The Federal Aviation Administration has released its final Transition Plan to Unleaded Aviation Gasoline, Version 1.0, dated July 2026, and piston-engine pilots now have a concrete four-phase map for leaving 100LL.
The plan is the document Congress ordered under Section 827 of the 2024 FAA Reauthorization Act. It aims for safe elimination of leaded aviation gasoline for piston-engine aircraft by the end of 2030 in the lower 48, with Alaska running on a later 2032 track.
If you own, fly, maintain, or fuel a spark-ignition piston airplane, this is an airport and fleet planning file, not airline cabin news. Treat Phase 1 authorization work and airport fuel choices as open decisions through at least late 2027.
- What landed: FAA final Transition Plan to Unleaded Aviation Gasoline, V1.0, July 2026.
- Hard dates: End of 2030 for national leaded-fuel elimination, end of 2032 for Alaska.
- Phase 1 focus: Finish fuel authorizations and comparison testing, projected through spring 2027.
- Next plan update: FAA commits to Transition Plan V2.0 after Phase 1, late 2027.
- Pilot action: Track which unleaded fuels your airframe and FBO can use before swapping tanks.
What the final plan actually says
The public Transition Plan PDF is a 72-page operating framework, not a single-day fuel ban. It implements the EAGLE initiative goal of eliminating leaded aviation fuels without grounding the existing general aviation fleet.
FAA says many transition outcomes will still be market driven. Private fuel producers, airports, FBOs, and aircraft owners will choose among authorized fuels based on cost, logistics, and aircraft fit.
The agency also lists open questions that Phase 1 must still answer, including final fuel identities in widespread use, owner costs, and whether unleaded fuels can be intermixed safely.
A 60-day public comment period on the draft plan ran from January 12 through March 13, 2026. Version 1.0 adds Phase 1 progress detail, commits to a late-2027 V2.0 plan after Phase 1, promises FAQs on flyEAGLE.org, and plans a public-comment summary document.
Industry members of EAGLE, including AOPA, EAA, GAMA, NBAA, NATA, NASAO, AAAE, API, and Vertical Aviation International, signed a support letter inside the plan. They frame V1.0 as an initial framework that must keep adapting as test data and market realities change.
The four phases pilots and airports will live through
Phase 1 is Fuel Authorizations and Comparison. Three high-octane unleaded candidates are already in the FAA pipeline: LyondellBasell UL100, GAMI G100UL, and Swift Fuels 100R.
The plan projects authorization and approval work to finish by spring 2027.
Phase 1 also funds comparative testing under identical conditions so owners can compare detonation, materials, and supply-chain issues. FAA will study co-mingling among unleaded fuels because offerors do not currently support mixing different unleaded products even when each fuel may mix with 100LL in an aircraft tank.
Phase 2 is Gaining Market Experience. Unleaded consumption expands beyond early adopters while 100LL remains available nationwide.
The phase is designed to surface in-service issues that lab testing misses.
Phase 3 is National Transition for all states except Alaska. Aircraft and airports outside Alaska are expected to move to unleaded fuel using lessons from the first two phases.
Phase 4 is the Alaska Transition, timed later because of unique logistics, climate, and fuel-distribution constraints.
Federal regulations will still be required to eliminate 100LL use. Airports and FBOs should not be forced to add tankage solely to cover the transition, according to the plan’s core design ideas.
That is why temporary dual-fuel operations and truck-based solutions matter in Phase 2.
What the three candidate fuels mean on the ramp
GAMI G100UL already holds engine and airplane AML STCs, with rotorcraft work still in progress. Swift Fuels 100R has initial and expanded STC paths and an ASTM production specification.
LyondellBasell UL100 is progressing through fleet-authorization testing, engine, materials, and flight work.
Two of the fuels have already seen demonstration or limited early-adopter use. That matters because Phase 2 depends on real ramp experience, not only paper approvals.
The plan is candid about past service issues that show why comparison testing is not optional. It cites valve-seat recession concerns reported with UL94 at the University of North Dakota, paint and O-ring findings reported around G100UL, and a Cirrus service advisory on fuel-tank sealant degradation with G100UL.
FAA also asked for more field reporting through a Special Airworthiness Information Bulletin issued in March 2025.
