered aircraft emissions would
rank ahead of Belgium, Czech Republic, Ireland, Sweden and about 150
other countries in the world.
c. Aircraft GHG Emissions Are Projected To Increase in the Future
    While overall GHG emissions from U.S. covered aircraft increased by
about 13 percent from 1990 to 2010, the portion attributable to U.S.
international aviation bunker fuels \181\ increased by about 90
percent.\182\ During this same time period, global aircraft GHG
emissions grew by about 40 percent, and the portion attributable to
global international aviation bunker fuels increased by 80
percent.183 184 Notwithstanding the substantial growth in
GHG emissions from U.S. international aviation bunker fuels, U.S.
covered aircraft emissions have not increased as much as global
aircraft emissions primarily because the U.S. aviation market was
relatively mature compared to the markets in Europe and other emergent
markets, and because during this time period the U.S. commercial air
carriers suffered several major shocks that reduced demand for air
travel.185 186 After consolidation and restructuring in
recent years, the U.S. commercial air carriers have regained
profitability and are forecasted by the FAA to grow more over the next
20 to 30 years.\187\ With regard to global aircraft GHG emissions, the
aviation markets in Asia/Pacific, Europe (where airline deregulation
has stimulated significant new demands in this period), and the Middle
East (and other emerging markets) have been growing rapidly, and the
global market is expected to continue to grow significantly over the
next 20 to 30 years.\188\
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    \181\ The U.S. international aviation bunker fuels category
includes emissions from combustion of fuel purchased in and used by
aircraft departing from the United States, regardless of whether
they are a U.S. flagged carrier. GHG emissions from U.S.
international aviation bunker fuels are a subset of GHG emissions
from U.S. covered aircraft. From 1990 to 2010, GHG emissions from
U.S. covered aircraft increased from 169 to 190 Tg CO2eq, and GHG
emissions from the portion attributable to U.S. international
aviation bunker fuels grew from 30 to 58 Tg CO2eq during this same
time period. From 1990 to 2011, GHG emissions from U.S. covered
aircraft increased from 169 to 192 Tg CO2eq (about 14 percent), and
GHG emissions from the portion attributable to U.S. international
aviation bunker fuels grew from 30 to 62 Tg CO2eq (about 110
percent).
    \182\ U.S. EPA, 2015: Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2013, 564 pp. Available at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html#fullreport, (last
accessed May 12, 2015).
    \183\ 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, pp. 599-670.
    \184\ According to IEA, from 1990 to 2011, global aircraft GHG
emissions grew by about 50 percent, and global international
aviation bunker fuels increased by 80 percent. International Energy
Agency Data Services, Available at http://data.iea.org (last
accessed May 12, 2015, 2015).
    \185\ FAA, 2014: FAA Aerospace Forecast Fiscal Years 2014-2034,
129 pp. Available at https://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2014-2034/media/2014_FAA_Aerospace_Forecast.pdf (last accessed May
12, 2015).
    \186\ These shocks include the September 11 terror attacks,
significant increases in fuel prices, debt restructuring in Europe
and U.S., and a global recession.
    \187\ According to the FAA Aerospace Forecast 2014-2034, in 2013
U.S. air carriers were profitable for the fourth consecutive year.
    \188\ According to the FAA Aerospace Forecast 2014-2034, the
International Air Transport Association (IATA) reports that world
air carriers (including U.S. airlines) are expected to register an
operating profit for 2013. Based on financial data compiled by ICAO
and IATA, between 2004 and 2013 world airlines produced cumulative
operating profits (with nine years out of ten posting gains) and net
profits (with six years out of ten posting gains).
---------------------------------------------------------------------------

    Recent studies estimate that both ICAO covered aircraft and U.S.
covered aircraft will experience substantial growth over the next 20 to
30 years in their absolute fuel burn, and that this will translate into
increased GHG emissions. ICAO estimates that the global fuel burn from
ICAO covered aircraft will increase by about 120 percent from 2010 to
2030 and by about 210 percent from 2010 to 2040 (for a scenario with
moderate technology and operational improvements).\189\ The FAA
projects that the fuel consumption from U.S. air carriers and general
aviation aircraft operating on jet fuel will grow by 49 percent from
2010 to 2035, corresponding to an average annual increase rate in fuel
consumption of 1.6 percent.\190\ These aircraft groups (U.S. air
carriers and general aviation aircraft operating on jet fuel) are of
similar scope to the U.S. covered aircraft whose engine GHG emissions
are the subject of this proposed finding. Using fuel burn growth rates
provided above as a scaling factor for growth in GHG emissions
(globally and nationally), it is estimated that GHG emissions from ICAO
covered aircraft and U.S. covered aircraft would increase at a similar
rate as the fuel burn by 2030, 2035, and 2040.
---------------------------------------------------------------------------

    \189\ ICAO CAEP, 2013: ICAO Environmental Report 2013, Aviation
and Climate Change, 224 pp. Available at http://cfapp.icao.int/Environmental-Report-2013/ (last accessed May 12, 2015).
    \190\ FAA, 2015: FAA Aerospace Forecast Fiscal Years 2015-2035,
134 pp. Available at https://www.faa.gov/about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/2015-2035/media/2015_National_Forecast_Report.pdf (last accessed May
12, 2015).
---------------------------------------------------------------------------

3. Proposed Contribution Finding for the Single Air Pollutant Comprised
of the of Six Well-Mixed Greenhouse Gases
    Taking into consideration the data summarized in section V.B.2
above, the Administrator proposes to find that GHG emissions from
classes of engines used in U.S. covered aircraft, which are 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, contribute to the air pollution
that endangers public health and welfare. The Administrator is not at
this time proposing a contribution finding for GHG emissions from
engines not used in covered aircraft (i.e., those used in smaller
turboprops, smaller jet aircraft, piston-engine aircraft, helicopters
and military aircraft). We solicit comment on the scope of the proposed
contribution finding, whether a broader contribution finding (e.g.,
including all engines used in aircraft certified by the FAA) would be
appropriate, and the extent to which EPA has discretion to establish
standards pursuant to a contribution finding that do not impose
requirements on every engine or class of engines within the scope of
that finding.
    It is the Administrator's judgment that the collective GHG
emissions from the classes of engines used in U.S. covered aircraft
clearly contribute, whether the comparison is domestic (10 percent of
all U.S. transportation GHG emissions, representing 3 percent of total
U.S. emissions) or global (26 percent of total global aircraft GHG
emissions representing 3 percent of total global transportation
emissions and 0.5 percent of all global GHG emissions). The proposed
scope of GHG emissions from engines used in U.S. covered aircraft under
this cause or contribute finding would result in the vast majority (90
percent) of U.S. aircraft GHG emissions being included in this
determination. The Administrator believes that consideration of the
global context is important for the cause or contribute test, but that
the analysis should not solely consider the global context. GHG
emissions from engines used in U.S. covered aircraft will become
globally well-mixed in the atmosphere, and thus will have an effect not
only on the U.S. regional climate but also on the global climate as a
whole, for years and indeed many decades to come. It is the
Administrator's view that the cause or contribute test used here

under CAA section 231 can follow the same reasoning that was used in
the 2009 GHG cause or contribute finding under CAA section 202; that
is, the Administrator believes a positive cause or contribute finding
for GHG emissions from engines used in U.S. covered aircraft is
justified whether only the domestic context is considered, only the
global context is considered, or both the domestic and global GHG
emissions comparisons are viewed in combination.
    As was the case in 2009, no single GHG source category dominates on
the global scale, and many (if not all) individual GHG source
categories could appear small in comparison to the total, when, in
fact, they could be very important contributors in terms of both
absolute emissions or in comparison to other source categories,
globally or within the United States. If the United States and the rest
of the world are to combat the risks associated with global climate
change, contributors must do their part even if their contributions to
the global problem, measured in terms of percentage, are smaller than
typically encountered when tackling solely regional or local
environmental issues.'' \191\ Moreover, as the Supreme Court explained
in Massachusetts v. EPA, agencies commonly take an incremental approach
to resolving large issues, stating that, ``[a]gencies, like
legislatures, do not generally resolve massive problems in one fell
regulatory swoop. . . . They instead whittle away at them over time,
refining their preferred approach as circumstances change and as they
develop a more nuanced understanding of how best to proceed.'' 549 U.S.
497, 524 (2007) (citations omitted). The Administrator continues to
believe that these unique, global aspects of the climate change
problem--including that from a percentage perspective there are no
dominating sources emitting GHGs and few sources that would even be
considered to be close to dominating--tend to support consideration of
contribution to the air pollution at lower percentage levels than EPA
typically encounters when analyzing contribution towards a more
localized air pollution problem. Thus, the Administrator, similar to
the approach taken in the 2009 GHG cause or contribute finding under
CAA section 202, is placing weight on the fact that engines \192\ used
in U.S. covered aircraft contribute 3 percent of total U.S. GHG
emissions for the proposed contribution finding and comprise the single
largest transportation source in the United States that has not yet
been regulated for GHG emissions.
---------------------------------------------------------------------------

    \191\ 74 FR 66543 (December 15, 2009).
    \192\ For a standard promulgated under CAA section 231 to be
``applicable to'' emissions of air pollutants from aircraft engines,
it could take many forms, and include multiple elements in addition
to numeric permissible engine exhaust rate. For example, under CAA
section 231, EPA's rules have long-standing regulations addressing
fuel venting, as well as test procedures. See 40 CFR part 87,
subparts B, G and H. 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 U.S. Court of Appeals for the DC
Circuit's 2007 NACAA v. EPA ruling that section 231 confers an
unusually broad degree of discretion in establishing aircraft engine
emission standards, it should be possible to reconcile an ICAO
``aircraft standard'' that effectively limits aircraft engine GHG
emissions with a CAA section 231 aircraft engine emission standard
that achieves the same result, even if the GHG standards take a
different form than the traditional thrust-based NOx aircraft engine
emission standards recently issued by ICAO and the EPA. See 40 CFR
part 87, subpart C.
---------------------------------------------------------------------------

4. Additional Considerations
    The Administrator is also concerned that reasonable estimates of
GHG emissions from engines used in U.S. covered aircraft are projected
to grow over the next 20 to 30 years. Given the projected growth in
aircraft emissions compared to other sectors, it is reasonable for the
Administrator to consider future emissions projections as adding weight
to her primary reliance on annual emissions. Recent projections reveal
that by 2035 GHG emissions from all aircraft and U.S. covered aircraft
engines are likely to increase by almost 50 percent.\193\ By contrast,
it is estimated that by 2035 the light duty vehicle sector will see a
30 percent reduction in GHG emissions from the 2010 baseline, while the
heavy duty vehicle sector will experience a 33 percent increase in GHG
emissions from the 2010 baseline (this projected increase does not
reflect the impact of GHG reductions anticipated from the Phase 2 heavy
duty GHG standards that have not yet been promulgated). In addition, by
2035 the rail sector is projected to experience a 6 percent reduction
in GHG emissions from 2010 baseline.\194\ Because the projected growth
in aircraft engine GHG emissions from U.S. covered aircraft appears to
be greater in percentage terms than other transportation sources, this
future consideration adds weight to the Administrator's proposed
positive contribution finding.
---------------------------------------------------------------------------

    \193\ As discussed in Section V.B.2.c fuel burn growth rates for
air carriers and general aviation aircraft operating on jet fuel are
projected to grow by 49 percent from 2010 to 2035 and this provides
a scaling factor for growth in GHG emissions which would increase at
a similar rate as the fuel burn by 2030, 2035, and 2040.
    \194\ U.S. Energy Information Administration (EIA), 2015: Annual
Energy Outlook (AEO) 2015 with projections to 2040, DOE/EIA-0383,
154 pp. EIA's reference case (used as the baseline in this
comparison) assumes fuel economy levels for light duty vehicles
required to meet federal light duty GHG standards for years 2012-
2025, and for heavy duty trucks GHG standards for years 2014-2018,
plus improvements in vehicles and engines for all subsectors due to
availability of fuel-saving technologies and fuel price effects. EIA
counts biofuels as zero tailpipe GHG emissions. Because the
comparison in this section focuses on tailpipe emissions, we include
them here, at volumes as forecast in the AEO 2015 reference case.
Available at http://www.eia.gov/forecasts/aeo/ (last accessed May
12, 2015).
---------------------------------------------------------------------------

VI. Advance Notice of Proposed Rulemaking: Discussion of Ongoing
International Proceedings To Develop Aircraft CO2 Emissions
Standard and Request for Comment

    For more than four years, the EPA and FAA have been engaged with
the ICAO's Committee on Aviation Environmental Protection (ICAO/CAEP)
to establish an international CO2 emissions standard which
the EPA could then consider proposing for adoption under its section
231 authority of the CAA. This section of this document serves as an
ANPR to discuss the key issues of the ongoing international proceedings
prior to February 2016, when ICAO/CAEP is expected to finalize an
international aircraft CO2 standard. An ANPR is intended to
solicit comments and/or information from the public prior to an agency
determining whether to propose a rulemaking. As such, an ANPR does not
propose or impose any regulatory requirements. The EPA may choose to
develop an ANPR for actions (such as the promulgation of standards
pursuant to CAA section 231 to implement an international aircraft
CO2 standard domestically) which are still in the early
stages of development and for which public input may be particularly
helpful. This also helps ensure transparency, while assisting the EPA
in obtaining input from a wide range of stakeholders as we continue
work within CAEP to establish an international CO2 aircraft
standard. The EPA is seeking comments from all interested parties,
including small businesses, on a variety of issues related to setting
an international CO2 standard for aircraft, including
whether such standards should apply to in-production aircraft instead
of new aircraft types only, the appropriate effective dates for the
potential international CO2 standard, as well as the
appropriate stringency levels.
    CAEP met an important milestone at its 9th meeting (CAEP/9) in 2013
in reaching an agreement on the

appropriate metric to be used in assessing fuel efficiency (or
CO2 emissions) \195\ of an engine/aircraft combination. They
also reached agreement on a mature certification requirement \196\ to
evaluate CO2 emissions for new aircraft types and also
agreed on certain aspects of the scope of applicability of the
CO2 emissions standard; however, work on applicability
options for in-production aircraft continues.
---------------------------------------------------------------------------

    \195\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard, Circular (Cir) 337, AN/192,
Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed May 12, 2015). The ICAO Circular 337
is found on page 85 of the ICAO Products & Services 2015 catalog and
is copyright protected; Order No. CIR337. Section 3.2 of this
Circular states the following: ``An important Phase 1 milestone in
the development of the CO2 Standard was reached on 11
July 2012, when the CAEP Steering Group agreed unanimously on a
CO2 metric system to measure the aeroplane fuel burn
performance and therefore the CO2 emissions produced.''
    \196\ ICAO defines a certification requirement as a combination
of metric, procedures, instrumentation and measurement methodology,
and compliance requirements.
---------------------------------------------------------------------------

    At the CAEP Steering Group meeting in November 2013, there was
agreement on a set of stringency options to be used for the cost-
effectiveness analysis, and at the Steering Group meeting in September
2014 there was a decision on the associated inputs for costs and
technology responses to be utilized in the cost-effectiveness analysis
of these stringency options. This analysis, and work on the
applicability of the standard to in-production aircraft and the
certification requirement are scheduled to be completed prior to the
10th CAEP meeting (CAEP/10) in February 2016. As described in section
II.A, the EPA and the FAA traditionally work within the ICAO/CAEP
standard-setting process to establish international emission standards
and related requirements. 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 of at least equal stringency as ICAO's standards.
This approach has been affirmed as reasonable by the U.S. Court of
Appeals for the DC Circuit. Provided the EPA makes a positive
endangerment finding \197\ under CAA section 231 and ICAO adopts an
international aircraft CO2 standard that is consistent with
CAA section 231 and U.S. domestic needs, we would expect to proceed
with a similar approach promulgating a CO2 emissions
standard (or GHG standard) of at least equivalent stringency
domestically.
---------------------------------------------------------------------------

    \197\ As shorthand in this action, in many places we will use
the term ``endangerment finding'' for both endangerment and cause or
contribute findings.
---------------------------------------------------------------------------

A. Purpose of the International Standard

    At the CAEP Steering Group meeting in 2011, the U.S provided a
paper recommending that CAEP agree that the purpose of the
international CO2 emissions standard be ``to achieve
CO2 emissions reductions from the aviation sector beyond
expected `business as usual'--i.e., a standard that achieves
CO2 emissions reductions from the aviation sector beyond
what would be achieved in the absence of a standard. This would be
analyzed using ICAO criteria of technical feasibility, environmental
benefit, cost effectiveness, and impacts of interdependencies.'' \198\
The Steering Group accepted the U.S. proposal for the purpose of the
international CO2 standard, and it is expected to be
included in the standard setting process. The metric system, stringency
options, costs, technology responses (inputs to be utilized in the
cost-effectiveness analysis), and applicability ultimately chosen will
all have an effect on whether the international CO2
emissions standard adheres to this stated purpose of the standard. The
U.S. continues to support the adoption of an international
CO2 emissions standard that meets this stated purpose, and
the EPA requests comment on this continued support. The EPA requests
comment on how to achieve the purpose of the standard.

B. Applicability of the International CO2 Emissions Standard
---------------------------------------------------------------------------

    \198\ CAEP (U.S. Working Paper), ``U.S. Position on the
Development of ICAO'S Aircraft CO2 Standard,'' CAEP-SG/
20112-WP/25, Presented by the United States, U.S. Working Paper for
CAEP Steering Group meeting, Beijing, China, 12 to 16 September
2011.
---------------------------------------------------------------------------

    The EPA requests comments on the applicability approaches that CAEP
is considering. Specifically, we request comment on whether the
aircraft CO2 standard should apply to in-production
aircraft, including aircraft with any engineered fuel efficiency
improvements (e.g., different engines, redesigned wings, or engine
performance improvement packages, etc.) or whether the aircraft
CO2 standard should apply only to completely new aircraft
type designs. CAEP is also considering a third, alternative approach,
which would redefine a new aircraft type for CO2 purposes to
include in-production aircraft that have a significant change in
CO2 emissions. We are also requesting comment on this
potential alternative option.
    In-production aircraft and new aircraft types are defined as
follows:
--In-production aircraft: Those aircraft types which have already
received a Type Certificate, and for which manufacturers either have
existing undelivered sales orders or would be willing and able to
accept new sales orders.199 200 201
---------------------------------------------------------------------------

    \199\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015).The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
    \200\ As described earlier in section D, in existing U.S.
aviation emissions regulations, in-production means newly-
manufactured or built after the effective date of the regulations--
and already certified to pre-existing standards (if emission
standards were established previously).). This is similar to the
current CAEP definition for in-production aircraft types for
purposes of the CO2 standard.
    \201\ According to ICAO Cir 337, a Type Certificate is ``[a]
document issued by a Contracting State to define the design of an
aircraft type and to certify that this design meets the appropriate
airworthiness requirements of that State''.
---------------------------------------------------------------------------

--New aircraft types: Aircraft types that have applied for a Type
Certificate \202\ after the effective date of a standard and that have
never been manufactured prior to the effective date of a standard.
---------------------------------------------------------------------------

    \202\ A Type Certificate is a design approval process whereby
the FAA ensures the manufacturer's designs meet the minimum
requirements for aircraft safety and environmental regulations. This
is typically issued only once for each aircraft, and modified as
needed as an aircraft is modified over the course of its production
life. This Type Certificate (for new aircraft types) would be the
initial or new Type Certificate for this aircraft.
---------------------------------------------------------------------------

    In addition, for context, out of production aircraft are those
aircraft types which have already received a Type Certificate, but for
which manufacturers either have no existing undelivered sales orders or
would not be willing and able to accept new sales orders. These
aircraft are aircraft types that are no longer in active
production.\203\
---------------------------------------------------------------------------

