Cradle to Grave Life Cycle Assessment and Carbon Footprint Analysis of Narrow Body Commercial Aircraft towards Sustainable Aviation
Abstract
This dissertation provides a cradle-to-grave Life Cycle Assessment (LCA) and carbon footprint analysis of narrow-body commercial aircraft, with a focus specifically on the Airbus A320 family. The study complies with ISO 14040/44 practices and uses PRISMA-directed data gathering to examine three major stages of the life cycle: manufacturing, operational, and end-of-life phase. At the production stage, the investigation encompassed raw materials extraction, intermediate forms, and final assembly, with a particular focus on aluminium alloys and carbon fibre reinforced polymers (CFRP), which were found both to have substantial embodied energy and GHG emissions. The operational phase was assessed based on the Well-to-Wake (WTW), Well-to-Tank (WTT), and Tank-to-Wake (TTW) frameworks, which cover Landing and Take-Off (LTO) cycles, cruise phase emissions, as well as maintenance activities. Results show that combustion of the fuel during the operational life is the main cause of life cycle emissions, accounting for a large share of aircraft carbon footprint. Yet manufacturing impacts are also significant, mostly because composite materials are used, while end-of-life activities, such as recycling, provide credits which only partly compensate for total impacts. Comparisons between various engine options showed significant differences in lifetime emissions. Newer engine technologies improved efficiency, but they weren't enough to change the operational dominance. The study also puts its results in the context of global rules, such as ICAO's CORSIA scheme, United Nations Sustainability Development Goals, the European Union Emissions Trading System (EU ETS), and IATA's promise to reach net-zero emissions by 2050. The research highlights the crucial role of sustainable aviation fuels (SAF), advanced propulsion systems, and circular economy strategies in mitigating aviation's environmental impact. This dissertation enhances the discourse on sustainable aviation by delivering a comprehensive environmental profile of narrow-body aircraft, offering pragmatic insights for policymakers, manufacturers, and operators seeking to align the industry with global climate objectives.
Full text
DE MONTFORT UNIVERSITY Master of Science in Engineering Management Master’s Degree Dissertation Cradle-to-Grave Life Cycle Assessment and Carbon Footprint Analysis of Narrow Body Commercial Aircraft towards Sustainable Aviation Supervisor: Candidate: Dr Leticia Ozawa-Meida Muhammet Cobanoglu Leicester,2025
pg. 2 Thanks to... Above all, I would like to thank those who have never stinted in their support since my childhood, my father and mother ‘Recep and Döndü Çobanoğlu”. I could not have achieved most of my successes without their love and dedication. Throughout my life, I have been blessed with an incredible family and a circle of friends whose unwavering sincerity and support have helped shape me into the person I am today. Lastly, I owe a debt of gratitude to all the teachers and lecturers, including my supervisor, Dr Leticia Ozawa-Meida, who have brought me to where I am today and made me an engineer passionate about my profession, without sparing their knowledge, effort, and patience throughout my educational journey.
pg. 3 Abstract This dissertation provides a cradle-to-grave Life Cycle Assessment (LCA) and carbon footprint analysis of narrow-body commercial aircraft, with a focus specifically on the Airbus A320 family. The study complies with ISO 14040/44 practices and uses PRISMA-directed data gathering to examine three major stages of the life cycle: manufacturing, operational, and end-of-life phase. At the production stage, the investigation encompassed raw materials extraction, intermediate forms, and final assembly, with a particular focus on aluminium alloys and carbon fibre reinforced polymers (CFRP), which were found both to have substantial embodied energy and GHG emissions. The operational phase was assessed based on the Well-to-Wake (WTW), Well-to-Tank (WTT), and Tank-to-Wake (TTW) frameworks, which cover Landing and Take-Off (LTO) cycles, cruise phase emissions, as well as maintenance activities. Results show that combustion of the fuel during the operational life is the main cause of life cycle emissions, accounting for a large share of aircraft carbon footprint. Yet manufacturing impacts are also significant, mostly because composite materials are used, while end-of-life activities, such as recycling, provide credits which only partly compensate for total impacts. Comparisons between various engine options showed significant differences in lifetime emissions. Newer engine technologies improved efficiency, but they weren't enough to change the operational dominance. The study also puts its results in the context of global rules, such as ICAO's CORSIA scheme, United Nations Sustainability Development Goals, the European Union Emissions Trading System (EU ETS), and IATA's promise to reach net-zero emissions by 2050. The research highlights the crucial role of sustainable aviation fuels (SAF), advanced propulsion systems, and circular economy strategies in mitigating aviation's environmental impact. This dissertation enhances the discourse on sustainable aviation by delivering a comprehensive environmental profile of narrow-body aircraft, offering pragmatic insights for policymakers, manufacturers, and operators seeking to align the industry with global climate objectives.
Table of Contents Table of Contents................................................................................................................................ 4 List of Tables ........................................................................................................................................ 6 List of Figures ....................................................................................................................................... 7 Acronyms and Abbreviations .......................................................................................................... 8 Chapter 1: Introduction ..................................................................................................................... 9 1.1. Relevance of the Project ............................................................................................ 10 1.2. Problem Definition and Contribution of the Study ............................................ 11 1.3. Aim and Objectives ..................................................................................................... 11 1.4. Contribution to UN Sustainable Development Goals ....................................... 12 SDG 9: Industry, Innovation and Infrastructure ............................................................. 12 SDG 12: Responsible Consumption and Production .................................................... 12 SDG 13: Climate Action ........................................................................................................ 12 1.5. Outline ............................................................................................................................. 13 Chapter 2: Literature Review ........................................................................................................ 14 2.1. ISO 14040/44 Framework for Life Cycle Assessment ..................................... 14 2.2. Regulations and Standards Relevant to the Aviation Industry ....................... 15 2.2.1. ICAO CORSIA ........................................................................................................... 15 2.2.2. European Green Deal & EASA Initiatives ......................................................... 15 2.3. Previous Research on LCA Studies ........................................................................ 16 2.3.1. Climate Change Mitigation Strategies in the Aviation Industry .................. 17 2.4. Chapter Summary ........................................................................................................ 18 Chapter 3: Methodology ................................................................................................................. 19 3.1. Research Design ........................................................................................................... 19 3.2. Life Cycle Assessment ................................................................................................ 19 3.2.1. LCA System Boundaries and Scope ................................................................... 20 3.2.2. Phase 1: Manufacturing (Cradle-to-gate) ........................................................... 20 3.2.3. Phase 2: Operational Usage................................................................................... 21 3.2.4. Phase 3: End-of-Life (EoL) ..................................................................................... 21 3.3. Data Collection Using the PRISMA Framework ................................................ 22 3.4. Data Analysis ................................................................................................................. 24 Chapter 4: Life Cycle Assessment ............................................................................................... 25
pg. 5 4.1. Phase 1: Aircraft Production (Cradle-to-Gate) .................................................... 25 4.1.1. Raw Material Extraction and Intermediate Process Stage .......................... 28 4.1.2. Assembly Stage ......................................................................................................... 29 4.1.3. Transportation ........................................................................................................... 30 4.1.4. Cradle-to-Gate Results ............................................................................................ 30 4.2. Phase 2: Operational Phase ...................................................................................... 32 4.2.1. Tank-to-Wake (TTW) .............................................................................................. 32 4.2.2. LTO vs. Cruise Emissions ...................................................................................... 34 4.2.3. Analysis of TTW Phase ........................................................................................... 34 4.2.4. Well-to-Tank (WTT) ................................................................................................ 36 4.2.5. Well-to-Wake (WTW) ............................................................................................. 37 4.2.6. Maintenance, Repair and Operations (MRO) .................................................. 38 4.3. Phase 3: End-of-Life (EoL) Treatment ................................................................... 40 Chapter 5: Discussion ...................................................................................................................... 43 Chapter 6: Conclusion ..................................................................................................................... 46 Appendices ......................................................................................................................................... 48 References ........................................................................................................................................... 52
