(26 pages) 

COMMITTEE ON AVIATION ENVIRONMENTAL PROTECTION (CAEP)

EIGHTH MEETING

Montréal, 1 to 12 February 2010

AGENDA ITEM 2

PART ONE

The attached constitutes the report on Agenda Item 2 and should be 

inserted at the appropriate place in the yellow report folder.

CAEP/8-WP/80

9/2/10

CAEP/8-WP/80

Report on Agenda Item 2 2-1

Agenda Item 2: Review of technical proposals relating to aircraft engine emissions

2.1 REPORT OF WG3 – EMISSIONS TECHNICAL

2.1.1 General Technical Issues

2.1.1.1 The Rapporteurs of Working Group 3 presented the group’s report. Most of the work 

items were examined within the three Task Groups (Characterisation of Emissions (CETG), Certification 

(CTG) and Long Term Technology Goals (LTTG)). Ad-hoc groups were formed to address very specific 

topics. The remaining items were retained under the direction of WG3 itself. Liaison with WG1, WG2, 

FESG, MODTF and SAE was carried out via focal points.

2.1.1.2 The group has been continuing its work to monitor and foster research to further 

characterise the air quality and global effects resulting from the current and future aircraft exhaust 

emissions, including aviation’s contribution relative to other sources. As an input to the consideration of 

aviation’s contribution relative to other sources, the established WG3 Science Focal Points and CAEP 

Local Air Quality Research Focal Point provided a tutorial and some conclusions on source 

apportionment, specifically under what circumstances the apportionment of impact by mass emitted from 

sources (AIME) is valid for assessment of climate and air quality impacts from aircraft emissions.

2.1.1.3 The WG3 also continued to monitor trends in aviation kerosene fuel composition and 

assess consequences for emissions. It noted that no changes are required to the ICAO test fuel 

specification at this time. However, in light of the information collected on global kerosene fuel 

specification and the ICAO emissions test fuel as well as the potential for a CO2 Standard and the 

emergence of alternative fuels, it was highlighted that work should continue on fuels used in certification 

tests. The information provided by WG3 on fuel supply composition was complemented by studies on 

ultra-low-sulphur fuels by a member and an observer.

2.1.1.4 Working with other CAEP WGs and in support of MODTF analysis, WG3 developed 

databases and technical inputs to support the assessment of associated trade-offs in the CAEP/8 work 

programme. These inputs comprise of the following:

 technology responses to NOx stringency options;

 assumptions on future technology improvements with respect to noise and emissions 

as input into MODTF for the ICAO Environmental Goals Assessment;

 a review of the current global fleet database (Campbell-Hill) and the associated 

aircraft noise and emissions characteristics;

 a Growth and Replacement Database, incorporating noise, NOx and fuel burn data, 

for use in populating the generic FESG future fleet forecast with actual airframeengines; and

 additional data on business jets and turboprops, accounting for the fact that available 

noise and emissions information was non-certificated data or simply unavailable.
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2-2 Report on Agenda Item 2

2.1.2 One member and an observer presented the work on potential reductions in sulphur 

content in aviation fuels. These issues are being coordinated within States for possible update of fuel 

specification Standards outside of ICAO.

Discussion and Conclusions

2.1.2.1 One member agreed with the WG3 Co-Rapporteurs that resources are limited and WG3 

especially may become overloaded with tasks. This was also discussed at the last Steering Group meeting 

where it was stressed that prioritization be done to address resource constraints. The member also 

mentioned that all efforts be made to keep abreast of technical work outside CAEP in order to avoid 

duplication of effort, but particularly for the area of alternative fuels.

2.1.2.2 The member also highlighted the importance of continuing the PM work which will also 

be discussed in section 2.4.

2.1.3 Proposed Changes to Annex 16, Volume II

2.1.3.1 The WG3 considered a number of proposals for the amendment of Annex 16, Volume II. 

Some of these proposals were a result of updates to SAE-E31 documentation.

2.1.3.2 For reflectometers’ Standards, it was determined that there is no need to change or amend 

current wording in Annex 16. In order to harmonise Annex 16 Volume II with ARP 1179 rev. C on the 

use of filters, some guidance text for the ETM was proposed (provided in Appendix B to the report on 

this agenda item and discussed in section 2.1.3 related to ETM Volume II).

2.1.3.3 In reviewing Annex 16, Volume II, Appendix 3, Attachment A, the group found 

inconsistencies with SAE ARP 1256C on the operating temperatures of the Total Hydrocarbon Analyzer. 

SAE E-31 has been contacted and they have initiated work to revisit ARP 1256 and ARP 1179 with the 

aim to achieve a harmonized approach. This work will continue during CAEP/9 and no Annex 16 

revisions are related to this work at this time. For the time, being guidance material has been developed 

for the ETM with respect to the HC analyser. Therefore, no change in language in Annex 16, Volume II is 

proposed.

2.1.3.4 An observer had requested a review of the Annex 16, Volume II humidity measurement 

requirements. Some initial work has been started but not yet finished. It is proposed to carry this work 

over to the CAEP/9 work programme.

2.1.3.5 The proposed changes to Annex 16, Volume II are summarized in the following section

and the ETM is covered in section 2.1.3 – Development of Environmental Technical Manual (ETM) 

Volume II.

Equivalent Procedures

2.1.3.6 CAEP/7 requested WG3 to consider harmonisation of the wording ―variations in 

procedures‖ within Annex 16, Volume II and ―equivalent procedures‖ in the ETM. While there was no 

clear definition from the review of historical records, the group concluded that the term ―variations in 

procedure‖ is effectively the same as ―equivalent procedure‖ which is defined in the ETM. Therefore, the 

language has been made consistent and now refers to ―equivalent procedure‖ throughout Annex 16,

Volume II.
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Report on Agenda Item 2 2-3

Other amendments to Annex 16 and ETM

2.1.3.7 The co-rapporteur of WG3 clarified to the group that any recommendation on a 

production cut-off Standard based on CAEP/6 NOx Standard will need to be included in Annex 16,

Volume II. In order to implement a potential CAEP/6 NOx production cut-off Annex 16, Vol. II, 

Chapter 2, paragraph 2.3.2 (d) needs to be amended to cover for the ceasing ―date of manufacture of the 

individual production engine‖ which is subject to CAEP/8 discussions and agreement. Various 

amendments are proposed to link the Annex 16 requirements on this issue with the associated guidance in 

the ETM (discussed in section 2.1.3 related to ETM Volume II).

2.1.3.8 In the same way, any potential increase in NOx stringency that may be agreed at CAEP/8 

will need to be included in Annex 16 Volume II. Paragraph 2.3.2 Regulatory levels would be amended by 

a subparagraph. The structure of this paragraph is dependent on the agreed stringency option. However, it 

would be similar to subparagraph d) containing applicability dates and subsequent formulae.

Editorial Corrections

2.1.3.9 Further edits with regard to typographical errors and moving of paragraphs to more 

appropriate places were identified.

Discussion and Conclusions

2.1.3.10 The meeting agreed to the proposed amendments and recommended that these be 

incorporated as part of the Annex 16, Volume II amendments included in Appendix A to the report on 

this agenda item.

2.1.3.11 A member brought to the attention of the meeting an issue in the French version of 

Annex 16, Volume II. He further suggested that the term ―production cut-off‖ be clarified so that it means 

―engine production cut-off‖. The meeting agreed to incorporate this clarification in Annex 16, Volume II 

as provided in Appendix A to this report. The meeting also agreed to his proposed French text for 

Annex 16, Volume II, Appendix B, page B-3, para 1.5:

1.5 Les Etats contractants reconnaîtront la validité des dérogations à une exigence de 

cessation de production de moteurs qui sont accordées...

2.1.3.12 A member expressed concern on the provision that exemption from production cut-off 

―shall be reported by engine serial number and made available via an official public register‖. The WG3 

representative explained that transparency in the process drove this requirement. One member clarified 

that process of granting exemption in her State involves issuing a notice in the Federal Register. Another 

member stressed the importance of transparency. The meeting agreed that having this information 

publicly available is desirable.

