GAES Advanced Emissions Model (AEM3) v1.5 - Validation … · 2019. 2. 18. · This validation exercise#4 also corroborated the influence of take-off weight (TOW) on the accuracy

GAESAdvanced Emissions Model (AEM3)

v1.5 - Validation Exercise #4

EEC/SEE/2006/007

GAES - Advanced Emissions Model (AEM3) v1.5 - Validation Exercise #4 This report was prepared for EUROCONTROL Experimental Centre GAES by: ENVISA. Author(s): Sandrine CARLIER

ENVISA, 38 rue des Gravilliers, 75003 Paris, France Email: [email protected] Web: www.env-isa.com

Frank JELINEK, EUROCONTROL Experimental Centre Review: Sarah BENTLEY EEC Note : EEC/SEE/2006/007

© European Organisation for the Safety of Air Navigation EUROCONTROL 2006

This document is published by EUROCONTROL in the interest of the exchange of information. It may be copied in

whole or in part providing that the copyright notice and disclaimer are included. The information contained in this

document may not be modified without prior written permission from EUROCONTROL.

GAES - Advanced Emissions Model (AEM3) v1.5 - Validation Exercise #4

EXECUTIVE SUMMARY

AEM3 validation exercise#4 builds on the AEM3 validation exercise#1 completed in early 2004, as did validation exercise#2 and #3 in the year 2004 and 2006. It addresses seven additional aircraft types, namely B767-300, B777-300, A330-GE, A330-RR, A340-500, ARJ-85 and ARJ-100. The data set used for this supplementary validation exercise consists of flight data recordings collected from an European airline. The data granularity varies depending on portions of flight. Predefined intervals between two flight points were of 10 seconds at low altitude, 1 minute during main climbing and descending phase and around 10 minutes during cruise.

Two flight profile completion options were addressed during AEM3 execution: • no completion (fuel burn and emissions calculated for the portion of FDR profile provided

only); • and full completion (missing portions of profile are added before (i.e. from departure airport

to first available FDR point) and after (i.e. from last available FDR point to arrival airport) provided FDR portion of flight profile in order to estimate fuel burn and emissions on complete trajectories).

Like previous AEM3 validation exercises, the current exercise indicates a very good ability to estimate fuel burn. The resulting average fuel ratio for the whole traffic sample (i.e. seven aircraft-engines combinations) indicates that AEM3 underestimates fuel burn by 8% when no flight profile completion is required. In case of flight profile completion, the resulting AEM3's error is an overestimation of fuel burn by only 3%. Nevertheless, if the error on duration due to flight completion is isolated, AEM3 seems to underestimate fuel burn by 8%. Results obtained during previous AEM3 validation exercises with FDR data are thus confirmed and the necessity of using as complete flight profiles as possible in input is once again demonstrated.

This validation exercise#4 also corroborated the influence of take-off weight (TOW) on the accuracy of fuel burn estimation through AEM3. Results confirm findings from validation exercise#1 and #3, that is to say AEM3 slightly underestimates fuel burn for flights with a high take-off weight.

The results for the 4371 flights of the data set are visualized below (no flight completion).


iv EEC/SEE/2006/007

Figure 1-1: AEM3 fuel burn vs. operational fuel burn for 4371 flights (no flight completion)

During AEM3 validation exercise#1, #2 and #3, significant differences were highlighted for low and high thrust fuel flows compared to fuel flows documented in the ICAO Engine Exhaust Emissions Data Bank [Ref 1.] and BADA data. Similar differences were observed for the seven supplementary aircraft types under study, leading to the same errors. The influence of many parameters on emissions for the specific data set exploited for this fourth validation exercise led to an increase of the proportion of CO and HC regarding NOx for all aircraft but ARJ-85. This was the case for FDR data during previous validation exercises as well.

As a conclusion of the whole AEM3 validation exercise, AEM3 fuel burn estimation offers a high level of realism. Emissions estimation compares with the results published by NASA and ANCAT; the quality of the results depends on the granularity of the AEM3 input data.

This extra validation exercise adds information on the reliability of seven aircraft types and confirms the tendency obtained for other aircraft types. As a result, based on 11721 flights, AEM3 is now validated for 21 different aircraft types as summarized in the conclusion.


i. EEC/SEE/2006/007 v

REPORT DOCUMENTATION PAGE

Reference: SEE Note No. EEC/SEE/2006/007

Security Classification: Unclassified

Originator: Society, Environment, Economy Research Area

Originator (Corporate Author) Name/Location: EUROCONTROL Experimental Centre Centre de Bois des Bordes B.P.15 91222 BRETIGNY SUR ORGE CEDEX France Telephone: +33 1 69 88 75 00

Sponsor: EUROCONTROL EATM

Sponsor (Contract Authority) Name/Location: EUROCONTROL Agency Rue de la Fusée, 96 B –1130 BRUXELLES Telephone: +32 2 729 90 11

TITLE: Advanced Emissions Model (AEM3) v1.5 - Validation Exercise #4, GAES Authors : Sandrine CARLIER EEC Contact: Frank JELINEK

Date 12/06

Pages 56

Figures 23

Tables 14

Appendix --

References 8

EATMP Task Specification -

Project AEM Validation (GAES)

Task No. Sponsor CE/8455/PAM/T06/22324TC/C1107/05

Period 2006/2007

Distribution Statement: (a) Controlled by: EUROCONTROL Project Manager (b) Special Limitations: None (c) Copy to NTIS: YES / NO Descriptors (keywords): Global Aviation Emissions, Aircraft Emissions, AEM, TEA, NOx, CO, HC, CO2, H2O, SOx, VOC, TOG, EEC, ICAO/CAEP, ANCAT, EMEP, etc Abstract: This report is an appendix to the AEM3 validation report EEC/SEE/2004/004 dealing with statistics and validation measures concerning seven supplementary aircraft/engine combinations. Seven additional aircraft types were already addressed in two previous appendices (EEC/SEE/2004/012 and EEC/SEE/2006/005).


vi EEC/SEE/2006/007

(This page intentionally blank)


i.EEC/SEE/2006/007 vii

TABLE OF CONTENTS

Table of Contents.................................................................................................... vii

List Of Figures........................................................................................................ viii

List of Tables............................................................................................................ ix

ABBREVIATIONS ...................................................................................................... x

1 INTRODUCTION .................................................................................................. 1

2 Data collection and preparation ........................................................................ 2 2.1 General Approach .................................................................................................................... 2 2.2 FDR#4 Data Preparation.......................................................................................................... 2 2.3 FDR#4 Data set........................................................................................................................ 4 2.4 AEM3 execution ....................................................................................................................... 6

3 Output data analysis and results – Fuel burn estimation with AEM3 ............ 7 3.1 Data reliability ........................................................................................................................... 7 3.2 Flight duration........................................................................................................................... 8

3.2.1 Duration with NoAdd option .............................................................................................. 8

3.2.2 Duration with AddAll option............................................................................................... 8

3.2.3 Duration of LTO cycles ................................................................................................... 11

3.3 Fuel burn ................................................................................................................................ 15

3.3.1 Fuel burn by aircraft type ................................................................................................ 15

3.3.2 Fuel Burn by Take-Off Weight ........................................................................................ 16

3.3.3 FDR#4 results versus SITA, FDR#1, FDR#2 and FDR#3.............................................. 20

3.4 Fuel flow analysis ................................................................................................................... 22

3.4.1 Fuel flow evolution .......................................................................................................... 22

3.4.2 Fuel flow limits ................................................................................................................ 26

3.5 Emissions estimation with AEM3 ........................................................................................... 30

3.5.1 NOx, CO and HC distribution .......................................................................................... 31

3.5.2 NOx average emission indices from ANCAT and NASA ................................................ 34

3.5.3 Emissions along the flight profiles .................................................................................. 35

4 CONCLUSIONS ................................................................................................. 39

5 REFERENCES ................................................................................................... 42


viii EEC/SEE/2006/007

LIST OF FIGURES

FIGURE 1-1: AEM3 FUEL BURN VS. OPERATIONAL FUEL BURN FOR 4371 FLIGHTS (NO FLIGHT

COMPLETION) ........................................................................................................................................ 4

