In tandem with continuing contrail management research and solutions development, initiating demand-side aviation customer engagement today can help raise awareness of contrail impact and advance exploration of comprehensive air travel climate impact accounting frameworks.

To initiate this engagement, in collaboration with leading management consultants Boston Consulting Group (BCG), Roland Berger and Estuaire, RMI has led a series of corporate contrail accounting and reporting pilots to develop and compare methodologies for measuring contrail impacts associated with business air travel.

Three proposed methodologies for contrail accounting with different levels of complexity and accuracy were assessed:

• Baseline Approach: Standard Multiplier — The baseline approach uses a single, static 1.7x multiplier on the CO₂ impact, to account for the non-CO₂ climate impacts of aviation, including contrails.

• Differentiated Default Approach: Tiered Multiplier — A tiered multiplier offers a more nuanced method by sorting flights into low, medium, and high-impact categories based on key flight characteristics such as time of departure, season, region, etc.

• Bottom-Up Approach: Flight Specific Modeling — The most granular and accurate method is the bottom-up approach, which models the specific climate impact of each individual flight. This technique uses detailed operational data to calculate climate impact.

These studies found that flight-by-flight, bottom-up accounting can significantly improve the accuracy of measured contrail and other non-CO₂ effects as well as CO₂ impact compared with current standard methods. Results revealed lower contrails and other non-CO₂ effects averaging a 1.3x impact compared to the baseline 1.7x multiplier as well as lower CO₂ emissions compared to standard emissions accounting practices. The pilot analysis also revealed 2% of flight bookings account for 80% of total contrail impact.

As a result of these findings, applying a uniform multiplier to all flight bookings may misrepresent the true climate impact of reporting companies.

Additionally, the results indicate the opportunity to significantly reduce corporate travel emissions by identifying key flight characteristics attributable to high warming impacts. Companies could use their air travel and transport data to make more informed decisions that help minimize travel on routes with higher contrail-formation potential, providing an additional lever to reduce climate impact.

Acting now to explore and pilot refined emissions accounting and reporting approaches can further support collective efforts to reduce the climate impact of contrails and unlock both environmental and economic benefits through lower aviation emissions.

Contrail management is a significant opportunity to tackle aviation’s full climate impact. According to ICCT’s September 2025 Aviation Vision 2050 outlook report, contrail avoidance is estimated to represent more than 40% of total avoidable warming from aviation by 2050. While critical decarbonization efforts such as increasing the uptake of Sustainable Aviation Fuel (SAF) and improving operational efficiency must continue to be pursued, it is clear that the climate-warming impact of contrails demands action.

Increased research attention in recent years has enhanced understanding of contrails as a potent aviation non-CO₂ effect¹, and the development and testing of technologies to predict and avoid contrail formation continue to advance. These contrail management activities have strongly improved the aviation industry’s opportunity to reduce contrail warming. However, contrail science and management is still nascent and requires continued collaboration across key groups, including corporates, airlines, standard setters, regulators, and other aviation and emissions accounting and reporting value chain stakeholders. Increased engagement across these stakeholders can help create the right data flows and incentives to more accurately measure and mitigate contrail warming impacts.

In tandem with continuing climate impact research and solutions development advancements, initiating demand-side aviation customer engagement today on the topic of contrail management can help raise awareness of contrail impact and advance exploration of comprehensive air travel climate impact accounting frameworks.

To initiate this engagement, RMI led a series of corporate aviation emissions accounting pilots, in collaboration with leading management consultancies BCG and Roland Berger, as well as flight analytics platform provider Estuaire. These studies found that flight-by-flight, bottom-up accounting can significantly improve the accuracy of measured contrail and other non-CO₂ effects, as well as CO₂ impact, compared with current standard methods. Current contrail and non-CO₂ accounting processes, while precise (as they are based on a fixed multiplier), are not necessarily accurate, as they lack the specificity derived from additional bottom-up data. Beyond refining report quality, the pilot results revealed data granularity can uncover opportunities to reduce air transport climate impacts.