pg. 6 List of Tables TABLE 1 FLEET SIZE IN OPERATION ............................................................................................................. 10 TABLE 2 A320 STRUCTURAL COMPONENTS AND MASS DISTRIBUTION OF THE AIRBUS A320 ....... 27 TABLE 3 AIRBUS A320 STRUCTURAL RAW MATERIAL EXTRACTION AND COMPONENT PRODUCTION ENERGY CONSUMPTIONS AND CO2-EQ EMISSIONS ............................................. 28 TABLE 4 A320 ASSEMBLY CONSUMPTIONS AND EMISSIONS BY RAW MATERIAL ............................... 29 TABLE 5 TTW PHASE EMISSIONS RESULTS BY ENGINES ......................................................................... 32 TABLE 6 JET-1A TANK-TO-WAKE (TTW) DETAILED RESULTS BY ENGINES ....................................... 34 TABLE 7 LTO & CRUISE PHASE LIFETIME GHG EMISSIONS RESULTS ................................................. 35 TABLE 8 WTT CO2-EQ EMISSIONS .............................................................................................................. 37 TABLE 9 WTW CO2-EQ EMISSIONS OF A320 LIFETIME BY ENGINE OPTIONS .................................. 38 TABLE 10 MATERIAL COMPOSITION, EMISSION FACTORS (EF), AND RECYCLING RATES FOR A320 AIRCRAFT ................................................................................................................................................. 41 TABLE 11 END-OF-LIFE CO₂ CREDITS BY MATERIAL ............................................................................... 41 TABLE 12 AIRBUS A320 LIFE CYCLE CO₂-EQUIVALENT EMISSIONS BY PHASE PER PASSENGERKILOMETRE .............................................................................................................................................. 45
List of Figures FIGURE 1 GLOBAL TRAFFIC OF FLIGHT DEPARTURES ................................................................................ 9 FIGURE 2 GLOBAL TRAFFIC OF PASSENGERS ............................................................................................... 9 FIGURE 3 LCA PHASES .................................................................................................................................... 14 FIGURE 4 LCA PHASES OF A320 AIRCRAFT ............................................................................................... 20 FIGURE 5 FLOW OF INFORMATION THROUGH DIFFERENT PHASES PRISMA FRAMEWORK ............ 23 FIGURE 6 LIFE CYCLE INVENTORY DIAGRAM ............................................................................................. 25 FIGURE 7 COMPONENT BREAKDOWN OF A320 .......................................................................................... 26 FIGURE 8 COMPARATIVE CO₂-EQ EMISSIONS OF RAW MATERIAL PROCESS & ASSEMBLY .............. 30 FIGURE 9 TOTAL EMISSIONS FOR PHASE 1 EXCEPT TRANSPORTATION BY MATERIAL ...................... 31 FIGURE 10 CRADLE-TO-GATE EMISSION PROPORTIONS .......................................................................... 31 FIGURE 11 COMPARATIVE TTW GHG EMISSIONS OF A320 LIFETIME ................................................ 36 FIGURE 12 ADDITIVE CO2-EQ CHART OF PHASE 1 AND PHASE 3 ......................................................... 42
Acronyms and Abbreviations CFRP Carbon Fibre Reinforced Polymer CO Carbon monoxide CORSIA Carbon Offsetting and Reduction Scheme for International Aviation EASA European Union Aviation Safety Agency EIA Environmentally Impact Assessment EOL End-of-life Eq Equivalent EU UTS European Union Emissions Trading System G Giga (109) gCO2 Gram Carbon dioxide GHG Greenhouse Gas GJ Gigajoule GWP Global Warming Potential HC Hydrocarbons IATA International Air Transport Association ICAO International Civil Aviation Organization ILCD International Life Cycle Data System IPCC Intergovernmental Panel on Climate Change ISO International Standards Organisation J Joule Kg Kilogram kgCO2 Kilogram Carbon dioxide Kt Kiloton KWh Kilowatt Hour kN Kilonewton LCA Life Cycle Assessment LCC Life Cycle Costing LCI Life Cycle Inventory LCIA Life Cycle Impact Assessment LTO Landing Take-Off Cycle M Mega (106) Mj Megajoule Mmt Million metric tons NOx Nitrogen Oxide PAX Passenger SAF Sustainable Aviation Fuel t Ton tCO2 Ton Carbon dioxide TTW Tank-to-Wake UN SDG United Nations Sustainability Development Goals WTT Well-to-Tank WTW Well-to-Wake
pg. 9 Chapter 1: Introduction The commercial aviation sector represents a growing share of the global transportation industry. Commercial aviation, regulated globally by the International Air Transport Association (IATA) and the International Civil Aviation Organization (ICAO), remains the preferred mode of transport while travelling long distances due to technological advancements and enhanced safety standards [1]. It is at the forefront of mobility choices, because it is a fast and safe choice. The number of flight and passengers, which decreased on a global scale due to health measures during the pandemic period, is remarkably close to the pre-pandemic period with total 4.2 billion passengers and 35.25 million departures in 2023. Data from June 2025 indicates that 4.8 billion passengers travelled in 2024, more than in the pre-pandemic period. In Figure 1 and Figure 2 these quantitative amounts are shown. Figure 1 Global Traffic of Flight Departures (millions) [1] Figure 2 Global Traffic of Passengers (billion) [2] IATA includes 341 airlines in 120 countries, representing more than 82% of global air traffic. This number includes the main airlines that operate large-scale and international flights. IATA's member list includes the most established and major players in the industry . Total worldwide fleet size currently counts 28,674 aircraft, with 23,513 active and 5,161 grounded [3]. A little over 14,350 of these aircraft are Airbus, and over 10,000 are Boeing . These numbers demonstrate that the two largest manufacturers in the commercial aircraft industry are Airbus and Boeing. Airbus, headquartered in Europe, and Boeing, based in the United States, are longstanding competitors and dominate the narrow-body aircraft market[2], [4]. Table 1 illustrates that most of the total commercial aircraft fleet consists of single-aisle passenger aircraft. Airbus' A320 family (A318, A319, A320, A321) dominates the industry with 11,563 aircraft. The most widely used aircraft model in this family is the A320. The A320 family consists of two primary variants: the A320ceo (current engine option) and the A320neo (new engine option). 38.79 22.47 24.92 31.21 35.25 0 5 10 15 20 25 30 35 40 45 2019 2020 2021 2022 2023 Millions 4.5 1.8 2.3 3.2 4.2 4.8 0 1 2 3 4 5 6 2019 2020 2021 2022 2023 2024 Billions
pg. 16 • Encouraging recycling and dismantling best practices via research under Clean Sky and Horizon Europe projects. The EASA [15] states that between 2013 and 2019, aviation CO₂ emissions rose by 5% yearly, while NOₓ emissions increased by 4% annually. The inclusion of cradle-to-grave life cycle assessment (LCA) into airline and manufacturer-level sustainability reporting is specifically called for in the report . Under these regulations and laws, the aviation industry must show transparent and measurable progress using internationally recognised assessment methods like ISO 14040/44-compliant LCA . Although there is not a certain aviation-specific LCA standard like ISO, practitioners frequently integrate ISO frameworks with databases particular to the sector, including EcoInvent, and frequently require customised process entries for aircraft manufacturing and materials. 2.3. Previous Research on LCA Studies While the body of existing literature offers a fundamental understanding of the environmental implications in aviation, a thorough, cradle-to-grave GHG footprint analysis for particular aircraft platforms, such as the Airbus A320, is still critically lacking [16]. An extensive life cycle assessment (LCA) of the Airbus A320 was carried out by Howe, Kolios, and Brennan [17], who found that although the operational phase accounts for the majority of an aircraft's GHG emissions, the manufacturing phase can account for as much as 15%. This includes impacts from the production of composite and aluminium materials, and component transportation between Airbus facilities. Although the main emphasis is on the operational and upstream manufacturing stages, Howe, Kolios, and Brennan's [17] study uses a cradle-to-grave system boundary structure to apply a life cycle assessment to commercial jet airliners. As opposed to a model-specific analysis, the functional unit used in this study is defined per aircraft, enabling comparisons across various aircraft types. The authors estimated material composition, fuel usage, and emissions primarily from secondary data sources, such as EcoInvent databases and published literature. Global warming potential (GWP), where operating emissions predominated, was the most important environmental impact found. Emissions from the manufacturing phase of composite and aluminium production followed second. However, recycling methods and endof-life scenarios were not fully taken into consideration in the study. Kolios [18] established a cradle-to-gate system boundary by focussing exclusively on the Airbus A320 manufacturing phase. Examining material flows and energy inputs per aircraft, the functional unit is based on a single A320 airframe. Using primary and secondary data, such as manufacturing process data and environmental databases like EcoInvent, the study applies process-based life cycle assessment (LCA). Important materials were evaluated, including titanium, carbon fibre reinforced polymer (CFRP), and aluminium. GWP, cumulative energy demand, and material-specific emissions are the primary environmental effects. The authors discovered that, despite its weight-loss benefits, CFRP production was the manufacturing process with the highest greenhouse gas emissions, underscoring a crucial trade-off between sustainable manufacturing and lightweight design [18]. The study by Bravo, Vieira, and Ferrer [19] worked on a partial LCA model with system boundaries focused on the production and operational phases of narrow-body aircraft, using aircraft similar to the A320. The functional unit was not clearly stated but can be inferred as