    \203\ Out of production aircraft that are still in operational
use would become subject to the international standard only if the
standard applied to ``in-use'' aircraft, which it will not since
CAEP has agreed that the international aircraft CO2
standard should not apply to out of production aircraft types. Note,
the EPA's CAA section 231 aircraft engine standards have applied to
in-use aircraft only in very limited situations, such as the
prohibition against fuel venting at 40 CFR 87.11 and smoke number
standards at 40 CFR 87.31. Note, however, that unlike the EPA's
authority to promulgate emission standards for motor vehicles under
CAA section 202(a) or for nonroad engines and vehicles under section
213(a), section 231 of the CAA does not restrict the EPA's authority
to set standards for only new aircraft.
---------------------------------------------------------------------------

    As described earlier in section II.E, CAEP's Steering Group meeting
in 2010

agreed that the scope of applicability for the international aircraft
CO2 standard will be subsonic jets with an applicability
weight threshold of maximum takeoff mass (MTOM) greater than 5,700 kg
(12,566 lb) and turboprop aircraft with a MTOM greater than 8,618 kg
(19,000 lb). CAEP also agreed that the international CO2
standard will apply to new aircraft types, but not apply to out of
production aircraft types, and that applying the standard to in-
production aircraft types should not be ruled out.\204\
---------------------------------------------------------------------------

    \204\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
---------------------------------------------------------------------------

    It is important to further describe the difference between new
aircraft types and in-production aircraft. There are three categories
of aircraft under consideration when describing a CO2
standard: New aircraft types submitted for certification (known as
clean sheet designs), those with lesser levels of design change, such
as a new series in an established type and model (considered to be
significant partial redesigns), or an aircraft with incremental
improvements.\205\ New aircraft types or new type designs are
significant investments for manufacturers and are used for new and
significantly different designs (also characterized as complete
redesigns). Significant partial redesigns may be characterized as a new
or later series of an established model that may incorporate newly
designed wings and give purchasers more choices of engines. Incremental
improvements are less extensive changes to an aircraft such as
performance improvement packages that may be added to an aircraft or
engine at some point during the production cycle.
---------------------------------------------------------------------------

    \205\ New aircraft types fall under the initial or new Type
Certificate, and significant partial redesigns and incremental
improvements fall under an amended Type Certificate. Significant
partial redesigns would be a new or later series of an established
model, and incremental improvements would be a part of the same
series as the established model.
---------------------------------------------------------------------------

    New aircraft types or new type designs are infrequent. The most
recent new type designs introduced in service, such as the Airbus A380
in 2007, the Boeing 787 in 2011, and the original Boeing 777 in
1995,206 207 208 indicate that it is unlikely a new type
design will seek certification in the next 10 to 15 years.\209\ (New
aircraft types (and similarly for significant partial redesigns)
typically yield large fuel burn reductions--10 percent to 20 percent
over the prior generation they replace, and as one might expect, these
significant fuel burn reductions do not happen frequently. Also,
aircraft development programs are expensive. It is not unusual for new
type designs to take 8-10 years to develop, from preliminary design to
entry into service. 210 211) Significant partial redesigns
do not occur often, but are slightly more frequent than new type
designs. For example, after the current significant partial redesign
wave \212\ has passed (which includes the Boeing 747-8, Boeing 737 Max,
Airbus 320 Neo, and Boeing 777-X), we do not currently have knowledge
of many additional significant partial redesigns anticipated over the
next decade (as the previous wave of significant partial redesigns
included the Boeing 777-200LR in 2004, 777-300ER in 2006, 737NG in
1998, Airbus 319 in 1996, and Airbus 330-200 in
1998).213 214 Incremental improvements will likely be
frequent and occur in the near term. One approach CAEP is considering
would be to limit the applicability of any international CO2
standard to only new type designs (or new aircraft types). Under this
approach the international CO2 standard would not apply to
significant partial redesigned aircraft and incremental improvements.
Under another approach CAEP is considering, CAEP would also apply the
international CO2 standard to in-production aircraft (in
addition to new aircraft types). Significant partial redesigned
aircraft and incremental improvements would be characterized as changes
made to in-production aircraft; thus, these categories of aircraft (or
these changes) would need to meet the international CO2
standard under this approach (or they would need to meet the standard
if it also applied to in-production aircraft).\215\
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    \206\ 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 May 12, 2015).
    \207\ The Independent, 2012: BA reveals Airbus A380 superjumbo
flight plans, by Peter Woodman, December 11. Available at http://www.independent.co.uk/travel/news-and-advice/ba-reveals-airbus-a380-superjumbo-flight-plans-8405961.html (last accessed May 12, 2015).
    \208\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
    \209\ Ibid.
    \210\ Ibid.
    \211\ Analysts estimate a new single aisle 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 aircraft design, manufacturers are
opting to re-wing or just re-engine their aircraft (significant
partial redesigns). 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 publically stated
they will need to spend $1-2 billion to re-wing the EMB-175 and
variants. (ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.)
    \212\ In general, design waves are prompted by the combination
of market demand for new aircraft performance needs (e.g., more
seats for longer range) and the age of existing aircraft, and design
waves are typically enabled by advances in propulsion technology.
    \213\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
    \214\ 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 Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.)
    \215\ As described earlier, CAEP has not ruled out applying the
international CO2 standard to in-production aircraft
types, which are aircraft types that have already received a Type
Certificate and are produced after the effective date of the
standard. In-production aircraft types would include significant
partial redesigned aircraft and incremental improvements. CAEP is
currently considering and analyzing in-production applicability.
---------------------------------------------------------------------------

    Another approach for applicability of the international
CO2 standard that CAEP could adopt (or CAEP is considering)
would be an approach based on criteria addressing significant changes
to aircraft designs, which could be considered an applicability
requirement different than that for new aircraft types only and in-
production aircraft. This alternative approach could redefine a new
aircraft type for CO2 purposes to include in-production
aircraft that have a significant change in CO2 emissions,
thus including in-production aircraft in the applicability of the
CO2 standard. The alternative approach could even cover
significant partial redesigned aircraft, depending upon the definition.
CAEP's current mature certification requirement for the international
CO2 standard \216\ provides further detail on technology
changes to aircraft that would affect the aircraft's CO2
metric value. A changed version of an aircraft could be defined as
follows: An aircraft which incorporates changes in type design that may
adversely affect \217\ its CO2 emissions. This possible
definition could also note the

following: (1) Where the proposed change in design, configuration,
power or mass is so extensive that a substantially new investigation of
compliance with the applicable airworthiness regulations is required,
the aircraft should be considered to be a new type design rather than a
changed version, and (2) ``adversely'' refers to an increase in
CO2 emissions of more than an amount (or percentage) that
has yet to be determined (this amount or criterion is still being
considered by CAEP). The EPA requests comment on this change-based
criteria approach, including how to identify those changes that would
result in treating in-production aircraft as new types subject to the
standard.
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    \216\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337. See Chapter 1.
    \217\ Due to substantial market forces to alleviate any adverse
effects on aircraft fuel burn or CO2 emissions, adverse
changes are rare.
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    If CAEP were to limit the scope of applicability to new aircraft
types only (and without the significant change criteria approach
described above), the international CO2 standard would not
apply to later series aircraft with redesigned wings, aircraft that are
available with different engines, or aircraft that undergo incremental
improvements. Following are several examples that illustrate this
situation. The re-engined Boeing 737 Max is an example of a significant
partial redesigned aircraft that is expected to enter into service in
2017.\218\ This aircraft would fall under the original Boeing 737 Type
Certificate that was issued in 1967 (and entered into service in
1968)--or more specifically it would fall under an amended Type
Certificate, and it would not be considered a new aircraft type as
defined by CAEP. The current in-production 737s (Next Generation 737s
or commonly abbreviated as 737 NGs) feature newer engines, have
redesigned wings, and entered service in 1998 under the original 737
Type Certificate that was issued in 1967, and these also were not
considered a new type aircraft when they were introduced in 1998.\219\
Another example of an aircraft that does not qualify as a new type is
the Boeing 747-8 aircraft, that entered into service in 2011, and which
included a new wing, new engines, and a lengthened fuselage but fell
under an amended Type Certificate for the original Boeing 747 that was
certified in 1969 (and entered into service in 1969). An example of
incremental improvements to in-production aircraft, is the Boeing Next
Generation 737 performance improvement package which was implemented
between 2011 and 2013 and the Boeing 767-300 winglets that entered into
service in 2008, both of which improve aircraft fuel efficiency. There
are many other examples that exist for different manufacturers and
aircraft around the world as well, but for conciseness, we are limiting
our discussion to these above examples. These examples illustrate the
typical certification for significant partial redesigns and incremental
improvements by various aircraft certificating or certifying
authorities (or national airworthiness authorities) around the world.
---------------------------------------------------------------------------

    \218\ Boeing, 737 Max Program ``LEAPS'' into Engine Testing,
Article by Eric Olson, July 11, 2014. Available at http://www.boeing.com/boeing/Features/2014/07/bca_737max_leap_07_11_14.page, (last accessed May 12, 2015).
    \219\ The original 737 entered service in 1968. The 737 Classic
entered service in 1984, and it had new high bypass engines, an
updated wing, and other aerodynamic improvements. The 737 NGs
entered service in 1998, and they featured a new wing and updated
engines. Several mid-life upgrades were produced for the 737 NGs,
offering improved range, payload, and efficiency. (ICF
International, CO2 Analysis of CO2-Reducing Technologies for
Aircraft, Final Report, EPA Contract Number EP-C-12-011, March 17,
2015.)
---------------------------------------------------------------------------

    Using CAEP's current definition of new aircraft types (clean sheet
designs, which are completely new aircraft) we cannot today identify
the first aircraft to which the new standard would apply. As the
examples above illustrate, new aircraft types are infrequent,\220\ and
there are no currently announced new type designs that are expected to
be introduced after the implementation dates being analyzed by CAEP--
2020 and 2023. Furthermore, based on provisions to which CAEP has
already agreed,\221\ new aircraft types subject to the CO2
standard would be aircraft that submit an application for a Type
Certificate after the implementation dates of 2020 and 2023 (dates for
the stringency analysis) which would likely result in entry into
service dates of about 2025 or 2028.\222\ If the international
CO2 standard is applied only to new aircraft types, then
CO2 emissions would not be expected to begin to deviate from
business-as-usual (in comparison to CO2 emissions reductions
that would be achieved in the absence of a standard) before 2025.
Therefore, an international standard developed for only new aircraft
types may not actually apply to any new aircraft for at least a decade.
Even if a few new type aircraft are introduced in this timeframe, it
will take even longer for these aircraft to comprise any significant
portion of the fleet. Therefore, applying an international standard
which applies only to new aircraft types will likely result in no
additional CO2 reductions beyond what would have occurred
absent a CO2 standard, either for the near- and mid-term,
about 5 to 10 years from 2016, or even in the longer-term of 20 years
plus.223 224
---------------------------------------------------------------------------

