Quantifying Reduction in Thermal contrails by Optimising SAF (QRITOS)

A handful of flights—those passing through ice-supersaturated air—produce most of the warming from aviation contrails, and this project will test whether steering limited supplies of sustainable aviation fuel (SAF) to those specific flights can shrink their climate impact. Contrails are a major but uneven source of aviation warming. Unlike CO₂, which spreads evenly with every mile flown, contrail warming is concentrated in a small fraction of flights. Targeting those flights with cleaner-burning fuel could cut warming without grounding planes or burning more fuel. The hypothesis is that SAF produces fewer soot particles during combustion, leading to thinner, shorter-lived contrails that trap less heat. The project brings together Rolls-Royce, British Airways, Heathrow, Air BP, and Imperial College London to work out the logistics of a real-world trial on commercial flights. If the strategy works, it would give airlines a practical way to get more climate value from the limited SAF they have, without disrupting schedules or routes. The research is applied and logistics-focused—it aims to verify whether a targeted fuel-switching strategy can be implemented at scale, not to explore fundamental aerosol physics. Success would quietly improve how aviation manages its non-CO₂ warming, a system most passengers never see.