pg. 17 emissions per aircraft or per flight hour based on modelling assumptions. The study utilized computational LCA tools and a mix of scenario-based and simulation data, including logistics pathways, material innovations, and energy consumption estimates. The environmental impacts analysed include GWP and energy use, with the results showing that incorporating greener logistics and advanced materials significantly reduces emissions. Yet, the study highlighted that achieving 2050 emission targets requires deeper design innovations beyond incremental material changes. A scenario-based life cycle assessment (LCA) of the Airbus A320 was carried out by Lewis (2013) using a well-to-wake system boundary. Lewis`s LCA focused on the operational phase across three flight profiles: short-, medium-, and long-haul. It included emissions from fuel extraction, production, distribution, and combustion during flights (well-to-wake). In order to assess emissions efficiency across flight types, the functional unit was defined as CO₂ emissions per passenger-kilometre. The study's data sources included ICAO emission coefficients, fuel consumption data, and flight performance simulations. GWP was the primary environmental impact evaluated, and the findings showed that medium-haul flights demonstrated superior fuel and emissions efficiency, while short-haul flights produced disproportionately high emissions because of the frequent take-off and landing cycles [20]. However, the study did not consider upstream manufacturing emissions or end-of-life stages. Spagnulo [21] employed a hybrid Life Cycle Costing (LCC) and Life Cycle Assessment (LCA) approach to perform a combined sustainability analysis for the A320 production line. The system boundary extended from the extraction of raw materials to early operational use, but it did not fully include end-of-life processes. The functional unit was framed as "per aircraft system," with an emphasis on environmental and economic performance. Literature-based emissions factors, industry reports, and enterprise-level simulations were used to gather data. Energy consumption and recycling rates are among the environmental effects that are examined. While a comprehensive cradle-to-grave assessment is still lacking, the study found that circular design strategies (such as remanufacturing and materials reuse) can significantly improve both cost-efficiency and environmental performance [21]. Despite these valuable contributions, a critical research gap remains due to the lack of a consolidated LCA model specifically isolating and segmenting cradle-to-grave emissions for the Airbus A320 platform. Past research and literature have largely focused on specific phases, and a comprehensive report is lacking. This research will utilize and combine data from the literature to develop a comprehensive and interpretational overview LCA for the A320. 2.3.1. Climate Change Mitigation Strategies in the Aviation Industry The aviation sector has looked into a number of ways to reduce its impact on the climate in response to growing environmental concerns. One important strategy is the use of substitute lightweight materials, like carbon fibre reinforced polymer (CFRP), which lower aircraft weight and hence fuel consumption. But there is a sustainability trade-off because these materials also require a lot of energy to produce [18]. Alternative fuels, particularly Sustainable Aviation Fuels (SAF), have emerged as a key solution. SAFs can reduce life-cycle emissions by up to 80% compared to the conventional Jet-A1 fuel, depending on the feedstock and production method [22]. Airbus and Boeing have both committed to achieving 100% SAF capability across their fleets by 2030 [23]
pg. 18 Innovations in technology also play a big role. Because of better thermodynamic cycles and materials, next-generation engines like the LEAP-1A and PW1100G have 15–20% higher fuel efficiency than earlier models like the CFM56 [20]. The CFM56, which was jointly developed by CFM International (a joint venture between GE Aviation and Safran), entered service in 1974 and became one of the best-selling turbofan engines in commercial aviation history, powering aircraft such as the Airbus A320ceo and Boeing 737 families. With a bypass ratio of 6:1, it established the performance benchmark for future single-aisle propulsion systems [24] . Its successor, the CFM LEAP engine, which began running for the first time in 2016, is a significant technology step forward, having a bypass ratio of nearly 11:1 and delivering around 15% lower fuel burn compared to the CFM56 [25]. It is enabled by technology advances such as composite fan blades, ceramic matrix composites in the hot section, and higher pressure ratios enabling more efficient thermodynamics. At the same time, the Pratt & Whitney PW1000G, which also entered service in 2016, features a geared turbofan (GTF) architecture in which a reduction gearbox allows the fan and low-pressure turbine to operate at their optimal speeds. This setup has a bypass ratio of almost 12:1 and has been demonstrated to be 16–20% more fuel efficient than the older CFM56-powered variants [26]. Collectively, these next-generation engines illustrate how new cycles, lightweight materials, and novel architectures are enabling the step-change improvements in efficiency and emissions required for sustainable aviation. Circular economy approaches such as component reuse, remanufacturing, and materials recycling are gaining momentum. End-of-life recycling of aircraft components can reduce upstream emissions and material demand by up to 20% [27]. Additionally, initiatives like modular design are facilitating more efficient disassembly and recovery. 2.4. Chapter Summary The fundamentals of life cycle assessment (LCA), aviation-specific environmental regulations, important conclusions from earlier LCA studies, and new climate mitigation techniques in the aviation industry were all covered in this chapter. Although a lot of research has been done to assess different phases of aircraft life cycles, there is still a lack of comprehensive, model-specific, and current cradle-to-grave life cycle assessments, especially for the popular Airbus A320. Current research frequently concentrates on discrete stages, like production or operations, without incorporating results into an all-encompassing sustainability evaluation. By providing a unified and interpretative LCA framework tailored to the A320 platform, this dissertation seeks to close that research gap.
pg. 19 Chapter 3: Methodology The chapter explains how the research was carried out. It introduces the LCA framework from ISO 14040/44, sets the study boundaries, and describes the functional units chosen for analysis. It also outlines how data was gathered using the PRISMA approach and how the production, operation, and end-of-life phases of the aircraft were examined to understand their CO2-eq environmental impacts. All data in this dissertation are reported using standard SI/ISO units (e.g., g, kg, tonne, kN, MJ, GJ) to ensure clarity and consistency. The use of these internationally recognised units allows results to be easily compared with other studies and aligns the analysis with global research and reporting standards. 3.1. Research Design This study employs a desk-based Life Cycle Assessment (LCA) methodology and draws on secondary data from industry publications, peer-reviewed academic research, and publicly accessible databases (such as DEFRA, EcoInvent, and CCalC). Assessing the environmental impact of an Airbus A320 aircraft with various engine types (CFM56, LEAP1A, and PW1100) is the main objective (see Section 1.3). In order to preserve methodological precision, the literature review uses the PRISMA framework, which organises the search, screening, and selection of research relevant to life cycle analysis, aviation sustainability, and fuel emissions [28]. The research design adopts a cradle-to-grave system boundary, encompassing manufacturing, transportation, operational use (via a well-to-wake scope) , and end-of-life recovery. This design is directly linked to the study objectives, which aim to quantify life cycle emissions of the Airbus A320, compare engine alternatives, and evaluate alignment with sustainability targets. To achieve these objectives, specific methods were employed. • To estimate life cycle emissions is achieved by applying an LCA framework populated with data from prior research across various flight profiles. • To compare the operational emissions of CFM56, LEAP-1A and PW1127G engines. This is conducted using well-to-wake emissions modelling, incorporating ICAO certified emission indices and fuel consumption data available from literature and regulatory databases [29]. • To link technological improvements to the UN Sustainable Development Goals (SDGs) is addressed through a qualitative mapping exercise aligned with SDG Targets. 3.2. Life Cycle Assessment In accordance with international standards, this study will use a thorough Life Cycle Assessment (LCA) approach to measure and examine the environmental effects of the Airbus A320 over the period of its entire lifespan. Goal and Scope Definition, Life Cycle Inventory (LCI) Analysis, Life Cycle Impact Assessment (LCIA), and Interpretation are the four interdependent phases (see Figure 3) that make up the International Organization for Standardization's (ISO) stringent standards for the Life Cycle Assessment (LCA) process. In this study, the four phases of LCA are applied to the Airbus A320. The goal and scope are to measure cradle-to-grave impacts over a 20-year lifetime and to compare efficiency per passenger-kilometre. The functional unit provides the reference point against which results are measured, and here two units are chosen. The first is one Airbus A320 over
pg. 20 its lifetime, which shows the total cradle-to-grave impact of a single aircraft. The second is one passenger-kilometre (pkm), which reflects the efficiency of carrying a passenger over distance. The lifetime unit highlights the overall burden, while the pkm unit allows comparisons across aircraft types and is consistent with industry and regulatory practice such as CORSIA and the EU ETS. The system boundary covers raw material extraction, manufacturing, operation (wellto-wake), and end-of-life. The inventory analysis compiles data on materials, fuel burn, flight hours and emissions from sources such as ICAO, Airbus and EcoInvent. In the impact assessment, these data are translated into indicators such as CO₂-equivalent and resource use. Finally, the interpretation identifies the dominant life cycle stages, acknowledges uncertainties, and highlights opportunities for improvement through advanced engines and sustainable fuels. 3.2.1. LCA System Boundaries and Scope Figure 4 illustrates that the LCA considered in this dissertation consists of 3 phases. When conducting an LCA on a cradle-to-grave basis, it is necessary to grab a period from the raw materials to the end-of-life treatment. As can be seen in Figure 4, the phases include the manufacturing process, the active operational use period of the aircraft after the cradle-to-gate phase, and end-of-life treatment. Figure 4 LCA Phases of A320 Aircraft 3.2.2. Phase 1: Manufacturing (Cradle-to-gate) This phase includes every upstream process used in the manufacture of the aircraft, from the extraction of raw materials to the final step of assembly. Based on the process-based LCA approach used by Kolios [18] and Spagnulo [21], the key components assessed include: • Energy consumption in material processing and assembly lines. • Logistics: Inter-facility transportation of fuselage, wings, engines, and subsystems across Airbus facilities in Europe. • Material production: This study uses only secondary data available in published academic literature, reports and LCA databases (e.g., DEFRA, EcoInvent, CCalC). The material scope is limited to aircraft components for which emission and material inventory data are publicly available. The included materials are: ➢ Aluminium alloys, CFRP, steel, and titanium for structural components ➢ Jet-A1 fuel for operational emissions. Phase 1 Manufacturing Phase 2 Maintenance Operational Fuel Usage Phase 3 End of Life