2.1.4 Development of Environmental Technical Manual (ETM) 

Volume II

2.1.4.1 A WG3 representative presented the work on the development of a second Volume of the 

Environmental Technical Manual (ETM) for emissions, consistent and compatible with the approach 

taken for noise (Volume I).
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Date of manufacture (Chapters 1 and 2)

2.1.4.2 The current Annex 16, Volume II applicability requirements are related to the ―date of 

manufacture of the first individual production engine‖, while for NOx production cut-off requirements the 

date of manufacture refers to ―date of issue of the document attesting that the 

individual.....engine....conforms to the requirements of the type‖. Explanatory information on this text 

and agreed interpretation has been incorporated into the ETM as provided in Appendix B to the report in 

this agenda item.

Applicability of Certification Requirements (Chapter 2)

2.1.4.3 Based on principles that take into account past and current certification practice, guidance 

has been developed on how to treat the changes in an engine design which have no or very little effect on 

emission levels. It also includes guidance on when new emissions levels would need to be determined, 

when a new certification test would be required, and whether the certification basis from the parent 

product would be retained or, due to substantial modifications, the latest Standard applied.

Process and criteria for NOx production cut-off exemptions (Chapter 2)

2.1.4.4 Significant discussions on a potential CAEP/6 production cut-off requirement have taken 

place since SG2009 in order to harmonise the approach on a global basis. The agreed guidance on the 

process and evaluation criteria for applications associated with NOx production cut-off exemptions has 

been prepared for the ETM. 

Validation of emissions sampling rakes (Chapter 2)

2.1.4.5 ETM guidance has been agreed clarifying the Annex 16, Volume II provision that ―the 

applicant shall provide evidence to the certificating authority, by means of a detailed traverse, that the 

proposed probe design and position does provide a representative sample for each prescribed power 

setting‖ requirement.

Status of supersonic engine emissions requirements (Chapter3)

2.1.4.6 WG3 has clarified their current position on this issue, which had previously been 

presented to CAEP/7, via the inclusion of text within the ETM.

Smoke emission evaluation (Appendix 2)

2.1.4.7 ETM guidance has been agreed specifically referring to the use of a specific filter as best 

practice.

Instrumentation and measurement techniques for gaseous emissions 

(Appendix 3)

2.1.4.8 ETM guidance has been agreed for Annex 16, Volume II, Appendix 3 on instrumentation 

and measurement techniques for gaseous emissions. This work included the need to clarify the post 

processing of measured emissions data taken during a certification test. In coordination with SAE E-31, 

the group has also begun to develop guidance associated with the Attachments to Annex 16, Volume II, 

Appendix 3 which contain the specifications for all gaseous emissions analysers.
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Report on Agenda Item 2 2-5

Outstanding issues for CAEP/9

2.1.4.9 Several ongoing issues that have not been completed are expected to be carried over into 

the CAEP/9 work programme. These include evaluation of Optical Smoke Meters (OSM) for use in 

certification tests, and development of further guidance on Annex 16, Volume II, Appendix 3 

Attachments.

Discussion and Conclusions

2.1.4.10 The meeting noted the group’s efforts in completing the ETM Volume II. Recalling past 

discussions at CAEP/7 where it was agreed to delay publication of the emissions ETM in anticipation of a 

revised version of Volume I of the ETM, it was agreed that, assuming finalization of the noise ETM in 

Agenda Item 4, both volumes of the ETM can be recommended for publication now. The proposed 

emissions ETM is attached as Appendix B to report on this agenda item.

2.1.4.11 A member pointed out that even within ―spare‖ and ―new‖ engine categories, there may 

be some overlap on the definitions which may lead to double-counting. The WG3 representative 

explained that these categories have been defined rigorously in the ETM and no such issues are foreseen.

The difference in ―spare‖ and ―new‖ is based on whether they increase the number of engines in operation 

or not. The intent of spare engines is not to increase the number of engines in operation.

2.1.4.12 Another member inquired into an effective cap per engine type (around 75) for exempted 

engines as described in the proposed text. The WG3 representative answered that this explains normal 

practice and is not a ―hard‖ cap. He explained that it is the same case for the time limit of 4 years for new 

engines after the implementation date of production cut-off. Overall it is a guidance document and as such 

is provided to States for their use at their discretion. The cap and time limit does not impact the engines 

produced to maintain in-service fleets.

2.1.4.13 The Secretary noted that the exact title of the Environmental Technical Manual and its 

two volumes will need to take into account harmonization with other ICAO publications and editorial 

practice. The meeting requested the Secretariat to finalize the exact title during the publication process.

2.1.5 Recommendation

2.1.5.1 In light of the foregoing discussions the meeting developed the following 

recommendation:

Recommendation 2/1 — Publication of Environmental 

Technical Manual, Volume II

That the Environmental Technical Manual, Volume II, contained 

in Appendix B to the report on this agenda item, be published as 

soon as possible.

2.2 CONSIDERATION OF CAEP/6 NOX PRODUCTION 

CUT-OFF

2.2.1 Based on a decision by CAEP/7 and at WG3’s request FESG conducted an economic 

assessment of introducing a production cut-off date for the engines to which the NOx Standards developed 

at CAEP/6 applied. The FESG analysis estimated the non-recurring costs of making affected engines 
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2-6 Report on Agenda Item 2

compliant with a production cut-off to the CAEP/6 NOx Standard. This effect was estimated to be 

approximately US$100 million in 2008 US dollars. In the event that the decision is made to bring the 

affected engines into compliance, recurring costs would arise. A broad analysis of recurring costs, based 

on the analysis of the NOx stringency options performed for CAEP/6 suggests that these may be higher by 

factors of between 4 and 9, depending on whether loss of resale value is included. In the case where 

airlines would not be able to acquire additional engines for spares, these costs could be significant, with 

serious implications for the continued operation and resale value of the affected aircraft. In these 

circumstances a 9 fold factor giving an overall cost of US$ 900 million provides a minimum estimate of 

these costs. At the same time, the environmental benefits will remain small. 

2.2.2 A member recalled that the CAEP/2 emission Standards incorporated a later production 

cut-off to ensure that appropriate emission control technologies were incorporated into all new engine 

designs and in-production engines by a certain date. Subsequently, CAEP/4 and CAEP/6 NOx Standards 

were adopted without such a production cut-off. 

2.2.3 The member recalled that the Steering Group in Salvador stated that ―although there was 

no objection in principle from the [Steering Group] members for a CAEP/6 NOx Standards production 

cut-off, there were some outstanding issues. CAEP SG agreed to address appropriately the issues related 

to exemptions and timing for the earliest implementation to allow for recommending to the ICAO Council 

at CAEP/8 the adoption of such a cut-off.‖ Subsequently, the ETM Ad-hoc group within WG3 submitted 

an updated version of the ETM on the process and criteria for the exemptions to the NOx production 

cut-off requirements. The approval of these exemption provisions via revisions to Annex 16, Volume II 

and guidance material in the ETM Volume II is expected as a result of CAEP/8.

2.2.4 The member invited CAEP/8 to agree that a production cut-off for the CAEP/6 NOx

emission Standards and the associated exemption provisions developed in the revised ETM and Annex 

16, Volume II should be adopted, and then implemented on the earliest practical ICAO effective date. 

Ultimately, a CAEP/6 production cut-off provides certainty that non-compliant engines will eventually no 

longer be produced – but with the flexibility of exemptions allowing for time adjustments to lessen 

economic impacts. A production cut-off takes full advantage of the CAEP/6 NOx Standards 

environmental benefits, ensures no backsliding, and communicates to the public the aviation sector’s 

commitment to improving its environmental performance.

2.2.5 An observer presented a proposed method to show compliance with the CAEP/6 Standard 

before the imposition of production cut-off for NOx Standard. For the most recent production cut off in 

2000, certificating authorities accepted data and analysis that had been submitted and approved in 

accordance with previous amendments of ICAO Annex, 16 Volume II as evidence of compliance with the 

latest Standard. However, the criteria for demonstration of compliance should be more clearly described 

in Annex 16, Volume II.