FIGURE 3-1: EVOLUTION OF FUEL FLOW – B763 – 1800 KM MISSION ........................................................ 22

FIGURE 3-2: EVOLUTION OF FUEL FLOW – B773 – 5900 KM MISSION ........................................................ 23

FIGURE 3-3: EVOLUTION OF FUEL FLOW – A332 – 4400 KM MISSION........................................................ 23

FIGURE 3-4: EVOLUTION OF FUEL FLOW – A345 – 5700 KM MISSION........................................................ 24

FIGURE 3-5: EVOLUTION OF FUEL FLOW – RJ1H – 650 KM MISSION.......................................................... 24

FIGURE 3-6: EVOLUTION OF FUEL FLOW – RJ85 – 750 KM MISSION........................................................... 25

FIGURE 3-7: FUEL FLOW LIMITS – B763 ............................................................................................................ 27

FIGURE 3-8: FUEL FLOW LIMITS – B773 ............................................................................................................ 28

FIGURE 3-9: FUEL FLOW LIMITS – A332 ............................................................................................................ 28

FIGURE 3-10: FUEL FLOW LIMITS – A345 .......................................................................................................... 29

FIGURE 3-11: FUEL FLOW LIMITS – RJ85........................................................................................................... 29

FIGURE 3-12: FUEL FLOW LIMITS – RJ1H.......................................................................................................... 30

FIGURE 3-13: EMISSIONS COMPARISON OF 757-200 FOR A 750 KM AND 5500 KM MISSION [REF 5.] .. 31

FIGURE 3-14: EMISSION DISTRIBUTION FOR THE WHOLE FDR#4 TRAFFIC SAMPLE............................. 33

FIGURE 3-15: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – B763 – 1800 KM MISSION......... 35

FIGURE 3-16: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – B773 – 5900 KM MISSION......... 36

FIGURE 3-17: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – A332 – 4400 KM MISSION......... 36

FIGURE 3-18: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – A345 – 5700 KM MISSION......... 37

FIGURE 3-19: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – RJ1H – 650 KM MISSION .......... 37

FIGURE 3-20: EVOLUTION OF NOX, CO AND HC EMISSION INDICES – RJ85 – 750 KM MISSION ........... 38

FIGURE 4-1: THE AEM3 FUEL BURN VS. OPERATIONAL FUEL BURN FOR 11721 FLIGHTS (NO FLIGHT

COMPLETION) ...................................................................................................................................... 40

FIGURE 4-2: THE AEM3 FUEL BURN VS. OPERATIONAL FUEL BURN FOR 10929 FLIGHTS (FULL

FLIGHT COMPLETION) ....................................................................................................................... 40


i.EEC/SEE/2006/007 ix

LIST OF TABLES

TABLE 2-1: FDR#4 FLEET ........................................................................................................................................ 4

TABLE 2-2: NUMBER OF FDR#4MOVEMENTS .................................................................................................... 5

TABLE 3-1: DURATION RATIO PER AIRCRAFT TYPE ....................................................................................... 9

TABLE 3-2: DURATION RATIO PER AIRCRAFT TYPE AND TAKE-OFF WEIGHT....................................... 10

TABLE 3-3: DURATION RATIO PER LTO FLIGHT PHASE................................................................................ 11

TABLE 3-4: DURATION RATIO PER LTO FLIGHT PHASE – BREAK DOWN PER AIRCRAFT TYPE......... 12

TABLE 3-5: FUEL RATIO PER AIRCRAFT TYPE ................................................................................................ 15

TABLE 3-6: WEIGHT CATEGORY FOR FDR#4 DATA (KG) .............................................................................. 16

TABLE 3-7: TRAFFIC SAMPLE WEIGHT LIMITS ............................................................................................... 17

TABLE 3-8: FUEL RATIO PER TAKE-OFF WEIGHT........................................................................................... 17

TABLE 3-9: GENERAL FUEL RATIOS FOR AEM3 VALIDATION EXERCISES.............................................. 20

TABLE 3-10: A330, A340 & B767-300 OVER THE FOUR VALIDATION EXERCISES .................................... 21

TABLE 3-11: EMISSION DISTRIBUTION FOR THE WHOLE STUDY............................................................... 32

TABLE 3-12: PUBLISHED AVERAGE EINOX (G/KG) OF REFERENCE PROJECT [REF 6.] .......................... 34


x EEC/SEE/2006/007

ABBREVIATIONS

AEM Advanced Emission Model AEM3 Advanced Emission Model, 3rd version ANCAT Abatement of Nuisances Caused by Air Transport BADA Base of Aircraft Data BEN Benzene BM2 The Boeing Method 2 EEC-BM2 The EUROCONTROL modified Boeing Method 2 CO Carbon Monoxide CO2 Carbon Dioxide EEC EUROCONTROL Experimental Center EEC-BM2 EEC corrected BM2 EI Emission Index FDR Flight Data Recordings FL Flight Level H2O Water HC Hydrocarbon ICAO International Civil Aviation Organisation Lat Latitude Long Longitude LTO Landing- and Take-Off cycle Max Maximum Min Minimum MS Microsoft MTOW Maximum Take-Off Weight NASA National Aeronautics and Space Administration NOx Oxides of Nitrogen OEW Operational Empty Weight SEE Society, Environment, Economy SOx Oxides of Sulphur TEA Toolset for Emission Analysis TOG Total Organic Gases TOW Take-Off Weight VOC Volatile Organic Compounds


i.EEC/SEE/2006/007 xi



EEC/SEE/2006/007 1

1 INTRODUCTION

The aim of the AEM3 validation exercise #4 is to build on the AEM3 validation work already carried out previously [Ref 2.].

The result of the supplementary analysis therefore, is to produce a new set of validation tables presented in this appendix to the existing report [Ref 2.] which deals only with statistics and validation measures concerning the specific aircraft types contained in new FDR data (B767-300, B777-300, A330-GE, A330-RR, A340-500, ARJ-85, ARJ-100). Two other appendices (AEM3 validation exercise#2 and #3 [Ref 7.] and [Ref 8.]) to the main validation report, addressing a total of seven additional aircraft types, were published in 2004 and 2006.

The three appendices (namely AEM3 validation exercise#2, #3 and #4) have the same focus. Therefore, the forth validation exercise developed in this report will follow the same structure as validation exercise#2 and #3 ([Ref 7.] and [Ref 8.]), unless specific features which were not assessable in validation exercise#2 or #3.

Since the desire for a supplementary validation exercise is to focus on new FDR data and corresponding additional aircraft types, it is not necessary to repeat many of the fundamental (non-aircraft specific) validation tests, focusing only on aircraft specific validation figures.

Results for CO2, H2O and SOx are not repeated either as they follow exactly the evolution of fuel burn. Similarly VOC/TOG are proportional to HC and thus do not need to be reported specifically in the current validation exercise.

To avoid a confusion between FDR data used in the main validation exercise [Ref 2.], in appendices validation exercises ([Ref 7.] & [Ref 8.]) and in the current validation exercise, FDR data concerning the current validation exercise are called "FDR#4" in the continuation of this report.


2 EEC/SEE/2006/007

2 DATA COLLECTION AND PREPARATION

2.1 General Approach

Operational flight data recordings in the form of FDR data were acquired from one European airline for seven1 aircraft types.

FDR data provide detailed information on routes taken by aircraft and different flight parameters among which fuel consumption all along the flight profile.

Detailed information is also provided for a certain number of significant flight profile positions such as 'Start of Taxi-out', 'Start of Take-Off', 35ft, 400ft, 1000ft, 1500ft, 2000ft, 3000ft and Touchdown for each flight, even when only a portion of the flight has been recorded (i.e., transatlantic flights often have incomplete profiles in FDR data).

A flight leg by flight leg comparison was thus possible, as well as more global assessments based on averages.