pg. 21 Materials excluded due to lack of publicly available data include textiles, cabin plastics, adhesives, paints, and in-flight entertainment systems. These components typically represent less than 1% of aircraft mass and are considered to have negligible impact on total life cycle emissions. The exclusion is justified based on data availability and methodological transparency. 3.2.3. Phase 2: Operational Usage The operational phase represents the most GHG-intensive part of the aircraft's life cycle. This phase includes: • Flight emissions during all typical operational stages: Landing Take-Off (LTO) cycle and Cruise. • Engine options comparison between the CFM56 (A320ceo), LEAP-1A (A320neo) and PW1127G with the latter providing significant gains in fuel efficiency. This study examines the effects of the engine options with three important engine options in the Airbus A320 series. With more than 33,000 delivered, the CFM56 is the bestselling commercial jet engine in the world, mainly powering the Boeing 737 and Airbus A320ceo aircraft [30]. LEAP‑1A was introduced in 2016 with the A320neo, provides approximately 15% lower fuel consumption and CO₂ emissions compared to CFM56 equipped aircrafts [31]. Since it is so common, it is the natural basis for comparison. Lewis [20] introduced a well-to-wake model considering three operational flight profiles (short-haul, medium-haul, long-haul), finding that short-haul routes produce disproportionately high emissions per passenger-kilometre (PAX-km) due to frequent take-off and landing cycles . In the context of Lewis’s study, the flight profiles are categorised based on typical sector lengths, short-haul (0–1,500 km), medium-haul (1,500–4,000 km), and long-haul (above 4,000 km). Howe [17] similarly identified the operational stage as contributing over 70% of the total life cycle emissions of commercial passenger aircraft. In this study, the operational phase is modelled to represent the lifetime of one Airbus A320 over 20 years. This corresponds to around 30,000 flights, 55,000 flight hours and about 45 million kilometres in total (see Table A1). On average each flight carries 147 passengers over a distance of 1,485 km. To reflect different patterns of use, flights are grouped into shorthaul, medium-haul and long-haul, following Lewis [20]. These assumptions connect the analysis with the functional units of per aircraft and per passenger kilometre and provide a realistic picture of how emissions accumulate throughout the aircraft’s service life. 3.2.4. Phase 3: End-of-Life (EoL) The EoL phase covers the disassembly, recycling, and disposal of the aircraft and its materials. Although this stage contributes a smaller portion of total emissions, it plays a critical role in circularity and sustainability. Spagnulo [21] highlighted that modular design and improved recycling strategies could enhance material recovery rates and reduce landfill dependency. In contrast, older models with lower recyclability ratios impose greater environmental costs post-retirement.
pg. 22 Based on methodologies presented by Cox [27], emissions savings from recycling are factored as environmental offsets against manufacturing burdens. The authors suggest that well-managed EoL strategies can reduce upstream material demand by up to 20%. For the End-of-Life phase, the Airbus A320 was broken down into its main material groups: aluminium, CFRP composites, titanium, steel, and smaller fractions such as copper, plastics and wiring (see Table 10). The approach follows ISO 14040/44 and the avoided burden method, where recycled material is assumed to replace virgin production. Each material was assigned a recycling rate based on industry averages and Aircraft Fleet Recycling Association (AFRA) guidelines. Aluminium and steel were treated as highly recyclable, titanium as moderately recyclable, and copper and other materials with partial recovery. CFRP, however, was given only a very small recovery rate, since fibre recycling technologies remain limited. For every material, the model uses emission factors for both primary and secondary production from EcoInvent and literature. The difference between the two values shows the potential saving per kilogram when recycling is applied. This saving is then multiplied by the total mass of each material and its recycling rate to estimate its environmental credit. In this way, the methodology captures both the benefits of materials like aluminium, which can be recovered efficiently, and the challenges posed by CFRP, which continues to be difficult to recycle. The process provides a structured way to include end-of-life treatment into the overall cradle-to-grave analysis of the aircraft. Together, these three phases form the comprehensive structure of the cradle-to-grave LCA model adopted in this study. The segmentation facilitates better understanding of where mitigation strategies can be most effective in reducing the total carbon footprint of commercial aviation systems. In addition, evaluations will be made on the basis of reuse and circular economy, and alternative solutions will be presented in Chapter 5. 3.3. Data Collection Using the PRISMA Framework The systematic literature review for this dissertation follows the PRISMA framework (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), which provides a structured and transparent method for identifying, screening, and synthesizing relevant literature [32]. All stages of PRISMA Framework can be seen in Figure 5. PRISMA is designed to improve the clarity, quality, and reproducibility of systematic reviews, especially where studies come from diverse disciplines such as environmental science, industrial engineering, and sustainable aviation. It ensures that the literature selection process is objective and minimizes bias through documented inclusion and exclusion criteria [28]. In this study, PRISMA was applied to gather and filter a wide body of literature related to Life Cycle Assessment (LCA) in commercial aviation. This framework aligns with the aim of compiling cradle-to-grave GHG data and literature on the Airbus A320 by enabling a comprehensive and unbiased synthesis of existing findings. The following databases were accessed to ensure coverage of both academic and grey literature: • ScienceDirect
pg. 23 • Scopus • Web of Science • SpringerLink • ICAO / EASA / Airbus / EU Commission / IATA Reports • ResearchGate • DMU Library • Google Scholar Examples of search strings include: • "Life Cycle Assessment" and "Airbus A320" • "Cradle-to-grave" and "aircraft emissions" • "Sustainable aviation fuel" and "carbon footprint" • "End-of-life aircraft recycling" and "narrow-body aircraft" While researching the literature and data, a few criteria were set for inclusion. These are: • Published between 2007–2025. • Studies on aircraft LCA, sustainable aviation fuel, aircraft material lifecycle. • Peer-reviewed journal articles, conference proceedings, industry whitepapers and environmental reports, business reports. Some of literature and data have been excluded due to: • Non-aviation-related LCA studies. • Wide-body aircraft analyses without relevance to narrow-body segment. • Studies lacking transparent methodology or full-text access. Figure 5 Flow of Information Through Different Phases PRISMA Framework [32] Included Studies included in synthesis (n=20) Eligibility Full-text articles assessed for eligibility (n=42) Full-text articles excluded ,with reasons (n=22) Screening Records after duplicates removed (n=42) Records screened (n=42) Records removed (n=0 at this stage) Identification Records idenfitied through database (n=43) Records idenfitied through other sources (n=22)
pg. 24 Although PRISMA originated in medical sciences, its use in engineering and sustainability research is growing rapidly due to the increasing demand for transparency in systematic reviews involving multi-source datasets [32]. This approach was particularly suited for this dissertation, given the fragmented and multi-dimensional nature of LCA literature on the Airbus A320 platform. The PRISMA framework-based literature selection procedure is depicted in the diagram in Figure 5. Through literature searches, 65 resources were found in the first pool. 42 full-text documents were evaluated for eligibility after duplicates were eliminated, and inclusion/exclusion criteria were applied. In the end, 20 studies which covered different LCA stages, technologies, and aircraft types relevant to the Airbus A320 were included into the final synthesis. 3.4. Data Analysis This research adopts a quantitative desk-based approach, grounded entirely in secondary data extracted from peer-reviewed literature, official regulatory sources , and aviation industry reports (e.g. IATA, Airbus). Existing LCA results, fuel burn data [29], and emission indices are methodically collected from academic studies rather than using any private or raw databases. In this study, all results were normalised to the functional unit of one Airbus A320 over a 20-year service life. This was modelled as around 32,220 flights, 55,000 flight hours and 45 million kilometres travelled (see Table A1). Data from different sources, such as fuel burn or emissions per flight or per hour, were scaled to this baseline so that everything referred to the same aircraft lifetime. In addition, values were also expressed per passenger-kilometre using an average capacity of 147 seats and an 80% load factor. This approach ensured that results could be compared consistently across engines, flight profiles and life cycle phases. This literature-based methodology ensures transparency, traceability, and feasibility while enabling evidence-driven evaluation of current and emerging aircraft design strategies.