    \220\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
    \221\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May.12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337. Section 1.5 states that that the date to be used in
determining the applicability of the CO2 standard is the
date the application for a Type Certificate was submitted to the
certificating authority having jurisdiction over the manufacturer
responsible for the aircraft design. Section 1.6 specifies that an
application shall be effective for the period specified in the
designation of the airworthiness regulations appropriate to the
aircraft type. An application for a Type Certificate is valid for 5
years.
    \222\ These dates assume 5 years from application for the
aircraft Type Certificate to entry into service, which is how long
an application is valid for a Type Certificate.
    \223\ Approximate time-scales are considered to be 5 years for
near-term, 10 years for mid-term, and 20 years or more for long-
term.
    \224\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
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    The EPA requests comments on the timeframes described above for
introducing new aircraft types and their subsequent penetration into
the fleet. Are there any aircraft manufacturer announcements that we
missed in regard to new aircraft types that will be introduced or apply
for a Type Certificate after 2020 and 2023 (or new aircraft types that
will be introduced or apply for a Type Certificate five years after
these dates)? \225\ If so, what are these new aircraft types? How many
new types are projected to enter the fleet in this timeframe and what
portion of the fleet will they represent?
---------------------------------------------------------------------------

    \225\ In November 2014, Boeing indicated that it would replace
the 737 with a new aircraft type in 2030. Earlier this decade,
Boeing was assessing an all new clean sheet 737 replacement, but
eventually they decided to re-engine the 737 (the 737 Max) instead.
(Flight Club, Paul Thompson, Here's The Skinny On What's Next For
Boeing, November 16, 2014. Available at http://flightclub.jalopnik.com/heres-the-skinny-on-whats-next-for-boeing-1656206527 (last accessed May 12, 2015), Also, Wichita Business
Journal, Daniel McCoy, Boeing planning 737 MAX replacement by 2030--
What it could mean for Spirit AeroSystems, November 5, 2014.
Available at http://www.bizjournals.com/wichita/blog/2014/11/boeing-planning-737-max-replacement-by-2030-what.html) (last accessed May
12, 2015). We would consider this as a Boeing projection or
sketching out of plans for a new aircraft type, but it is not a
commitment from Boeing.
---------------------------------------------------------------------------

    The alternative approach being considered by CAEP and described
earlier (addressing changes in design of in-production aircraft) may
offer an opportunity to cover more aircraft in an earlier timeframe
(including significant partial redesigns), but it is unclear what
effect this approach would have on

additional CO2 emissions reductions compared to a standard
for only new aircraft types. The EPA requests comments on the timeframe
for CO2 emissions reductions and the likely share of annual
aircraft production (or share of in-production aircraft built annually)
that would be affected under this alternative approach.
    If ICAO applies the aircraft CO2 emission standard to
in-production aircraft, and subsequently (provided the EPA makes a
positive endangerment finding under CAA section 231(a)) the EPA
establishes domestic aircraft engine standards that are equivalent to
the ICAO international aircraft CO2 standard, this means
that all aircraft built (in-production) after the effective date would
need to certify and comply with the standard to remain in production.
This includes (as described earlier) in-production aircraft with
incremental improvements (though we reiterate this would not include
in-use aircraft). As an example of in-production aircraft, the
Gulfstream G650, which is currently in production and expected to
remain so after 2020, would need to certify and comply with the new
CO2 standard. In the next section we discuss in more detail
how applicability to in-production aircraft could work.

C. CAEP Discussion on In-Production Aircraft Applicability

    At the request of the CAEP Steering Group meeting in November 2013,
CAEP began work on defining potential options to implement
applicability requirements for in-production aircraft. Subsequently,
based on the options provided to the 2014 Steering Group meeting, CAEP
decided that it should continue to investigate potential in-production
aircraft applicability options, and that these should be presented at
the July 2015 Steering Group meeting, so that a decision can be taken
at the 10th meeting of CAEP (CAEP/10) in February 2016 regarding
whether the international CO2 standard will apply to in-
production aircraft. There are a wide range of options under
consideration, including both mandatory and voluntary options for
reporting and certification processes for in-production aircraft
applicability, but the 2014 Steering Group meeting requested that CAEP
focus on defining the mandatory options (in contrast to options such as
voluntary reporting and certification).
1. Applicability to In-Production Aircraft and Date of Implementation
    At the 2014 Steering Group meeting, CAEP also agreed that 2023
represented the earliest possible date for an in-production aircraft
standard to allow time to promulgate domestic regulations and process
manufacturer certification applications. CAEP did not rule out later
dates though and could consider implementation dates for an in-
production aircraft CO2 standard later than 2023 (CAEP could
consider applicability dates for in-production aircraft that are five
years following the new aircraft type applicability date, i.e. dates
ranging from 2023 to 2028).
    The EPA seeks comments on both a 2023 implementation date and on
possible later implementation dates for an in-production domestic
CO2 (or GHG) aircraft engine emissions standard that would
be adopted under CAA section 231,\226\ the impact the date of
implementation might have on per-aircraft GHG or CO2
emissions rates \227\ and the ability of a domestic GHG or
CO2 standard to achieve aircraft emission reductions beyond
what would occur in the absence of such a standard.
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    \226\ Traditionally, international emission standards have first
been adopted by ICAO, and subsequently the EPA had initiated
rulemakings under CAA section 231 to establish domestic standards
equivalent to ICAO's standards where appropriate. Provided ICAO
adopts an international aircraft CO2 standard that is
consistent with CAA section 231 and it is appropriate for domestic
needs in the United States, we expect to proceed along a similar
approach for the future CAA section 231 aircraft engine
CO2 standard (or aircraft engine GHG standard), provided
the EPA issues final positive endangerment and cause or contribute
findings under CAA section 231.
    \227\ For a standard promulgated under CAA section 231 to be
``applicable to'' emissions of air pollutants from aircraft engines,
it could take many forms, and include multiple elements in addition
to numeric permissible engine exhaust rate. For example, under CAA
section 231, EPA's rules have long-standing regulations addressing
fuel venting, as well as test procedures. See 40 CFR part 87,
subparts B, G and H. 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 U.S. Court of Appeals for the D.C.
Circuit's 2007 NACAA v. EPA ruling that section 231 confers an
unusually broad degree of discretion in establishing aircraft engine
emission standards, it should be possible to reconcile an ICAO
``aircraft standard'' that effectively limits aircraft engine GHG
emissions with a CAA section 231 aircraft engine emission standard
that achieves the same result, even if the GHG standards take a
different form than the traditional thrust-based NOX
aircraft engine emission standards recently issued by ICAO and the
EPA. See 40 CFR part 87, subpart C.
---------------------------------------------------------------------------

    As described in section VI.F.2, the technologies considered for the
CAEP analyses are those technologies that will be widely used on in-
production aircraft by 2016 or shortly thereafter.\228\ The EPA
requests comments regarding whether applying an international
CO2 standard to in-production aircraft is consistent with
the purpose of the standard as accepted by the CAEP Steering Group
meeting in 2011: ``to achieve CO2 emission reductions from
the aviation sector beyond expected `business as usual' . . . analyzed
using ICAO criteria of technical feasibility, environmental benefit,
cost effectiveness, and impacts of interdependencies.'' \229\ The
International Coalition for Sustainable Aviation (ICSA),\230\ which is
a CAEP Observer organization, submitted papers to CAEP that analyzed
this issue. Also, a member of ICSA \231\ has developed similar analyses
which indicate that applying the international standard only to new
aircraft types would likely result in no additional CO2
reductions beyond what would have occurred absent a CO2
standard, either for the near- and mid-term, about 5 to 10 years from
2016, or even in the longer-term of 20 years plus. This occurs, the
ICCT states, because the development cycles for new aircraft are very
lengthy and it is not unusual for new aircraft to take 8 to 10 years to
develop from preliminary design to entry into service and once in
service it takes significant time for new aircraft types to penetrate
the fleet.232 233

Another study funded by the EPA corroborates this analysis.\234\ The
EPA requests comments on whether applying the international
CO2 aircraft standard only to new aircraft types would be
consistent with the accepted purpose of the international standard (the
purpose of the standard that has been accepted by the CAEP Steering
Group). Lastly, the EPA requests comment on the appropriateness of a
possible EPA regulation following either of these approaches
(applicability to only new aircraft types or applicability to both new
types and in-production aircraft) which are under consideration at
CAEP.
---------------------------------------------------------------------------

    \228\ CAEP determined in 2012 that all technology responses
would have to be based on technology that would be in common use by
the time the standard was to be decided upon in 2016 or shortly
thereafter. This generation of technology was defined within CAEP as
a Technology Readiness Level (TRL) 8--an actual system completed and
``flight qualified'' through test and demonstration--by 2016 or
shortly thereafter.
    \229\ CAEP (U.S. Working Paper), ``U.S. Position on the
Development of ICAO'S Aircraft CO2 Standard,'' CAEP-SG/
20112-WP/25, Presented by the United States, U.S. Working Paper for
CAEP Steering Group meeting, Beijing, China, 12 to 16 September
2011. Available at http://www.epa.gov/otaq/aviation.htm. (last
accessed May 12, 2015).
     International Coalition for Sustainable Aviation (ICSA),
``ICAO'S CO2 Standard as Part of a Basket of Measures to
Meet Emission Reduction Goals'', ICAO Assembly--38th Session,
Executive Committee, Agenda Item 17--Environmental Protection, A38-
WP/297, EX/99, September 19, 2013.
    \230\ The International Coalition for Sustainable Aviation
(ICSA) is a structured network of environmental non-governmental
organizations (NGOs) who share a common concern with civil
aviation's contribution to air quality issues, climate change and
noise, and who are committed to developing and providing technical
expertise, common policy positions and strategies with a view to
reducing emissions and noise from aviation. See http://www.icsa-aviation.org/ (last accessed May 12, 2015).
    \231\ The International Council on Clean Transportation (ICCT)
is a member of ICSA, and ICCT is an independent nonprofit
organization founded to provide research and technical and
scientific analysis to environmental regulators. See http://www.theicct.org/ (last accessed May 12, 2015).
    \232\ ICCT, Efficiency Trends for New Commercial Jet Aircraft
1960 to 2008, November 2009. Available at http://www.theicct.org/sites/default/files/publications/ICCT_Aircraft_Efficiency_final.pdf
(last accessed May 12, 2015).
    \233\ ICCT, ``Could ICAO's CO2 Standard Not Actually
Cover Any Aircraft? Yes, If Nobody's Watching''. Blog, December 9,
2014. Available at http://www.theicct.org/blogs/staff/could-icaos-co2-standard-not-cover-any-aircraft (last accessed May 12, 2015).
    \234\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
---------------------------------------------------------------------------