Today, companies are likely to inaccurately report contrail climate impacts by applying broad, static multipliers to their CO₂ emissions. Applying the flight-specific bottom-up approach, results revealed lower contrails and other non-CO₂ effects averaging a 1.32x impact compared to the baseline 1.7x multiplier as well as lower CO₂ emissions compared to standard emissions accounting practices. The pilot analysis revealed 2.14% of flight bookings account for 80% of total contrail impact. As a result, applying a uniform multiplier to all flight bookings would misrepresent their true climate impact. Additionally, the results indicate the opportunity to significantly reduce corporate travel emissions by identifying key flight characteristics attributable to high warming impacts. Companies could use their air travel and transport data to make more informed decisions that help minimize travel on routes with higher contrail-formation potential, providing an additional lever to reduce climate impact.

With data-driven and consistent contrail accounting and reporting methodologies in place, corporate customers of aviation have the opportunity to measure and disclose both the CO₂ and non-CO₂ climate impact of business air travel more accurately than reported under current processes. This could help enable companies to explore internal travel policy adjustments based on improved reporting processes that may limit contrail impacts associated with future business air travel. Additionally, with more granular data, companies can better ensure that climate impact compensation strategies reflect the emissions they actually generate. Refined emissions accounting approaches enable companies to align reported impacts more closely with actual flight-level conditions, improving accuracy and strengthening consistency with compensation mechanisms such as carbon credit purchases.

Strengthening corporate emissions accounting and reporting practices for contrail impacts can help air transport customers, such as corporate travelers and freight shippers, better understand aviation’s full climate impact. By piloting and applying refined emissions accounting methods, these customers can begin to account and report contrail impacts more accurately, while identifying practical actions to reduce them.

By engaging constructively with data providers, airlines, standard setters, and other aviation and emissions accounting value chain stakeholders, corporate customers can help shape emerging contrail management practices and contribute to more comprehensive aviation climate accountability. Acting now to explore and pilot refined emissions accounting and reporting approaches can further support collective efforts to reduce the climate impact of contrails and unlock both environmental and economic benefits through lower aviation emissions.

In 1998 the Greenhouse Gas Protocol (GHG Protocol) was established to “develop internationally accepted greenhouse gas (GHG) accounting and reporting standards for business and to promote their broad adoption.”² GHG Protocol provides frameworks to inventory GHG emissions from private and public sector operations, value chains, and mitigation actions. Emissions are divided into three categories: ​

• Scope 1 direct emissions from sources owned or controlled by the reporting company.

• Scope 2 indirect emissions from the generation of energy purchased by the reporting company.

• Scope 3 all indirect emissions not covered by Scope 2, including both upstream and downstream sources. Activities are further subdivided into 15 categories of emissions.

Different aviation stakeholders report emissions under distinct scopes and categories depending on their role in the aviation value chain. Aircraft operators, such as airlines, report fuel combustion from flight operations as Scope 1 emissions, while corporate travelers account for their business air travel emissions under Scope 3, Category 6 (“Business Travel”). Primarily focused on CO₂, the standard also addresses GHGs such as methane, nitrous oxide, and chlorofluorocarbons, among others. To calculate business travel emissions, companies can use one of three methods:

• Fuel-based method, which involves determining the amount of fuel consumed during business travel (i.e., Scope 1 and Scope 2 emissions of transport providers) and applying the appropriate emission factor for that fuel.

• Distance-based method, which involves determining the distance and mode of business trips, then applying the appropriate emission factor for the mode used.

• Spend-based method, which involves determining the amount of money spent on each mode of business travel transport and applying secondary (EEIO) emission factors.³

While organizations such as the GHG Protocol acknowledge contrails climate impact, accounting for these impacts is currently considered optional or recommended and not required. Similarly, Science Based Targets Initiative (SBTi) aviation sector guidance at this time recommends that corporate travelers exclude contrails from near-term target boundaries given the nascency of contrail science and contrail management. When it comes to accounting for contrails and other non-CO₂ radiative forcing impacts of air travel, businesses are provided with limited guidance and are broadly advised to disclose the factors that they may use when accounting and reporting emissions from these sources.

