--- title: "What is sustainable aviation fuel (SAF)? | FlightLogic" description: "Sustainable aviation fuel (SAF) is jet fuel made from approved non-fossil feedstocks that meets the same safety specification as conventional Jet A-1, so it…" url: https://flightlogic.co.uk/learn/what-is-sustainable-aviation-fuel/ lastModified: 2026-08-05 source: FlightLogic (flightlogic.co.uk) licence: "Content © Elite Digital AI Solutions Ltd. Cite the URL above and the page author." --- *Links marked * may earn us a commission at no extra cost to you. We do not provide financial advice. How we make money .* # What is sustainable aviation fuel (SAF)? Sustainable aviation fuel (SAF) is jet fuel made from approved non-fossil feedstocks that meets the same safety specification as conventional Jet A-1, so it blends into existing aircraft and airport fuel systems. It can cut lifecycle emissions substantially — the mandates, costs, and green-claims caveats follow. ## Drop-in fuel, not a new kind of engine Airliners need energy-dense liquid fuel. Batteries work for small, short hops in research programmes; they do not yet replace kerosene on a packed Gatwick–Málaga sector. SAF is designed as a drop-in: chemically similar enough to Jet A-1 that today’s engines, pipes and bowsers can handle it when mixed with fossil fuel. Airliners need energy-dense liquid fuel. Batteries work for small, short hops in research programmes; they do not yet replace kerosene on a packed Gatwick–Málaga sector. SAF is designed as a **drop-in**: chemically similar enough to Jet A-1 that today’s engines, pipes and bowsers can handle it when mixed with fossil fuel. ASTM International approves production pathways (different recipes from waste oils, residues and other feedstocks). Airlines and fuel suppliers then blend SAF with conventional jet fuel — commonly up to about **50%** under current approvals — unless a special 100% SAF trial is running. ## Why “up to 80% less CO₂” needs small print The carbon benefit is usually measured across the lifecycle — growing or collecting feedstock, refining, transport and combustion — compared with fossil jet. Well-documented pathways can show large percentage cuts; poorly documented ones should not get a free pass because the acronym says “sustainable”. The carbon benefit is usually measured across the **lifecycle** — growing or collecting feedstock, refining, transport and combustion — compared with fossil jet. Well-documented pathways can show large percentage cuts; poorly documented ones should not get a free pass because the acronym says “sustainable”. Combustion in the engine still releases CO₂ on the day you fly. SAF’s advantage is mainly about where the carbon came from and what was displaced earlier in the chain — which is why offsets (paying for reductions elsewhere) are a different product entirely. ## Mandates vs marketing Governments are starting to force blend shares upward. The UK’s SAF Mandate (see GOV.UK) and the EU’s ReFuelEU rules target fuel suppliers, not individual passengers. Separately, airlines sell voluntary “SAF contributions” or green fares — those may use book-and-claim accounting rather than putting labelled molecules in your specific aircraft. Governments are starting to force blend shares upward. The UK’s SAF Mandate (see GOV.UK) and the EU’s ReFuelEU rules target fuel suppliers, not individual passengers. Separately, airlines sell voluntary “SAF contributions” or green fares — those may use book-and-claim accounting rather than putting labelled molecules in your specific aircraft. For the UK ticket-price angle and how to read badges, see [/guides/uk-saf-mandate-flight-tickets/](https://flightlogic.co.uk/guides/uk-saf-mandate-flight-tickets/). ## What you will notice as a passenger Almost nothing in the cabin. SAF does not change seat pitch, Wi‑Fi or boarding group. Over years you may see gradual fare pressure as compliant fuel costs more, or optional checkout extras. Treat industry tallies from groups such as ATAG as background scale — production is still a tiny fraction of global jet fuel — and keep booking decisions anchored on schedule, rights and product. Almost nothing in the cabin. SAF does not change seat pitch, Wi‑Fi or boarding group. Over years you may see gradual fare pressure as compliant fuel costs more, or optional checkout extras. Treat industry tallies from groups such as ATAG as background scale — production is still a tiny fraction of global jet fuel — and keep booking decisions anchored on schedule, rights and product. [Aviation jargon A–Z](https://flightlogic.co.uk/learn/jargon/) · [Take the aviation quiz](https://flightlogic.co.uk/learn/quiz/) · [How planes fly: lift, thrust, drag and weight explained](https://flightlogic.co.uk/learn/how-planes-fly/) · [Turbulence explained: what it is, why it happens, and why aircraft shrug it off](https://flightlogic.co.uk/learn/turbulence-explained/) · [Air traffic control explained: who's guiding your flight, and when](https://flightlogic.co.uk/learn/air-traffic-control-explained/) · [Why twin-engine jets now rule the oceans: ETOPS explained](https://flightlogic.co.uk/learn/why-twinjets-fly-across-oceans/) ## Frequently asked questions ### Can today’s airliners fly on SAF? Yes, when the fuel meets jet specifications and is blended (or specially approved) as allowed. The constraint is supply and cost, not whether a modern A320 or 787 can burn a compliant blend. ### Is SAF the same as biofuel in cars? Related idea, different specification. Aviation SAF must meet strict jet-fuel standards (freeze point, energy density, safety) and approved pathways — you cannot pour roadside biodiesel into a wing tank. ### Will electric airliners replace SAF? Electric and hydrogen concepts may appear first on short, thin routes. For the long-haul and dense short-haul fleets that carry most passengers, liquid fuels — increasingly SAF — remain the industry’s main decarbonisation bet this decade. Written by [Sarah Mitchell](https://flightlogic.co.uk/authors/sarah-mitchell/) Senior Editor, Star Alliance & Loyalty Sarah specializes in Star Alliance carriers and mileage-run strategy. She has flown Singapore Airlines' Suites Class more than a dozen times purely on miles and writes FlightLogic's redemption breakdowns.