    Also, there have been concerns raised in CAEP about applying the
international CO2 standard to in-production aircraft. These
concerns include (a) the added resource burden on certificating
authorities \235\ to process manufacturers' certification applications,
which will be more numerous compared to new aircraft types; and (b) the
potential added costs to manufacturers to certify in-production
aircraft. The EPA requests comment on these two concerns, including
providing supporting documentation on the extent of these concerns and
any other issues the commenters may identify with applying the
international CO2 standard to in-production aircraft.
---------------------------------------------------------------------------

    \235\ Pursuant to CAA section 232, the FAA, after consultation
with the EPA, shall prescribe regulations to insure compliance with
all standards prescribed by the EPA under CAA section 231. Section
232 then directs the FAA to include provisions making the EPA's
standards applicable in the issuance, amendment, modification,
suspension, or revocation of any certificate authorized by the FAA
under part A of subtitle VII of Title 49. Under this unique
statutory structure, the EPA promulgates the substantive emission
standards, and the FAA enforces the EPA's standards and insures all
necessary inspections are accomplished.
---------------------------------------------------------------------------

2. Reporting Requirement for New In-Production Aircraft
    CAEP is working to define mandatory in-production aircraft options,
and one possible option is a reporting requirement
236 237 238  for in-production aircraft CO2
emissions rates (measured according to the aircraft test procedure that
was agreed upon at CAEP/9) as an alternative to establishing an
aircraft CO2 standard for in-production aircraft. Although a
reporting requirement provides policy relevant information, it does not
necessarily translate into specific emissions reductions. The EPA
recognizes that only a mandatory standard for in-production aircraft
would ensure that the aircraft CO2 standard reduces per-
aircraft CO2 emissions rates. However, a reporting
requirement could be an important component of an in-production
aircraft CO2 standard, especially if it is implemented
shortly after an in-production aircraft standard is adopted. It would
ensure that CO2 emissions rates data are gathered quickly
prior to an effective date for the final standard (tracking
CO2 emissions rates is beneficial for the reasons discussed
later in this section and for potentially assisting with the assessment
of a future CO2 standard). The EPA requests comment on an
aircraft manufacturer reporting requirement that is implemented soon
after the adoption of an in-production international aircraft
CO2 standard, as a component of the in-production aircraft
CO2 standard.
---------------------------------------------------------------------------

    \236\ Currently, CAEP is developing a publicly available
database for aircraft CO2 emissions (CAEP is now
considering format, parameters, etc. for the database), but
submissions to this database by aircraft manufacturers would be
voluntary. There will not be a CAEP mandatory reporting requirement
associated with this potential CO2 database. In addition,
if the international aircraft CO2 standard applies to
only new aircraft types, it could be many years before any data
exists in this database.
    \237\ For many years, ICAO has maintained an Aircraft Engine
Emissions Databank for landing and takeoff certificated emissions
values of NOX, hydrocarbon, carbon monoxide, and smoke
number (ICAO and the EPA also have aircraft engine emission
standards for these pollutants). It contains certified emissions
data voluntarily reported from each aircraft engine manufacturer.
This databank is available at https://easa.europa.eu/document-library/icao-aircraft-engine-emissions-databank (last accessed May
12, 2015).
    \238\ In 2012, the EPA promulgated annual reporting requirements
for aircraft engine emissions of NOX, hydrocarbon, carbon
monoxide, and smoke number and related parameters. One of the
reasons that the EPA issued these reporting requirements was due to
the varying amount of voluntary data reported by aircraft engine
manufacturers. (U.S. EPA, ``Control of Air Pollution from Aircraft
and Aircraft Engines; Emission Standards and Test Procedures.''
Final Rule, 77 FR 36342 (June 18, 2012)).
---------------------------------------------------------------------------

    In 2009 the EPA promulgated a final GHG reporting rule that applies
to many sectors in the United States, including manufacturers of heavy-
duty and offroad vehicles and engines, and manufacturers of aircraft
engines.239 240 The EPA's experience with reporting programs
indicates that the EPA and the public would be able to track
CO2 emissions rates trends (i.e., trends of aircraft cruise
fuel burn rates) from aircraft over time. Requiring the reporting of
aircraft CO2 emissions rates trends from aircraft over time
is appropriate and feasible. Requiring aircraft manufacturers to report
aircraft CO2 emissions rates shortly after an in-production
international aircraft standard is adopted would enable and expedite
the tracking and understanding of these emission trends. In addition,
reporting programs typically raise awareness of emissions and can
improve the understanding of the factors that influence emission rates
as well as the actions that can be taken to reduce emissions. When
similar methods for monitoring, measurement, and reporting are applied
across an industry, it can lead to more consistent, accurate, and
timely data to inform decision-making for individual manufacturers and
the EPA (including a comparison of the CO2 emissions rates
from aircraft of various manufacturers). Thus, a reporting requirement
could potentially contribute to efforts to identify and implement
future aircraft CO2 emission reduction opportunities.
---------------------------------------------------------------------------

    \239\ EPA's 2009 rule on Mandatory Reporting of Greenhouse Gases
included engine manufacturers for the following mobile source
sectors: Highway heavy-duty (engine and vehicle), non-road,
aircraft, locomotive, marine, snowmobiles, and motorcycles.
Manufacturers of aircraft jet engines of rated output (or thrust)
greater than 26.7 kilonewtons are required under this program to
report annually to the EPA CO2 and NOX
emissions from aircraft engines during the landing and takeoff
cycle. Manufacturers of these engines were already measuring and
recording CO2 emissions as part of existing criteria air
pollutant emission requirements for the landing and takeoff cycle,
but prior to this 2009 rule, these data were not reported to the
EPA. Manufacturers voluntarily reported the data to ICAO, but there
was no assurance that the EPA would receive this information, and
thus, the 2009 rule required reporting of the aircraft engine
CO2 and NOX emissions during the landing and
takeoff cycle to the EPA.
    \240\ An aircraft manufacturer reporting requirement for in-
production aircraft CO2 emission rates would require the
reporting of aircraft CO2 emissions during the cruise
phase of operation to the EPA. The majority of aircraft
CO2 emissions occurs in the cruise phase of operation,
and thus, reporting CO2 emission rates from this phase
will improve our ability to track full-flight aircraft
CO2 emission rates over time (in addition to reporting
the aircraft engine CO2 emissions during the landing and
takeoff cycle). Also, the aircraft test procedure that was agreed
upon at CAEP/9 now enables us to measure aircraft CO2
emissions during cruise.
---------------------------------------------------------------------------

    Independent of action that CAEP may or may not take in February
2016, the EPA could under its CAA section 114(a) authority pursue a
reporting requirement for aircraft cruise GHG or CO2
emissions rates--to ensure we have GHG or CO2 emissions
rates data on all in-production aircraft (and any new aircraft types
that enter service).241 The EPA could use the same metric
agreed to at CAEP/9 (and in ICAO circular 337). This will be described
in detail in

VI.D.1 below. In general, the EPA asks for comment on a mandatory
reporting requirement for in-production aircraft GHG or CO2
emissions rates--either as part of the CAEP international standard or
as an independent domestic requirement to be adopted by the EPA. If the
EPA were to pursue this requirement independently from CAEP, what lead
time would be appropriate for manufacturers to report the GHG or
CO2 emissions rates from all of their in-production aircraft
242 (after we promulgate such a requirement)? Additionally,
if we were to pursue such an independent reporting requirement, should
we require the annual reporting of the GHG or CO2 emissions
rates from in-production aircraft (and any new type aircraft)
243 to enable us to track any updates? We are not at this
time proposing to promulgate such a requirement in advance of ICAO's
decision. Due to the possibility of ICAO's adoption of a reporting
requirement, we believe it is reasonable to await the outcome of that
decision in order to determine whether to strictly follow ICAO's
possible reporting requirement or make changes to it in the form of an
additional U.S. domestic requirement, as appropriate.
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    \241\ This GHG or CO2 emissions rate data will help
to track trends, raise awareness, better understand the technology
in the fleet, etc.
    \242\ In this case, manufacturers would need to report the GHG
or CO2 emission rates for in-production aircraft
(aircraft types which have already received a Type Certificate, and
for which manufacturers either have existing undelivered sales order
or would be willing and able to accept new sales orders) that are
built after a certain date, which has yet to be determined but would
likely be a date that occurs shortly after we promulgate the
requirement.
    \243\ By applying a reporting requirement to in-production
aircraft after a certain implementation date, this reporting
requirement also includes new aircraft types that are produced after
this implementation date.
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D. Metric System, Applicability, and Certification Requirement

