Frequently Asked Questions

What Is The EAGLE Initiative?

EAGLE (Eliminate Aviation Gasoline Lead Emissions) is a broad and collaborative initiative among the Federal Aviation Administration (FAA), the general aviation (GA) community, fuel suppliers and distributors, airports, engine and aircraft manufacturers, research institutions, associations, local communities, environmental groups and other key stakeholders. EAGLE partners are committed to ensuring the GA sector can safely transition to a lead-free future by the end of 2030 (at the latest) without affecting the safe and efficient operation of the piston-engine fleet.  

How is EAGLE Structured?

The EAGLE initiative is modeled after CAAFI (Commercial Aviation Alternative Fuels Initiative) and overseen by an executive committee that comprises senior leaders in aviation and the FAA. The daily work is led by a Senior Coordinator selected jointly by industry and government. Work on the EAGLE initiative is organized into four pillars, each led by an industry expert or government leader. 

What Are EAGLE’s 4 Focus Areas, Or Pillars?

The EAGLE framework encompasses four pillars designed to foster the necessary evaluation, authorization, regulatory, innovation, and infrastructure solution sets to enable the commercial viability of unleaded aviation gasoline needed to facilitate the transition. The initiative supports the White Houses’s sustainable transportation and broader environmental priorities and is part of the ongoing effort to build a sustainable aviation system.  


Some aircraft can already use the available 94-octane unleaded fuel from Swift Fuels and, in some cases, unleaded automotive fuel of certain octane levels and without ethanol. However, it is the pilot’s and aircraft owner’s responsibility to know if their aircraft has been approved for these unleaded fuels (and, if so, have purchased the appropriate supplemental type certificate [STC]) and where they may be able to buy it. The industry is working on a smart transition toward an unleaded solution that will work for the entire GA fleet.

Why IS THIS ISSUE important?

The effort was launched to help bring about a lead-free aviation future, addressing the need for urgent multi-stakeholder collaboration to eliminate lead from aviation gasoline (avgas). EAGLE is based in part on recommendations in the National Academies of Sciences, Engineering, and Medicine (NASEM) January 2021 report mandated by Congress in the 2018 FAA Reauthorization Act.  


Many aircraft in the current general aviation fleet need 100-octane fuel in order to avoid engine detonation and catastrophic engine failure. Lead has long been used as an additive to boost fuel octane, allowing these aircraft to fly safely. Finding a suitable unleaded substitute has long been a goal of the general aviation industry and FAA. While the mission has been challenging, there has been recent progress. As important, the unleaded transition must be safe and smart, and airports and communities must provide a supply of 100LL for all aircraft to fly safely during this transition.


While the industry’s goal is that unleaded fuel will not be significantly more expensive than 100LL, it is too early to communicate specific costs. Any slight cost increase may be offset with lower maintenance costs.


Avgas: Avgas (aviation gasoline) is an aviation fuel with spark-ignited internal combustion engines. In aviation, Avgas is distinguished from conventional gasoline (petrol) used in motor vehicles, termed mogas (motor gasoline). Unlike motor gasoline, formulated since the 1970s to allow platinum-content catalytic converters for pollution reduction, the most commonly used grades of avgas still contain tetraethyllead (TEL), a toxic substance used to prevent engine knocking (premature detonation). Ongoing experiments aim to reduce or eliminate the use of TEL in aviation gasoline.

Drop-In Fuel: A “drop-in” fuel does not affect the airworthiness and performance of the existing aircraft and engines and typically does not require new aviation fuel-related operating limitations. An extensive qualification test program that encompasses fuel property evaluation and engine and aircraft testing would be required to determine if a new fuel is a drop-in.

Non-Transparent Fleet: The segment of the existing fleet of engines and aircraft for which a new fuel is not a drop-in is called the “non-transparent fleet.” FAA approval of new operating limitations and changes such as new or modified hardware, adjustments, or new operating procedures/limitations will be required for aircraft and engines in the non-transparent fleet.

OEM Service Bulletin: Original Equipment Manufacturer (OEM) Service Bulletins are communication vehicles used by engine and aircraft type certificate (TC) holders to advise owners/operators of approved aviation fuels. New aviation fuels added to a TC are approved under traditional certification procedures and airworthiness standards, after which the OEM service bulletin is updated with the newly added fuel.

Special Airworthiness Information Bulletin (SAIB): A Special Airworthiness Information Bulletin is an information tool that alerts, educates, and makes recommendations from the FAA to the aviation community. SAIBs contain non-regulatory information and guidance that are not mandatory and do not meet the criteria for a mandatory FAA Airworthiness Directive (AD).

Transparent Fleet: The segment of the existing fleet of engines and aircraft for which a new fuel is a drop-in is called the “transparent fleet.” Changes such as new or modified hardware, adjustments, or new operating procedures/limitations are not required for the aircraft and engines in the transparent fleet. Still, FAA approval may be required to enable operation under the existing operating limitations.

The EAGLE initiative will be modeled after CAAFI (Commercial Aviation Alternative Fuels Initiative) and will be led by an Executive Director selected jointly by industry and government. Work on the EAGLE initiative will be organized in four pillars, each led by an industry expert or government leader.

The EAGLE initiative is a comprehensive public-private partnership consisting of aviation and petroleum industry and U.S. government stakeholders, working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030, without compromising safety or economic health of the general aviation industry