Reducing CO2 emissions is critical for the aviation industry's goal of becoming Net Zero by 2050. It’s a collaborative target: stakeholders need to monitor the direct CO2 impact that their operations have while being mindful and cooperative in sharing their data to work with relevant stakeholders to reduce interconnected emissions.

Here’s when Scope 3 emissions come into the frame. The entity itself does not produce these emissions and are not the result of activities from assets owned or controlled by them, but are applicable to the whole value chain outside of the entity's direct control.  In the case of aviation, jet fuel consumption is the major contributor to greenhouse gas emissions, and it also falls into the Scope 3 emissions for airports.

Why is collaboration between airports and airlines in addressing Scope 3 emissions changing the big picture? How does measuring Scope 3 emissions help reduce the carbon footprint and refine its reporting? Let’s look into the topic in depth.

The collaborative approach of measuring CO2 in aviation

There is currently no clear consensus between aviation authorities on environmental regulations, and the requirements vary, leaving many initiatives voluntary. Nevertheless, with the highly regulated nature of aviation, a change in regulations in one region directly affects the other. For example, airlines operating within the European Economic Area are obligated to report their greenhouse gas emissions under the EU Emissions Trading System (ETS), even if they are not based in the EU.

ICAO member states agreed to launch CORSIA shortly after the adoption of the Paris Agreement in 2015, which set collective targets to maintain the temperature increase to 1.5 degrees Celsius. The goal of CORSIA is to regulate the volume of carbon emissions from international flights and offset the increase over a certain baseline. ICAO also promotes the Global Coalition for Sustainable Aviation, which has 58 partners.

Many stakeholders choose to participate in non-mandatory sustainability programs in the absence of a central protocol. The ACI Airport Carbon Accreditation (ACA) is one of them. With this step, they anticipate future regulations, avoid the painful necessity of a sudden change, and show sustainability efforts that are highly rewarded on a reputational level.

Eleven IATA member states and four aircraft manufacturers formed the TrackZero 2050 industry support group that created a comprehensive emissions tracking methodology. It’s attentive to maintaining data ownership and adhering to international standards, for example, in classifying non-revenue passengers and no-shows in reporting or not counting retired offsets paid by passengers in the overall score. The Airline Sustainability Reporting Handbook facilitates tools for airlines to comply with sustainability regulations.

Not only airlines benefit from IATA’s efforts toward net zero aims. The ADRM (Airport Development Reference Manual) is a guide to addressing net zero challenges for airports.

The OLGA project (hOlistic and Green Airports), was started by Aeroports de Paris SA (ADP), with Paris Charles de Gaulle Airport and Zagreb Airport in 2021. The consortium operates as part of the European Green Deal plan. Currently, there are 4 airports in the program focused on 73 deliverables, including the development of SAF evolving and infrastructure, demonstration of net zero turnarounds with APU reduction, and hydrogen usage in mobility and airport design.

Some emission reduction targets are highly ambitious. The Science Based Targets Initiative (SBTi) is comprised of four non-governmental organizations: the United Nations Global Compact, the Carbon Disclosure Project (CDP), World Wildlife Fund for Nature (WWF), and World Resources Institute (WRI). Recently, they provided guidance to aviation on reducing CO2 emissions per revenue ton kilometer (RTK) by more than 30% against the 2019 base year by 2030.

Source: McKinsey

Three levels of emissions: what do you need to know?

The Greenhouse Gas Protocol sets an accounting and reporting standard for carbon dioxide emissions, as well as a standard for the ACI ACA.

Source: ACI

Scope 1 emissions stand for the direct Greenhouse Gas (GHG) emissions as a result of the organization’s activity. This includes the CO2 footprint from the usage of buildings, land, vehicles, and other assets. For airlines, off-block periods are associated with Scope 1 emissions. For airports, Scope 1 emissions are those on site, directly associated with the assets of the airport, including electricity and vehicles.

Scope 2 emissions are the indirect emissions caused by the organization when consuming or buying certain products, such as energy used for heating or cooling the terminal building.

Scope 3 emissions are indirect emissions distributed through the value chain. Examples include emissions from airline and tenant activities, as well as ground transport vehicles not owned and controlled by the airport operator. Jet fuel consumption is the major contributor to greenhouse gas emissions, and it also falls into the Scope 3 emissions for airports meaning airline taxi times and APU use are included in Scope 3.

In the EU, according to the EU ETS, airports are required to report on their Scope 1 and Scope 2 CO2 emissions, while Scope 3 is left voluntary. In the US, there is no state-wide regulation; however, some states have already implemented initiatives to tighten emissions control.