For a flight school or owner, the decision is not “unleaded good, leaded bad” in the abstract. It is which authorized fuel matches the engine, sealants, elastomers, and local supply chain, and what mechanic work the Fleet Authorization or STC path requires.
Owner and mechanic actions by certificate type
Aircraft with a standard airworthiness certificate need changes performed by a certificated mechanic or authorized entity under 14 CFR section 43.3. That can mean Fleet Authorization documentation, OEM service bulletins, or STC installation that matches the type certificate path.
Special airworthiness certificates follow similar mechanic rules, but STCs may not cover every category. Light-sport SLSA aircraft can be covered by FAA Fleet Authorization or by the original manufacturer’s determination.
Experimental owners must decide fuel suitability themselves, using fleet-authorization data or STC-holder data where engines and systems match certificated aircraft.
Those distinctions are why a one-size ramp policy fails. An FBO that stocks only one unleaded product may still leave experimental or special-category customers without a legal or practical path until more authorizations land.
Travelers who connect general aviation with Alaska or the Lower 48 should also track the separate Alaska clock. Deep Arrival’s Alaska Airlines guide is not a GA fuel manual, but it remains a useful commercial-air context page when a piston trip feeds an Alaska itinerary that will live under the later Phase 4 fuel calendar.
For destination-side Alaska planning tied to that later phase, the Alaska cruise and travel hub helps map ports and routes that still depend on GA feeder fields even when the long-haul segment is jet powered.
| If you are | What to do now |
|---|---|
| A piston owner flying in the lower 48 | Match your engine to UL100, G100UL, or 100R, then ask your shop what Fleet Authorization or STC work is required. |
| An FBO or airport fuel manager | Plan Phase 2 dual-fuel logistics without assuming new tankage is mandatory, and track co-mingling test results before stocking multiple unleaded products. |
| A flight school operator | Use FAA and EAGLE flight-school guidance, log unleaded experience carefully, and avoid a fleetwide switch until authorization and materials data match your engines. |
| An Alaska-based operator | Budget to the 2032 Alaska track and treat Lower 48 Phase 3 milestones as advance signals, not immediate local deadlines. |
- Do not scrap 100LL plans overnight: The plan keeps 100LL available during early phases and says airports cannot be forced to ban it before statutory criteria are met.
- Budget shop time: Standard-category aircraft need certificated maintenance work for Fleet Authorization or STC changes, not owner self-install improvisation.
- Watch co-mingling science: If unleaded fuels cannot share tanks or trucks, regional fuel segmentation becomes a real trip-planning risk.
- Track flyEAGLE.org: FAA will push Phase 1 updates, FAQs, and the late-2027 V2.0 plan through the EAGLE channel rather than only through one press release.
- Spring 2027 authorization finish line: Whether all three candidate fuels complete planned approval or fleet-authorization work on schedule.
- Co-mingling test results: Whether multiple unleaded fuels can share infrastructure without misfuel risk.
- Transition Plan V2.0: Late-2027 update that is supposed to lock schedules for Phases 2 through 4.
- Local airport fuel policy: Early dual-fuel experiments that change what you can buy on a cross-country without changing the national end dates.
Download the July 2026 V1.0 plan, match your airframe to a real authorization path, and ask your FBO which unleaded product it can stock before you treat 2030 as a next-month fuel crisis.
Does this plan ban 100LL at my airport tomorrow?
No. Version 1.0 is a phased national framework.
100LL remains available during early phases, and the 2024 reauthorization still protects continued 100LL availability until statutory replacement criteria or the 2030 or 2032 dates are met.
Which unleaded fuel should I buy first?
There is no single answer yet. The market will choose among authorized fuels after Phase 1 authorizations and comparison testing finish.
Match your engine and materials data to a specific authorization path before changing tanks.
Why is Alaska on a different clock?
The plan and the statute give Alaska until the end of 2032 because of unique logistics, climate, and fuel-distribution challenges. Phase 4 is written as a separate national step after the Lower 48 transition.
Do airline passengers need to change tickets because of this plan?
No. This is a piston-engine general aviation fuel transition.
Jet fuel and airline operations are outside the unleaded avgas plan, even when a GA airport shares a field with commercial traffic.
Where will FAA publish updates after this PDF?
The plan points stakeholders to flyEAGLE.org for Phase 1 progress, FAQs, and later plan versions, in addition to the formal FAA unleaded-fuel program pages.