Although commendable progress in both research and solutions development has been made in recent years, guidance on contrail impact accounting remains limited. As a result, corporate reporting on contrails and other non-CO₂ effects remains inconsistent and lacks accuracy. However, even though non-CO₂ reporting is not yet mandatory, many corporates see value in starting now because:

• It positions them as leaders in climate accountability.

• It enhances the quality and credibility of Scope 3 emissions management.

• It enables them to influence emerging standards rather than simply complying later.

• It anticipates future regulatory shifts, especially in Europe considering the EU monitoring, reporting, and verification (MRV) framework for non-CO₂ inclusion in the emissions trading scheme (ETS).

These points strengthen the justification for action: the demand for non-CO₂ data is growing, but the lack of a consistent methodology is holding back adoption at scale.

Additional contrail science and management research is needed to understand the scale of contrails’ climate impact and the feasibility of levers available to mitigate it. In the absence of certainty, best practice to date has been to apply a multiplier of 1.7x to CO₂ emissions to account for non-CO₂ impacts, including contrails. This multiplier was identified based on the European Union Aviation Safety Agency (EASA) analysis of the non-CO₂ climate impacts of aviation released in 2020. Although establishing this initial multiplier has been a positive step in the right direction, its application is far too broad considering the remaining uncertainty bands associated with contrail impact – despite tightening consensus among research conducted over the last five years — as well as significant climate impact variability from flight to flight based on factors such as region of travel, season, flight time of day, actual weather conditions at the time of flight, and aircraft performance characteristics. By using a singular multiplier in this way, companies may be significantly under- or over-reporting their emissions attributable to contrails. Moreover, using a flat multiplier does not provide any incentive to make more informed, sustainable flight choices with a lower likelihood of contrail warming.

Additionally, differences in emissions calculation methodologies set by regulatory agencies can make it difficult to compare emissions reported from one company to another. Depending on the emissions factor agency source, two or more companies, for example, may report significantly different results even if they theoretically were to have traveled on the exact same flights for the year.

Furthermore, even within the same regulatory agencies, emissions factors can change from year to year and are subject to global economic activity. This can make it difficult for companies to contextualize emissions from one year to the next. For example, UK Department for Energy Security and Net Zero (DESNZ) 2025 GHG emissions factors for business air travel were adjusted downward between 16% to 42% depending on seating class from 2024 emissions factors. Emissions factors used in 2023 and 2024 were still based on 2021 data, a year that was impacted by the COVID pandemic resulting in lower air travel demand. This inflated annual per passenger emissions factors for 2023 and 2024 reporting years, which saw air travel demand normalize during the post pandemic recovery. In this case, CO₂ emissions (and non-CO₂ emissions) were likely over reported in general during this period. Therefore, emissions factor update delays such as this can significantly impact the ability of companies to accurately report emissions and achieve their climate targets.

The recently adopted EU MRV framework for including non-CO₂ effects within the existing ETS must also be acknowledged here. Given the evolution of the EU ETS MRV framework, what is currently voluntary for corporates in terms of non-CO₂ reporting (Scope 3) could soon become a formal requirement in Europe. On September 23, 2024, the existing EU ETS MRV regulation was amended to include the monitoring and reporting of aviation non-CO₂ emissions. As of January 1, 2025, on an annual basis through 2026, airlines operating jet aircraft between airports within the European Economic Area (EEA) are required to monitor and report the non-CO₂ emissions from each flight. Based on the annual results through 2026, by December 31, 2027, the European Commission will submit a report and, if appropriate, a legislative proposal to expand the scope of the EU ETS to include non-CO₂ effects of aviation. By understanding this evolutionary MRV process and the impact on airline Scope 1 emissions, companies can better prepare for potential downstream Scope 3 implications.

As part of the MRV framework the EU has developed the Non-CO2 Aviation Effects Tracking System (NEATS) tool to support airlines in measuring non-CO₂ impacts flight by flight, a prerequisite for enabling more accurate Scope 3 data for corporate clients in the future. While the EU MRV framework establishes a significantly higher fidelity approach to measuring the impact of aviation non-CO₂ effects, its applicability at present is limited to A) the geographic boundaries of the European Economic Area (EEA) and B) accounting for the Scope 1 emissions of air carriers themselves and does not extend to address the Scope 3 emissions of corporate customers. Given the existing challenges to accurately account for and report Scope 3 business air travel non-CO₂ emissions, as well as emissions from CO₂ itself, it is critical for organizations to explore more harmonized methodologies and leverage robust, transparent data collection tools to ensure consistent, reliable, and comparable emissions disclosures across the aviation sector.

In collaboration with leading management consultancies BCG and Roland Berger and flight analytics platform provider Estuaire, RMI has led a series of corporate contrail accounting and reporting pilots to develop and compare methodologies for measuring contrail impacts associated with business air travel. Three proposed methodologies for contrail accounting with different levels of complexity and accuracy were assessed.

Baseline Approach: Standard Multiplier

The baseline approach uses a single, static multiplier to account for the non-CO₂ climate impacts of aviation, including contrails. This method is straightforward, applying a universal multiplier value of 1.7x to a flight’s CO₂ emissions and requiring no additional flight-level data for calculation. While this method is simple to implement for quick estimates, it fails to account for key factors that influence contrail formation, such as weather conditions, flight trajectory, aircraft characteristics, time of day, season, and region. As a result, in addition to having limited ability to accurately account for contrails as previously discussed, this approach fails to incentivize better operational practices. Without understanding and improved visibility of contributing contrail impact variables, businesses are limited in their ability to explore meaningful opportunities to reduce their Scope 3 emissions.

Differentiated Default Approach: Tiered Multiplier

A tiered multiplier offers a more nuanced method by sorting flights into low, medium, and high-impact categories based on key factors mentioned above. For example, known factors such as time of departure, season, region, etc. could apply contrail risk scores that are summed and then allocated into impact categories based on standard scoring thresholds. Average multipliers per category could then be applied per flight. This method encourages better business air travel policy opportunities when compared to the baseline approach. By grouping general flight characteristics and knowing the emissions multiplier to apply to the flight in advance of travel, companies may be able to manage emissions more effectively.

However, as an approximation of the potential contrail impact, this approach remains limited to inform accurate decision-making: flights with significantly different contrail risk may still fall into the same category, limiting the ability to target high-impact routes. This weakens both the accuracy of Scope 3 reporting and the effectiveness of corporate travel emissions strategies. Additionally, the forecast contrail impact from a selected flight may differ significantly from the actual impact once the flight has been completed, which again may limit emissions accounting and reporting accuracy.

Bottom-Up Approach: Flight-Specific Modeling

The most granular and accurate method is the bottom-up approach, which models the specific climate impact of each individual flight. This technique uses detailed operational data, including aircraft and engine type, flight trajectory, and altitude in combination with weather conditions, time of day, flight origin and destination, and flight booking class to calculate climate impact. This approach provides the highest accuracy impact calculation — for both contrails and other non-CO₂ effects and CO₂ emissions — and best incentivizes the implementation of targeted travel emissions reduction policies. Additionally, the bottom-up analysis is currently the most closely aligned approach to the EU non-CO₂ MRV framework for airline reporting, which can result in greater transparency and consistency in emissions disclosures from both corporate travelers and airlines. This approach, however, may have higher costs associated with detailed data collection requirements and the need for specialized service providers to conduct analyses.

Pilot Key Findings and Insights

For this set of pilots, Estuaire conducted an analysis of the contrail impact associated with flight bookings over 2024. Applying the flight-specific bottom-up approach, results revealed lower contrails and other non-CO₂ effects averaging a 1.3x impact compared to the baseline 1.7x multiplier as well as lower CO₂ emissions compared to standard emissions accounting practices. The study revealed 2% of flight bookings account for 80% of the total contrail impact, as illustrated in Exhibit 2 below. This highlights the highly uneven distribution of contrail effects across flights, including flights that produced contrails with cooling effects. As a result, applying a uniform multiplier to all flight bookings would misrepresent its true climate impact. Additionally, analyses confirmed initial hypotheses such as higher radiative forcing impact during winter and cool spring and fall months, evening and nighttime flights, and along medium- and long-haul routes. Based on these results, each company is now better positioned to take additional steps toward more informed decisions on opportunities that can reduce the full climate impact of their business air travel.

Further analysis confirmed the non-linearity of contrail impact with respect to both seasonality and departure time. Specifically, Exhibit 3 below shows that flights departing in winter months exhibit a higher mean contrail impact per distance flown compared to those departing in summer.

Exhibit 4 below highlights that morning departures tend to have a lower mean contrail impact per distance than late afternoon flights.

It is well known that you can’t manage what you don’t measure. Companies that are able to leverage data to understand the complexity and feasibility of potential reduction levers have the opportunity to be better positioned to convert information into actionable context-sensitive travel policies. Tools and service providers are now available to conduct detailed flight-level emissions analysis. Additionally, resources such as the Travel Impact Model (TIM) can help companies estimate future air travel impacts associated with specific flights.

Although significant advancements have been made in recent years, it is important to note that accurate contrail forecasting remains a challenge, given contrail formation is highly dependent on real-time weather conditions, which are difficult to measure with accuracy in real time, and aircraft operating characteristics such as altitude. These challenges make the exercise of identifying specific flights that may reduce air travel climate impact more complex. Without certainty that contrail forecasts will result in contrail formation or understanding the aircraft operating characteristics, companies risk making well-intentioned decisions to reduce flight impacts that may not be realized for unforeseen reasons. Reducing this risk calls for companies to use detailed historic company-level air travel emissions analysis in combination with tools such as TIM to help make informed travel policy adjustments that may reduce their future business air travel climate impacts.

It is also important to acknowledge that business travel decisions are not made in a vacuum. Not only do businesses need to account for their air travel emissions footprint, but they must also take additional factors into consideration, such as client needs, cost of travel, as well as other Scope 3 emissions that impact business decisions. For example, a business may have the option to take a flight that is likely to have low contrail impact compared to another flight at a different time of day, but if this alternative doesn’t meet the needs of a client, then a higher potential impact flight may be necessary to meet project demands. Similarly, if a lower contrail impact flight is available but would require an additional night of lodging, for example, the additional cost and emissions associated with the trip extension could exceed the available travel budget and/or negate the avoided contrail impact.

Therefore, companies could benefit from exploring comprehensive, customized travel policy guidelines based on the relationship between contrail impact forecasts, flight time and availability, cost considerations, and regional/local emissions at the business destination, enabling more effective and targeted reductions in aviation-related climate impacts. To help generate employee buy-in, companies could explore embedding incentives within travel booking tools for employees to encourage the selection of low-emissions options. Companies could also consider developing educational and policy training materials that detail the importance of more accurate emissions accounting and the role company personnel can play in reducing emissions.

Key Stakeholders

The corporate emissions accounting and reporting chain is a complex ecosystem with a diverse range of stakeholders, each with a vested interest in the accuracy, transparency, and use of the reported data. Each plays a distinct role in defining, generating, managing and verifying the data that underpin credible corporate disclosures, and together they form the foundation on which future contrail and other non-CO₂ accounting and reporting can build. As air travel contrail impact and non-CO₂ emissions corporate accounting processes continue to develop, each stakeholder group will need to be engaged to raise awareness and ensure cohesion and practicality.

