Combined impact of jet stream and turbulence on long-term trans-oceanic flight routes over North Atlantic Ocean using ERA5 reanalysis

Transatlantic aviation operations routinely enhance flight efficiency by leveraging daily jet streams, but they face growing safety risk from clear-air turbulence (CAT). Previous studies have assessed the climatological impacts of winds and turbulence separately, yet a comprehensive assessment integrating their effects along dynamically optimized flight routes has remained absent, despite the close relation between jet and CAT. Here, using an integrated routing framework applied to 44 years of reanalysis data, we provide the first multi-decadal quantification of safety-efficiency trade-off. While changing wind patterns shortened the fastest round-trip routes by about two minutes, the additional time required to avoid CAT has grown so substantially that it negates and even reverses these efficiency gains for the safest routes. This rising cost is driven by a significant increase in CAT, which disproportionately affects eastbound flights. Our findings highlight the need for integrated approaches to assess aviation's evolving risks in a changing climate.