Aviation impacts of terrain-induced wind shear

The extensive study of aviation impacts of terrain-induced wind field anomalies, near Juneau Airport, provides fertile ground for the investigation of the similarities and differences of terrain-induced turbulence and wind shear. Our investigations focus on impacts on aircraft operations at flight altitudes from 300m to 1500m near the airport. The data come from flight operations of instrumented aircraft near Juneau Airport in the proximity of rugged terrain and they include many cases with tight turns. The interest is in both the nature of the phenomena and on the impacts on flight operations. We determine that wind shear at the conventional 1 Km scale is relatively rare, but that there is frequent wind shear at the .5 Km scale. These wind shear events usually have an oscillatory structure, which raises the question of whether they should be viewed as wind shear or as large-scale turbulence. Evidence is presented to support the position that they should be viewed as wind shear events, including the rather low correlation of the intensities of wind shear events with intensities of turbulent events and their differing impacts on aircraft performance.