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.