Is 100LL avgas going away immediately?

No. There's no urgent deadline for pilots today, but the industry is targeting a full transition to unleaded avgas by 2030. Supply of 100LL will not be cut off before a safe replacement is available.

What is the difference between an ASTM fuel and an STC fuel?

An ASTM fuel has an industry-wide specification and can flow into the existing distribution system for broad use. An STC (Supplemental Type Certificate) approves a specific fuel for specific airframe and engine combinations and must be added to your aircraft records.

Can I burn unleaded avgas in my airplane right now?

Possibly. GAMI's G100UL is available today by STC and covers essentially the entire piston fleet. You must purchase and document the STC before using it in your aircraft.

How do I know if my engine needs 100 octane?

Check your aircraft's type certificate data sheet for the minimum grade fuel. That tells you whether you need full 100 octane or can use a lower-octane unleaded option.

Why is general aviation still using leaded fuel when cars stopped decades ago?

High-compression aircraft engines need the octane that tetraethyl lead provides to make rated power without destructive detonation. Developing an unleaded fuel that delivers full 100 octane safely across all conditions has been the core technical challenge.

The FAA Updates Its Unleaded Avgas Transition Plan and What It Means for Your Airplane's Next Fill-Up

SUMMARY: The FAA’s July 2026 update to its unleaded avgas transition plan details where each replacement fuel stands and what it means for your airplane.

On July 30, 2026, the FAA released the first major update to its Transition Plan to Unleaded Aviation Gasoline, according to reporting from the Aircraft Owners and Pilots Association (AOPA). The plan sets the framework for eliminating tetraethyl lead (TEL) from the avgas that most piston airplanes have burned for nearly a century, and the target for finishing the job remains 2030. If your airplane runs on 100 low lead (100LL), the fuel in your tanks is on a clock - not a fast one, but a clock.

Why Is There Lead in Avgas at All?

Tetraethyl lead does one job well: it boosts octane. Octane is a fuel’s resistance to detonation - the destructive, uncontrolled banging in the cylinders that can wreck an engine in seconds under high power and high heat.

High-compression engines, including the big-bore six-cylinder powerplants in much of the fleet, need that octane to make their rated power safely. The lead isn’t an accident. It’s engineering from an era that didn’t have a better answer.

The problem is straightforward: lead is a neurotoxin. It left automotive gasoline decades ago, and general aviation is now the largest remaining source of lead emissions into the air in the United States.

Two years earlier, the Environmental Protection Agency (EPA) issued an endangerment finding on leaded avgas, starting the regulatory countdown the industry has watched ever since.

What Is the EAGLE Initiative?

The industry’s response is an initiative called Eliminate Aviation Gasoline Lead Emissions, shortened to EAGLE. Its stated goal is a safe, smart transition to unleaded avgas for the entire piston fleet by 2030.

The new FAA document is the updated roadmap for reaching that goal. Its most important contribution isn’t the date - the 2030 target was already known - but the detail. The FAA added specifics on where each unleaded fuel candidate stands right now.

What Actually Changed in the Update?

There isn’t one replacement fuel. There are several, and they’re moving through approval on different tracks. This update functions as the status board that owners have been asking for.

Two main pathways exist to get an unleaded fuel into your tank:

The ASTM route. The American Society for Testing and Materials (ASTM) produces an industry-consensus fuel specification - the same kind of spec that defines 100LL today. A fuel with an ASTM spec can flow into the existing distribution system and be used broadly.
The Supplemental Type Certificate (STC) route. An STC authorizes a specific fuel in specific airframe and engine combinations. You buy the STC, add it to your aircraft records, and you’re legally cleared to burn that fuel.

Here is where the candidates stand:

GAMI’s G100UL - an unleaded 100-octane fuel already available by STC from General Aviation Modifications (GAMI). Its approval has been expanded to cover essentially the entire piston fleet by type certificate. It is flying today in airplanes whose owners have purchased the STC.
Swift Fuels - already sells a lower-octane unleaded product and is developing a 100-octane unleaded fuel on the ASTM track.
Lyondell and VP Racing - a partnership continuing work on an additional candidate fuel.

How Does This Affect My Airplane?

If you fly a low-compression airplane - a Cessna 172, a Piper Cherokee, anything with an engine that doesn’t need full 100 octane - you have the most options and the earliest runway. Lower-octane unleaded fuels are the easier technical problem, and an approved option is available now or close for many of these aircraft. Your transition may be nearly seamless.

If you fly a high-performance piston - a big-bore turbocharged twin, a high-compression single, a warbird - you are the reason this is hard. Your engine needs full 100 octane, and delivering that safely across every cylinder in every operating condition is the entire technical challenge. The 100-octane solutions are progressing, but yours is the fleet the 2030 timeline is really built around.

If you operate at an airport under pressure over leaded fuel - some fields, particularly in certain states, have faced real push to stop selling 100LL - the concern has always been that lead disappears from the pump before a replacement is available, stranding pilots. The purpose of a national transition plan, and of EAGLE behind it, is to prevent exactly that. Safety of the existing fleet comes first: no airplane left without fuel it can legally and safely burn.

Why This Matters for Pilots

The real value of this document is transparency. When the FAA publishes where each fuel stands in the pipeline, owners can make concrete decisions: whether to buy an STC now, wait for an ASTM fuel to reach the field, or factor fuel availability into where the airplane is based or into an upcoming engine overhaul. Those are calls you can make on a status report, not a slogan.

What Should I Do Right Now?

Nothing is urgent today, but two steps are worth your time:

Find out what your engine actually requires. Pull your type certificate data sheet and check your minimum grade fuel. That single fact tells you whether you’re a full-octane airplane and which side of this transition you’re on.
If your aircraft already has an approved unleaded option, read up on the STC and its cost now, so it’s a decision you’ve thought through rather than a surprise at the pump. Knowledge in the logbook beats scrambling at the fuel island.

The lead is coming out of avgas - that much is settled. The question was never whether, but how and how safely, and this FAA update fills in much of the how.

Key Takeaways

The FAA released its first major update to the Unleaded Aviation Gasoline Transition Plan on July 30, 2026, per AOPA reporting.
The EAGLE initiative aims to move the entire piston fleet to unleaded avgas by 2030.
Two approval pathways exist: industry-wide ASTM specs and aircraft-specific STCs.
GAMI’s G100UL is already approved by STC for essentially the full piston fleet; Swift Fuels and a Lyondell/VP Racing effort are progressing.
Low-compression aircraft have the most and earliest options; high-performance 100-octane engines define the difficulty and the 2030 timeline.