As a consequence, the fourth validation exercise concentrates on seven aircraft types:

• B767-300 (Boeing B767-341ER): 588 flights • B777-300 (Boeing B777-300ER): 762 flights • A330-GE (Airbus A330-202): 538 flights • A330-RR (Airbus A330-243): 711 flights • A340-500 (Airbus A340-541): 558 flights • ARJ-85 (BAe Avro 146-RJ85): 605 flights • ARJ-100 (BAe Avro 146-RJ100): 625 flights

2.2 FDR#4 Data Preparation

Data preparation consists of two main activities:

• Reconstitution of flight profiles and estimation of the amount of fuel burnt and emissions due to the data set, using AEM3.

1 Six different aircraft types; two similar aircraft types equipped with different engines.


EEC/SEE/2006/007 3

• Extraction of fuel flow or fuel burn information indicated by the airline all along each flight profile, in order to compare actual fuel burn with AEM3 estimation.

Data was provided in a very similar format to FDR#3 data used for validation exercise #3 [Ref 8.]. Therefore description of data preparation methodology for the current validation exercise is not repeated here. For more details, see section ‘FDR#3 data Preparation’ of [Ref 8.].

Every single data problem highlighted during previous validation exercises was systematically addressed and filtered. Nevertheless, extra filtering was required because of specific errors in FDR#4 data due to sensor problems, namely:

• 20 flights holding negative fuel quantities, • 13 flights presenting wrong GMT time for some points, • 3 flights described with wrong longitudes. While negative fuel quantities problem was overcome, last two items lead to the deletion of respectively 13 and 3 flights deleted. As a result, 16 flights (out of the 4,387 flights initially in the FDR#4 data set) were excluded from the exercise.

Moreover, GMT times order in FDR data did not always fit altitude profile. Typically, in a descent phase, FL10 was sometime indicated as reached before FL15 in the ‘flight’ file from the airline, while flight profile in ‘events’ file did not show the same inversion (23 flights concerned). In addition negative GMT times disrupt the assessment of FDR flight duration for 22 flights.

Although problems were identifiable for these flights, sensors do not seem to be faulty. Therefore the level of information’s accuracy for these flights has no reason to be worse than for other flights in the dataset for which no obvious problem was detected. As problems mentioned above did not generate significant errors on flight duration extracted form FDR data, no arbitrary correction was done.

As a result, the FDR duration (considered as ‘real’ in this validation exercise) for these flights does not reflect the exact reality. This problem artificially adds an error in duration ratios (AEM flight duration / airline flight duration).


4 EEC/SEE/2006/007

2.3 FDR#4 Data set

Useful information on FDR#4 fleet is reported in table below.

Table 2-1: FDR#4 fleet

ACType ICAO code

BADA aircraft

Number of

engines AEM3 Engine Real engine2

B767-300 B763 B763 2 PW4060 General Electric CF6-80C2

B777-300 B773 B772 2 JT8D-7B GE90-115B1

A330-GE A332 A332 2 Trent 772 GE CF6-80E1A4

A330-RR A332 A332 2 Trent 772 Rolls Royce Trent 772B-60

A340-500 A345 A343 4 CFM56-5C2 Rolls Royce Trent 553

ARJ-85 RJ85 RJ85 4 LF507-1F, -1H LF 507-1F

ARJ-100 RJ1H B461 4 ALF 502R-53 LF 507-1F

Aircraft performances, and in particular fuel flows for four out of the seven aircraft types in this assessment are directly modelled by BADA (B767-300, A330-GE, A330-RR and ARJ-85). Other aircraft types are associated to BADA equivalents for estimating fuel burn.

The engine used by AEM3 is close to the actual engine installed on A330-RR and ARJ-85. As AEM3 aircraft/engine match is based on the most common engine for each aircraft type, engines in AEM for B767-300, B777-300, A330-GE, A340-500 and ARJ-100 are slightly different from actual engine. The resulting error will be investigated in the following paragraphs.

The following table indicates the number of movements available for each aircraft type.

2 Real engines for the airline providing the FDR data were determined using JPFleets database [Ref 3.]. 3 ALF-502R-5 and LF 507-1F are both developed by Textron Lycoming, thus belonging to the same

engine family.


EEC/SEE/2006/007 5

Table 2-2: Number of FDR#4movements

Aircraft Type Initial Deleted (GMT

problem)

Deleted (Longitude problem)

Available for validation#4

B767-300 588 588

B777-300 762 762

A330-GE 538 538

A330-RR 711 711

A340-500 558 558

ARJ-85 605 -3 602

ARJ-100 625 -13 612

Total 4387 -13 -3 4371

16 flights were deleted from the data set. Therefore 4371 movements were available for validation exercise#4

The granularity of data depends on portions of flight: predefined intervals between two flight points are of +/-10 seconds during take-off, climb, descent and landing, +/-1 minute during main climbing and descending phases and +/-10 minutes during main cruising phase.


6 EEC/SEE/2006/007

2.4 AEM3 execution

AEM3 available options were discussed during validation exercise#1 [Ref 2.] and do not need to be repeated here. This section only presents AEM3 user options used for validation exercise#4.

Two profile completion options were run:

• No flight completion: only portions of flights described in the input profiles were considered. This option is called "NoAdd" in this document.

• Flights were completed by AEM3 when flight profiles retrieved from FDR#4 recordings were not complete. This mainly adds the first/last part of the profile from the first/last available point to the departure/arrival airport. This option is called "AddAll" in this document.

"First leg start" option was selected as "traffic sample entry time" since, similarly to FDR data used during validation exercise#1 and #3, FDR#4 take-off and off-block times were not always correct.

Other user options, discussed in [Ref 2.] section "AEM3 User Options for Validation", were chosen similarly to the AEM3 validation exercise#1.


EEC/SEE/2006/007 7

3 OUTPUT DATA ANALYSIS AND RESULTS – FUEL BURN ESTIMATION WITH AEM3

Similarly to AEM3 validation exercises#1 [Ref 2.], #2 [Ref 7.] and #3 [Ref 8.], results of the comparisons between airline and AEM3 fuel burn estimation and flight duration are presented as follows:

=

=

ninformatio burn fuel Airlineestimation burn fuel Aem3Ratio Fuel

duration flight Airlineduration flight AEM3ratio Duration

In an ideal case, duration ratio and fuel ratio would be equal to one. A value greater (resp. lower) than one indicates that AEM3 overestimates (resp. underestimates) the real duration or fuel burn.

3.1 Data reliability

The validation exercise #4 totally relies on FDR#4 data quality. Therefore, in addition to systematic checking process, random manual checks were performs on the data. Specific problem were thus identified, as detailed in section “2 Data collection and preparation”. Nevertheless, as no recording error warning appears in the data files, other inaccuracies may no have been identified during data preparation.

Consequences of errors in the FDR#4 data set are dual:

• Impact on the quality of AEM3 results: AEM3 flight completion is based on ground speeds as well as rates of climb and descent indicated in the input files. As FDR#4 horizontal and vertical speeds were used to create AEM3 input files, the impact of erroneous values is really significant in AEM3's flight profile completion and may even lead to unrealistic flight profiles.

• Impact on AEM3 versus FDR#4 comparison: When "actual" duration and fuel burn extracted from FDR#4 data set are not accurate, duration and fuel ratios based on such errors are not correct, which hangs over the quality of the whole validation exercise. Indeed duration is the key item for fuel burn and emission calculation.


8 EEC/SEE/2006/007

When obvious for individual flights, errors in the FDR#4 data were corrected before any comparison with AEM3 results. However, since a “manual” verification of each parameter for each profile is not possible, most of FDR#4 information was used "as is".

This section, and thus duration and fuel ratios obtained for the validation exercise #4, relies on FDR#4 data quality and would read significantly different with another data set.

3.2 Flight duration

Similarly to validation exercise#1 and #3 ([Ref 2.] and [Ref 8.]), flight duration can be compared to AEM3 calculation. This test aims at addressing the quality of estimated duration of legs added by the tool when input flight profiles are not complete.

Legs duration estimation by AEM3 and it's importance are discussed in [Ref 2.]. This section thus only provides duration ratios for FDR#4 data set and focuses on the influence of various criteria.