The California Air Resources Board (CARB) has established the Airport Emissions Reduction Program, which requires airports in the state to report their greenhouse gas emissions. A similar initiative comes from the Massachusetts Department of Environmental Protection (MassDEP) as part of the Massport Climate Action Plan. The Port of Seattle, which operates Seattle-Tacoma International Airport, voluntarily reports its greenhouse gas emissions as part of its commitment to sustainability.

As of 2023, the stakeholders in the aviation industry are not obliged to report on Scope 3 emissions. Some industries, like financing, however, already see a change in legislative expectations.

The complexities of Scope 3

According to Deloitte, Scope 3 emissions account for nearly 70% of the carbon footprint of most businesses. For airport operations, the number can increase even further. In 2021, Edinburgh Airport (EDI) reported their Scope 3 emissions to form 95.6% of the total.

ICAO states the measures to reduce international aviation CO2 emissions are comprised of SAF, improved technology and aircraft efficiency, and operational improvements. Scope 3 emissions are directly related to all three measures.

Source: ICAO

There are several reasons why monitoring Scope 3 emissions in the aviation industry can be complex.

  • The operations of many stakeholders are interconnected, leading to a collective responsibility for deviations. For example, extended times of taxiing and queuing for takeoff might lead to increased emissions, even if the airline maintains a modern fleet.
  • Some initiatives can be negotiated but will be complex to monitor and report on. One example would be an agreement to turn off the APU within a specific time window once the aircraft has parked, which eventually falls under the responsibility of the pilot in command.
  • Sharing of data and double counting. Some of the points provoke ambiguity, such as the necessity to share cooperative data with stakeholders or double counting in carbon offsetting. Double counting is when a carbon credit is claimed by more than one entity, even though no additional carbon benefit is produced.
  • Prioritization of economic and safety factors over sustainability. Aviation partners are selected on a complex basis of factors, where environmental figures are yet to be prioritized.

Despite the challenges, there are clear signs that addressing Scope 3 emissions is important if aviation is to truly meet its net zero targets. Carbon taxes are becoming a major driver for organizations to turn their operations into a greener state, where just in Europe they can reach $130 per ton of carbon emissions. Many airports include carbon emissions monitoring requirements in their SLA agreements. Having a solid sustainability policy also opens doors to green bonds and gives airports an advantage over other investment applicants.

The GHG protocol outlines several benefits of Scope 3 emissions reduction, among which are decreased costs and improved operational efficiency. A conscious approach to the impact of your business and its partners improves the stakeholder and customer relationship.

Scope 3 and Airport Carbon Accreditation

The ACI Airport Carbon Accreditation (ACA) is a voluntary program to recognize airports' sustainability and emission reduction efforts. It is the only international airport-based standard that is accepted all around the world and conforms to regional laws.

To apply for the program, the airports must submit their carbon reports to one of the approved verifiers, in accordance with ISO 14064 (Greenhouse Gas Accounting). There are six levels of accreditation, starting as simple as measuring (i.e., collecting and reporting) emissions. There are 556 airports in the program as of 2023, which account for 45.9% of the global air passenger traffic.

Scope 3 emissions are attributed to Level 3, entitled 'Optimization'. For those airports that aim to pass level 3 and reach the highest level 4+, full reporting of Scope 3 emissions is essential. Those include:

  • Take-off and landing cycle emissions.
  • Emissions during the turnaround.
  • Staff transportation and travel.

There are several steps that an airport has to take prior to reaching level 3. The most important are to prove a reduction in emissions on a year-by-year basis and to have a low carbon and energy policy. However, level 3 accreditation requires not only communicating emissions performance to relevant stakeholders but also coming to a mutual agreement with them to reduce emissions.

Scope 3 emissions include aircraft movements, ground service equipment, and ground access vehicles not owned by the airport but present on the airport’s territory. Collaboration is essential for reducing emissions on airport territory, as isolated actions will have less effect if they are not aligned with the operations of others. The recent suspension of the flight cut plans at Amsterdam Schiphol Airport has shown that there are no easy ways to tackle environmental restrictions.

Reaching agreements on shared sustainability goals is not something just the airport will benefit from. Many aviation organizations, including ATAG and IATA, have echoed the theme of collaboration. The airport can become a provider of tools and means to improve their stakeholder’s carbon impact. And secure a long-term relationship that is beneficial for the whole operation. Munich Airport has recently shared how they are collaborating with their airlines to decrease Scope 3 emissions.