2.2.6 In order to minimize administrative costs and avoid delays in demonstrating compliance 

with requirements for continued production, use of existing approved certification data and analysis 

should be allowed to demonstrate compliance with the CAEP/6 Standard, even if the data and analysis 

were obtained under a previous amendment of the procedures described in the Annex. Publication of 

explicit advice on the applicability of existing certification test data and analysis, either in the Annex or 

the ETM, would be helpful to manufacturers and certificating authorities. The observer proposed to add a 

paragraph to the ETM Volume II where guidance is provided to the relevant ICAO Annex 16 provisions.
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Report on Agenda Item 2 2-7

2.2.7 The meeting agreed to the addition of this proposed text to the section in ICAO 

Environmental Technical Manual (ETM), Volume II where guidance is provided to 2.1.1.1 of ICAO 

Annex 16. The agreed text is incorporated in Appendix B to the report under this agenda item.

2.2.8 In another presentation, the same observer proposed that in order to allow sufficient time 

for member States that issue type certificates for aviation to fully adopt the CAEP/6 Production Cut-off 

Standards, and for manufacturers to demonstrate compliance, where necessary, the implementation date 

should be set for 31 December 2012.

2.2.9 Discussion and Conclusions

2.2.9.1 One member expressed his concern with a potential CAEP/6 production cut-off when, in 

his view, FESG had identified that market forces had already responded to the Standard with very few 

exceptions and that it was not cost effective. Effective exemption provisions for in-service aircraft are 

also necessary to ensure that low-volume high-cost markets, especially in remote areas, are not impacted. 

He also expressed the hope that acceptance of this proposal does not introduce a trend towards 

conservatism in the development of future Standards.

2.2.9.2 Several members pointed out that this production cut-off should be understood as only 

applying to CAEP/6 Standard and not for any future Standards. The meeting agreed that any future 

proposal for production cut-offs would need to be considered on a case-by-case basis.

2.2.9.3 There was general support for the production cut-off proposal and also the applicability 

date of 31 December 2012. In light of this general support, the meeting recommended that a production 

cut-off for CAEP/6 NOx Standards be applied by 31 December 2012 and the associated exemption 

provisions developed in the revised ETM and Annex 16, Volume II be updated.

2.2.9.4 The meeting recommended that the provisions for a production cut-off based on CAEP/6 

NOx Standard be incorporated as part of the Annex 16, Volume II amendments as indicated in Appendix 

A to the report on this agenda item.

2.3 CONSIDERATION OF NEW NOX STRINGENCY 

OPTIONS

2.3.1 The FESG and MODTF Co-Rapporteurs presented an overview of the assessment of the 

environmental benefits and economic costs of stringency scenarios to reduce emissions of nitrogen oxides 

(NOx) relative to the ICAO CAEP/6 Standard. They briefly discussed the models, databases, methods and 

assumptions used by MODTF and FESG to conduct the environmental benefit and economic cost 

assessments. 

2.3.2 As part of the NOx stringency assessment framework, WG3 provided 10 scenarios for 

modelling, as shown in the following Table 1.
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2-8 Report on Agenda Item 2

Table 1. NOx Stringency Scenarios

NOx Stringency

Scenario

Small Engines Large Engines

[26.7 kN / 89 kN Foo]1,2 OPR3>30 Slope4

1 -5% / -5% -5% 2

2 -10% / -10% -10% 2.2

3 -10% / -10% -10% 2

4 -5% / -15% -15% 2.2

5 -15% / -15% -15% 2.2

6 -5% / -15% -15% 2

7 -15% / -15% -15% 2

8 -10% / -20% -20% 2.2

9 -15% / -20% -20% 2.2

10 -20% / -20% -20% 2.2

2.3.3 The 10 stringency scenarios were analyzed for each of 3 future years, 2016, 2026 and 

2036. The assessment framework also called for two stringency introduction dates, 31 December 2012 

and 31 December 2016.

2.3.4 The emissions reduction results from the MODTF assessment and the FESG assessment 

of the cost impact were presented, as follows, along with a discussion on environmental trade-offs.

Table 2 - Cost Results

NOx Stringency

Scenarios

Low Cost Estimate ($M)

3% discount, 2016, LRV5

High Cost Estimate ($M)

3% discount, 2016, LRV

1 - 5 $ 1,922 $ 2,500

6 - 7 $ 6,412 $ 9,470

8 - 10 $ 10,878 $ 21,507

2.3.5 Finally the cost-effectiveness results were presented as costs per tonne of NOx reduction 

during the ICAO Landing Take Off (LTO) cycle, including the ranking of the stringency scenarios.

 

1

 Foo – Thrust rating. For engine emissions purposes, the maximum power/thrust available for takeoff under normal operating 

conditions at ISA (International Standard Atmosphere) sea level static conditions without the use of water injection as 

approved by the certificating authority. Thrust is expressed in kilonewtons (kN).

2

 Incremental stringency options defined for small engines with thrust ratings (Foo) comprised between 26.7 kN and 89 kN.

3

 OPR – Overall Engine Pressure Ratio. The engine pressure ratio is defined as the ratio of the mean total pressure at the last 

compressor discharge plane of the compressor to the mean total pressure at the compressor entry plane, when the engine is 

developing its takeoff thrust rating (in ISA sea-level static conditions).

4

 Slope of the line of the NOx stringency options at engine pressure ratio (PR) greater than 30.

5

 LRV – Loss in Resale Value.
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Table 3 – Cost-Effectiveness Ranking, Large Engines

Ranking Stringency Reference NOx Reduction % / Slope of Dp/Foo

1 NS01, NS02, NS03, NS04, NS05 -5% / 2.0, -10% / 2.2, -10% / 2.0, -15% / 2.2

2 NS06, NS07 -15% / 2.0

3 NS08, NS09, NS10 -20% / 2.2

Table 4 – Cost-Effectiveness Ranking, Small Engines

Ranking Stringency Reference NOx Reduction %

1 NS01, NS04, NS06 -5% / -5%, -5% / -15%

2 NS08 -10% / -20%

3 NS02, NS03 -10% / -10%

4 NS10 -20% / -20%

5 NS09 -15% / -20%

6 NS05, NS07 -15% / -15%

2.3.6 Cost Results

2.3.6.1 Costs were estimated for each stringency scenario for the two implementation dates for 

small and large engine categories separately, with a range of values for a number of key assumptions, 

including non-recurring costs, fuel burn penalty, fuel price, loss of resale value (LRV) and a variety of 

discount rates. As summarized in Table 2, total costs for small and large engines combined are broadly 

similar for stringency scenarios 1 through 5, but for scenarios 6 through 10 costs increase steeply, driven 

by non-recurring costs for engines driven by need of a major technology response. While efforts were 

made to comprehensively quantify all costs, some costs were not included. For example, increased 

industry operational costs in scenarios involving higher fuel burn were partially itemized to include fuel 

costs and costs associated with loss in payload for payload limited flights.

2.3.7 Environmental Trade-offs

2.3.7.1 An important part of the NOx stringency assessment is the consideration of environmental 

trade-offs between the various NOx stringency scenarios, fuel burn, and noise. WG3 recommended a fuel 

burn penalty range of between 0% and 0.5% for engine families requiring a major (MS3) modification. 

MODTF included the maximum of 0.5% penalty in its modelling and calculations. Figures 8 and 9 

provide the maximum potential fuel burn penalty for the full-flight case, presented in terms of total fuel 

and percent, respectively. These are MODTF consensus results calculated with AEDT and confirmed by 

other CAEP approved models. In accordance with WG3 recommendations for the stringency scenarios 

assessed, the MS3 fuel burn penalty only applies to large engines and only for some engines in scenarios 

6 through 10. The maximum potential annual fuel burn penalty ranges from about 28,000 metric tonnes to 

1.1 Mt (1.1 x 106 metric tonnes), or from 0.01% to 0.19% relative to the baseline no stringency case. This 

translated into additional annual CO2 emissions of between 88,000 metric tonnes and 3.5 Mt. In 

accordance with WG3 recommendations the minimum fuel burn penalty is zero.