3.2.1 Duration with NoAdd option

When NoAdd option is applied, AEM3 uses FDR GMT times. Duration ratios with NoAdd option thus are always equal to 1.

Nevertheless a range of duration ratios between 0.88 and 1.044 (i.e. -12% to +4% difference) was highlighted although the overall average is close to 1. This reflects the discrepancy between GMT information indicated for each flight point and general information for each flight in FDR#4 data set.

This discrepancy is not linked to AEM3 and thus not further investigated in this document. However the whole validation exercise is subject to be affected by equivalent inconsistencies in the FDR#4 data set, as detailed in the "Data reliability" section.

3.2.2 Duration with AddAll option

The duration ratio for the total FDR#4 traffic sample is 1.11. This means that the total flight duration indicated by AEM3 for 4371 flights under study is 11% higher than the real total flight duration.

The breakdown by aircraft type presented in Table 3-1 below highlights disparities between

4 If one flight with a duration ratio of 2.34 is ignored. The error for this flight is due to a first profile point in

FDR data appearing 6 hours before the next one, thus artificially increasing AEM3’s duration estimation.


EEC/SEE/2006/007 9

aircraft, even if an overestimation of flight duration is observed for all the aircraft types under study. The completion of the raw input flight profiles leads to a slight overestimation of the mission duration which varies between +3% and +23%.

Among reasons why aircraft type has an influence on flight duration lies airport congestion. Indeed, heavier aircraft generally use congested airports. This is confirmed by Table 3-1 where lighter aircraft (ARJ-85, ARJ-100 and B767-300) show higher AEM’s overestimation.

Another reason is that climb/descent rates and ground speed values vary with the aircraft type, its actual take-off weight and meteorological conditions. As a consequence, the completion of flight profile by AEM3 differs depending on the aircraft performances.

Table 3-1: Duration ratio per aircraft type

Aircraft Type Number of movements AddAll Duration Ratio

B767-300 588 1.14

B777-300 762 1.04

A330-GE 538 1.10

A330-RR 711 1.03

A340-500 558 1.05

ARJ-85 602 1.23

ARJ-100 612 1.23

For this reason, the breakdown to address take-off weight influence is also performed by aircraft type.

Table 3-2 shows the same tendency: duration ratio is higher for lighter aircraft for all aircraft type but A330. This is a logical result: with the same engine setting, LTO operations (especially take-off and climb-out) and the climb phase are longer for heavy aircraft. AEM3 duration overestimation is thus less important for heavy aircrafts.


10 EEC/SEE/2006/007

Table 3-2: Duration ratio per aircraft type and take-off weight

Aircraft Type Bada

Nominal Weight (kg)

Weight Category

No of movements

Average Take-off

Weight (kg)

AddAll Duration

Ratio

Low 159 117,782 1.26

Medium 429 143,314 1.09 B767-300 150,000

High 0 - -

Low 0 - -

Medium 36 240,861 1.05 B777-300 208,700

High 726 275,520 1.04

Low 90 164,574 1.06

Medium 415 192,723 1.11 A330-GE 190,000

High 33 205,049 1.15

Low 19 173,679 1.03

Medium 498 192,173 1.03 A330-RR 190,000

High 194 209,698 1.04

Low 0 - -

Medium 3 210,316 1.09 A340-500 200,000

High 555 273,072 1.05

Low 0 - -

Medium 6 39,362 1.39 ARJ-85 38,000

High 596 41,492 1.23

Low 0 - -

Medium 0 - - ARJ-100 36,000

High 612 42,941 1.23


EEC/SEE/2006/007 11

3.2.3 Duration of LTO cycles

Similarly to FDR#1 and FDR#3, FDR#4 data hold information on LTO cycles duration. Large disparities in terms of durations can be observed between the certification times of the ICAO Engine Exhaust Emission Data Bank [Ref 1.] used in AEM3 and the duration information extracted from the FDR#4 data, especially for climb-out and taxi-out phases. Table 3-3 shows FDR#4 duration ratio for four LTO phases. Duration ratios obtained with FDR#1 and FDR#3 data set are also indicated.

Table 3-3: Duration ratio per LTO flight phase

FDR#1 FDR#3 FDR#4

AEM3 Phase

Number of flights for

which actual duration is available

Duration Ratio


which actual duration is available

Duration Ratio


which actual duration is available5

Duration Ratio

Taxi-out 3,827 1.62 1,552 2.12 4367 2.33

Take-off 3,840 1.08 2,707 1.14 3918 0.98

Climb-out 3,840 1.64 2,707 1.66 4371 1.41

Approach 3,837 1.04 2,706 1.08 4381 0.92

At first glance, duration rations for Take-off, Climb-out and Approach phases seems better (i.e. closer to 1) in the fourth validation exercise than in first and third exercises. On the opposite, Taxi-out’s duration ratio is significantly higher than previously obtained.

Taxi-out results show a growing overestimation of AEM3 with time. This does not indicate a decrease of AEM3 quality but a diminution of congestion at airports mainly used by the airline providing FDR data. Indeed, FDR#1 holds data dating back to 2002-2003, FDR#3 to 2004-2005 and FDR#4 to 2004. Eurostat6 website indicates an increase of the total number of movements in Europe between 2003 and 2005 but a decrease of traffic in the country mainly concerned by the airline in the same time period. This decrease of traffic explains the decrease of congestion and thus of taxi-out time in the FDR#4 data.

5 Based on the original data set provided from an European airline, i.e. 4387 flights. 6 http://epp.eurostat.ec.europa.eu/portal/page?_pageid=0,1136228,0_45572945&_dad=portal&_schema=PORTAL


12 EEC/SEE/2006/007

A break down per aircraft type (


EEC/SEE/2006/007 13

Table 3-4) confirms the weakness of general averages announced above. Indeed, these figures are highly aircraft dependant.

The ARJ family show a much higher duration ratio than other aircraft types. As taxi-out was incorrect or equal to zero for all the FDR#3 data set but one aircraft type, the figure indicated in Table 3-3 does not reflect duration ratio of the whole third exercise. Therefore average duration ratio from exercise #4 is not directly comparable with the previous exercise. However taxi-out is the longest LTO phase and is very dependent on factors like the airport or the traffic, which can explain the percentage of variation, and especially the high ratio for light ARJ aircraft. Moreover FDR quality of duration information may partially explain high figures in Table 3-3, since a manual check of LTO durations, and especially taxi-out, highlighted weaknesses for a consequent number of flights (see section "3.1 Data reliability").

Similarly to FDR#1 and FDR#3 results, the aircraft type dependency for take-off is verified. Considering first, third and fourth validations, the range of take-off duration ratios is spread from 0.74 (A340 in #1) to 1.30 (B735 in #3).

If overall duration ratios are comparable for climb-out in Table 3-3, the range of figures seems to be smaller for the Boeing family (i.e. #3 and #4) than Airbus family (i.e. #1 and #4). Indeed Boeing's duration ratios vary from 1.51 to 1.72 while Airbus shows a 0.97 to 1.95 duration ratio variation.

Although lower than #1 and #3’s averages, Approach figures for FDR#4 are comparable with FDR#1 and FDR#3. This tends to demonstrate that approach phase is not specifically aircraft dependant.


14 EEC/SEE/2006/007

Table 3-4: Duration ratio per LTO flight phase – Break down per aircraft type

AEM3 Phase Aircraft type Number of movements for which

actual duration is available Duration Ratio

B767-300 588 2.05

B777-300 762 2.14

A330-GE 538 2.39

A330-RR 711 2.02

A340-500 558 2.11

ARJ-85 603 2.87

Taxi-out

ARJ-100 607 2.80

B767-300 588 1.28

B777-300 762 1.11

A330-GE 538 0.97

A330-RR 711 0.94

A340-500 558 0.81

ARJ-85 369 0.79

Take-off

ARJ-100 392 0.80

B767-300 588 1.63

B777-300 762 1.57

A330-GE 538 1.22

A330-RR 711 1.42

A340-500 558 1.05

ARJ-85 597 1.53

Climb-out

ARJ-100 617 1.36

B767-300 588 0.87

B777-300 762 0.95

A330-GE 538 0.77

A330-RR 711 0.88

A340-500 558 0.89

ARJ-85 605 1.01

Approach

ARJ-100 619 1.04


EEC/SEE/2006/007 15

These figures thus confirm an overestimation of AEM3 for taxi-out and climb-out phases, but the magnitude of AEM3's overestimation may be lower than suggested by Table 3-3. The consequences of such an overestimation are discussed in [Ref 2.]. The tendency for take-off and approach phases is less obvious since under- or overestimation depends on the aircraft type.

