One chart per airport: X = year, Y = % adoption. Two series — unleaded share of fuel sales (gallons) and STC adoption (share of the based fleet that has obtained the unleaded STC) — over a timeline of dated milestones. Only KAPA has a full reported series; other fields show reported status points and modeled ramps. Numbers are estimates with stated assumptions and sources, as of June 2026. © 2026 FRISA.