Reporting companies (i.e., air transport customers such as corporate travelers and freight shippers) compile air travel and freight transport data from internal systems and external partners to calculate aviation emissions. Within companies, ESG, finance, accounting, and air transport management teams coordinate disclosure and data governance, integrating both CO₂ and non-CO₂ effects into their business operations. Continued engagement in pilot projects could help to refine contrails and other non-CO₂ emissions accounting methodologies and test their viability in real-world settings. By sharing learnings transparently, corporates could help to collectively strengthen the evidence base for refined accounting methods.

Travel management companies or freight forwarders act as intermediaries connecting corporate customers to airlines and carriers. They provide flight-level booking and activity data, such as routes, distances, and seating classes, that serve as key inputs for aviation emissions accounting. Coordination between data providers, reporting companies, and emissions accounting providers could help to develop data management processes that enable improved efficiency in data analysis.

Emissions accounting and analytics providers (including both internal corporate teams and external modeling partners) convert flight activity data into quantified CO₂, contrail impact, and other non-CO₂ outputs. Depending on data availability and other factors, they may apply standard emission factors or calculate results using actual flight-level information through bottom-up modeling approaches provided. Continued engagement in pilot projects to test accounting methodologies could help these service providers better understand existing challenges to data collection activities and support the development of solutions to address them in collaboration with data providers and reporting companies.

Verification and assurance providers review corporate emissions data for completeness, consistency, and credibility. As flight-level and contrail-related accounting practices mature, these actors could play an important role in developing corresponding verification criteria. Engaging them early could help identify what evidence and data transparency are necessary for acceptance within established assurance processes.

Voluntary standard setters and guidance providers, including GHG Protocol and SBTi provide voluntary frameworks for stakeholders across the aviation value chain to establish accounting boundaries, methodological consistency and disclosure expectations. These organizations play a foundational role in shaping how corporate emissions are measured and disclosed. GHG Protocol is currently revising its corporate, Scope 2, and 3 standards guidance with plans to finalize updates in 2027. In parallel, SBTi is undertaking a major update to its Corporate Net-Zero Standard (v2.0) and the initiative has indicated plans for a formal aviation sector update process. Together, these revision efforts create a key window for aviation and corporate stakeholders to contribute insights that reflect advances in refined accounting methodologies and the growing understanding of contrails and other non-CO₂ effects.

Regulatory bodies such as the European Commission, the European Environment Agency (EEA), the US Environmental Protection Agency (EPA), and the UK Department of Energy Security and Net Zero (DESNZ) design and implement compliance frameworks, such as the EU’s MRV regulation, that are beginning to include non-CO₂ effects and may influence future corporate reporting. These bodies influence methodology and emissions factors development. Engaging in early dialogue with these regulators could potentially improve alignment across frameworks and avoid duplicative or inconsistent requirements as contrails and other non-CO₂ effects accounting matures.

Aircraft operators (i.e., airlines, carriers) hold primary operational data, such as fuel use, aircraft type, flight trajectory, and increasingly contrail-related parameters. Their participation in research pilots and collaboration with data and modeling providers could significantly support improving the quality and accessibility of flight-level information that supports more accurate accounting. Additionally, industry associations and standardization bodies such as the International Air Transport Association (IATA) and the International Civil Aviation Association (ICAO) could potentially serve as critical conveners to align aviation accounting practices. Their collaboration could help ensure alignment with air travel provider emissions accounting developments.

Broader aviation value-chain participants, including SAF suppliers, airports, aircraft lessors, financial institutions, and original equipment manufacturers (OEMs), all share accountability for the emissions generated through air transport. Each may also influence the accuracy and flow of emissions of data through their operations, financing, infrastructure and technology innovation.

Data platforms and registries serve as connective infrastructure for emissions information across the aviation value chain. The emerging Sustainable Aviation Fuel certificate (SAFc) book and claim system and SAFc Registry illustrate how verified GHG emissions information can move transparently along the value chain, providing a useful model for how shared data infrastructure might support future contrail and non-CO₂ accounting.