Anyway the use of actual LTO durations based on aircraft or airport is an option in AEM3 although information in the current version of AEM3 is not available for all airports in the world. This feature will be enhanced as and when aircraft and/or airport specific LTO durations will become available. Duration ratios will thus gradually get closer to 1 as new versions of the tool will be issued.


16 EEC/SEE/2006/007

3.3 Fuel burn

3.3.1 Fuel burn by aircraft type

The fuel ratio for the overall traffic sample is 0.92 with NoAdd option and 1.03 with AddAll option. Seeing that the duration error for AddAll option is around +11%, the resulting fuel error can be considered as an underestimation of fuel around 8%7. Underestimation is thus equivalent for both options.

Table 3-5 below shows fuel burn ratios as a function of aircraft type.

Table 3-5: Fuel ratio per Aircraft Type

Fuel Ratio Duration Ratio Aircraft Type Number of movements

NoAdd AddAll AddAll

B767-300 588 1.10 1.32 1.14

B777-300 762 0.87 0.88 1.04

A330-GE 538 0.99 1.11 1.10

A330-RR 711 0.98 1.03 1.03

A340-500 558 0.75 0.79 1.05

ARJ-85 602 0.92 1.05 1.23

ARJ-100 612 0.86 1.08 1.23

With NoAdd option, fuel burn estimation error of AEM3 lies between -25 and +10%.

When AddAll option is used, the completion of the raw input flight profiles combined with the underestimation of the fuel flow as indicated above leads to a final fuel burn estimation error of AEM3 varying between -21 and 32%.

With a duration ratio of 1, the fuel ratio for this data set would read -26 to +18%. Table 3-5 confirms that AEM3 globally underestimates the fuel burn during all flight phases except the LTOs (see [Ref 2.]). B767-300 is an exception. Nevertheless the same aircraft with an actual engine identical to AEM’s engine was addressed in the third validation exercise [Ref 8.]. The overestimation was 1% with NoAdd option and 0% with AddAll option (when corrected

7 AddAll duration overestimation=11.36% and AddAll fuel overestimation=3.29%, the resulting fuel

underestimation thus lies around 8.07%.


EEC/SEE/2006/007 17

regarding duration ratio). This discrepancy highlights the influence of engine modelling in AEM.

Moreover, take-off weight for this aircraft is on average lower than BADA weight used in AEM3. As a consequence, AEM3 overestimates fuel burn for this aircraft type.

3.3.2 Fuel Burn by Take-Off Weight

An important factor in fuel consumption is the actual weight of the aircraft. AEM3 validation exercise#1 and #3 ([Ref 2.] and [Ref 8.]) presented a detailed study of fuel ratio depending on take-off weight. Similarly, 'gross weight' information was used for validation exercise#4 to consider the influence of weight variation of real flights.

Three categories of take-off weight have been defined to group the results. The difference (MTOW – 1.2 × OEW) has been divided into equal 3 parts called in below table Low, Medium and High:

• Low = 0 to 33% of the difference • Medium = 33 to 66% of the difference • High = 66 to 100% of the difference The categories have been estimated based on BADA weights, as discussed in the main validation report [Ref 2.], section "Fuel burn by take-off weight".

Table 3-6: Weight category for FDR#4 data (kg)

<---Low---> <---Medium---> <---High--->

Aircraft Type BADA Low

Weight 0%

Limit Inf

33%

BADA Nominal Weight

Limit Sup 66%

BADA High

Weight 100%

B767-300 107,880 132,387 150,000 156,893 181,400

B777-300 165,720 206,147 208,700 246,573 287,000

A330-GE 150,000 176,667 190,000 203,333 230,000

A330-RR 150,000 176,667 190,000 203,333 230,000

A340-500 156,000 188,500 200,000 221,000 253,500

ARJ-85 30,720 35,147 38,000 39,573 44,000

ARJ-100 28,680 33,187 36,000 37,693 42,200

The table below shows the minimum and maximum take-off weight provided with FDR#4 data for the fleet in the study.


18 EEC/SEE/2006/007

Table 3-7: Traffic sample Weight Limits

Aircraft Type Minimum TOW Maximum TOW

B767-300 102,283 148,370

B777-300 229,289 311,854

A330-GE 150,276 208,180

A330-RR 167,938 226,578

A340-500 204,552 345,692

ARJ-85 38,761 44,654

ARJ-100 40,644 47,673

Note that the weight information found in the FDR#4 data exceeds the weight limit envelope as defined in the BADA aircraft performance tables for all aircraft but A330. B767-300 shows lighter aircrafts than supposed by BADA while some B777-300, A340-500, ARJ-85 and ARJ-100 from the data set are heavier than BADA's supposition.

This tendency is confirmed by Table 3-8: no B767-300 in the ‘high’ category; almost all A340-500, ARJ-85 and ARJ-100 in ‘high’ category. This discrepancy between BADA’s and actual weight mainly explain why results from this validation exercise show higher fuel ratios (absolute values) than previous exercises.

As detailed in [Ref 2.], calculations in AEM3 are performed with BADA "nominal" mass. Heavy aircraft are expected to burn more fuel than AEM3 indicates, as opposed to light aircraft which should use less fuel than estimated by AEM3.

In the context of global emission studies, this variation should not have significant impact if the “nominal” weight and fuel burn corresponds to a high extent to the average real operating weight of the flights under analysis.

In Table 3-8, weight information for each flight has been considered to evaluate the influence of real weight against AEM3 normalised reference weight.

Table 3-8: Fuel ratio per take-off weight


EEC/SEE/2006/007 19

Fuel Ratio Duration

Ratio Aircraft Type

BADA Nominal Weight

(kg)

Weight Category

No of movements

Average Take-off Weight

(kg) NoAdd AddAll AddAll

Low 159 117,782 0.89 1.29 1.26

Medium 429 143,314 1.18 1.33 1.09 B767-300 150,000

High 0 - - - -

Low 0 - - - -

Medium 36 240,861 0.92 0.94 1.05 B777-300 208,700

High 726 275,520 0.87 0.88 1.04

Low 90 164,574 1.05 1.18 1.06

Medium 415 192,723 0.97 1.10 1.11 A330-GE 190,000

High 33 205,049 0.98 1.09 1.15

Low 19 173,679 1.07 1.14 1.03

Medium 498 192,173 0.99 1.04 1.03 A330-RR 190,000

High 194 209,698 0.95 0.99 1.04

Low 0 - - - -

Medium 3 210,316 0.70 0.80 1.09 A340-500 200,000

High 555 273,072 0.75 0.79 1.05

Low 0 Medium 6 39,362 0.86 1.12 1.39 ARJ-85 38,000

High 596 41,492 0.92 1.05 1.23

Low 0 - - - - Medium 0 - - - - ARJ-100 36,000

High 612 42,941 0.86 1.08 1.23

As almost all A340-500, ARJ-85 and ARJ-100 belong to the same category (i.e. ‘high’), no tendency can be extrapolated from these aircraft. The tendency is respected for all other aircraft but B767-300 whichever option is used8. Nevertheless B767-300 with a different engine followed the expected tendency during validation exercise #3 [Ref 8.]. This confirms that the modelling of B767-300 in AEM3 is not ideal for the B767-300 under study.

8 Although not following a strict decreasing evolution, A330-GE with NoAdd option shows very close


20 EEC/SEE/2006/007

Anyway the influence of weight category regarding BADA is obvious and explains variations in Table 3-5.

