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 the 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 100 low-lead (100LL) for all aircraft to fly safely during this transition.

While levels of airborne lead in the United States have declined 99% since 1980, there is still more work to be done to lower risks of lead exposure to communities adjacent to general aviation airports. Accordingly, the general aviation industry and the FAA are working hard to eliminate all lead in aviation fuel as soon and safely as possible, through the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative.