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Homepage / The big rocks don’t always go first: near and long-term sustainable aviation levers

The big rocks don’t always go first: near and long-term sustainable aviation levers


As the aviation industry efforts to support “net zero” by 2050(1) continue to progress and evolve, we have many discrete efforts, or “levers”, by which to act. Of course, CO2 emissions are not the only target of sustainable aviation efforts, but they are the major target. It is estimated that aviation accounts for 2.5% of global emissions, with non-CO2 effects making the contribution to global warming proportionally higher due to the high-altitude atmospheric effects(2).

The launch of the Global Sustainable Aviation Exchange (GSAE) took place in December 2023, sponsored by Cranfield University and the Air Transport Action Group (ATAG), in partnership with Khalifa University and the University of Waterloo. The many challenges and opportunities ahead were showcased. This writer spoke at the GSAE event regarding near-term challenges and opportunities, focusing on the many things which can be done today, especially around digital aviation. To support this discussion, a version of the following simple diagram was presented.  

This diagram shows examples of known levers which support sustainable aviation, including those that are existing and mature, in-development, and long-term and aspirational. It divides these levers into three major categories:

  1. Aircraft and propulsion,
  2. Fuels and energy carriers
  3. Operations

The first two are the “big rocks”, with the largest net gains. Operations contains the relative “small rocks”(3). Across the bottom in green are exogenous factors which are required to support progress and velocity. These include public sentiment regarding the imperative to invest in sustainable actions, related government policies across the globe, the continued profitability of the aviation sector, and overall industrial infrastructure at the transportation level supporting efforts such as hydrogen and sustainable aviation fuel (SAF).

While not an exhaustive list, the diagram shows many of the well-known levers, and some lessor known levers, or ones which have lost awareness over the years.

Aircraft and propulsion

This includes next generation aircraft, technology updates, electric propulsion from various power sources, higher efficiency engines, and hydrogen propulsion. Since the dawn of the jet age of aviation aircraft, engines have become significantly more efficient and quieter, and this efficiency increases with each new generation. This will undoubtedly continue apace. These are “big rocks”.

Fuels and energy carriers

This includes sustainable aircraft fuel (SAF) and low carbon aircraft fuels (LCAF), hydrogen and batteries. The timeline for ubiquitous SAF is on the order of approximately 10 years, whereas estimates for hydrogen are longer, varying from 2035 to 2045, with much depending upon governments’ policies and industrial investments. While much focus is on batteries, these will remain restricted for use in the commuter and smaller aircraft for the foreseeable future due to their intrinsic power-to-weight ratio. These are also “big rocks”.


This is the area where most of the near-term opportunity exists. Due to the relatively smaller impact of these, individually they are often overlooked or are acted upon strictly for economic reasons and the resulting 1st, 2nd and 3rd order sustainability benefits are not always captured. In addition, the sustainability benefits go beyond CO2 emissions. Moreover, by their nature they are executed by different verticals within an operator’s organisation. In fact, the domains listed under operations mirror many airline structures: flight operations, technical operations (e.g., maintenance and engineering), ground operations, passenger and cabin operations. In addition, air traffic management is a key operational element with key sustainability levers.

It is generally accepted that operations will contribute approximately 10%(4) to the ultimate net zero picture. Given this we can confidently name these as “small rocks”. However, this does not tell the whole story. If we look closer at the 26 example levers listed within operations, we see that the vast majority are mature and available and in use today, and there is no major technological barrier to their full adoption in the near term. In addition, if we look at these, we see a common thread: a robust digital aviation(5) and data-driven approach is required to both execute these on a continuing basis to reap the economic and sustainability benefits within operations, and to deliberately measure and capture those benefits.

If we take a step back and consider the “present value” of a simplified scenario we can argue that the contribution of these many smaller actions or levers is on par or greater than some “big rock” items. For example, the figure below shows some hypothetical actions taken over time.

In this example above we have 11 different theoretical actions which deliver sustainability benefits over a 20-year period. Action A delivers very material benefits starting in year 10, ramping up between years 10 and 20 from one to 50 (arbitrary units of benefit), as the actions are deployed after a ten-year investment and development period, 50 being very material. Actions B through K represent ten currently available actions which are increased from 0.5 to 1.0 in the next five years. While each of these ten is seemingly not material, together they deliver ~30% more “present value” of benefits than the much greater single Action A (using a 10% discount rate). This is a rough and inexact estimate, but illustrates the point that doing more actions, however individually small, sooner is materially beneficial.

To summarise, as we strive to drive near-term actions towards net zero, it behooves us to reconsider the way we look at operations and digital aviation within the larger sustainable aviation picture. While these are relative “small rocks”, in a real sense they can and should go before the upcoming “big rocks”. Moreover, we need to break down the stovepipes between the operations domains and further drive the adoption of these important levers as quickly as possible. This will be one of the focus items of the newly formed Global Sustainable Aviation Exchange.


(1) International Civil Aviation Organization (ICAO) has agreed to a long-term aspirational goal (LTAG) of net-zero carbon dioxide (CO2) emissions from aviation by 2050.
(2) David S. Lee et al, “Uncertainties in mitigating aviation non-CO2 emissions for climate and air quality using hydrocarbon fuels”. Royal Society of Chemistry, 28 November 2023.
(3) The “Big Rocks” metaphor for business, and the need to address them first, was famously coined by Stephen R. Covey.
(4) Jim Angus, John Maggiore. “Planning for a digital future”. Aircraft IT · Mar 23, 2022. 
(5) Digital aviation here refers to embodying knowhow and methods within software to aviation job roles to provide operational efficiency.

Are you interested in finding out more about this area of research? Join our webinar, Leading the change: industry and manufacturing’s journey to net zero, on Tuesday 30 January 2024 at 09.30am BST. 

Register now

John Maggiore

Written By: Antonia Molloy

John Maggiore is a senior aerospace leader and industry consultant. A former Boeing executive leader, John spent more than two decades developing an industry-leading portfolio of digitally driven capabilities deployed across the globe. He is a recognised digital aviation expert, with expertise in vehicle health management and digital MRO. John holds two US patents for innovations in vehicle health management and is the Principal Consultant at Meridian Insights. He is a Senior Advisor to the Integrated Vehicle Health Management (IVHM) Centre at Cranfield University and is a Visiting Professor at the university.  John is also a Fellow of the Royal Aeronautical Society.

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