2.3.7.2 WG1 recommended a noise penalty range of between 0 decibel (dB) and 0.5 dB per 

certification point for 10% of engines requiring a major (MS3) modification, i.e. 10% of all engines. As 

with fuel burn, the MS3 noise penalty only applies to large engines and only for scenarios 6 through 10. 
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The effect of the MS3 noise penalty on the 55, 60 and 65 DNL6contour area expressed as a percentage 

change was in the worst case less than 0.12%. Based on these findings, MODTF concluded that the 

analysis indicates there is no noise trade-off associated with any of the CAEP/8 NOx stringency 

scenarios. This conclusion has been verified at the global, regional and airport levels.

2.3.8 Cost-effectiveness Results

2.3.8.1 The cost-effectiveness results are dominated by large engines, which account for 

approximately 99% of the benefits. Scenarios 1 through 5 are the most cost effective, all providing 

relatively low cost per tonne of NOx reduced. For scenarios 6 and 7, cost per tonne of NOx reduced 

increased by a factor of 3 to 4, using a 3% discount rate. Scenarios 8, 9 and 10 result in a further doubling 

of cost per tonne of NOx reduced. Cost-effectiveness rankings for large and small engines are shown in 

Tables 3 and 4, respectively. Although the analysis concentrates on NOx reduction up to 3,000 ft, 

stringencies also have an effect on climb/cruise NOx emissions. If these were taken into account, the total 

reduction achieved would increase by an approximate factor of 7 to 8, and the costs per tonne would 

diminish accordingly.

2.3.8.2 The early implementation date of 2012 gives overall lower values for the costs per tonne 

of NOx reduced. This is enabled by an extra four years of NOx reduction compared to 2016 

implementation, coupled with roughly the same costs for both implementation dates. This implies that an 

early implementation year would be more cost effective. However, in the approach used, it is assumed 

that the non-recurring costs for the technology responses start four years in advance of implementation 

(from 2009). This may mean that in practice a somewhat later date than 2012 is more obvious, 

particularly for those scenarios involving MS3 modifications. The CAEP/6 decision made in 2004 with an 

implementation date of 2008 would be consistent with a CAEP/8 implementation date of 2014.

2.3.8.3 One member presented a proposal for NOx stringency basing it on the analysis carried out 

by FESG and MODTF. The member stated that in order to make greater progress in reducing aviation’s 

contribution to air pollution and to move meaningfully towards the long term technology goals, CAEP 

should consider adopting the most stringent NOx Standard at CAEP/8, consistent with its principles for 

Standard-setting. The member’s recommendations were based on analysis done within their State by 

using outputs from the APMT economics and impacts models. Based upon the FESG analysis and its own 

qualitative analysis of costs and benefits as provided to the meeting using APMT, the need for continuous

air quality improvements, continued technology research and development evidenced during NOx

emissions reduction technology reviews for goal-setting, conservative estimates of additional 

environmental impacts that are still being matured, and additional information being provided on 

cost/benefit, the NOx stringency scenario 6 for large and small engines (-15% and slope 2.0 for large 

engines and -5% / -15% for small engines) with a December 31, 2012 implementation date should be 

considered for adoption at CAEP/8. Alternatively, stemming solely from FESG’s cost effectiveness 

results and the continued need for air quality improvements, at least the NOx stringency scenario 4 for 

large and small engines (-15% and slope of 2.2 for large engines and -5% / -15% for small engines) with a 

31 December 2012 implementation date should be considered for adoption.

2.3.8.4 Elaborating on the proposal, the member proposed that a slope of 2.0 be maintained for 

further stringency in recognition of likely future combustor technology development to meet mid- and 

long-term CAEP NOx emissions reduction technology goals, and to foster engine and combustor 

technology development that considers the balance between fuel efficiency improvements and NOx

 

6

 DNL – Day-Night Noise Level.
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emissions reduction particularly for engines with pressure ratios greater than 35 to 40. Changing the slope 

to 2.2 would be an unnecessary relaxation of the slope that could potentially compromise this balance.

2.3.8.5 In summary, the proposal was for CAEP/8 to agree that NOx stringency scenario 6 (-15% 

and slope of 2 for large engines and -5% / -15% for small engines) should be adopted, based on the 

discussion above and the need for air quality improvements including knowledge related to airport-local 

effects, cruise emissions influence on air quality, and future background concentration changes, as well as 

detailed APMT impacts calculations for cost/benefit. However, if CAEP/8 wishes, at least the NOx

stringency scenario 4 (-15% and slope of 2.2 for large engines and -5% / -15% for small engines) should 

be adopted, based on the need for air quality improvement and FESG’s cost effectiveness results. 

Furthermore, it was proposed that the implementation date of 31 December 2012 should be adopted at 

CAEP/8 for both large and small engines applicability, regardless of stringency scenario.

2.3.8.6 A member introduced some data on recent analysis done on aviation emissions inventory 

in her country. The member further pointed out that analysis performed in her State showed that NOx

stringency scenario 1 through 7 have a similar impact on manufacturers, engine types, and engine orders. 

The NOx stringency scenarios 8, 9, and 10 (-20% and slope 2.2 for large engines) impact many more 

engine types and orders compared to the other scenarios. The meeting noted the information shared by the 

member.

2.3.8.7 Two observers presented their position that, upon review of the data and analyses 

produced in the CAEP/8 process, adoption of new NOx certification Standards (colloquially referred to as 

―stringency‖ Standards) for both large and small engines is warranted under the CAEP Terms of 

Reference. They stated that of the NOx stringency scenarios analyzed by CAEP for large engines, the data 

and analyses best support adoption of FESG Scenario 2, a 10% increased stringency with a slope of 2.2. 

Scenario 4 (15% stringency increase at slope 2.2) would be less cost effective because it would require 

more extensive technology response and thus pose the risk that manufacturers would be unable to 

accomplish that development in time to meet any future production cut-off date. They noted that FESG 

and MODTF did not consider an intermediate scenario between a 10% and 15% stringency increase. As a 

result, there are no detailed analyses to support selecting such an intermediate stringency. Nevertheless, 

an intermediate stringency increase at slope 2.2 could potentially be the appropriate increase based on the 

CAEP Terms of Reference. The observers believed that the FESG data support adoption of a 5% 

increased stringency for small engines at the low end of the thrust range (26.7kN). Assuming that the 

selected stringency is Scenario 2, 10% at 2.2 slope (or in any event less than 15% with slope of 2.2), the 

analysis favours an effective date of year-end 2012, but in practice, this date might not provide enough 

time to respond to the new requirements. They proposed that a slightly later implementation date of yearend 2013 should be considered with a new Standard for large engines at -12% with a slope of 2.2 and for 

small engines at 5% (at 26.7 kN thrust).

2.3.8.8 Another observer highlighted the need for a new NOx stringency. He expressed support 

for the NOx Stringency Scenario NS7, (-15%/-15%, -15%/Slope 2.0) with an implementation date of 31 

December 2012. Explaining his reasoning, he stated that Scenarios NS8-10 (2012 implementation) are 

calculated to provide a 9.7% reduction in NOx below 3000 ft. For these options, however, the potential 

cost for manufacturers wishing to modify their in-production engine families could be significant. 

Scenarios NS6 and NS7 are predicted to provide more modest reductions of 7.3% in NOx (in 2036) with 

considerably less cost for engine modifications. Scenarios NS1 to NS3, with engine NOx reductions of 

only 5-10%, will provide less environmental benefit (<6% total NOx reduction in 2036), albeit for less 

cost than other scenarios.
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2.3.8.9 It was observed that new technology engines are typically at least 15% below CAEP/6 

Standards, and that ICAO Standards should strive to reflect the achievements of the best technology. 

