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The end of leaded avgas has had a soft target of 2030 for years. Most operators assumed it would slip. It won't. The date is now codified in federal law and further reinforced by the single company that still makes the lead. General aviation has about four years to get ready for a fuel it does not yet fully have.As the name implies, 100LL (low lead) is the avgas that piston aircraft burn today, and the lead is what lifts it to 100 octane. Engines built for high compression need that octane to avoid detonation, the uncontrolled knock that can wreck a cylinder. Unleaded fuels like UL94 already serve lower-compression engines, but that fuel is incompatible with the high-compression aircraft that consume most of the avgas sold. Most of the piston fleet uses engines that were designed before lead was identified as an environmental issue. With the inability to run on any unleaded fuel now in production, pulling 100LL before a true replacement exists would simply ground them. The FAA Reauthorization Act of 2024 directs the transition and requires airports that sold 100LL in 2022 to keep selling it until 2030, or until a certified unleaded replacement becomes available (2032 for Alaska). The FAA and its partners launched the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative in 2022 with the goal of eliminating leaded aviation fuel in piston aircraft. It aims to identify at least one unleaded fuel acceptable for general aviation, with companies like GAMI and Swift Fuels racing to be first.These potential fuels have to clear three separate stages: an ASTM specification, FAA fleet authorization, and STCs for the aircraft that will use them. An ASTM production specification means the fuel has an agreed industry recipe, so it can be made consistently and at volume. An STC authorizes it for a specific aircraft. And the FAA must grant PAFI fleet authorization for a fuel to be approved across the fleet. A fuel can hold an ASTM spec and still not be approved for certain aircraft.There is no fuel in the FAA's Piston Engine Aviation Fuels Initiative (PAFI) has cleared all hurdles. GAMI's G100UL took the STC route and holds an approval covering nearly all spark-ignition engines and airframes; it is available for purchase at a handful of airports in California, Oklahoma, and Mississippi, though Cirrus has advised against using it in its SR series. Swift Fuels' 100R received an ASTM production specification in September 2025 and FAA approval for a limited set of around 840 engines, but on a restricted-use basis. UL100E, the last to enter the initiative, earned its first ASTM specification in November 2025 and remains in PAFI testing, with completion targeted for around September 2026.Outside of politics, there is another reason leaded fuel will likely disappear in 2030. TEL, or tetraethyl lead, is the essential ingredient in leaded avgas that gives it its anti-knock quality. Innospec, the world's only TEL manufacturer, has announced it will discontinue manufacture in 2028 or 2029, with its inventory running out around 2030. Part of the reason is the process itself: producing TEL is corrosive and degrades the equipment used to make it, according to General Aviation News. With the end of leaded avgas in sight, the company has done the math and decided it's not worth it to continue production. This transition will touch many in aviation. As 2030 approaches, eligibility and engine compatibility will become a top-line concern for owners and operators. Fuel availability by airport will become both a cost and a route issue as inventory thins with the loss of TEL.The thin supply map of unleaded fuel could split resale values between aircraft approved to run one or more of the new fuels and those that are not. The more fuel options an aircraft has, the better its odds of staying in the air once the deadline arrives. The date is set. The fuel and the infrastructure to meet it are not here yet. General aviation has a narrow window to lock down the unleaded alternative it needs and keep its aircraft flying, before it runs out of gas.