Measuring and Analyzing Scope 3 Emissions

The first step to reducing emissions for aircraft on the ground cycle is accurate data gathering. In many examples, the measurement of Scope 3 emissions at the airport are based on averages. However, with the use of technologies integrated into airport operations, both the entity and their stakeholders can raise their accuracy on sustainability data. Carbon footprint reduction begins with CO2 emissions monitoring, just as efficient management is impossible without the ability to measure things.

One of the proven frameworks to study and mitigate sustainability-level issues for airports has been related to the CDM (Collaborative Decision Making) defined by Eurocontrol in Europe and FAA in the USA.

According to IATA, aircraft ground operations (taxi, runway movements, and APU usage) account for nearly 8% of the total aircraft emissions. As small as it may seem without context, it’s a sufficient number that can be reduced with the help of technologies outside of major upgrades in aircraft engines and the usage of SAF. In the UK, the Royal Society reported that the UK alone would have to dedicate half of its Arable land to SAF production to meet the current demand so all solutions are critical to achieving net zero.

Assaia’s Benchmark Report shows that APUs typically consume 1.7 kg (3.7 lbs) per minute. Therefore, this reduced use of ground power equates to 27.2 kg (60 lbs) of extra fuel. At today's prices, that means approximately $26 per minute, equivalent to the profit from 11 passengers.

TurnaroundControl includes the calculated Predicted Off-Block Time (POBT) during the turnaround. The POBT can be used to clear a holding aircraft for taxi-in before the gate is available. While the data synchronization service allows further usage of POBT in the planning of departure queues.

The use of Assaia’s Computer Vision system and POBT measurement enabled Seattle-Tacoma International Airport to reduce excess gate holding time by 79% resulting in a reduction of 1,462,867 kg of CO2 emissions and fuel costs by $1 million per annum.

Assaia’s EmissionsControl provides airports with real-time monitoring of APU engine usage, ensuring reporting and compliance with guidelines and regulations. Our AI technology utilizes sensors at gates to detect APU activity. By analyzing flight data, the application offers users an up-to-date overview of any violations. With mobile alerts, users can be notified when intervention is necessary.

Everyone wins when APU runtime is reduced. Airlines save money by reducing fuel burn and maintenance runtime costs, airports demonstrate reduced emissions and ground noise, and communities benefit from the reduction of environmental impacts.

Reducing APU runtime is as simple as flipping a switch in the cockpit. When to flip that switch and establishing an airport environment with reliable gate systems for power, heating, and cooling aircraft that allows that switch to be turned off is a more challenging problem. To understand the problem correctly, the industry needs robust structured data of the turnaround process.

By knowing precisely when (1) the 400hz ground power is connected and (2) when preconditioned hot/cold air begins flowing into the aircraft, users know (3) when the APU should be shut off. If there is a misalignment of these three activities, questions should be asked to understand why.

With robust data sets of APU monitoring, we begin to understand more clearly why the APU is left running and how to correct the measures, whether that be human error (a pilot forgot because it isn’t on the checklist) or that a system is inoperative. Many airports are eligible for grant funding opportunities to deploy reliable ground power and preconditioned air systems, which eliminates many of the initial investment hurdles.

Once APU monitoring systems such as Assaia’s EmissionsControl are in place, users can quickly demonstrate a return on investment. For example, if an airline or airport with 1200 flights a day reduces just 6 minutes of APU runtime per flight they could realize $5.2 million in cost savings annually (fuel cost savings plus maintenance savings) and CO2 reduction of 30.4 million lbs (13.7 million kg) a year.

This is a capability that Assaia can deliver to airports and airlines today and doesn’t require any new breakthroughs in novel propulsion systems or mass global production of SAF. The first step is measuring existing activity levels, and Assaia is the leader in this space.

Being proactive in learning how to meet the rising sustainability challenges helps your organization stay ahead of the curve. Contact Assaia today to learn more about innovative technologies to improve your turnaround times and carbon emissions monitoring.