Scenarios NS4 and NS5 (with the steeper slope of 2.2 for OPR>30) include engine NOx improvements of 

up to 15%, but provide less ambitious Standards for very large engines (i.e., the very engines responsible 

for the most NOx emissions). When comparing NS6 and NS7, the only distinction is the Standards for the 

Small Engine families (26.7<Foo<89 kN and OPR<30 – typically regional and business jets 99 seats or 

less), with reductions of -5% and -15%, respectively. The observer preferred NS7 because it treats small 

and large engine manufacturers more equitably and yields additional benefits of 300 t of NOx reduction 

per annum in 2036. It was further noted that the emissions from Large Engines dominate those of Small 

Engine families. Thus the overall reductions calculated for NS6 and NS7 are virtually identical. However, 

at many smaller airports the Large Engine families do not dominate aircraft NOx emissions inventories; 

therefore these airports will not see the benefit of Large Engine family NOx reduction. While on a global 

scale, the difference between NS6 and NS7 is very small, at a local level for smaller airports, the NS7 

improvement in the NOx performance of smaller aircraft will be very important.

2.3.8.10 The observer supported an implementation date of 31 December 2012. He stated that the 

Panel of Independent Experts had noted the compelling need for action. The economic analysis shows a 

modest additional cost for engine modifications whereas the earlier engine modifications will result in a 

NOx saving of 8.5 kt per year.

2.3.9 Discussion and Conclusions

2.3.9.1 The meeting congratulated the FESG and MODTF and all their participants for putting 

together this detailed package. There was general appreciation for the amount of work that was put in this 

analysis not just by FESG and MODTF but also by groups within CAEP such as WG3 and from outside 

CAEP from the modelling communities.

2.3.9.2 The environmental trade-offs were done in terms of emissions inventories. Some 

members hoped that analysis in terms of impacts on passenger demand could be part of the future work. 

Some members expressed that there was a need to account for costs that might be potentially transferred 

to airlines and passengers which is currently not a part of the analytical procedure. The FESG CoRapporteurs clarified that CAEP had requested only a cost impact analysis to the industry and not to the 

passengers and public in general. The Chair agreed with this position that the mandate given to the FESG 

and MODTF was from this committee and if there is identified a need to expand the analysis to impacts 

(cost to passengers or in terms of impacts), it should be made part of future work.

2.3.9.3 A member highlighted the trade-offs between aviation growth and its environmental 

responsibility. A member queried whether CIS built aircraft were part of the analysis and the Chair 

indicated that no CIS built aircraft were included due to lack of data.

2.3.9.4 A member queried that whether the impact on developing countries was a part of the 

study. The FESG co-rapporteur clarified that the analysis was done by engine families and not for how 

the engines were operated in different regions of the world. The member further remarked that current 

economic crisis might add more complications to the analysis.

2.3.9.5 Another member emphasized the relevance of the current economic crisis and the passing 

of any industry costs to the passengers. The FESG and MODTF accomplished the task they were given 

but now the need to study this aspect has increased. Therefore, this issue needs to be made a part of future 
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assessments. He suggested that a decision made now could be revisited if additional analysis was done 

that showed adverse economic impact.

2.3.9.6 Another member, taking this point further, stated that the current economic crisis may 

necessitate that the implementation date should be end 2016.

2.3.9.7 The Chair clarified that revisiting a decision on stringency Standards is neither practical 

nor possible. The Chair stressed that such an approach would not be procedural. Once a Standard has 

been agreed, it goes through a number of steps for formal global approval. Therefore, once a decision is 

reached by CAEP, it is not feasible to change it during the subsequent steps.

2.3.9.8 A member mentioned that their modelling capabilities do allow calculating consumer 

impact. Such an analysis, although it cannot be formally introduced in this CAEP meeting, was done and 

did not show a significant impact on consumers or the overall economy.

2.3.9.9 Regarding the issue of the impact on passengers, a member clarified that FESG did 

address the impact on demand which is directly related to consumer impact, and the conclusion was that 

the effect was minimal. Although this aspect was not the focus of extensive analysis, it was addressed.

2.3.9.10 A member expressed concern on basing a new Standard on MS3 technology and that 

such action may not allow time for market forces to adjust in an effective way.

2.3.9.11 A member pointed out that this is a certification Standard and therefore any engines 

complying with this Standard will not go into service until at least 2017 or later. Thus, any consumer 

impact would be smoothed out and should be minimal. Another member highlighted the 

interdependencies within the environmental parameters and between environmental and economic issues 

and that they should be incorporated in any future analyses. The meeting agreed that all interdependencies 

should be taken into account in future analysis.

2.3.9.12 An observer asked whether the sales volume of current aircraft/engines was taken into 

account for future fleets. The MODTF rapporteur clarified that future fleet composition was driven by 

assumption of equal manufacturer split. The same observer commented that the emissions benefit of 

current engines which perform much better than any future Standards are not being taken into account 

adequately. Another observer commented that if environmental benefit of such engines is taken into 

account then the cost of such engines would also have to be accounted for.

2.3.9.13 An observer clarified that he was proposing a slope of 2 above OPR45 because of the fact 

that increasing slope to 2.2 may result in worse than the CAEP/6 Standard at higher OPRs, which is not 

the intent.

2.3.9.14 During discussions on the level of a new NOx stringency, some members and observers 

preferred NS6 or NS7, whereas other members and observers considered NS2-NS4 more appropriate.

2.3.9.15 An observer speaking on behalf of a group of countries stated that they preferred NS7 

scenario which differs from NS6 mainly in application to small engines. The reason for the preference 

was stated to be that small engines have not had any stringency increase over the last few years. It was 

further proposed that an implementation date of end of 2013 be adopted. The observer recommended to 

the meeting that CAEP not consider any production cut-off based on this Standard before 2016 and any 

potential cut-off should not be implemented before 2018. Several members supported this position.
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2.3.9.16 An observer stated that cost effectiveness should be the criterion for making any 

stringency decision. His preference was for NS7 with an implementation date of end 2012.

2.3.9.17 Regarding the small engine issue, a member said that a decision should be driven by the 

availability of technology and not by how long the same Standards have been in place. Also looking at the 

study data on large engines, the NS4 scenario seems the best for a future Standard.

2.3.9.18 Two members, in the spirit of compromise, proposed adoption of NS5 with an 

implementation date of end 2012 or end 2013.

2.3.9.19 A member expressed his preference for NS6 with an implementation date of end 2013 in 

order to give industry time to adapt to the change.

2.3.9.20 After extensive discussions among the CAEP members, the Chair was pleased to inform 

the CAEP plenary that a consensus was reached about the question of which new NOx stringency level 

should be applicable to aircraft engines in the future. After a thorough discussion of the options, members 

converged to the adoption of a new Standard based upon option 6 (i.e. NS6).

2.3.9.21 Although some members were of the view that a less stringent Standard according to 

option 4 would be more appropriate to adopt, after further discussions during which there was consensus 

that any new stringency evaluation in the future should be undertaken by carrying out a more thorough 

assessment of economic impacts especially on airlines and passengers and that there will be no production 

cut-off considered based upon a CAEP/8 stringency Standard before 2018, a consensus on option 6 was 

reached.

2.3.9.22 The meeting came to the following decision:

a) Adoption of a new CAEP/8 stringency according to option 6, which means reduction 

of small engines -5% and -15% with respect to the CAEP/6 Standard, and for large

engines, reduction of -15% with respect to the same Standard with the slope of 2.

b) This stringency should be implemented by 31 December 2013, and it should be 

clearly noted that no production cut-off before year end 2018 will be taken into 

consideration or should be applied before this date.

2.3.9.23 An observer pointed out that some in-production engines, although not required to 

comply with this Standard, requiring MS3 changes may not be able to comply with this Standard by 2013.

Another observer sought clarification on the consideration or application of future production cut-off 

before year end 2018. The Chair clarified that there should be no implementation of a production cut-off 

before year end 2018.

