Cathay Pacific and Google Cut Contrail Warming with AI-Powered Flight Routes

Cathay Pacific and Google have partnered to test AI-driven contrail avoidance on ultra-long-haul flights. The trial, which began in late 2025, saw Cathay Pacific fly over 80 routes adjusting cruise altitude to steer clear of the thin bands of humid air where aircraft exhaust freezes into clouds that trap heat.

According to Google's satellite analysis, the contrails from these flights would have had a warming impact reduced by roughly 40%. The trial targeted ultra-long-haul services, meaning flights of more than 16 hours, and is the first time the technique has been tested at this duration.

The Hong Kong to Singapore route accounted for more than half of the estimated reduction in contrail warming. The AI-powered system provided predictions on the flight deck through Cathay's electronic flight folder over in-flight Wi-Fi.

Only a small share of flights make contrails that persist and warm, with research finding that 2% to 3% of flights produce around 80% of contrail warming. Google's earlier work with American Airlines suggests that flying off the optimal altitude burns more fuel, but the extra fuel adds roughly $5 to $25 per tonne of CO2 equivalent.

The EU has already decided to measure and report non-CO2 effects from aviation, including persistent contrails. The European Commission estimates that these effects account for two-thirds of aviation's total climate impact, with contrails alone accounting for roughly a third.