Author: Diana Vidstrom


  1. Assaia Turnaround Benchmark Report
  2. Pietro Achatz Antonielli “A Framework for Monitoring, Modeling, and Management of Airport Ground Power Systems During Airport Ground Power Systems During Aircraft Turnaround Operations” Ph.D. dissertation University of California, Berkeley, 2023.
  3. Anil Padhra “Emissions from auxiliary power units and ground power units during intraday aircraft turnarounds at European airports” // Transportation Research Part D: Transport and Environment. Volume 63, August 2018, pp. 433-444.
  4. IATA “Net Zero 2050 Progress Tracking Methodology” and “Airport Environmental Sustainability.”
  5. Axel Esqué, Frederik Franz, Geert Mulder, Robin Riedel, Daniel Riefer (McKinsey & Company) “Decarbonizing aviation: Executing on net-zero goals”. June 16, 2023.
  6. IPCC “Climate Change 2023 Synthesis Report” and “Aviation and the Global Atmosphere
  7. ICAO “Overview of Climate Goals and ICAO’s Work on a Long-Term Aspirational Goal for International Aviation (LTAG).”
  8. The Royal Society Net zero aviation fuels: resource requirements and environmental impacts report


The use of Assaia's TurnaroundControl has provided our Airline Partners, Ground Handlers, and Service Providers with full visibility of the aircraft turn processes. The data, predictability, and visibility enhances our collective efficiency and resilience at Toronto Pearson. Paired with our A-CDM initiative, Assaia's TurnaroundControl provides crucial data driving A-CDM processes, a reduction in turn times, and a noticeable increase in on-time performance.

Dean Wright
Associate Director, Gating & Airport Flow

The way Turnaround 2.0 uses AI and machine learning to boost our zone controllers' efficiency is remarkable. They can now manage multiple gate activities with more focus on handling exceptions, rather than multitasking. Turnaround 2.0 is more than a tool for the present; it's a foundation for 'United Next,' growing with us and helping us surpass our operational goals efficiently.

Daniel Reed
Director of Station Operations, United Airlines

Our focus is to use innovation to make our operations smoother. We have selected Assaia because of the capabilities of the tool. But it is also really important for us that it has a good record of successful implementation, so we know it will deliver for us, for our airlines and ultimately for our passengers.

Dr Babett Stapel
Managing Director, Fraport Slovenjia

We are optimizing all our processes on the apron to shorten the time each aircraft needs to be on the ground, which benefits both our passengers and our airline partners. This is a common issue across our airports and we are talking to all of them about this technology.

Claus Grunow
VP of Corporate Strategy and Digitalization at Fraport

We are pleased to partner with Assaia to implement the ApronAI Turnaround Control solution at T4. This new solution will not only optimize operations and our work with our business partners, but will also help us to ensure a first-class customer experience at T4.

Roel Huinink
President and CEO, JFKIAT

For most airports, the apron is a a black box. Assaia finally gives our ground staff full insight into every turnaround. This allows them to focus on what really matters, while simultaneously making the work environment safer.

Jason Aspelund
Former Manager Strategic Performance, Alaska Airlines

The real-time and historical insights that can inform both airport and airline operations make this solution a clear winner for everyone.

Craig Paul
Director of Technology & Innovation , Halifax Stanfield International

Assaia's product allows airports and airlines to collect, track, and analyze data in real time; this innovation removes inefficiencies and optimizes performance.

Jim Lockheed
JetBlue Ventures

We’re creating the airport of the future, and innovation in apron operations will directly improve the passenger experience. We are laser focused on innovations that will make Pearson and its whole apron ecosystem more efficient while reducing our carbon footprint.

Deborah Flint
President and CEO GTAA

SEA needed an innovative solution to our capacity problem and have worked with Assaia to optimize the turnaround process resulting in reduced taxi times and increased passenger satisfaction. Assaia has exceeded our expectations, consistently delivering on-time & on-budget.

Samer Tirhi
Airline Scheduling Coordinator, Seattle-Tacoma International Airport

With the help of Predicted Off Block Time from Assaia. JFKIAT Operations can be proactive to reduce or eliminate any delays and gate holds

Stephen Tukavkin
VP IT & Digital, JFKIAT

I had mentioned before, great innovation on your part. With these types of improvements, T4 is always leading at JFK. Thank you

COPA Station Manager

We are proud to be partnering with the Assaia team in our mission to use technology to improve the efficiency and safety of the airport environment.

Raghbir S. Pattar
Director of Airports Transformation, IAG

We’re working hard on becoming an airport of the future, and this involves rethinking every part of our ground operations. Assaia’s ApronAI is an integral component of our vision for the ramp of the future.

Abhi Chacko
Head of Innovation & Commercial IT Services, Gatwick Airport

Assaia’s technology adds critical data points to CVG’s early-stage neural network for operational advancements. Structured data generated by artificial intelligence will provide information to make decisions, optimize airside processes, and improve efficiency and safety.

Brian Cobb
CIO, CVG Airport


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