2.3.9.24 The meeting recommended that the provisions for a CAEP/8 NOx Standard as outlined in 

2.3.9.22a) be incorporated as part of the Annex 16, Volume II amendments as indicated in Appendix A to 

the report on this agenda item.
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2.3.10 Recommendation

2.3.10.1 In light of the foregoing discussions, as well as the prior discussions on amendments to 

Annex 16, Volume II and NOx production cut-off, the meeting developed the following recommendation:

RSPP Recommendation 2/2 — Amendments to Annex 16, Volume 

II – Aircraft Engine Emissions

That Annex 16, Volume II be amended as indicated in 

Appendix A to the report on this agenda item.

2.4 STATUS OF PARTICULATE MATTER SCIENCE AND

STANDARDS

2.4.1 A member reported that Particulate Matter (PM) related to aircraft engine exhaust can be 

divided into two broad categories: non-volatile PM and volatile PM. The science is more advanced on 

non-volatile PM and it is certain that reducing non-volatile PM from aircraft engines will reduce health 

impacts due to aircraft emissions and will also help to mitigate aviation climate impacts.

2.4.2 Recently, the U.S. Federal Aviation Administration (FAA), U.S. Environmental 

Protection Agency (EPA), and European Aviation Safety Agency (EASA) have agreed to pursue the 

definition of a non-volatile PM emissions certification requirement. However, it is to be noted that EPA 

plans to continue investigating volatile PM emissions.

2.4.3 In March 2009, the SAE-International E-31 committee published the Aerospace 

Information Report (AIR) 6037 on measurement methods for non-volatile PM emissions from aircraft 

engines. The FAA, EPA, and EASA have requested that final Aerospace Recommended Practices (ARP) 

that focuses on metrics and the quantification of non-volatile PM mass and number as metrics be 

published by the end of 2011. Outstanding research to address technical questions would have therefore to 

be completed in the latter part of 2010. Among the most pressing research is the need for reference 

instrument calibration Standards, as well as a robust sampling and measurement methodology.

2.4.4 The development of the ARP by the SAE E-31 committee is a critical task that still needs 

to be accomplished before proceeding to developing the non-volatile PM emissions certification 

requirement. The timing of the work on a PM emissions certification requirement by WG3 will therefore 

occur late in the three year CAEP/9 cycle, although ongoing dialogue and coordination should continue to 

occur between participants of the SAE E-31 committee and CAEP.

2.4.5 The CAEP Air Quality Research Focal Points and WG3 Science Focal Points reported on 

two important areas of interest, viz., the latest understanding of aviation PM impacts on both ambient air 

quality and climate change, and the assessment of the availability of necessary data elements required for 

environmental impact studies of such effects. An update on policy-relevant scientific results related to 

these two areas was also provided.
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2.4.6 Discussion and Conclusions

2.4.6.1 A member noted the importance of research on PM issues and suggested that it be made 

part of the future work. Several CAEP members and observers expressed support for this task.

2.4.6.2 The meeting agreed on considering this item as part of future work, focusing on nonvolatile PM for now, with certification requirement targeted by CAEP/9 and a certification Standard to be 

established by CAEP/10. It was also noted that aspects of this work should be addressed in the Impacts 

Experts Group (discussed in section 1.3.13). The Chair noted that further discussions on prioritization 

may be held under the future work agenda item.

2.5 AIRCRAFT CO2 EMISSIONS

2.5.1 Fuel Efficiency Metrics

2.5.1.1 During discussions on assessment of ICAO environmental goals, air traffic operational 

goals, and aircraft and engine technology goals, the question of metrics has been extensively debated. An 

ad hoc group was formed to address the task of defining simple metrics that can be applied to global 

commercial aviation activity, noting that one single metric might not be appropriate for the three different 

proposed uses.

2.5.1.2 For application to the CAEP/8 trends assessment of the ICAO environmental goals task, a 

metric named the Commercial Air System Fuel Efficiency (CASFE) metric was developed. The CASFE 

metric takes the familiar form of fuel consumed divided by sum of (payload x distance). However, it is 

important that the metric is not separated from its data sources, applicability and caveats.

2.5.1.3 While the CASFE metric is considered suitable for application to the CAEP/8 

Environmental Goals trends analysis, further work on improvement of payload data and on further 

validation of the CASFE metric against actual airline data was suggested. It was also stated this metric is 

suitable for kerosene-like fuels only keeping in mind that this does not take into account life-cycle CO2

costs of any potential alternative fuels.

2.5.1.4 Work on the air traffic operational goals and fuel burn reduction technology goals has not 

been completed within this CAEP cycle. As a result, fuel efficiency metrics applicable to these types of 

goals cannot be developed yet. However, for the air traffic operational goal input to CAEP/8, application 

of the CASFE metric was offered as an interim measure with the same caveats and issues as for the 

application of CASFE to the ICAO Environmental Goals trends assessment. Beyond CAEP/8, it was 

recommended that given the complex relationship between fuel efficiency and operational efficiency, 

consideration of a fuel efficiency metric applicable to future Operational Goals is not regarded as a 

separate task but is undertaken as part of the Goals process itself. This tasking should include the metric 

development and also the data and caveats to support it.

2.5.1.5 Similarly, it was recommended that the development of an appropriate fuel efficiency 

metric (and the data and caveats to support it) for application to the fuel burn reduction technology goals 

be included as part of the goals establishment process itself.

2.5.1.6 In addition to the three types of metrics mentioned above, the ad hoc group considered 

issues surrounding a metric accounting for alternative fuels as well as a fuel intensity metric that had been 
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Report on Agenda Item 2 2-17

introduced in GIACC. It was noted that the task of identifying appropriate applications, data sources, and 

associated clarifications would need to be made part of future work.

2.5.1.7 An observer highlighted that the future work programme for CAEP should include the 

evaluation of an alternative efficiency metric appropriate for business aviation operations based on 

maximum payload instead of revenue payload. He explained that business aviation’s main purposes are 

on demand and point to point transportation of people or goods and therefore the payload weight needs to 

be calculated differently.

2.5.2 Discussion and Conclusions

2.5.2.1 The meeting acknowledged the importance of selection of the right metric for a given 

use. It was highlighted that work should be continued with relevant bodies (e.g. CANSO) and 

independent experts panels and duplication of effort should be avoided. The meeting also noted the 

contribution of business aviation and its relatively small share of overall aviation emissions and that 

appropriate metrics should be used when calculating efficiencies.

2.5.2.2 The meeting agreed that development of fuel efficiency metrics should be continued 

within the ad-hoc group in coordination with relevant organizations and bodies. 

2.5.3 Recommendation

2.5.3.1 In light of the foregoing discussions the meeting developed the following 

recommendation:

Recommendation 2/3 — Fuel Efficiency and CO2 Emissions 

Metrics

That the CASFE metric be established as the metric for 

assessment of ICAO environmental goals for global civil aviation 

and that work be continued on defining other appropriate metrics 

for operational and technology goals and Standards.

2.5.4 Consideration of Aircraft CO2 Emissions Standard

2.5.4.1 As a result of a recommendation from GIACC/4 and the High-level Meeting, the ICAO 

Council decided to seek to develop a global CO2 Standard for new aircraft types consistent with CAEP 

recommendations. As a result, CAEP and its technical working groups were requested to carry out a 

scoping analysis to help inform discussions on a potential CO2 emission Standard at CAEP/8 and to help 

define a future work item within the CAEP/9 work programme.