• When mainly lighter than BADA weight (B767-300), AEM3 overestimates fuel burn. • When mainly heavier than BADA weight (B777-300, A340-500, ARJ-85 and ARJ-100), AEM3

underestimates fuel burn. • When corresponding to BADA range of weight, fuel burn estimation of AEM3 is close to

reality (-1 to -2% with NoAdd option and 0 to 1% with AddAll option, if duration error is corrected).

One reason why BADA weights do not always correspond to actual weight is that BADA considers a typical mission length for each aircraft type. If performing a longer/shorter mission, the actual take-off weight is heavier/lighter. As FDR#4 data comes from one airline only, the use of aircraft by this airline may not represent the typical use in the world.

values for medium and high category: 97.49 to 97.87. The tendency is therefore considered as respected.


EEC/SEE/2006/007 21

3.3.3 FDR#4 results versus SITA, FDR#1, FDR#2 and FDR#3.

Table 3-9 below repeats average fuel ratios obtained for the whole AEM3 validation exercise.

Table 3-9: General fuel ratios for AEM3 validation exercises

AEM3 validation exercise

Data set NoAdd

Fuel Ratio AddAll

Fuel Ratio

AddAll Corrected9 Fuel Ratio

SITA - 1.24 1.08 #1

FDR#1 0.97 1.01 0.99

#2 FDR#2 0.94 - -

#3 FDR#3 0.97 1.10 0.9910

#4 FDR#4 0.92 1.03 0.92

Note that both FDR#1 and FDR#3 validation exercises lead to the same fuel ratios ("corrected fuel ratio" with AddAll option) while this value is lower with FDR#4. One of the reasons for this lies on the fact that, although all acquired from the same provider and thus having the same level of granularity, the fourth validation highlighted weight discrepancies, as explained in sections 3.3.1 and 3.3.2.

Moreover the extraction of FDR#4 actual flight duration may not be as precise as other datasets (see section 2.2), which would artificially increase AEM3’s error.

Anyhow the fourth validation addresses different aircraft types than previously considered which, logically, cannot lead to the same results.

A330-223, A340-313 and B767-300 were already addressed during previous validation exercises but with different engines. Thus Table 3-10 indicates the influence of different engines for the same airframe compared to the aircraft/engine match used in AEM3.

9 "AddAll corrected" column corresponds to the resulting fuel ratio after compensation of the error due to

AEM3 duration estimation. For more details, see [Ref 2.] section "Flight Profile Analysis: Fuel burn". 10 See "3.3.1 Fuel burn by aircraft type"


22 EEC/SEE/2006/007

Table 3-10: A330, A340 & B767-300 over the four validation exercises

Fuel Ratio Aircraft type Data set

Number of movements NoAdd AddAll

FDR#1 (A330-223 PW) 1317 1.01 1.01

FDR#4 (A330-202 GE) 538 0.99 1.11 A330-200

FDR#4 (A330-243 RR) 711 0.98 1.03

SITA 5 - 1.30

FDR#1 (A340-313) 86 0.99 1.01 A340

FDR#4 (A340-500) 558 0.75 0.79

FDR#3 672 1.01 1.07 B767-300

FDR#4 588 1.10 1.32

Results from the fourth validation exercise are consistent with previous results.

Although modelled by a Rolls Royce engine in AEM3, all the three A330-200 validated so far show the same range of ratios. For this aircraft type, engine modelling is thus correct. On the other hand, the influence of engine modelling is determining for B767-300 (see section 3.3.3). It can thus be deduced that aircraft/engine match and modelling in AEM3 is a way of improvement to be considered for future evolutions of the tool. In particular, one aircraft type should be associable with different engines, either manually for a small specific study or respecting the repartition of world’s fleet.

Results for A340 are not surprising. Indeed FDR#1 actual aircraft was A340-300 equipped with a CFM56-5C4/P modelled by a A340-300 with CFM56-5C2 engines. As expected, AEM3 fuel burn estimation was particularly close to reality.

During FDR#4, the same modelling was used for an A340-500 with Rolls Royce engines. Neither airframe nor engine corresponds to the modelling, which explains a lower accuracy of AEM3 for this specific case.11. This example highlights a limitation due to BADA limited set of aircraft. Nevertheless, main aircraft types are modelled by BADA, which ensures that similar discrepancies have a minimal impact on the accuracy of AEM3 results in the scope of a whole study.

11 The airline experienced significant differences in term of fuel burn and emission when using Trent 500

(A340-500 &-600) or CFM engine (A340-300).


EEC/SEE/2006/007 23

3.4 Fuel flow analysis

3.4.1 Fuel flow evolution

The evolution of AEM3 fuel flow versus time regarding actual FDR#4 fuel flow was plotted for six12 aircraft types under study. A different distance range flight was picked out for each aircraft type in order to have a representative view of the sample.

The plots are presented in Figure 3-1 through Figure 3-6. In each figure, the blue curve represents fuel flow estimated by BADA in AEM3; the pink curve represents the real fuel flow provided with FDR data; and the dotted curve shows the flight profile. The scale used for this third curve refers to the secondary axis on the right of the plot. For more readability, the four plots were represented using the same scale.

B763 - 1800 km mission

0

1

2

3

4

5

6

7

8

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL

AEM FuelFlow (kg/s)FDR#4 FuelFlow (kg/s)AEM Flight Profile

Figure 3-1: Evolution of fuel flow – B763 – 1800 km mission

12 A330-RR and A330-GE were both represented by A332. Indeed no conclusion could be drawn from

comparison between two individual flights.


24 EEC/SEE/2006/007


0

1

2

3

4

5

6

7

8

0 5000 10000 15000 20000 25000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL


Figure 3-2: Evolution of fuel flow – B773 – 5900 km mission

A332 - 4400 km mission

0

1

2

3

4

5

6

7

8

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL


Figure 3-3: Evolution of fuel flow – A332 – 4400 km mission


EEC/SEE/2006/007 25


0

1

2

3

4

5

6

7

8

0 5000 10000 15000 20000 25000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL


Figure 3-4: Evolution of fuel flow – A345 – 5700 km mission

RJ1H - 650 km mission

0

1

2

3

4

5

6

7

8

0 500 1000 1500 2000 2500 3000 3500 4000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL


Figure 3-5: Evolution of fuel flow – RJ1H – 650 km mission


26 EEC/SEE/2006/007

RJ85 - 750 km mission

0

1

2

3

4

5

6

7

8

0 500 1000 1500 2000 2500 3000 3500 4000

Time (s)

Fuel

Flow

s (k

g/s)

0

50

100

150

200

250

300

350

400

450

FL


Figure 3-6: Evolution of fuel flow – RJ85 – 750 km mission


EEC/SEE/2006/007 27

Blue and pink curves for the six plots have the same trends. Fuel flows calculated by AEM3 are thus close to reality.

Plots are very similar to figures previously obtained for validation exercise #1 and #3 ([Ref 2.] and [Ref 8.]) and comments in "Evolution of Fuel Flow" section of [Ref 2.] remain valid here. Several further observations are nevertheless coming out with these new plots:

• If concentrating on the different aircraft types validated so far, it appears that over- and underestimations of AEM3 are dependent on aircraft type and flight phase. Indeed during climb, plots in the main validation report globally showed an overestimation of AEM3 regarding FDR, while an underestimation was visible for all aircraft types on the third validation exercise. This fourth validation exercise showed both tendencies depending on the aircraft type. This phenomenon comes from many factors among which the way aircraft are used regarding BADA assumptions.

• AEM3 remains sensible to every single change of altitude. This is noticeable on Figure 3-6 during the first minutes of the flight: climbing phase alternately with horizontal flight leads to a temporarily overestimation of fuel flow. This illustrates the importance of data granularity.

• The evolution of aircraft weight is visible for FDR#3 data (pink curve decreasing during cruise) but not directly considered in the current version of AEM3. Indeed an average distance flown by aircraft type, and thus an average weight all along a typical mission, are considered in BADA and this constant mass is used in AEM3. This has a small impact when aircraft actually perform shorter or longer missions. Tiny discrepancies would also appear in a leg by leg study; but it is clear from the plots that AEM3 uses an average value all along the cruise phase which lead to a correct fuel estimation if all the main cruise phase is considered.