    The CO2 metric system and mature certification procedure
were agreed upon by CAEP in 2013.244 This section describes
the metric system that was developed, the scope of aircraft to be
covered by the international CO2 standard, the certification
test procedures that would be used to demonstrate compliance with the
international CO2 standard, and CAEP's decision to focus on
the entire aircraft for the international CO2 standard.
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    \244\ As described earlier, the certification requirement is the
combination of metric, procedures, instrumentation and measurement
methodology, and compliance requirements. We are using the terms
metric system and certification test procedures to describe these
elements of the certification requirement.
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1. CO2 Metric System
    The metric system was developed to cover a wide range of aircraft
types, designs, technology, and uses. To do this, the metric system was
designed to differentiate between generations of aircraft and to
equitably capture improvements in aerospace technology (structural,
propulsion, and aerodynamic) that contribute to a reduction in the
airplane CO2 emissions. In addition, the metric system
accommodates a wide range of technologies and designs which
manufacturers may choose to implement to reduce CO2
emissions from their aircraft.
    The metric system agreed to at CAEP uses multiple Specific Air
Range (SAR) test points to represent cruise fuel burn. SAR is a
traditional measure of aircraft cruise performance which measures the
distance an aircraft can travel for a unit of fuel. This is similar to
the instantaneous ``miles per gallon'' readings in many cars today.
However, here the inverse of SAR is used (1/SAR); therefore a lower
metric value represents a better fuel efficiency. The SAR data are
gathered at three gross weight points. The three equally weighted
points are used to represent a range of day to day aircraft
operations.\245\ The functional form of the metric system is provided
below.
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    \245\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
[GRAPHIC] [TIFF OMITTED] TP01JY15.000

(1/SAR)avg is calculated at 3 gross weight fractions of
Maximum Takeoff Mass (MTOM):
High gross mass: 92% MTOM
Mid gross mass: Average of high gross mass and low gross mass
Low gross mass: (0.45 * MTOM) + (0.63 * (MTOM-0.924))

    The Reference Geometric Factor (RGF) is a measure of the fuselage
size on a given aircraft. In analyzing various metric system options it
was found that in some instances, namely stretch aircraft, changes in
aircraft size, and thus capability, were not reflected in changes to
the aircraft's gross weight (MTOM). To account for these occurrences,
and the variety of methods that manufacturers may use to make such a
change, an adjustment factor was added (the RGF with a 0.24 exponent
used in the metric system).
2. Applicability
    CAEP has decided the scope of applicability for a future
international CO2 standard should be subsonic jet and
propeller-driven aircraft meeting the following criteria:
    All subsonic jet aircraft over 12,566 lbs (5,700 kg) MTOM.
    All subsonic propeller driven (e.g., turboprop) aircraft over
19,000 lbs (8618 kg) MTOM, except amphibious airplanes and those
designed and used for fire-fighting operations.
    No military aircraft will be subject to this international
standard.
3. Certification Requirement
    CAEP has developed a mature certification requirement \246\ that
would allow for the determination of an aircraft CO2 metric
value for any aircraft meeting the applicability criteria set forth
above. This certification requirement incudes the metric system and
test procedure. The test procedure was based upon industry's current
best practices for establishing the cruise performance of their
aircraft, and input from certification authorities. These procedures
include specifications for aircraft conformity, weighing, fuel
specifications, test condition stability criteria, required confidence
intervals, measurement instrumentation required, and corrections to
reference conditions.
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    \246\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR337.
---------------------------------------------------------------------------

    These CO2 test procedures are based upon manufacturer's
existing practices when certifying new aircraft. This means that there
is a very heavy reliance on dedicated flight testing of the aircraft.
This potentially poses challenges for the certification of in-
production aircraft. Manufacturers have stated that there could be
logistical challenges associated with the certification of aircraft for
CO2 that have previously been type certificated (e.g.
procuring and instrumenting an aircraft for flight testing). To address
this, the EPA is currently working within CAEP to encourage the
development of a modified or separate equivalent certification test
procedure that would reduce this burden on manufacturers

and allow for quicker/simpler certification of in-production types.
4. Regulating the Entire Aircraft Instead of the Engine
    The CO2 metric system intends to equitably reward
improvements in aircraft technologies that reduce emissions, including
advances in structures (aircraft weight), propulsion (engine specific
fuel consumption), and aerodynamics. These three factors are key to the
overall aircraft CO2 emissions. In addition, CAEP has
indicated (and EPA agrees) that it is best to consider the aircraft as
a whole instead of only the aircraft engine technology in addressing
factors that influence CO2 emissions, because of the effects
and interaction these key factors have on the aircraft CO2
emissions from engines.\247\ The three factors--and technology
categories that improve these factors--are described as follows: \248\
    Structures: Reducing basic aircraft weight to increase the
commercial payload or extend range for the same amount of thrust and
fuel burn;
    Propulsion (thermodynamic and propulsion efficiency): Advancing the
overall specific performance of the engine, to reduce the fuel burn per
unit of delivered thrust; and
    Aerodynamics: Advancing the aircraft aerodynamics, to reduce drag
and its associate impacts on thrust.
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    \247\ ICAO, 2013: CAEP/9 Agreed Certification Requirement for
the Aeroplane CO2 Emissions Standard. Available at http://www.icao.int/publications/catalogue/cat_2015_en.pdf (last accessed
May 12, 2015). The ICAO Circular 337 is found on page 85 of the ICAO
Products & Services 2015 catalog and is copyright protected; Order
No. CIR33.
    \248\ ICAO, Environmental Report 2010--Aviation and Climate
Change, 2010, which is located at http://www.icao.int/environmental-protection/Pages/EnvReport10.aspx (last accessed May 12, 2015).
---------------------------------------------------------------------------

    Specific examples of technologies that affect these three factors
help to further illustrate that it is best to consider the aircraft as
a whole in addressing CO2 emissions. For structural
improvements, aircraft manufacturers have shown significant weight
reduction results over time due to the progressive introduction of new
technologies such as: Advanced alloys and composite materials, improved
and new manufacturing processes and techniques (including integration
and global evaluation simulation), and new systems (e.g. fly-by-
wire).249 250
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    \249\ Ibid.
    \250\ Fly-by-wire refers to a system which transmits signals
from the cockpit to the aircraft's control surfaces electronically
rather than mechanically. AirlineRatings.com, Available at http://www.airlineratings.com/did-you-know.php?id=18 (last accessed on May
12, 2015, 2015).
---------------------------------------------------------------------------

    For propulsion improvements, technologies include enhanced
compressors (e.g., intercooled compressors) and reduced hub-tip ratio
fans.\251\ As another example, manufacturers seek higher operating
pressure ratios (OPR) to improve combustion and engine cycle
refinements.
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    \251\ ICF International, CO2 Analysis of
CO2-Reducing Technologies for Aircraft, Final Report, EPA
Contract Number EP-C-12-011, March 17, 2015.
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    For aerodynamics, friction and lift-dependent drag are the biggest
contributors to aerodynamic drag. Advances in aerodynamics enable
significant lift-dependent drag reduction by maximizing effective wing
span extension. For example, wing-tip devices can give an increase in
the effective aerodynamic span of wings, particularly where wing
lengths are limited by airport gate sizes. Manufacturers are also
looking at ways of decreasing the drag caused by skin friction. An
example of a technology to improve aircraft local skin friction is to
utilize riblets (which are micro-grooves on the surface) to maintain
laminar flow via Natural Laminar Flow and Hybrid Laminar Flow Control
(HLFC) to reduce turbulent skin friction.\252\ The first production
example of a HLFC system went into service on the new Boeing 787-9 in
2014.
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    \252\ ICAO, Environmental Report 2010--Aviation and Climate
Change, 2010, which is located at http://www.icao.int/environmental-protection/Pages/EnvReport10.aspx.(last accessed May 12, 2015).
---------------------------------------------------------------------------

E. Stringency Options
    At the Steering Group meeting in November 2013, CAEP agreed to
analyze a range of CO2 stringency options that cover the
full range of aircraft in-production and in-development around the
world (within the applicable weight thresholds and categories), and
this includes the wide range of technology that is currently in the
aircraft fleet.\253\ Generally, the stringency options that are being
evaluated fall into three categories as follows: (1) CO2
stringency levels that could impact \254\ only the oldest, least
efficient aircraft in-production around the world, (2) middle range
CO2 stringency levels that could impact many aircraft
currently in-production and comprising much of the current operational
fleet, and (3) CO2 stringency levels that could impact
aircraft that have either just entered production or are in final
design phase but will be in-production by the time the international
CO2 standard becomes effective. We are requesting comment on
the level(s) at which the CO2 stringency options should be
set, what factors should be considered in establishing the stringency
of the CO2 standard, and on their potential relationship to
any future CAA section 231 standard.
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    \253\ The ICAO standard has the following applicability weight
thresholds: Maximum takeoff mass greater than 5,700 kilograms for
subsonic jet aircraft and maximum takeoff mass greater than 8,618
kilograms for turboprops.
    \254\ The aircraft shown in these charts are in-production and
current in-development. These aircraft could be impacted by an in-
production standard in that, if they were above the standard, they
would need to either implement a technology response or go out of
production. For a new type only standard there will be no regulatory
requirement for these aircraft to respond.
---------------------------------------------------------------------------

    The figures below are intended to show the range of stringency
levels under consideration at CAEP and CO2 metric value
levels of today's in-production and in-development \255\ aircraft. The
data shown were generated by the EPA using a commercially available
aircraft modeling tool called PIANO.\256\ This model contains non-
manufacturer provided estimates of the performance of various aircraft.
In contrast, CAEP is using manufacturer-provided estimates of the
aircraft metric value performance.
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    \255\ Aircraft that are currently in-development but will be in
production by the applicability dates. These could be new types or
significant partial redesigned aircraft.
    \256\ PIANO (Project Interactive Analysis and Optimization),
Aircraft Design and Analysis Software by Dr. Dimitri Simos, Lissys
Limited, UK, 1990-present; Available at www.piano.aero (last
accessed May 12, 2015). This is a commercially available aircraft
design and performance software suite used across the industry and
academia.
---------------------------------------------------------------------------