pg. 25 Chapter 4: Life Cycle Assessment LCA requires collecting all environmentally significant flows associated with a product or activity. These consist of waste, energy, materials, emissions, and natural resources. Included are all flows associated with the manufacture, usage, and end-of-life phases of a product's life cycle. A product's life cycle environmental impacts are defined as the totality of these environmental flows. The flow model for an A320 aircraft is shown in Figure 6. From the extraction of raw materials to the disposal of end-of-life materials, it describes the life cycle steps in order, with matching inputs (materials, energy, and transportation) and outputs (waste and emissions) at each stage. This is a classical LCI representation, focusing on quantifying elementary flows in and out of the techno sphere for each subsystem. Figure 6 Life Cycle Inventory (LCI) Diagram A systematic LCI framework for the Airbus A320, consisting of three different phases. Manufacturing, usage, and decommissioning. This system boundary technique has been used regularly in several LCA studies, including Lopes [33], Cox [27], and Howe [17]. It is in accordance with ISO 14040/14044 standards [12]. The CCalC2 LCA tool and its embedded datasets with the EcoInvent (v2.2)[34] database were used to calculate quantitative inputs and outputs for background life cycle inventories. In addition, at the points where the datasets were insufficient, the most up-to-date and consistent data were preferred by making use of the literature and publications. By preferring articles that clearly provide unitary data, especially in Phase 1 calculation, it is aimed to calculate the unit constants (kgCO2, MJ) in the most up-to-date and consistent way by making a comparative article search. Although the basic functional unit (f.u) during LCA was based on 1 Aircraft, it was evaluated as Passenger-km (PAX-km) for comparison in the operational phase. In addition, the calculations were mass-based. Although process-based LCAs are more consistent and detailed, mass-based analysis, which is more accepted, has been performed due to both the lack of publicly available data and limited resources about changing and developing technologies. 4.1. Phase 1: Aircraft Production (Cradle-to-Gate) During Phase 1, raw materials are extracted, intermediate processing is carried out, and final components are manufactured. Materials such as aluminium, CFRP, steel, and
pg. 32 European Union. More accurate and realistic assumptions could come off as more negative results. 4.2. Phase 2: Operational Phase Aviation is a significant contributor to environmental impacts, not only from fuel combustion (CO₂ and other exhaust gases) but also from Maintenance Repair and Operations (MRO) and fuel production. To fully understand an aircraft’s environmental footprint, a life cycle assessment (LCA) is used, considering all stages from fuel production (well) to combustion (wake) and including maintenance operations. In this report, the selected functional unit considers 20 years operational life of an Airbus A320 aircraft (45 million km of travel) carrying ~147 passengers on average (about 81.5% load factor). 4.2.1. Tank-to-Wake (TTW) Tank-to-Wake (TTW) emissions refer to the greenhouse gas output generated directly during the combustion of fuel. In aviation, TTW covers the emissions primarily in the form of carbon dioxide (CO₂) released into the atmosphere when the chemical energy of the fuel is converted into mechanical energy within the aircraft engine. This stage is assessed independently from upstream processes such as fuel extraction, transportation and storage, focusing solely on the combustion phase. Especially today, more environmentally friendly engines and fuels are preferred in the field of aviation. The amount of GHG emitted by three different engines in use in A320ceo and A320neo aircraft due to operation under the same conditions and life-span will be shown. Each engine’s performance and emissions profile differ due to technological advancements (e.g. higher bypass ratios and advanced combustors), which in turn influence the LCA results. The A320's life cycle GHG footprint is dominated by the operational usage phase because manufacturing and EoL emissions are greatly outweighed by fuel burn throughout the course of 20 years of service. The ICAO Engine Emissions Databank [29] fuel flow/emission index data and a standard flight profile (ICAO LTO cycle & cruise [37] are used to quantify the overall fuel consumption and CO₂ emissions of an A320 over its lifetime. Table 5 summarizes the results for three engine configurations. The baseline is A320ceo with CFM56-5B5/3 engines, and the A320neo with either LEAP-1A26/26E1 or PW1127G-JM engines per flight on average. The functional unit is taken as both total emissions per aircraft lifetime and normalized emissions per passenger-kilometre (kgCO₂eq/pkm) for comparability. Engine Configuration Fuel Use (t) CO₂ Emitted (t) Emissions per pkm (kgCO₂-eq) A320ceo CFM56-5B5/3 (Jet-A1) 122,500 387,047 0.0586 A320neo LEAP-1A26/26E1 (Jet-A1) 109,300 345,406 0.0523 A320neo PW1127G-JM (Jet-A1) 99,500 313,930 0.0475 Table 5 TTW Phase Emissions Results by Engines CO₂-equivalent (CO₂-eq) emissions for every engine type and flight phase are calculated in this study using the measured or modelled fuel mass burnt. The generic formula is used to convert fuel mass to CO₂-eq mass: 𝐶𝑂2𝑒𝑞(𝑡)= 𝐹𝑢𝑒𝑙 𝑀𝑎𝑠𝑠(𝑡)× 𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟( 𝑡 𝐶𝑂2 𝑡 𝐹𝑢𝑒𝑙)
pg. 33 The emission factor utilized in this analysis for Jet-A1 aviation fuel is 3.16 tCO₂ per ton of fuel consumed. According to the IPCC's definition and the ICAO environmental modelling guidelines, this factor is based on Jet-A1's carbon content and the molecular weight ratio of CO₂ to carbon [37]. Although they are also by-products of combustion, hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOₓ) contribute very little to the total CO₂equivalent value when compared to the CO₂ generated from fuel oxidation. The combined global warming potential of HC, CO, and NOₓ emissions, for example, usually amounts to less than 1% of the CO₂-equivalent value resulting from fuel consumption in traditional kerosenepowered aircraft, according to ICAO and IPCC research. The CO₂-eq calculation in this study did not include these species due to their low proportional impact and to preserve methodological simplicity. Fuel-derived CO₂, which accounts for the majority of operating greenhouse gas emissions from jet aircraft, continued to be the main emphasis. The baseline A320ceo configuration, equipped with CFM56-5B5/3 engines, is estimated to consume approximately 1.225 × 10⁵ tonnes of Jet-A1 fuel over its 20-year operational lifespan, corresponding to 3.87 × 10⁵ tCO₂-eq. Under the stated assumptions, this equates to roughly 0.0586 kgCO₂ per passenger-kilometre (pkm). Replacing the CFM56 engines with more efficient LEAP-1A26/26E1 turbofans, as in the A320neo, reduces lifetime fuel consumption to 1.093× 10⁵ t (3.454 × 10⁵ tCO₂-eq), representing an approximate 11% reduction in operational greenhouse gas (GHG) emissions relative to the baseline. An even greater improvement is observed with the PW1127G-JM geared turbofan, which consumes 0.995 × 10⁵ t of fuel (3.139 × 10⁵ tCO₂-eq) over the same period, achieving about 18% lower operational GHG emissions compared with the CFM56 configuration. This corresponds to 0.0475 kgCO₂/pkm, versus 0.0586 kg CO₂/pkm for the baseline. These results align with the anticipated performance enhancements of the A320neo program, wherein next-generation engines like the LEAP-1A and PW1100G generally yield fuel efficiency gains of 15–20% above the CFM56 series. Although the smaller-than-stated reduction for the LEAP-1A in this model (11% vs. 15% claimed) may be explained by realworld operational factors (such as route structure, average flight length, and engine power settings), both new engine types clearly outperform the legacy CFM56 in terms of fuel consumption and related CO₂ emissions. Detailed phase-by-phase results for the three engine configurations are presented in Table 6.
pg. 34 Phase Fuel (t) CO2-eq (t) CFM56-5B5 Total 122,483.11 387,046.63 CFM56 Taxi (2x) 8,674.35 27,410.94 CFM56 Take-Off 2,269.40 7,171.31 CM56 Climb 5,927.71 18,731.57 CFM56 Cruise 94,833.99 299,675.40 CFM56 Approach 10,777.66 34,057.41 LEAP-1A26/26E1 Total 109,305.86 345,406.52 LEAP-1A Taxi (2x) 8,580.06 27,113.00 LEAP-1A Take-Off 2,185.63 6,906.59 LEAP-1A Climb 5,664.44 17,899.62 LEAP-1A Cruise 89,336.36 282,302.91 LEAP-1A Approach 3,539.37 11,184.40 PW1127G-JM Total 99,345.23 313,930.92 PW1127G Taxi (2x) 7,542.91 23,835.60 PW1127G Take-Off 2,030.78 6,417.28 PW1127G Climb 5,345.31 16,891.19 PW1127G Cruise 81,089.93 256,244.18 PW1127G Approach 3,336.29 10,542.67 Table 6 Jet-1A Tank-to-Wake (TTW) Detailed Results by Engines 4.2.2. LTO vs. Cruise Emissions Fuel flow data were segmented into standard operational phases to assess emissions during the Landing/Take-Off (LTO) cycle versus cruise. A complete flight cycle, including taxi, take-off, climb and approach, consumes approximately 600 to 680 kg of fuel for the A320 (two engines combined). For example, the CFM56-5B5/3 (2 unit) burns about 686 kg per LTO cycle, whereas the PW1127G-JM requires only 606 kg under identical conditions, representing a 12% reduction due to its higher bypass ratio and more efficient thermodynamic cycle. The LEAP-1A26/26E1 lies between these two, at 660 kg per LTO cycle, a 4% reduction compared with the CFM56 baseline. These reductions in high-thrust phases translate directly into proportionally lower CO₂ emissions for the A320neo engines during take-off and climb. However, over the aircraft’s lifetime operational distance, cruise fuel burn accounts for the majority of total emissions. In this study, cruise represented approximately 80% of total fuel consumption, for instance 9.48 × 104 t for the CFM56 configuration.. The detailed calculation results and inputs are presented in Table 6, Table A2 and Table A6 in the appendices. While the original data sources are explicitly presented and cited, reasonable engineering assumptions were applied in cases where complete datasets were unavailable. 4.2.3. Analysis of TTW Phase Table 7 presents operational phase emissions and fuel use for three A320 engine configurations. The totals at the bottom of each engine section are consistent with the phaseby-phase sums for HC (Hydrocarbons), CO (Carbon Monoxide), NOx (Nitrogen Oxides), and fuel consumption. The distribution of thrust percentages and thrust (kN) aligns with ICAO Landing and Take-Off (LTO) cycle definitions and cruise profiles.