3.4.2 Fuel flow limits

Similarly to three previous validation exercises, limits of actual fuel flow as absolute values were compared to the limits of modelled fuel flow determined with BADA and ICAO. Graphical representations are shown for each aircraft type addressed in this document on Figure 3-7 to Figure 3-12.


28 EEC/SEE/2006/007

Item plotted are the following:

• Real limits in the input data. Values are directly extracted from FDR#4 recordings. • BADA limits. This item corresponds to the minimum and maximum fuel flows indicated in the

BADA files used in AEM3. • ICAO13 limits for engine used by AEM3. This bar shows the range of fuel flows corresponding

to the engine used in AEM3. • ICAO limits for real engine. This bar shows the range of fuel flows corresponding to the

actual engine installed on the aircraft.

ICAO limits for real engine (2 X General Electric CF6-80C2)

ICAO limits for engine used by AEM3 (2 X PW4060)

BADA limits for B763 (B763)

Real limits for B763 in input data

0.0 1.0 2.0 3.0 4.0 5.0 6.0

FuelFlow (kg/s)

ICAO limits for real engine (2X General Electric CF6-

80C2)

ICAO limits for engine usedby AEM3 (2 X PW4060)


Real limits for B763 in inputdata

B763

Figure 3-7: Fuel flow limits – B763

13 ICAO Engine Exhaust Emissions Data bank [Ref 1.]


EEC/SEE/2006/007 29

ICAO limits for real engine (2 X GE90-115B1)

ICAO limits for engine used by AEM3 (2 X JT8D-7B)


Real limits for B773 in input data

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

FuelFlow (kg/s)

ICAO limits for real engine (2X GE90-115B1)

ICAO limits for engine usedby AEM3 (2 X JT8D-7B)


Real limits for B773 in inputdata

B773

Figure 3-8: Fuel flow limits – B773

ICAO limits for real engine (A330-GE) (2 X GE CF6-

80E1A4)

ICAO limits for real engine (A330-RR) (2 X Rolls Royce

Trent 772B-60)

ICAO limits for engine used by AEM3 (2 X Trent 772)

BADA limits for A332 (A332)

Real limits for A332 in input data

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

FuelFlow (kg/s)

ICAO limits for real engine (A330-GE) (2 X GE CF6-80E1A4)

ICAO limits for real engine (A330-RR) (2 X Rolls RoyceTrent 772B-60)

ICAO limits for engine used by AEM3 (2 X Trent 772)



A332

Figure 3-9: Fuel flow limits – A332


30 EEC/SEE/2006/007

ICAO limits for engine used by AEM3 (4 X CFM56-5C2)



0.0 1.0 2.0 3.0 4.0 5.0 6.0

FuelFlow (kg/s)

ICAO limits for engine usedby AEM3 (4 X CFM56-5C2)


Real limits for A345 in inputdata

A345

Figure 3-10: Fuel flow limits – A345

ICAO limits for real engine (4 X LF 507-1F)

ICAO limits for engine used by AEM3 (4 X LF507-1F, -1H)

BADA limits for RJ85 (RJ85)

Real limits for RJ85 in input data

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

FuelFlow (kg/s)

ICAO limits for real engine (4X LF 507-1F)

ICAO limits for engine usedby AEM3 (4 X LF507-1F, -1H)

BADA limits for RJ85 (RJ85)

Real limits for RJ85 in inputdata

RJ85

Figure 3-11: Fuel flow limits – RJ85


EEC/SEE/2006/007 31

ICAO limits for real engine (4 X LF 507-1F)

ICAO limits for engine used by AEM3 (4 X ALF 502R-5)

BADA limits for RJ1H (B461)

Real limits for RJ1H in input data

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

FuelFlow (kg/s)

ICAO limits for real engine (4X LF 507-1F)

ICAO limits for engine usedby AEM3 (4 X ALF 502R-5)

BADA limits for RJ1H (B461)

Real limits for RJ1H in inputdata

RJ1H

Figure 3-12: Fuel flow limits – RJ1H

Conclusions of the plots are similar to findings from other aircraft: real FDR#4 fuel flows do not fit either BADA nor ICAO fuel flow envelopes. Discussions included in section "Fuel Flow Limits" of [Ref 2.], [Ref 7.] and [Ref 8.] remain valid for the four new aircraft types.

3.5 Emissions estimation with AEM3

The estimation of level of realism for the NOx, CO and HC emissions is based on ANCAT and NASA projects, as detailed during the AEM3 validation exercise#1 [Ref 2.]. As a reminder, a brief summary of ANCAT and NASA findings can be found at the beginning of the following sections.


32 EEC/SEE/2006/007

3.5.1 NOx, CO and HC distribution

The NASA Scheduled Civil Aircraft Emission Inventories for 1992 [Ref 4.] indicates that the internal distribution between the three above pollutants should vary between 72.5 and 90% for Oxides of Nitrogen, 25 and < 10% for Carbon Monoxide and <1 - 2.5% for Hydrocarbon, dependent on the mission length. The estimation is based on Boeing standard mission profiles, for a mission range between 750 and 5500 km (400 NM and 3000 NM) for a B757-200.

Figure 3-13: Emissions Comparison of 757-200 for a 750 km and 5500 km Mission [Ref 5.]

Previous sections of the report foresaw a consequent amount of CO and HC regarding NOx emission for the FDR#4 data set.


EEC/SEE/2006/007 33

Table 3-4 shows that this prediction is respected.


34 EEC/SEE/2006/007

Table 3-11: Emission distribution for the whole study

NoAdd AddAll Aircraft Type

Number of movements % NOx % CO % HC % NOx % CO % HC

B767-300 588 72.30% 25.67% 2.03% 72.19% 25.76% 2.05%

B777-300 762 79.51% 16.23% 4.26% 77.89% 17.49% 4.62%

A330-GE 538 74.68% 24.32% 1.00% 74.36% 24.50% 1.14%

A330-RR 711 70.99% 28.04% 0.97% 70.87% 28.04% 1.09%

A340-500 558 66.82% 30.65% 2.53% 65.48% 31.65% 2.87%

ARJ-85 602 94.51% 5.31% 0.18% 85.74% 13.09% 1.17%

ARJ-100 612 57.45% 39.88% 2.67% 49.02% 46.82% 4.16%


EEC/SEE/2006/007 35

Figure 3-14 provides the same information in a graphic.

Figure 3-14: Emission distribution for the whole FDR#4 traffic sample

If ARJ family is ignored, NOx proportion evolutes between 65.48 and 79.51%, while CO varies from 16.23 to 31.65% and HC from 0.97 to 4.62%. These percentages are in accordance with NASA range of values obtained with a B757-200.

The situation for ARJ family is different: ARJ-85 presents very high NOx whereas the opposite situation is observed for ARJ-100. Both aircraft suffer from the following unsuitability.

• The reason for such a high CO and HC percentage lies in the extrapolation of emissions indices outside the ICAO fuel flows, as observed in section 3.4.2 “Fuel flow limits”. This extrapolation to further low fuel flows leads to very high emission indices for CO and HC.

• On the other hand, take-off weight for ARJ family in the FDR#4 data is particularly high regarding BADA’s averaged weight. Thrust thus has to be higher than required for a standard flight, especially during climbing and cruising phases. This leads to high NOx emissions.

Depending on which factor is predominant, the proportion of pollutant is affected.


36 EEC/SEE/2006/007

3.5.2 NOx average emission indices from ANCAT and NASA

NASA and ANCAT researchers have analyzed the NOx emission estimates for larger traffic inventories and calculated the amount of NOx emissions in relation to the estimated amount of fuel burn. These calculated values are called Average NOx Emission Indices (EINO).

This analysis led to the following estimations for average NOx Emissions Indices in g per kg fuel burn:

Table 3-12: Published average EINOx (g/kg) of reference project [Ref 6.]