    The stringency options under consideration at CAEP are functions of
the aircraft CO2 Metric Value and have a correlating
parameter of MTOM. They are upwards sloping and have a ``kink'' at
60,000 kilograms MTOM. The ``kink'' was included in the stringency
options as a technical approach to reflect the different behaviors
observed between the larger and smaller aircraft.
    The official stringency options under consideration at CAEP have
not been cleared for release outside of the participating members since
deliberations on the standard are still ongoing (proceedings are
expected to be completed at CAEP/10 in February 2016). To show the
relative efficiency of the aircraft, Figure 1 and Figure 2 below show
the aircraft metric values \257\ versus MTOM. In place of the official
stringency options under consideration, lines of constant technology
are used to notionally show how the stringency options were set across
the fleet. These lines reflect the three ranges of options discussed
above. Lower metric values, for a given MTOM, represent an increased
fuel efficiency. Figure 1

shows the makeup of the current production fleet and the in-development
aircraft. This is what CAEP is using as the starting point for modeling
the effect of the CO2 standard. Figure 2 shows what the EPA
expects the market to look like in 2023, considering the publicly
announced plans by industry to replace existing aircraft with new
products.
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    \257\ Metric values were generated using PIANO.
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    A standard set near the upper-most line of constant technology in
Figures 1 and 2 would affect a very modest number of aircraft, namely
the oldest, least efficient types. Many of the aircraft that would be
affected by such a stringency level are being produced in very limited
numbers and may not be eligible to operate in U.S. air space (e.g.,
Russian and Ukraine aircraft).
    Aircraft around the middle two lines of constant technology in
Figures 1 and 2 reflect the performance of many aircraft that are
currently in production and compose much of the current operational
fleet. The current generation of single aisle aircraft from Boeing and
Airbus are in this middle range.
    Aircraft near the lowest line of constant technology in Figures 1
and 2 reflect the most advanced aircraft currently for sale on the
market. These are aircraft that have either just entered production or
are still in-development

but will be in-production by the effective date of a potential in-
production the standard. The replacement single aisle aircraft and new
twin aisle aircraft from Boeing and Airbus are modeled to be clustered
around the lowest line.
    While Figures 1 and 2 show the ranges of stringency under
consideration and how aircraft fall within those ranges, because of the
scale, it is hard to see the range of technology present in the fleet.
Therefore Figure 3 and 4 expand the view and show percent differences
between the four constant technology lines represented in Figures 1 and
2. This allows for a clearer view of best and worst performing
aircraft; Figure 3 provides the perspective from the current in-
production and in-development fleet, and Figure 4 projects out to the
2023 fleet. In addition, these figures allow one to compare the
technology level and efficiency of aircraft with differing MTOMs.

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BILLING CODE 6560-50-C
    The EPA requests comment on a range of stringency options within
the constant technology lines identified in Figure 1 and Figure 2, on
their potential impact, and on their potential relationship to any
future CAA section 231 standard.
    CAEP is considering the possibility of adopting two separate
CO2 stringency levels, one for new type aircraft and one for
in-production aircraft. This would allow stringencies to be set for
both new types and in-production aircraft at a level closer to what
could be achieved by each aircraft type. Issues surrounding the
potential for in-production standards are discussed in section VI.C.1.

    There is ongoing discussion on what appropriate levels of
stringency may be for new type and in-production aircraft. Any final
decisions will have to wait until the full analysis has been conducted
at CAEP. As explained in sections VI.B and VI.C.1, new types are
infrequently developed and typically represent a step change in
technology. It may be possible to set a level of stringency that is
reasonable for in-production aircraft to meet, but at the same time
provide an incentive for new type aircraft to improve. However, this is
challenging to develop because of the significant efficiency
improvements typically seen between in-production and new type
aircraft. The EPA requests comment on the potential for developing a
standard with two stringency levels at CAEP.
    The development of a new aircraft type standard must take into
consideration the standard's potential effect on any future type
designs. Even the most stringent option under consideration at CAEP is
still based on technology available today. Any new type aircraft that
may be developed and certified 10 years or more from now would be
expected to use more advanced fuel efficient technology that is not yet
developed or tested.
    The implications for an in-production standard are more significant
in the near term for manufacturers. Aircraft currently in-production,
and not meeting the level of an in-production standard, would need to
be modified to meet the standard to remain in production; this would
take time and resources from the manufacturers. The full implications
of this have not yet been resolved in CAEP. However, we expect that the
effect on aircraft CO2 emissions would be minimal for less
stringent options. The aircraft with the highest CO2 metric
values generally rely on older technology and were designed in the
1980's to early 1990's. Many of these aircraft are also expected to be
replaced with updated versions in the near future, before a
CO2 standard would be implemented and go into effect. The
EPA requests comment on the levels at which in-production and new type
standards might be set and on what factors should be considered in
establishing the stringency.

F. Costs, Technology Responses for Stringency Options, and Cost-
Effectiveness Analysis

    The EPA has been involved in CAEP's effort to analyze the
CO2 stringency options and the potential costs and
environmental impacts that would result from both new type only
CO2 standards and in-production international CO2
standards. CAEP is still determining the best way to conduct portions
of this analysis. The inputs that have been developed by the CAEP
include non-recurring costs data and technology responses for the
various stringency options under consideration. This section describes
the development of these inputs. The EPA requests comments on how the
modeling should be conducted to differentiate in-production and new
type scenarios.
1. Non-Recurring Costs (engineering development costs)
    CAEP developed a single cost estimate that could be used for all
aircraft as a function of MTOM and percent metric value improvement
required. Based on past practice, industry provided estimates for
developing clean sheet designs and significant partial redesigns, only
including high level information that has been made available to the
public. This was considered to be a top down estimate because it
included all aircraft development costs (airworthiness certification,
noise, etc.) not just those for CO2 improvements.
    Since the initial dataset provided by industry only included major
changes (or major improvements), the EPA saw the need to supplement
this dataset with an estimate of CO2-only changes (or
CO2-only improvements), which was considered to be a bottom
up estimate. These changes would be much smaller, on the order of a few
percent, and could be applied to in-production aircraft at a cost much
lower than projected by industry. The EPA contracted with ICF
International to develop an estimate of the cost to modify in
production aircraft to comply with a CO2 standard. ICF
International conducted a detailed literature search, conducted a
number of interviews with industry leaders, and did its own modeling to
estimate the cost of making modifications to in production
aircraft.\258\ The results from this peer-reviewed study (small
changes) were then combined with inputs from the industry and the other
CAEP participants (large changes) to develop the CO2
technology response and cost estimation. For the cost estimation, the
CAEP combined the two different methodologies to develop the final cost
surface.\259\
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    \258\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
    \259\ The two datasets were merged together and a single cost
surface was then generated to calculate the cost to modify any
aircraft based on the MTOM, and percent metric value change needed.
---------------------------------------------------------------------------

    A top-down approach is being used to model large changes to
aircraft design, such as what would be seen in significant partial
redesigns or new types. For significant partial redesigns that result
in new series of an established model, these types of changes may
include: Redesigned wings, new engine options, longer fuselages,
improved aerodynamics, or reduced weight. When making significant
changes to an aircraft many other changes and updates get wrapped into
the process that do not have an effect on the CO2 emissions
of the aircraft, and significant partial redesigns may not have been
spurred by changes to fuel efficiency (CO2 reductions). This
confluence of changes led CAEP to agree that it was reasonable to use
the full development cost for a new type (clean sheet) or significant
partial redesign for major changes. Total costs for past projects were
used to estimate non-recurring cost for the CAEP analysis. This type of
aircraft improvement/development program has historically ranged
approximately from 1 to 15 billion Dollars (U.S.) depending on the size
of the aircraft and scope of the improvements desired.
    A bottom-up approach was used, by CAEP, to model smaller
incremental metric value changes to aircraft design. The CAEP agreed
that the above top-down approach would not be the best approach for
minor changes or incremental improvements because the significant
design efforts include many changes that would not be required for
smaller CO2 reductions. The EPA used the information
gathered by ICF International to provide input on the cost for
individual technologies which were used to build up non-recurring costs
for these incremental improvements (a bottom-up approach). The
technologies available to make incremental improvements to aircraft is
wide ranging and aircraft specific. Some examples of technologies that
could be integrated into an aircraft for incremental improvements
include improved fan blade design or reduction in turbine clearances in
the engine, reducing the gap between control surfaces, carbon brake
pads, or advanced wing tip devices. As an example, ICF International
estimated that depending on the additive nature of specific
technologies and the magnitude improvement required, the cost to
incrementally improve the Boeing 767 could range from approximately 230

million to 1.3 billion US dollars (3.5% to 11% metric value
improvement).\260\
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    \260\ ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, March 17, 2015.
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2. Technology Responses
    When CAEP started to develop the technology responses for the
stringency options, a determination needed to be made on what level of
technology could be considered as a response to the standard. At the
outset, CAEP decided the international CO2 standard would be
a technology following standard, rather than a technology forcing one.
This means that the international standard would reflect a level of
emissions performance that is already achieved by some portion of
current in-production aircraft.
    Additionally, CAEP determined in 2012 that all technology responses
would have to be based on technology that would be in common use by the
time the standard was to be decided upon in 2016 or shortly thereafter.
This generation of technology was defined within CAEP as a Technology
Readiness Level (TRL) 8 \261\--an actual system completed and qualified
through test and demonstration--by 2016 or shortly thereafter. This
means that the technology responses considered for the future
international CO2 standard, going into effect in 2020 or
2023 for new types and potentially in 2023 or later for in-production,
are based on what will be in operation by 2016 or shortly thereafter.
Considering the technology response assumptions agreed to at CAEP, the
EPA requests comment on how the international CO2 standard
should be established so that it meets the purpose of the standard--to
achieve reductions beyond what would have been achieved in the absence
of a standard.
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    \261\ TRL is a measure of Technology Readiness Level. CAEP has
defined TRL8 as the ``actual system completed and `flight qualified'
through test and demonstration.'' TRL is a scale from 1 to 9, TRL1
is the conceptual principle, and TRL9 is the ``actual system `flight
proven' on operational flight.'' The TRL scale was originally
developed by NASA. ICF International, CO2 Analysis of CO2-Reducing
Technologies for Aircraft, Final Report, EPA Contract Number EP-C-
12-011, see page 40, March 17, 2015.
---------------------------------------------------------------------------

3. Cost Effectiveness Analysis
    CAEP is currently conducting the cost effectiveness analysis for
new-type and in-production aircraft. With rare exceptions CAEP has
historically developed new type only standards. To model cost impacts
of a new type standard, CAEP has historically used an assumption that
the in-production aircraft will respond to the new type standard, even
though the standard would not apply to them and has assumed that the
aviation sector is competitive enough that market forces will drive
manufacturers to voluntarily upgrade their fleet to meet any new type
aircraft standard. This scenario is modeled no differently from a
mandatory in-production standard. The EPA requests comment on modeling
cost and environmental impacts of new-type standards based on the
assumed attainment of such emissions levels by in-production aircraft.
    Because CAEP has modeled all in-production aircraft as responding
by the implementation date of the new-type standard, CAEP has by
definition, performed an in-production analysis. More stringent options
for new-type aircraft may be restricted due to the assumed in-
production impacts.
    CAEP has recognized that its past methods for modeling a new-type
only standard (by assuming in-production aircraft comply) may not be
sufficient for the CO2 standard analysis. Thus, CAEP
developed new methods to model what cost and environmental impacts
would result from only new types being regulated under a new-type
emission standard. CAEP is still determining the best way to conduct an
analysis of impacts only on new types using the agreed upon technology
responses and cost estimates. The EPA requests comments on how to model
cost impacts for only new types for the future international
CO2 standard, if it were to apply only to new types. The EPA
also requests comment on how the modeling should be conducted to
differentiate in-production and new type scenarios.

