Cathay Pacific and Google Expand AI Contrail-Avoidance Trials

Persistent aircraft contrails are an important aviation climate problem that can potentially be addressed before fleets transition to new aircraft or fuels. Cathay Pacific and Google have expanded trials of an AI-based system intended to help flights avoid the atmospheric conditions where those heat-trapping trails form. 1315

The expansion follows an operational trial that started in late 2025. More than 80 Cathay flights used contrail-avoidance routes from a program targeting more than 100 flights, and Google estimated that the selected flights achieved roughly a 40% reduction in contrail warming impact. That result is an early estimate for participating flights, not evidence of a 40% reduction across Cathay’s whole fleet. 413

How the AI contrail-avoidance system works

Contrails form when aircraft operate in particular high-altitude atmospheric conditions. Google’s forecasting approach combines AI prediction models with satellite imagery and weather data to identify relatively narrow areas that are cold and humid enough for persistent contrails to develop. 612

That forecast information is provided to flight dispatchers and pilots, who can consider modest altitude adjustments to avoid the predicted zones. The goal is not to reroute every flight, but to make targeted operational changes where conditions and flight operations allow. 212

What is changing in the second phase

Cathay and Google are taking the trials to a wider set of routes within Asia and across the Pacific, including ultra-long-haul operations. The larger program is designed to assess operational feasibility, constraints and climate effects at a broader scale, while contributing real-world information from an Asia-Pacific region that has been less represented in contrail research. 31315

Cathay is Google’s first commercial airline partner in Asia-Pacific to trial the technology. It is also the first airline globally to test contrail avoidance on ultra-long-haul flights. 15

Why persistent contrails matter

Unlike short-lived trails that quickly dissipate, persistent contrails can spread into cloud formations that retain heat in the atmosphere. Cathay and Google cite research indicating that contrails may account for roughly one-third of aviation’s total climate impact. 815

That makes contrail avoidance a potentially useful complement to reducing carbon dioxide emissions. It does not eliminate the need for cleaner fuels, more efficient aircraft or other emissions measures; instead, it tests whether existing aircraft and fuel can be operated differently when forecasts identify conditions likely to create persistent contrails. 1315

The practical significance of the trial

The early 40% figure is promising, but it should be read in context: it is Google’s estimate from a limited operational sample of flights following recommended avoidance routes. The expanded phase will determine how consistently the approach can work across more routes and operational conditions. 413

For the partners, the project is a live test of predictive AI in airline operations. Cathay Digital and IT Director Lawrence Fong said the collaboration combines airline operational expertise with Google’s AI capabilities to address sustainability challenges at scale. Google Hong Kong Managing Director Michael Yue said the work shows how predictive AI could help address contrail effects in live operations using today’s aircraft and fuel. 15