ANCAT 1A ANCAT 2A NASA NASA 1992 1992 1990 1992

Horizontal resolution (°)

2.8 × 2.8 1 × 1 1 × 1 1 × 1

Vertical resolution (°)

1 1 1 1

EINOx (g/kg) 16.8 13.7 10.9 11.1

NASA results are based on Boeing Method 1 and Method 2.

ANCAT 1A results have been obtained using a thermo-dynamic NOx emission model which has been replaced during ANCAT 2 by the DLR NOx estimation method. The ANCAT/EC2 inventory in the base year 1991/1992 (published in 1998) estimates that the civil subsonic fleet average emissions index (EINOx: g NOx/kg fuel) is 13.7. This estimation is significantly lower than the previous ANCAT/EC1A study published in 1995 which indicated an average of 16.8 g NOx/kg fuel. This difference is due to revisions to the movement data base and use of a different methodology for the prediction of NOx at cruise altitudes.

The average NOx emission indices for the 4371 flights under study lie at 11.97g/kg fuel burn with NoAdd option and 12.02g/kg fuel burn with AddAll option. These results are both about 0.08% higher than NASA results [Ref 4.] from 1992 and respectively 0.13% and 0.12% lower than ANCAT2 results [Ref 5.].

Average EINOx for the fourth AEM3 validation exercise are perfectly in accordance with ANCAT and NASA findings, and similar to results from other validation exercises (especially #1 and #2).


EEC/SEE/2006/007 37

3.5.3 Emissions along the flight profiles

Figure 3-15 to Figure 3-20 show the evolution of NOx, CO and HC emission indices. Six14 typical flights are plotted as done for fuel flow in section "Fuel flow analysis: Fuel flow evolution". The flight profiles (flight level versus time) are also plotted and refer to the secondary axis on the right.

EINOx is expected to be highest during climb phase, remain high during cruise phase and decrease during descent phase. On the other hand, EICO and EIHC are supposed to be high during descent phase, where the combustion process is less complete.


0

10

20

30

40

50

60

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450

FL

EINOxEICOEIHCFL

Figure 3-15: Evolution of NOx, CO and HC emission indices – B763 – 1800 km mission

14 A330-RR and A330-GE were both represented by A332. Indeed no conclusion could be drawn from

comparison between two individual flights.


38 EEC/SEE/2006/007


0

10

20

30

40

50

60

0 5000 10000 15000 20000 25000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450

FL

EINOxEICOEIHCFL

Figure 3-16: Evolution of NOx, CO and HC emission indices – B773 – 5900 km mission


0

10

20

30

40

50

60

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450FL

EINOxEICOEIHCFL

Figure 3-17: Evolution of NOx, CO and HC emission indices – A332 – 4400 km mission


EEC/SEE/2006/007 39


0

10

20

30

40

50

60

0 5000 10000 15000 20000 25000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450

FL

EINOxEICOEIHCFL

Figure 3-18: Evolution of NOx, CO and HC emission indices – A345 – 5700 km mission

RJ1H - 650 km mission

0

10

20

30

40

50

60

0 500 1000 1500 2000 2500 3000 3500 4000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450FL

EINOxEICOEIHCFL

Figure 3-19: Evolution of NOx, CO and HC emission indices – RJ1H – 650 km mission


40 EEC/SEE/2006/007

RJ85 - 750 km mission

0

10

20

30

40

50

60

0 500 1000 1500 2000 2500 3000 3500 4000

Time (s)

EI (

g/kg

fuel

)

0

50

100

150

200

250

300

350

400

450

FL

EINOxEICOEIHCFL

Figure 3-20: Evolution of NOx, CO and HC emission indices – RJ85 – 750 km mission

The tendencies are verified in above figures and comments in "Emission along the flight profiles" section of [Ref 2.] remain valid here.

Once again, AEM3 appears as very sensible to climb or descent phases. Every single short climb leads to a peak of EINOx while descents lead to peaks of EICO and EIHC.


EEC/SEE/2006/007 41

4 CONCLUSIONS

The AEM3 validation exercise#4 confirmed results obtained during exercise#1, #2 and #3. As a conclusion of these four AEM3 validation exercises, AEM3 fuel burn estimation offers a high level of realism. AEM3 fuel burn is globally underestimated by -8 to -3% when no flight completion is required. In case of flight completion, the error on fuel burn lies around -8 to -1% underestimation if the error on duration is isolated. The error on duration is highly dependent on input data, and especially the percentage of flight profile actually described as well as horizontal and vertical speeds.

It is obvious that the better a real aircraft compares to the underlying aircraft model assumptions (BADA) in AEM3, the higher is the level of realism obtained by AEM3 for fuel burn and emissions estimation. The influence of take-off weight is significant as well as mission length for which aircrafts are designed.

The following figures compare AEM3 fuel burn estimation to actual FDR operational data for NoAdd and AddAll option, i.e. for the whole AEM3 validation exercise.


42 EEC/SEE/2006/007

Figure 4-1: The AEM3 fuel burn vs. operational fuel burn for 11721 flights (no flight completion)

Figure 4-2: The AEM3 fuel burn vs. operational fuel burn for 10929 flights (full flight completion)


EEC/SEE/2006/007 43

The correlation between AEM3 fuel burn and actual fuel burn is of high level for almost 11,000 flights corresponding to 21 different aircraft types.

As for previous validation exercises, emissions cannot be compared to actual data since such information was not available. Nevertheless they compare to NASA and ANCAT estimations which allows concluding that emissions indicated by AEM3 are realistic.

The four different AEM3 validation exercises exploited different kinds of data granularity leading to comparable positive results. Based on the good results for the 2115 aircraft types validated so far, it is assumed that the AEM3 fuel burn and emission estimation for other aircraft types is of similar quality. AEM3 validation for additional aircraft-types will continue with availability of FDR data.

15 18 different aircraft types validated with FDR data and 3 aircraft types validated with SITA data.


44 EEC/SEE/2006/007

5 REFERENCES

[Ref 1.] ICAO Engine Exhaust Emissions Data Bank; ICAO; Doc 9646-AN/943: First Edition – 1995; Internet Issue 1 (10/03/1998); Internet Issue 2 (08/02/1999), Internet Issue 10(19/05/2003)

[Ref 2.] The Advanced Emission Model (AEM3) Version 1.5 – Validation Report; EUROCONTROL Experimental Centre; Society, Environment and Economics Business Area; Jelinek, Carlier, Smith; EEC/SEE/2004/004

[Ref 3.] JP airline-fleets international Aviation Database – BUCHair UK ltd

[Ref 4.] Scheduled Civil Aircraft Emission Inventories for 1992: Database Development and Analysis; April 1996; NASA LRC; Contractor Report 4700; Steven L. Baughcum, Terrance G. Tritz, Stephen C. Henderson, David C. Picket

[Ref 5.] ANCAT/EC2: Global Aircraft Emissions Inventories for 1991/92 and 2015 – Report by the ECAC/ANCAT and EC working group – Editor R.M. Gardner

[Ref 6.] Impact de la flotte aérienne sur l'environnement atmosphérique et le climat; Rapport no.40, Décembre 1997, Institut de France, Académie des sciences – Académie Nationale de l'air et de l'espace

[Ref 7.] Advanced Emission Model (AEM3) v1.5 – Validation Exercise#2; EUROCONTROL Experimental Centre; Society, Environment and Economics Business Area; Jelinek, Carlier, Smith; EEC/SEE/2004/004

[Ref 8.] Advanced Emission Model (AEM3) v1.5 – Validation Exercise#3; EUROCONTROL Experimental Centre; Society, Environment and Economics Business Area; Jelinek, Carlier, Smith; EEC/SEE/2006/005


For more information about the EEC Society, Environment and Economy Research Area please contact:

Ted Elliff

SEE Research Area Manager,

EUROCONTROL Experimental Centre

BP15, Centre de Bois des Bordes

91222 BRETIGNY SUR ORGE CEDEX

France

Documents

GAES Advanced Emissions Model (AEM3) v1.5 - Validation … · 2019. 2. 18. · This validation exercise#4 also corroborated the influence of take-off weight (TOW) on the accuracy