2.5.4.2 The WG3 had performed a scoping analysis on a global CO2 Standard for aircraft. 

Several members and observers have made important contributions in this regard and presented additional 

material to CAEP/8. The presentations by WG3 and other members and observers outlined a number of 

significant policy and technical questions and issues which should be considered and assessed in 

developing an aircraft based CO2 emission Standard.
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2.5.4.3 The WG3 recommended that a potential Standard in this area be referred as a ―CO2

Standard‖ based on ―fuel efficiency‖ concepts within the certification requirement metric. In addition, the 

WG3 proposed the following definitions:

 Parameter – a measured or calculated quantity that describes a characteristic of an 

aircraft (e.g. Foo, MTOW, Optimum Cruise Speed)

 Metric – a certification unit consisting of one or more parameters (e.g. Dp/Foo)

 Procedures – specific certification procedures, including applicability requirements 

(e.g. Annex 16 Volume II, Chapter 2)

 Instrumentation and measurement methodology – technical measurement procedures 

(e.g. Annex 16 Volume II, Appendix 3)

 Certified level – approved for a specific product by a certification authority to 

demonstrate compliance with a regulatory level, as determined by the certification 

requirement

 Regulatory level – a limit which a certified level must meet (e.g. CAEP/6 NOx)

 Certification requirement – the combination of metric, procedures, instrumentation 

and measurement methodology, and compliance requirements

 Standard – combination of a certification requirement and a regulatory level

2.5.4.4 The WG3 identified high level objectives of the overall Standard setting exercise in order 

to assess future proposals and, as far as practicable, to identify an optimum way forward:

 Provide an additional incentive to improve aircraft fuel efficiency and thus global 

fleet fuel burn performance

 Measure fuel burn performance and relevant capabilities (e.g. range, size, speed) 

across different aircraft types

 Ensure it is technically robust (now and future) with an acceptable level of accuracy

 Represent key aircraft design characteristics and environmental performance with 

respect to individual design philosophies (e.g. 2 / 3 spool engines or regional jet / 

narrow body / wide body aircraft types)

 Equity across products and manufacturers

 Permit flexibility in aircraft design to comply with requirement

 Minimise counterproductive incentives

 Minimise adverse interdependencies
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 Base it on existing certified data

 Account for proprietary data protection concerns

 Not require an inappropriate level of resources on the part of National Airworthiness 

Authorities and ICCAIA to implement

 Be simple, transparent and easily understood by the general public

 Develop a standard as soon as reasonably practicable to ensure that ICAO maintains 

its leadership in addressing aviation emissions issues

2.5.4.5 The WG3 presented results of its scoping analysis for a Standard on Aircraft CO2

emissions. Based on this scoping analysis, the WG3 concluded the following with respect to developing 

an aircraft CO2 Standard:

 previous CAEP work related to this issue should be considered and, where 

appropriate re-examined, in order to benefit from past lessons learnt;

 consistent use of agreed terminology is essential in order to structure future 

discussions on this issue;

 proposals for an aircraft CO2 Standard should be assessed against the high level 

objectives;

 the initial scope of any future work should focus on the sub-sonic jet aircraft 

category, which represents approx. 95%+ of global fuel use from commercial 

aviation, in order to improve the potential of agreeing on a CO2 Standard during the 

CAEP/9 cycle;

 discussions on further focusing the scope of a Standard on a sub-category of the 

subsonic jet aircraft have identified two options for consideration in defining the 

future work item remit:

 A MTOW threshold of ≥ 50,000 kg (110,231 lb); 

 A MTOW threshold of ≥ 32,500 kg (71,650 lb) and a maximum passenger 

seating capacity of ≥ 20 (freighter aircraft above 32,500kg would be included). 

 the certification metric(s) is a critical aspect to any future CO2 Standard which 

should, as far as practicable, meet key criteria (e.g. reflect fuel efficiency of an 

aircraft at a design and operational level, include parameters which characterise 

aircraft output, equitable, accuracy, limit interdependencies and easily understood), 

although associated timescales may result in compromises;

 the certification procedure will need to incorporate relevant aircraft design and 

performance characteristics;
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 a kerosene-type fuel specification (e.g. Annex 16 Volume II Appendix 4) should be 

part of the certification requirement in order to remove any fuel burn performance 

variations resulting from variation in fuel properties;

 recognising that the SG2009 suggested that the initial focus should be on ―new 

aircraft types‖, and that they also agreed to defer further debate and discussions to 

WG3, the ad-hoc group concluded that all applicability options in terms of ―new 

aircraft types‖, ―new production aircraft‖ or ―in-service aircraft‖ should remain open 

for assessment at this point in time;

 in defining the applicability requirements, including the treatment of modified 

products, any associated standard and its effective date should be taken into account;

 the certification measurement methodology and required instrumentation is highly 

dependent on the discussions concerning the certification metric and procedure, and 

there may be a need to consult expert groups outside of CAEP;

 the current CAEP terms of reference and standard/goal setting approach may provide 

sufficient flexibility to be used to assess and agree on CO2 Standards. Any different 

perspective may need to be considered by CAEP while taking into account the 

broader implications;

 to the degree possible, work on assessing regulatory level options should be done in 

parallel to the development of the certification requirement;

 further work should consider the advantages and disadvantages of all available 

approaches to manufacturer compliance, including those mentioned above and in 

further detail in CAEP/8-IP/21, when applied specifically to the aviation sector;

 timescales to develop a CO2 Standard will be dependent on the priority placed on this 

issue and the provision of resources to take this work forward;

 establishing interim milestones with target completion dates will be necessary in 

order to manage the development of an aircraft CO2 Standard;

 prioritisation of this issue in the future work programme may lead to delays in other 

work items; and

 the resources required to implement the certification requirement will be highly 

dependent on how it is designed and the associated workload for regulatory 

authorities and manufacturers.

2.5.4.6 A member presented her position on two points related to CO2 Standard applicability, 

viz. a) to determine whether a CO2 Standard should be applied to ―new aircraft types‖, ―new production 

aircraft‖ and/or to ―in-service aircraft‖ and b) to determine an aircraft size and/or seating capacity above 

which a CO2 Standard should initially apply.

2.5.4.7 For the first point, the member stated a preference that the CO2 Standard should apply to 

new in-production aircraft and not only to new aircraft types and recommended that CAEP not rule out 

applicability to new in-production aircraft. While realizing that to achieve near-term reductions, actions 

would have to be taken to improve in-service aircraft, the member expected that the ongoing ICAO 
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process that follows the recommended programme of action from the GIACC and direction coming out of 

the High Level Meeting (HLM) should result in recommended additional actions that would address the 

CO2 emissions contribution from in-service aircraft. Depending on the outcome of this ongoing process 

the member would consider the need for recommendations to CAEP/9 for appropriate work to be carried 

out to address in-service aircraft as part of the CAEP/10 work program.

2.5.4.8 For the second point, the member recommended the 32.5 tonnes MTOW option be 

pursued because the 50 tonne MTOW option does not achieve the targeted level of global fuel burn 

coverage and there is an expectation for growth in global and regional future fuel burn that should not be 

ignored. The member also recommended that the maximum seating capacity threshold of at least 20 

passengers be dropped, for reasons of complexity and minimal environmental benefit. The member 

furthermore recommended that the CO2 Standard’s certification and reporting requirements should be 

applied to all commercial subsonic jet aircraft, including business jet aircraft, even though they may not 

be subject to any regulatory level when the CO2 Standard is initially implemented. This would ensure an 

orderly process in the future, when these aircrafts’ regulatory levels might be considered.

2.5.4.9 The member also expressed that in light of the criticality of this task, it is essential that 

the process be completed during the CAEP/9 cycle. She highlighted that this was feasible and in line with 

the need for ICAO leadership. She suggested a project plan which included four milestones before 

CAEP/9. Milestone 1, to be completed no later than May 2010, would be to agree on a Program 

Development Strategy. Milestone 2, to be completed prior to the 1st Steering Group Meeting would 

approve the Basic Program Construct including but not necessarily limited to areas such as Applicability, 

Scope, Certification Metric, and Fuel Specifications. Milestone 3, to be completed prior to the 2nd 

Steering Group Meeting, would conclude with a Basic Approach to Emission Standards, Stringency, and 

Timing. Elements for consideration would include the Regulatory Level and Form of the Standard, the 

Certification Procedure, the Timing of Initial and Subsequent Requirements, and Programmatic Structure 

Options and Flexibilities. Milestone 4, to be completed no later than October 2012, would analyse options 

identified earlier. This milestone would also include activities related to drafting of amendments to Annex 

16 and the Environmental Technical Manual as required. The expectation would be that after these 

milestones and activities are complete and timelines are met, CAEP would have all the information 

needed to act on a CO2 emission Standard during the CAEP/9 meeting in 2013.