pg. 35 Engine Data HC (t) CO(t) NOx(t) THRUST (%) THRUST (kN) FUEL (t) CFM565B5/3 Taxi (2x) 30.79 362.33 33.05 7.00 13.71 8,674.35 Take-Off 0.07 0.34 37.26 100.00 195.80 2,269.40 Climb 0.18 1.19 83.05 85.00 166.43 5,927.71 Cruise 28.45 94.83 1,138.01 25.00 48.95 94,833.99 Approach 0.47 29.28 47.60 30.00 58.74 10,777.66 Total 59.96 487.97 1,338.97 - - 122,483.11 LEAP1A26/26E1 Taxi (2x) 2.49 185.59 39.55 7.00 16.88 8,580.06 Take-Off 0.04 0.52 67.32 100.00 241.20 2,185.63 Climb 0.11 1.47 75.79 85.00 205.02 5,664.44 Cruise 22.33 71.47 848.70 25.00 60.30 89,336.36 Approach 0.14 9.38 30.97 30.00 72.36 3,539.37 Total 25.12 268.43 1,062.33 - - 109,305.86 PW1127GJM Taxi (2x) 3.47 185.03 39.22 7.00 16.86 7,542.91 Take-Off 0.14 0.55 42.26 100.00 240.88 2,030.78 Climb 0.37 1.92 90.60 85.00 102.37 5,345.31 Cruise 16.22 56.76 689.26 25.00 120.44 81,089.93 Approach 0.20 16.31 35.33 30.00 72.26 3,336.29 Total 20.40 260.58 896.68 - - 99,345.23 Table 7 LTO & Cruise Phase Lifetime GHG Emissions Results For LTO modes (idle/taxi, take‑off, climb‑out, approach) the ICAO sheets give emission indices in g pollutant per kg fuel (g/kg) and fuel flow in kg/s (with mode times). These quantitative details are given in Table A1 and Table A2 in appendix section. It is taken into account that the aircraft has 2 engines. Since GHG production depends on the amount of fuel consumption, there is no multiplier effect, but since fuel consumption is given per unit engine in ICAO (2025) data, the double value is taken into account. For any LTO or Cruise mod, results are calculated by the equation: 𝐺𝐻𝐺 𝑀𝑎𝑠𝑠 (𝑡)=(𝐹𝑢𝑒𝑙𝑚𝑜𝑑𝑒[𝑘𝑔]) × (𝐸𝑙[𝑔/𝑘𝑔]) 106 • El: Emission Factor by mode (see Table A2). In terms of lifetime fuel consumption, the baseline CFM56-5B5/3 engine configuration uses 122,483 tonnes of Jet-A1 over 20 years of operation. The LEAP-1A26/26E1 reduces this to 109,306 tonnes, which is a 10% decrease compared with the baseline. The PW1127G-JM achieves the lowest total at 99,345 tonnes, representing a 18.9% reduction. Across all three engine types, the cruise phase is the dominant contributor to total fuel consumption, accounting for 78% for the CFM56, 81% for the LEAP-1A, and 82% for the PW1127G. For the taxi and take-off phases combined, the CFM56-5B5/3 consumes 8,674.35 tonnes during taxi and 2,269.40 tonnes during take-off, for a total of 10,943.75 tonnes. The LEAP-1A burns 8,580.06 tonnes in taxi and 2,185.63 tonnes in take-off, totalling 10,765.69 tonnes (a 1.63% reduction). The PW1127G-JM records 7,542.91 tonnes for taxi and 2,030.78 tonnes for take-off, totalling 9,573.69 tonnes, which is 12.50% lower than the CFM56 baseline.
pg. 36 During climb, the CFM56 consumes 5,927.71 tonnes, the LEAP-1A 5,664.44 tonnes (a 4.45% reduction), and the PW1127G 5,345.31 tonnes (a 9.82% reduction). This indicates that the PW engine delivers greater fuel efficiency during high-power climb operations. Certain aspects of engine design are associated with these performance improvements. With composite fan blades, a high bypass ratio of 11.10, and enhanced aerodynamic efficiency, the LEAP-1A has a lower specific fuel consumption (SFC) than the CFM56, which has a bypass ratio of 6.00. The geared turbofan architecture of the PW1127G-JM decouples the fan from the low-pressure turbine, enabling both to run at their ideal rotational speeds and increasing efficiency during all flight phases. In conclusion, compared to the CFM56 baseline, the LEAP-1A and PW1127G both produce measurable decreases in lifetime fuel consumption and CO₂ emissions. While the PW1127G demonstrates the most noteworthy advantages, especially in the cruise and highthrust phases, the LEAP-1A produces moderate savings throughout all phases, which is in line with the A320neo program's efficiency goals. In Figure 11, visualized in a comparative format the total GHG emissions for each engine type for better demonstrating. Figure 11 Comparative TTW GHG Emissions of A320 Lifetime 4.2.4. Well-to-Tank (WTT) WTT emissions account for the upstream processes before fuel combustion. These include the energy requirements of oil extraction, refinery processing, and the logistics of moving fuel to airports. According to the UK Government’s Greenhouse Gas Reporting Conversion Factors 2025 dataset [38] the WTT emission factor for aviation turbine fuel is 661.79468 kgCO₂eq/t fuel. 𝑊𝑇𝑇 𝐶𝑂2𝑒𝑞 (𝑡)= 𝐹𝑢𝑒𝑙 𝑀𝑎𝑠𝑠 (𝑡)× 0.66179468( 𝑡 𝐶𝑂2 𝑡 𝐹𝑢𝑒𝑙) The total WTT emissions for each engine types for 2 unit, calculated using the DEFRA 2025 factor of 0.66179468 tCO₂ per tonne of fuel, are shown in Table 8. HC CO NOx CFM56-5B5/3 60 488 1338 LEAP-1A26/26E1 25 268 1062 PW1127G-JM 20 261 896 60 488 1338 25 268 1062 20 261 896 TON/LIFE-SPAN
pg. 37 Engine Fuel Mass (t) WTT CO2-eq (t) CFM56-5B5/3 122,483.11 81,058.67 LEAP-1A26/26E1 109,305.86 72,338.04 PW1127G-JM 99,345.23 65,746.14 Table 8 WTT CO2-eq Emissions The CFM56-5B5 records the highest WTT emissions due to its greater lifetime fuel consumption. LEAP-1A26 shows a reduction of approximately 11% compared to the CFM565B5, while the PW1127G-JM exhibits a reduction of approximately 19%, indicating improved fuel efficiency in newer engine designs. When expressed as a proportion of total Well-to-Wake (WTW) emissions, WTT contributes between 17% across all three engines. This consistent percentage reflects the fixed fuel-based WTT factor in DEFRA’s dataset, making the absolute values proportional to total fuel burn. 4.2.5. Well-to-Wake (WTW) Well-to-Wake (WTW) is a life-cycle assessment (LCA) approach that measures the total amount of greenhouse gas (GHG) emissions from the extraction of a fuel to its final combustion during consumption. The WTW profile for Jet A-1 aviation turbine fuel is made up of two primary parts: • Well-to-Tank (WTT): Upstream emissions from resource extraction, crude oil transport, refining into Jet A-1, storage, and delivery to the aircraft. • Tank-to-Wake (TTW): Direct emissions generated during the combustion of the fuel in aircraft engines during flight. 𝑊𝑇𝑇 + 𝑇𝑇𝑊 = 𝑊𝑇𝑊 The sum of these two components represents the full WTW emissions of the fuel. In section 4.2.1, TTW consumptions and GHG impacts are explained widely. Direct emissions from fuel combustion (TTW), fuel supply chain emissions (WTT), and the total Well-to-Wake values for the three engine alternatives taken into consideration in this study are compared in Table 9. The comparative WTT, TTW, and WTW CO₂-equivalent emissions for three distinct engine options introduced on the Airbus A320 family are shown in Table 9. With 387,047 tCO₂eq (TTW), 81,059 tCO₂-eq (WTT), and 468,105 tCO₂-eq (WTW), the baseline configuration, the CFM56-5B5/3, has the highest lifetime emissions. In contrast, the LEAP-1A26/26E1 and PW1127G-JM engines show substantial improvements in both operational and upstream emissions. The LEAP-1A reduces WTW emissions to 417,745 tCO₂-eq, corresponding to a 11% decrease relative to the CFM56, while the PW1127G achieves the most significant reduction with 379,677 tCO₂-eq, amounting to a 18.9% improvement compared to the baseline.
