Pilots have been hearing that unleaded avgas is “coming soon” for so long that it’s become a bit like the weather forecast for the weekend you planned the big trip. Everybody talks about it, nobody quite believes it, and then one day you’re sitting on the ground watching it happen.
Well, the forecast just firmed up. On July 30, 2026, the FAA released its final plan to move the piston fleet off 100LL, with a target of no leaded avgas in the lower 48 states after the end of 2030 (AeroCorner). That’s four years and change. For an owner, that’s about four annuals, a couple of insurance cycles, and possibly one very important STC.
Here’s what the plan says, what it doesn’t say (which is most of what you’d want to know about your wallet), and how to plan for it.
What the FAA’s Plan Actually Says
The plan, labeled Version 1.0, responds to a requirement in the 2024 FAA Reauthorization Act and lays out four phases (FAA; AeroCorner):
- Fuel authorization and comparison. Approve the candidate unleaded fuels and compare them side by side. The FAA says it is still in this phase, which is expected to wrap up by the end of 2027 (Inside Climate News).
- Gaining market experience. More airports and operators start using unleaded fuel while 100LL stays available nationwide.
- National transition. 100LL is phased out everywhere except Alaska, targeted for completion by the end of 2030.
- Alaska transition. Alaska follows on a longer timeline, with 2032 as the target.
The FAA has also committed to a Version 2.0 of the plan after Phase 1, in late 2027 (Deep Arrival).
What the Plan Doesn’t Say
Here’s the frustrating part. The plan doesn’t answer several of the questions owners care about most, including what the new fuels will cost, whether they can be mixed in the same tank, when the FAA would start rulemaking to actually ban leaded fuel, and what happens to leftover 100LL (AeroCorner).
So if you were hoping for a nice tidy number to put in your budget, the FAA’s answer is, more or less, “we’ll get back to you.” Which, to be fair, is also what my mechanic says when I ask how long the annual will take.
The Three Unleaded Avgas Contenders
Three high-octane unleaded fuels are in the FAA pipeline (Deep Arrival):
| Fuel | Maker | Where it stands |
|---|---|---|
| G100UL | General Aviation Modifications, Inc. (GAMI) | Already approved for use in nearly all certified piston-engine aircraft (Inside Climate News) |
| 100R | Swift Fuels | Swift projects it could replace 95% of 100LL by 2030 (Inside Climate News) |
| UL100E | VP Racing Fuels and LyondellBasell | In the FAA authorization process |
Notice what’s missing: a winner. The FAA has chosen not to pick one. It expects the market to sort it out based on availability, cost, compatibility, and operator acceptance (AVweb). That’s very American of them, and it means the fuel at your airport may depend on what your FBO decides.
Why your FBO’s choice matters
Many airports only have one avgas tank. The FAA expects most of them to keep selling 100LL and then switch directly to a single unleaded fuel, rather than juggle several grades at once (AVweb). And the fuel makers don’t currently support mixing different unleaded fuels with each other, even though each may mix with 100LL in your tank (Deep Arrival). So a cross-country trip through airports that picked different fuels could get interesting. Plan your fuel stops like you plan your restaurant stops: carefully, and with a backup.
What We’ve Learned from Early Adopters
Some places didn’t wait. As of August 2026, neither Reid-Hillview nor San Martin airport in Santa Clara County, California, was selling 100LL (Inside Climate News).
The early experience has been mixed. Some pilots have shared photos they say show fuel leaks and paint damage after using G100UL. GAMI’s co-founder says neither GAMI nor the FAA has found a material-compatibility issue unique to G100UL that affects flight safety (Inside Climate News). Both things can be true at once: a problem can be cosmetic or a maintenance cost without being a safety-of-flight issue. Your wallet, however, does not distinguish between the two.
What to Budget for the Switch to Unleaded Avgas
Since nobody has put firm numbers on this yet, here are the cost categories to plan around. Treat any figures as placeholders until your airport chooses a fuel.
- Fuel price difference. 100LL averaged $6.67 a gallon self-serve and $7.75 full-service nationally in September 2026 (AVweb). If unleaded costs more, multiply the difference by your annual gallons. For example, an airplane burning 10 gallons an hour for 100 hours uses 1,000 gallons a year. Every extra 50 cents a gallon adds $500 a year. That’s a hypothetical, not a forecast.
- STC or approval paperwork. Some fuels require an STC for your aircraft. Check the current fee and whether your airport or state offers help.
- Seals, sealant, and paint. Ask your mechanic to look at fuel-system seals and the paint around fuel caps at your next annual, and set a little money aside in your maintenance reserve.
- Local subsidies. Some airports are offering support. Longmont, Colorado’s transition plan, for example, proposes covering 50% of STC costs up to $500 per qualifying aircraft and subsidizing the price difference during the initial switch (City of Longmont). Ask your airport whether something similar is planned.
Five Things to Do Now
- Ask your FBO which fuel they’re leaning toward, and when. They may not know yet, but asking puts you on their list of people who care.
- Confirm your airplane’s eligibility for each candidate fuel with your type club or mechanic. The type clubs are usually first to know.
- Add a line to your maintenance reserve for fuel-system items. Even a few hundred dollars a year builds a cushion.
- Watch for Version 2.0 of the FAA plan in late 2027. That’s when cost and mixing answers may finally show up.
- Factor fuel into any purchase decision. If you’re buying an airplane now, ask how it does on unleaded fuels. It may matter when you sell it.
Fuel is the biggest hourly cost for most owners. To see how it fits with everything else, read The True Annual Cost of Owning an Airplane in 2026.
Frequently Asked Questions
When will 100LL be phased out?
The FAA’s final transition plan targets no leaded avgas in the lower 48 states after the end of 2030, with Alaska following by 2032.
Which unleaded fuel will replace 100LL?
The FAA is not picking one. G100UL, Swift Fuels 100R, and UL100E are all in the pipeline, and the market is expected to decide based on cost, availability, and compatibility.
Will unleaded avgas cost more than 100LL?
The FAA plan does not answer that yet. Owners should watch prices at airports that already sell unleaded fuel and budget for a possible difference.
Can I mix unleaded avgas with 100LL?
Each unleaded fuel may be mixable with 100LL, but fuel makers do not currently support mixing different unleaded fuels with each other. Check the guidance for the specific fuel and your aircraft.
Sources
- Federal Aviation Administration, Transition Plan to Unleaded Aviation Gasoline, Version 1.0, July 2026.
- AeroCorner, “The FAA just set a date to end leaded fuel in American aviation,” July 31, 2026.
- Deep Arrival, “FAA finalizes unleaded avgas transition plan for GA.”
- Inside Climate News, “The clock is ticking on leaded aviation fuel,” August 18, 2026.
- AVweb, “A first look at the FAA’s unleaded avgas transition plan.”
- AVweb, “Aviation fuel prices hit new 2026 highs.”
- City of Longmont, Vance Brand Airport Unleaded Aviation Fuel Transition Plan.
Disclaimer: This article is for educational purposes only and is not financial, tax, or maintenance advice. Fuel approvals and compatibility vary by aircraft; always follow your aircraft’s approved documentation and your mechanic’s guidance. Consult a qualified financial advisor and tax advisor about your specific situation.
Want to see how the fuel switch fits into your long-term ownership plan? Schedule a free initial consultation.
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