At present, coordination among these stakeholders remains limited, with data and responsibility distributed across different parts of the value chain. Developing a cohesive and transparent accounting and reporting ecosystem capable of addressing aviation’s full climate impact calls for expanding collaborative pilots, improving data-sharing protocols, and engaging in explorative discussions with standard setters.

Envisioning a Future State

As we look forward to when accounting and reporting for contrails and other non-CO₂ effects of aviation become standard practice, we can compare the existing process steps to a future state. For the most part, steps remain consistent. The primary difference lies in the increasing accuracy and consistency of data inputs and the tools used to analyze them.

In today’s process, corporates often rely on broad emissions factors and multipliers to estimate non-CO₂ impacts including contrails. In the future, these generalized methods may be complemented by more differentiated, data-driven approaches that better capture variation across flights and conditions. Depending on the data access and analytical capability, corporates could use tiered multipliers or detailed flight-by-flight analyses to enhance accuracy and transparency. Companies can coordinate with their travel management or logistics service providers and emissions modeling and data providers to conduct analyses.

To enable more consistent and verifiable data exchange, a minimum standard for flight-information reporting (e.g., flight number, date and time, aircraft type) could be established across airlines, travel or logistics service providers. Such alignment would improve data quality and interoperability, supporting high-fidelity inputs for both CO₂ and emerging contrails and other non-CO₂ effects accounting and reporting practices.

To achieve this future state, an illustrative phased framework is envisioned (see Exhibit 8). This preliminary framework could help guide organizations through incremental steps, beginning with the adoption of current best practices in emissions accounting and gradually integrating more advanced, differentiated default and bottom-up methodologies for greater accuracy and comprehensiveness.

This pilot initiative and report fall into Phase 1, focusing on the conceptualization and initial testing of refined accounting methodologies and processes that allow corporates to capture aviation’s full climate impact. The pilots have demonstrated how refined, flight-by-flight data can improve the accuracy of reported emissions.

Phase 2 could focus on enhancing awareness and building capacity by engaging key stakeholders, as previously discussed. Additional corporates could begin to explore, pilot, and refine emissions accounting approaches. These follow-on pilot projects could continue to provide valuable insights into the practical challenges and opportunities of detailed emissions measurement, informing future improvements and standardization efforts.

As experience and confidence in advanced emissions methodologies grows and sufficient data has been collected and analyzed, Phase 3 of the framework could support the development of customized low emissions travel policies and broader adoption across the corporate sector. Corporates could start to explore alignment opportunities with air service providers on contrails and other non-CO₂ emissions accounting practices, deepening partnerships with travel management and emissions accounting providers, strengthening internal capacity through training and education for employees, and help build coalitions to accelerate alignment with revised, science-based emissions accounting standards.

Last, Phase 4 could recognize the adoption of refined emissions accounting approaches, enabling scaled application.

Ultimately, a phased approach could ensure that the transition to comprehensive, high-fidelity corporate emissions accounting is both practical and sustainable, enabling businesses to play a pivotal role in reducing aviation climate impacts and advancing industry wide best practices.

In summary, the evolution of corporate aviation emissions accounting toward more refined methodologies represents a meaningful step toward improving the accuracy and completeness of emissions accounting and reporting of aviation’s full climate impact. Early pilots have shown that more detailed data and analytical approaches can reveal significant insights into both CO₂, contrails, and other non-CO₂ effects of aviation, helping corporates understand and manage their contribution to climate impact.

While this work signals important progress, the focus in the near term lies in strengthening the underlying data, transparency, and collaboration that enable future standardization. Expanding data sharing practices and engaging openly with stakeholders across the aviation and emissions accounting and reporting value chains on additional pilot projects with corporate travelers and freight shippers to test refined emissions calculation methodologies will be key to establishing a stronger evidence base.

By sharing pilot learnings and continuing to test emerging methods, businesses can help shape the evolution of aviation emissions accounting and reporting. As collective understanding grows, these efforts can position corporates to contribute meaningfully to reducing aviation’s total climate impact and advancing credible, scalable best practices across the industry.