2.5.4.10 The member recommended that the CAEP technical emissions working group (WG3) be 

assigned this task and be directed to establish a stand-alone task group (the ―CO2 Standards Task Group”) 

with dedicated and empowered task group co-leaders (to ensure for contingencies) to lead the task to 

develop the CO2 emission Standard. These task group co-leaders should come from a member state 

government or regulatory agency and the member volunteered an expert from its environmental 

protection agency to take one of the co-leader positions.

2.5.4.11 An observer recalled that WG3, in its scoping paper on a CO2 Standard for new aircraft, 

identified three options for applying that Standard: to new aircraft ―types‖ (designs) only; to all newly 

delivered aircraft; or to all new and in-service aircraft. Recent analysis done by the observer organization 

on historical trends in new aircraft efficiency suggests decreasing gains in average new aircraft due to a 

lack of new aircraft designs. A CO2 Standard covering new aircraft types only is an inferior means of 

reducing emissions. Such a Standard could actually increase emissions by providing manufacturers with a 

disincentive to introduce new aircraft designs. Given pressing resource and time constraints faced in 

expeditiously developing a Standard, the observer invited CAEP to recommend that a CO2 Standard be 

developed for application to all newly delivered aircraft.
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2.5.4.12 An observer noted that this approach suggested a technology-forcing perspective in 

CAEP and reminded the meeting that the CAEP principles are technical feasibility, economic 

reasonableness, and environmental benefit, and that technology-forcing is not one of the principles of 

CAEP.

2.5.4.13 With regard to the two potential applicability thresholds: 32.5 tonnes maximum takeoff 

weight (MTOW) with a maximum seating capacity of at least 20 passengers, and 50 tonnes MTOW 

without an associated seating capacity, the observer summarized an analysis of the global fuel burn 

coverage of these two options for newly delivered aircraft. It was estimated that the 32.5 tonne MTOW 

threshold would cover approximately 96% of the fuel burn of new aircraft in 2008, while a 50 tonne 

threshold would cover between 88 and 90% of fuel burn depending on how regional jet manufacturers 

market model variants falling on either side of the threshold. Given the general desire to cover 95+% of 

global fuel burn, to maintain forward momentum in developing a Standard, and in the interest of 

developing a robust Standard resistant to gaming, the observer recommended that CAEP provisionally 

accept the 32.5 tonne MTOW threshold as the basis of ongoing work, subject to final confirmation at the 

CAEP/9 meeting. He further recommended that regional and business jets below the threshold continue to 

be included in CAEP’s work to develop a certification requirement even if they are not subject to an 

associated regulatory level when the CO2 Standard is initially implemented.

2.5.4.14 An observer stated that a more inclusive approach to evaluate a metric and certification 

scheme for all subsonic jet aircraft is more likely to avoid future market distortion. It was therefore 

recommended that the scope of CO2 Standard work during the CAEP/9 cycle include initial evaluation of 

a more inclusive approach in parallel with the consideration of the MTOW threshold. Final 

recommendations on applicability could be made in a Steering Group meeting early in the CAEP/9 cycle. 

Such an approach would ensure due consideration is given to all categories of subsonic jet aircraft and 

will minimize unintended consequences. The observer believed that leaving the threshold open now will 

not delay the agreeing of a metric for CO2 Standard related work in this coming CAEP cycle. He also 

expressed his commitment to devote the appropriate resources and to complete the necessary work to 

deliver the material that CAEP needs during the CAEP/9 cycle, even given the above recommendation to 

keep the applicability threshold open at this time. It should be further noted that limitations on the 

applicability of a new CO2 Standard at any point should not be construed to limit the scope of the analysis 

nor participation in relevant work.

2.5.4.15 An observer, speaking on behalf of a group of States stressed that work on a CO2

Standard should be given top priority in the CAEP/9 work programme. The three essential elements of 

such an effort are that the Standard be timely, well structured and effective. To ensure a successful 

outcome within this timeframe, it was proposed that the work be taken forward in a number of stages, 

with time built in for evaluation, and that the technical group be given responsibility for agreeing to the 

timetable for the work. It was also proposed that, for CAEP/9, the certification requirement should apply 

to larger new aircraft types greater than 50 tonnes. The CAEP was also invited to commit the resources, 

during the CAEP/10 cycle, for the work to set a regulatory Standard for new aircraft types and to extend 

the applicability to smaller and ―in-production‖ aircraft. Undertaking the above tasks in parallel, with 

sufficient resources and commitment, it should be possible for a draft certification requirement to be

considered at the CAEP/9 meeting in February 2013. It is anticipated that the applicability of such a 

requirement would initially be new aircraft types after 31 December 2015. There would initially be no 

associated regulatory level but it would provide transparency on the CO2 emissions of different aircraft 

types and configurations. The observer committed to provide a co-leader of the CO2 Standard task from 

the group of countries represented by him.
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Report on Agenda Item 2 2-23

2.5.4.16 A member, noting the urgency and importance of the CO2 Standard, suggested that a new 

working group or task force be created to undertake this task. He pointed out that aircraft performance is a 

system level issue and therefore would necessitate formation of a new group. He also recommended that 

the analysis on establishing a lower applicability threshold be continued. Ideally, all aircraft should be 

included but a thorough study based on technological feasibility, environmental benefit and economic 

cost is needed to make a decision. Therefore, a decision should be made in a Steering Group meeting after 

relevant analysis has been completed. The member also committed to provide experts for the effort 

leading to establishment of a CO2 Standard.

2.5.5 Discussion and Conclusions

2.5.5.1 A member expressed her concern with the proposal of establishing a new group. She was 

concerned with splitting the resources when the necessary expertise already resides in WG3. The member 

with the original proposal replied that a new group will avoid multiple levels of approval. He was 

concerned with overloading WG3 and noted that the same expertise will be used whether it is in a task 

group under the working group or a in a separate working group.

2.5.5.2 In answer to a question, the Secretary clarified that a Standard does not always need to be 

adopted at fixed three year intervals, as long as the appropriate approval procedures are followed. The 

three year interval has worked well in the past in terms of coordinating with amendments of other 

Annexes and also the typical work duration of a majority of CAEP work items has so far been three years.

2.5.5.3 Some members emphasized that it is generally desirable that all jet aircraft be covered in

the analysis and a decision on a lower applicability threshold may be premature. It was suggested that 

data analysis to be conducted in the future to determine this threshold. One member noted that expanding 

the analysis to all jet aircraft has the danger of market distortion since the lower weight turbojets compete 

with other types of aircraft. He also pointed out the trade-off between expanding the scope and the length 

of time to complete the task.

2.5.5.4 Several members committed to providing resources to the group in order to ensure timely 

and effective completion of the CO2 Standard task.

2.5.5.5 A member expressed his doubts about application of a new Standard to any aircraft 

except new certifications since it is not clear how it will be applied or what the economic cost could be.

2.5.5.6 A member inquired whether the meeting would discuss the choice between classical passfail certification test and a corporate average type of Standard since these were mentioned by the Chair. 

The working group representative clarified that the WG did not intend to bring this issue as something to 

be decided at CAEP/8, since an analysis of the advantages or disadvantages of a corporate average 

approach had not yet been conducted.

2.5.5.7 A member agreed with the high priority accorded by ICAO to CO2 Standard but 

highlighted that CAEP should not lose sight of other mandates from ICAO. Therefore, an appropriate 

balance in priorities needs to be maintained.

2.5.5.8 The Chair acknowledged the high quality of presentations and the subsequent discussion 

on the issue of a CO2 Standard. He summarized that the main topics identified were applicability

thresholds (e.g. MTOW), to which aircraft this Standard would apply (e.g. new aircraft types, inproduction, in-service) to, and whether this Standard would be a pass-fail type or use some other criteria. 
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2-24 Report on Agenda Item 2

He also highlighted that timelines and resources would have to be identified to complete this task in the 

most efficient manner. The discussion was very helpful in understanding and setting out various positions 

and priorities. The Chair requested that these issues be further discussed under the future work agenda 

item.

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