pg. 38 Engine WTT CO2-eq (t) TTW CO2-eq (t) WTW CO2-eq (t) CFM56-5B5/3 81,058.67 387,046.63 468,105.3 LEAP-1A26/26E1 72,338.04 345,406.52 417,744.56 PW1127G-JM 65,746.14 313,930.92 379,677.06 Table 9 WTW CO2-eq Emissions of A320 Lifetime by Engine Options The proportional decreases in TTW and WTT are the same because constant emission factors were used in both computations. This result is anticipated because, like direct combustion emissions, upstream emissions scale linearly with fuel consumption. The WTT, TTW, and WTW of the LEAP-1A26/26E1 are reduced by about 11% in comparison to the CFM56-5B5/3 baseline, whereas the PW1127G-JM is reduced by almost 19%. The WTW footprint's relative distribution is unchanged in spite of these decreases, with direct combustion during flight (TTW) making up 83% of total emissions and upstream processes (WTT) contributing roughly 17%. This suggests that while supply chain emissions are not negligible, the most immediate and significant reductions in aviation's carbon footprint come from efficiency enhancements that lower in-flight fuel consumption. In conclusion, the table illustrates three main aspects; • The PW1127G-JM provides the greatest overall reduction with nearly 18% lower WTW emissions. • The LEAP-1A offers a moderate but consistent improvement of about 11%. • Even though TTW accounts for the majority of emissions, advancements in engine technology continue to be the principal means of achieving near-term decarbonisation; nevertheless, more extensive long-term reductions must also take upstream emissions into account within a whole life cycle framework. 4.2.6. Maintenance, Repair and Operations (MRO) The aviation sector is facing increasing request to measure greenhouse gas (GHG) emissions from all sources. The focus currently is on in-flight fuel economy. But life cycle assessments (LCAs) should also account for indirect emissions from aeroplane maintenance. Over the course of an Airbus A320's 20-year service life, this study calculates the greenhouse gas emissions produced by maintenance procedures. It is anticipated that the Airbus A320 will remain in service for 20 years. The estimated number of flights per year is 1,511, with an average duration of 108 minutes. The aircraft is anticipated to complete 30,220 flights, accrue ~55,000 flying hours, and cover ~45 million km over its lifetime. The maintenance phase of a commercial aircraft such as the Airbus A320 represents an important contributor to its overall life cycle environmental impact. The primary source of greenhouse gas (GHG) emissions is still the combustion of operating fuel, but maintenance operations also play a part. Production of spare parts, component replacement, lubrication, inspections, and waste management are some of these tasks. Over the course of the aircraft's service life, they all add to the energy and material consumption. Depending on the engine type and airline operating environment, maintenance costs for the A320 family are generally projected to be between $1,000 and $2,000 USD per flying
pg. 39 hour [35] . In terms of the environment these expenses related to the consumption of resources, the production of replacement parts, energy consumption in workshops, and the handling of replaced components at the end of their useful lives [39]. The life cycle maintenance emissions of an Airbus A320 were estimated by examining key categories of routine and scheduled maintenance that occur throughout the aircraft’s operational life. The study focuses on activities that have measurable energy consumption, material use, and associated indirect emissions. The primary maintenance activities considered are as follows: • Routine line and base checks, including A-checks and C-checks • Engine overhauls • Replacement of consumables such as filters and fluids • Transport of parts and materials • Energy used in maintenance hangars All of these processes require metals, composites, lubricants, and energy, and they generate waste that must be recycled or managed. The environmental impact of planned maintenance activities was measured over the course of the Airbus A320 family's 25-year operational lifespan in a thorough life cycle assessment study. The reference scenario, representing a full-service network carrier (FSNC) operating primarily short-haul flights, revealed that the total GHG attributable solely to maintenance activities amounted to 1,555 tonnes of CO₂-equivalent (tCO₂-eq). Furthermore, when normalized by total flight hours over the service life, the study reported an average emission intensity of 28.3 kg of CO₂-equivalent per flight hour (kgCO₂-eq/FH). These findings emphasize the value of considering MRO activities in aviation-related sustainability assessments and draw attention to the non-negligible but frequently disregarded environmental burden associated with aircraft maintenance [39]. In our case, the service life is not 25 years, and the values will differ. Below are the results and formula; The total number of flights over the aircraft's lifetime is calculated by multiplying the average annual flight frequency by the total service years. 𝑇𝑜𝑡𝑎𝑙 𝐹𝑙𝑖𝑔ℎ𝑡𝑠 (𝑇𝐹)= 𝐹𝑙𝑖𝑔ℎ𝑡𝑠 𝑝𝑒𝑟 𝑌𝑒𝑎𝑟 × 𝑆𝑒𝑟𝑣𝑖𝑐𝑒 𝑌𝑒𝑎𝑟 𝑇𝐹 =1511 ×20 =30,220 Given an annual flight frequency of 1,511 flights and a 20-year service period, the aircraft is expected to complete 30,220 flights in total. Total block hours are estimated by multiplying the average flight block time by the total number of flights. 𝑇𝑜𝑡𝑎𝑙 𝐻𝑜𝑢𝑟𝑠 (𝑇𝐻)= 𝐵𝑙𝑜𝑐𝑘 𝑇𝑖𝑚𝑒(ℎ𝑜𝑢𝑟𝑠)×𝑇𝐹 𝑇𝐻 = 1.8 × 30,220 ≅54,396 𝐹𝑙𝑖𝑔ℎ𝑡 𝐻𝑜𝑢𝑟𝑠 (𝐹𝐻) Assuming an average block time of 1.8 hours per flight, the total operational time amounts to approximately 54,396 flight hours (FH) across the entire fleet lifetime.
pg. 40 The cumulative maintenance-related emissions are calculated by multiplying the emission intensity per flight hour by the total flight hours. 𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒 𝑀𝑎𝑖𝑛𝑡𝑒𝑛𝑎𝑛𝑐𝑒 𝐸𝑚𝑖𝑠𝑠𝑜𝑛 (𝐿𝑀𝐸) = 𝑅𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝐹𝑎𝑐𝑡𝑜𝑟 × 𝐹𝐻 𝐿𝑀𝐸 = 28.3𝑘𝑔𝐶𝑂2𝑒𝑞 𝐹𝐻 ×54,396(𝐹𝐻)= 1,539.4𝑡𝐶𝑂2𝑒𝑞/𝑓𝑢 Using the reference intensity of 28.3 kgCO₂-eq per flight hour, the total lifetime maintenance emissions are estimated to be 1,539.4 tonnes of CO₂-equivalent per functional unit (A320). Notably, the lifetime maintenance emissions calculated in this analysis using operating parameters closely match the 1,555 tCO₂-eq over 25 years number stated in the Rahn`s study [39] reference scenario. This consistency validates the accuracy of the underlying flight hour calculations and supports the validity of the emission factor (28.3 kgCO₂-eq/FH). 4.3. Phase 3: End-of-Life (EoL) Treatment The End-of-Life phase, which covers tasks including decommissioning, dismantling, component reuse, material recycling, and waste management, is the last step of an aircraft's life cycle. Even while this stage has a far less impact on an aircraft's overall global warming potential (GWP) than the operating stage, it is becoming more and more significant in aviation's efforts to preserve resources while implementing circular economy principles [27], [33]. At retirement (typically 20–25 years of service), aircraft are decommissioned and transported to specialized facilities for dismantling. High-value components such as engines, avionics, and landing gear are usually removed first for reuse or resale, extending their service life in secondary markets [40]. The airframe is subsequently divided into streams of material. Besides aluminium alloys, which make up 72% of the structural mass of an A320 family aircraft, steel, titanium, copper, and composites come after [33], [40] While metals like titanium and aluminium can be recycled and recovered at high rates, carbon fibre reinforced polymers (CFRPs) are more difficult to work