Invisible Threats: How Jet Stream Shifts are Amplifying Clear Air Turbulence in U.S. Aviation (1980 - 2023)

Over the last 10 years, there has been a noticeable increase in Clear Air Turbulence (CAT) incidents reported by commercial airlines, including several recent accidents that have resulted in passenger injuries. This trend is alarming, as CAT poses significant risks to aviation safety and comfort due to its unpredictable nature and lack of visual warning for pilots. Additionally, CAT can lead to increased fuel consumption and delays as pilots are forced to circumvent affected areas, further impacting the efficiency of flight operations. One possible explanation for this increase is the impact of changing atmospheric conditions, particularly on the jet stream. We have analyzed jet stream changes over a 43-year period, with a specific focus on deviations from climatological norms in the last decade. The study has concentrated on parameters relevant to commercial aviation and major airline routes over CONUS, including wind speed, vertical wind shear, omega, moisture, temperature, potential vorticity, among others. We have found an increase in zonal wind speeds within the jet stream, contributing to a poleward shift during winter months in recent years. Additionally, increases in vertical wind shear at critical flight levels (in between 150 hPa – 300 hPa) correspond to regions where CAT is more likely to occur. Moreover, rising mean absolute values of omega throughout the year indicate more pronounced regions of upward and downward air movement that may interact with the jet stream to produce CAT. These findings suggest that conditions conducive to CAT are becoming more prevalent, particularly along major airline routes. In this presentation, we will discuss these findings in detail and introduce CAT indicators we have developed to forecast and mitigate CAT risks based on climatology, improving flight safety and operational efficiency.