G. Request for Comment on EPA's Domestic Implementation of
International CO2 Standards

    As described earlier in section II.E, traditionally international
emission standards for aircraft engines have first been adopted by
ICAO, and subsequently the EPA has initiated rulemakings to establish
domestic standards that are of at least equal stringency as ICAO's
engine standards. However, the Chicago Convention,\262\ which
established ICAO, recognizes that ICAO member states may adopt their
own unique standards that are more stringent than ICAO standards. A
participating member state (or nation) that adopts more stringent
standards is obligated to notify ICAO of the differences between its
standards and ICAO's standards.\263\
---------------------------------------------------------------------------

    \262\ ICAO, 2006: Doc 7300-Convention on International Civil
Aviation, Ninth edition, Document 7300/9. Available at: http://www.icao.int/publications/ICAOProducts&Services2015catalogue/cat_2015en.pdf (last accessed May 12, 2015). The ICAO Document 7300
is found on page 1 of the ICAO Products & Services 2015 catalog and
is copyright protected; Order No. 7300.
    \263\ According to the Chicago Convention, a participating
member State that adopts regulations or practices differing in any
particular respect from those established by an international
standard is obligated to notify ICAO of the differences between its
standards and ICAO's standards. However, member States that wish to
use aircraft in international transportation must adopt emissions
standards and other recommended practices that are at least as
stringent as ICAO's standards. Member States may ban the use of any
aircraft within their airspace that does not meet ICAO standards.
---------------------------------------------------------------------------

    Section 231(b) of the CAA requires that any emission standards
``take effect after such period as the Administrator finds necessary
(after consultation with the Secretary of Transportation) to permit the
development and application of the requisite technology, giving
appropriate consideration to the cost of compliance during such
period.'' 42 U.S.C. 7571(b). Section 231(a)(2)(B) provides that the
Administrator shall consult with the Administrator of the FAA on
standards, and ``shall not change the aircraft engine emission
standards if such change would significantly increase noise and
adversely affect safety.'' 42 U.S.C. 7571(a)(2)(B).
    As discussed in the 2005 rule (CAEP/4 aircraft engine
NOX standard),\264\ the EPA needs to have a technical basis
for expecting the standards will be achievable in a specific period of
time. While the statutory language of section 231 is not identical to
other provisions in title II of the CAA that direct the EPA to
establish technology-based standards for various types of mobile
sources, the EPA interprets its authority under section 231 to be
similar to those provisions that grant us significant discretion to
identify a reasonable balance of specified emissions reduction, and
cost without adversely affecting safety or increasing noise. See, e.g.,
Husqvarna AB v. EPA, 254 F.3d 195 (D.C. Cir. 2001) (upholding the EPA's
promulgation of technology-based standards for small non-road engines
under section 213(a)(3) of the CAA). In this regard, we note CAEP's
intent for the purpose of the international CO2 standard (as
accepted by the CAEP Steering Group in 2011), which is to achieve
aircraft CO2 emissions reductions beyond that which would

have occurred in the absence of a standard.
---------------------------------------------------------------------------

    \264\ U.S. EPA, ``Control of Air Pollution from Aircraft and
Aircraft Engines; Emission Standards and Test Procedures;'' Final
Rule, 70 FR 2521, November 17, 2005.
---------------------------------------------------------------------------

    In ruling on a petition for judicial review of the 2005 rule,\265\
the U.S. Court of Appeals for the D.C. Circuit held that the EPA's
approach in that action of tracking the ICAO standards was reasonable
and permissible under the CAA. NACAA v. EPA, 489 F.3d 1221, 1230-32
(D.C. Cir. 2007). The Court also held that section 231 of the CAA
confers a broad degree of discretion on the EPA to adopt aircraft
emission standards that the Agency determines are reasonable. Id.
---------------------------------------------------------------------------

    \265\ Ibid.
---------------------------------------------------------------------------

    Although the EPA has traditionally established domestic standards
that track the ICAO standards, for purposes of having a robust ANPR
process, we ask for comment on the possibility of the EPA adopting a
more stringent aircraft engine emissions standard than ICAO, provided
ICAO/CAEP promulgates a standard in 2016 and the EPA makes a positive
endangerment finding. In the same vein, the EPA requests that
commenters consider the following factors (among others): The potential
to reflect the CO2 emissions performance of products from
U.S. manufacturers, competitive advantages and disadvantages for U.S.
manufacturers, certification reciprocity with certificating authorities
of other nations, and the EPA's role in the ongoing ICAO negotiations.
In addition, the EPA asks for comment on what action the EPA should
take if the ICAO/CAEP process fails to result in the adoption of an
aircraft CO2 emissions standard.

VII. Statutory Authority and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is a significant regulatory action because it raises
novel policy issues. Accordingly, it was submitted to the Office of
Management and Budget (OMB) for review. This action proposes a finding
that GHG emissions from aircraft cause or contribute to air pollution
that may be reasonably anticipated to endanger public health and
welfare along with an ANPR which provides an overview of the
international efforts to reduce GHG emissions, progress to date in
establishing global aircraft standards that achieve meaningful
CO2 reductions and, if the EPA finds that aircraft GHG
emissions do cause or contribute to endangerment, the potential use of
CAA section 231 to implement these standards domestically ensuring
transparency and the opportunity for public comment. Any changes made
in response to OMB recommendations have been documented in the docket.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under
the PRA. The proposed endangerment and cause or contribute findings
under CAA section 231 do not contain any information collection
activities.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. The proposed
endangerment and cause or contribute findings under CAA section 231 do
not in-and-of-themselves impose any new requirements but rather set
forth the Administrator's proposed determination that GHG emissions
from certain classes of aircraft engines--those used in U.S. covered
aircraft--cause or contribute to air pollution that may be reasonably
anticipated to endanger public health and welfare. Accordingly, this
action affords no opportunity for the EPA to fashion for small entities
less burdensome compliance or reporting requirements or timetables or
exemptions from all or part of the proposal.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. The proposed endangerment and cause or
contribute findings under CAA section 231 do not in-and-of-themselves
impose any new requirements but rather set forth the Administrator's
proposed determination that GHG emissions from certain classes of
aircraft engines--those used in U.S. covered aircraft--cause or
contribute to air pollution that may be reasonably anticipated to
endanger public health and welfare. Thus, Executive Order 13175 does
not apply to this action.

G. Executive Order 13045: Protection of Children from Environmental
Health Risks and Safety Risks

    This action is not subject to Executive Order 13045 because it is
not economically significant as defined in Executive Order 12866. The
Administrator considered climate change risks to children as part of
this proposed endangerment finding under CAA section 231. This action's
discussion of climate change impacts on public health and welfare is
found in section IV of this preamble. Specific discussion with regard
to children are contained in sections IV and I.D of the preamble titled
``Children's Environmental Health.'' A copy of all documents pertaining
to the impacts on children's health from climate change have been
placed in the public docket for this action.

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use

    This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. Further, we have concluded that this
action is not likely to have any adverse energy effects because the
proposed endangerment and cause or contribute findings under section
231 do not in-and-of themselves impose any new requirements but rather
set forth the Administrator's proposed determination that GHG emissions
from certain classes of aircraft engines--those used in U.S. covered
aircraft--cause or contribute to air pollution that may be reasonably
anticipated to endanger public health and welfare.

I. National Technology Transfer and Advancement Act (NTTAA)

    This action does not involve technical standards.

J. Executive Order 12898: Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations

    The EPA believes this action will not have potential
disproportionately high and adverse human health or environmental
effects on minority, low-

income, or indigenous populations because this action does not affect
the level of protection provided to human health or the environment.
The Administrator considered climate change risks to minority, low-
income, and indigenous populations as part of this proposed
endangerment finding under CAA section 231. This action's discussion of
climate change impacts on public health and welfare is found in section
IV of the preamble. Specific discussion with regard to minority, low-
income, and indigenous populations are found in sections IV and I.E of
this preamble titled ``Environmental Justice.'' A copy of all documents
pertaining to the impacts on these communities from climate change have
been placed in the public docket for this action.

K. Determination Under Section 307(d)

    Section 307(d)(1)(V) of the CAA provides that the provisions of
section 307(d) apply to ``such other actions as the administrator may
determine.'' Pursuant to section 307(d)(1)(V), the Administrator
determines that this action is subject to the provisions of section
307(d).

VIII. Statutory Provisions and Legal Authority

    Statutory authority for this action comes from 42 U.S.C. 7571, 7601
and 7607.

List of Subjects

40 CFR Part 87

    Environmental protection, Air pollution control, Aircraft, Aircraft
engines.

40 CFR Part 1068

    Environmental protection, Administrative practice and procedure,
Confidential business information, Imports, Motor vehicle pollution,
Penalties, Reporting and recordkeeping requirements, Warranties.

    Dated: June 10, 2015.
Gina McCarthy,
Administrator.
[FR Doc. 2015-15192 Filed 6-30-15; 8:45 am]
BILLING CODE 6560-50-P