with since fibre recovery techniques are still in their infancy [41]. Industry-led initiatives, such as Tarmac Aerosave have demonstrated that up to 92% of an aircraft’s materials can be recycled or recovered by weight. This rate is given as 99% for engine parts that are rich in steel, titanium and aluminium [40]. This represents a significant increase compared to historical recovery rates of 60%. Recycling has significant positive effects on the environment, especially when it comes to materials that require a lot of energy. For example, producing secondary (recycled) aluminium consumes only about 5–10% of the energy required for primary aluminium production, translating into major greenhouse gas savings [21]. In life cycle accounting, these benefits are often modelled as “credits”, offsetting a fraction of the manufacturing phase emissions. Cox [27] estimate that effective recycling strategies can reduce the upstream material demand of new aircraft production by up to 20%. Since composite materials are being used more and more in today's aircraft designs (e.g. the Boeing 787 and Airbus A350, use more than 50% CFRP by weight), recycling them continues to be the key problem at EoL. Current recycling methods such as pyrolysis or mechanical grinding recover fibres of lower quality, limiting their reuse in structural applications [41]. Another challenge is the safe disposal of hazardous materials (e.g., fire suppressants, hydraulic fluids), which require careful handling to avoid environmental harm [27]
pg. 41 Looking forward, design strategies such as design for disassembly and modular components can facilitate easier dismantling and higher-value recovery. The work of the AFRA and ongoing regulatory emphasis on circular economy principles will further raise recovery rates and reduce landfill dependency. Although EoL now only has a small part in aircraft life cycle assessments (LCAs), its significance will grow as aviation aims to show sustainability over the whole life cycle, not only in fuel use. Based on the functional unit of one Airbus A320 type aircraft, the OEW of 42.4 tonnes is distributed across five primary material categories in Table 2. Aluminium dominates at 68%, followed by CFRPs at 15%, steel at 9%, titanium at 6%, and miscellaneous materials at 2%. These values reflect modern narrowbody composition trends [18] The avoided burden approach was used to capture the environmental consequences. Because recycled material reduces the need for primary production, it gets an environmental credit. The net credit for each material is determined as follows; 𝐶𝑟𝑒𝑑𝑖𝑡 (𝑡𝐶𝑂2)=𝑀𝑎𝑠𝑠(𝑡)× 𝑟 × ∆𝐸𝐹 1000 • r = recycling rate • ΔEF = (EF-primary – EF-recycled) in kgCO₂/kg In Table 10, inputs for EoL calculations are given. Material Share (%) Mass (t/f.u.) EF-primary (kg CO₂/kg) Recycling rate (%) Aluminium 68 28.8 10.9–12.0 95 CFRP (Composites) 15 6.40 20–29 0–10 Titanium 6 2.55 36–40 70 Steel 9 3.81 1.9–2.1 90–95 Misc. (Cu, plastics, wiring, etc.) 2 0.85 2–6 ~60 Table 10 Material Composition, Emission Factors (EF), and Recycling Rates for A320 Aircraft [17], [41] In Table 11, results of EoL phase for materials and environmental credits are given. Material Mass (t) Recycling (t) ΔEF (kgCO₂/kg) Credit (tCO₂) Aluminium 28.8 27.36 10.4 284.5 CFRP 6.40 0.00 0 0.0 Titanium 2.55 1.79 26.0 46.4 Steel 3.81 3.43 1.5 5.1 Misc. 0.85 0.51 3.0 1.5 Total 42.41 33.1 0 337.5 Table 11 End-of-Life CO₂ Credits by Material
pg. 48 Appendices Data Value Unit Data Service Life 45,000,000 Km Lifespan Distance Calculation Life Span 20 Year [17], [42] Service Span 54,396 Hours Block time x Lifespan Flights Operating Empty Weight (OEW) 42,400 Kg [42] Yearly Flight 1511 Flight/Year [35] Average Flight Distance (AFD) 1485 Km [17] Avg. Block Time 108min/1.8hours [29] Average Maintenance Cost 1000-2000 $/hr [35] Load Factor (LF) %81.5 [17], [42] Load Passenger (LP) 147 Passenger [17], [42] Flight Cycle 30,220 Flight/Life Max Distance 6,100 Km [20], [42] Average Flight Time 108.7 Minutes [14] Average Taxiing Time per Flight Cycle 26 Minutes [20], [29], [44] Average Take-Off Time per Flight Cycle 0.7 Minutes [20], [29], [44] Average Climbing Time per Flight Cycle 2.2 Minutes [20], [29], [44] Average Cruise Cycle per Flight Cycle 88.8 Minutes Block time – Mods` time Average Approach Time per Flight Cycle 4 Minutes [20], [29], [44] Average Cruise Altitude 36,000 Feet [29], [45] Average Cruise Speed 0.78 Mach [29], [45] Table A1 Operational Data for LCA
pg. 49 Data Explanation CFM565B5/3 LEAP1A26/26E1 PW1127GJM OEW (t) Operating Empty Weight (ton) 42.400 41.000 41.100 Fuel Flow T/O (kg/sec) Take-Off Fuel Flow (kg/sec) 1.79 1.72 1.60 Fuel Flow C/O (kg/sec) Climbing Fuel Flow (kg/sec) 1.49 1.42 1.34 Fuel Flow App (kg/sec) Approach Fuel Flow (kg/sec) 0.53 0.49 0.46 Fuel Flow Idle (kg/sec) Taxi Fuel Flow (kg/sec) 0.18 0.18 0.16 Fuel LTO Cycle (kg) Total Landing Take-Off Cycle Fuel Flow 686.00 660.00 606.00 B/P Ratio By-pass Ratio 6.00 11.10 12.28 Rated Thrust (kN) Certificated Max Thrust Force 97.90 120.60 120.44 HC EI T/O (g/kg) Take-Off HC Emissions 0.030 0.02 0.07 HC EI C/O (g/kg) Climbing HC Emissions 0.0 0.02 0.07 HC EI App (g/kg) Approach HC Emissions 0.08 0.04 0.06 HC EI Idle (g/kg) Taxi HC Emissions 3.55 0.29 0.46 HC Characteristic (g/kN) Characteristic Amount of HC Emissions in Regulation 6.20 0.49 0.88 HC LTO Total mass (g) Total Landing Take-Off Cycle HC Emission 520 46 69 CO EI T/O (g/kg) Take-Off CO Emissions 0.15 0.24 0.27 CO EI C/O (g/kg) Climbing CO Emissions 0.20 0.26 0.36 CO EI App (g/kg) Approach CO Emissions 4.94 2.65 4.89 CO EI Idle (g/kg) Taxi CO Emissions 41.77 21.63 24.53 CO Dp/Foo Characteristic (g/kN) Characteristic Amount of CO Emissions in Regulation 70.10 30.81 34.39 CO LTO Total Mass (g) Total Landing Take-Off Cycle CO Emission 6343 3259 3374 NOx EI T/O (g/kg) Take-Off NOx Emissions 16.420 30.800 20.810 NOx EI C/O (g/kg) Climbing NOx Emissions 14.010 13.380 16.950 NOx EI App (g/kg) Approach NOx Emissions 8.030 8.750 10.590 NOx EI Idle (g/kg) Taxi NOx Emissions 3.810 4.610 5.200 NOx Dp/Foo Characteristic (g/kN) Characteristic Amount of NOx Emissions in Regulation 33.00 32.22 33.090 NOx LTO Total mass (g) Total Landing Take-Off Cycle NOx Emission 3047 3535 3438 HC Cruise (kg/t) kg/t 0.3 0.25 0.2 CO Cruise (kg/t) kg/t 1 0.8 0.7 NOX Cruise (kg/t) kg/t 12 9.500 8.5 CO2 Cruise (kg/t) kg/t 3160 316 316 Fuel Flow Cruise (kg/sec) kg/min 0.69 0.65 0.59 Table A2 Technical Specifications for Each Engine Unit with Respect to LCA [29], [37]
pg. 50 Material Water Consumption (L/kg) CCaLC Input (m³/kg) Source Aluminium (primary) 350 0.35 [34] Epoxy resin (liquid) 190 0.19 [46] PAN fibres (for CFRP) 160 0.16 [46] Steel (low alloy) 70 0.07 [34] Titanium (primary) 300 0.30 [34] Titanium dioxide 150 0.15 [34] Nitrogen, liquid 25 0.025 [34] Miscellaneous 100 0.10 Assumption Energy 0.0033 [34] Table A3 CCalC Inputs for Water Consumptions Material Amount (kg) Transport Mode Distance (km) ton.km GWP Factor (kg CO₂-eq/ton.km) Aluminium 28,800 Road 500 14,400,000 0.13 CFRP 3,800 Airfreight 1,500 5,700,000 0.90 Titanium 2,500 Road 800 2,000,000 0.13 Steel 3,600 Road 300 1,080,000 0.13 Miscellaneous 1,407 Road 400 562,800 0.13 Table A4 CCalC Transportation Inputs for Materials [17], [36]
pg. 51 Inputs for 1Kg CFRP Production Quantity Nitrogen, liquid, at plant/RER U 6.33 Kg Polyacrylonitrile fibres (PAN) 0.93 Kg Epoxy resin, liquid 0.398 Kg Heat, natural gas 105,3 MJ Electricity 135,85 KWh Table A5 Carbon Fibre Reinforced Polymer LCA Data (CFRP) [33] Phase Avg. Power Setting (%) Avg. Time Phase (min) Idle (Taxi) 7 19 Take-Off 100 0.7 Climb 85 2.2 Approach 30 4 Landing N/A 0.7 Taxi-in 7 7 Table A6 Average Power Setting and Time for Flight Phases [20]
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