Wind shear is a change in wind speed and/or direction over a short distance. In aviation, low-level wind shear and microbursts pose a serious threat to aircraft during take-off and landing. Today, there are two main types of wind shear alert systems on the market.
The ground-based LLWAS (Low-Level Wind Shear Alert System) use data from anemometers installed within and around the aerodrome. The data is processed via a sophisticated LLWAS algorithm to calculate the resulting wind shear and to derive the alerts. Different software packages allow convenient control of the LLWAS system and user-friendly display of wind shear alerts.
Wind shear can also be detected via a weather radar and a scanning Doppler-lidar. When combined, both sensors make up an all-weather wind shear detection system. The lidar system provides wind data in no-rain weather situations while the weather radar performs best in the presence of rain. Dedicated software packages process data from both systems, combine wind shear information and display alerts.