Low Level Wind Shear Alert System (LLWAS)

Low Level Wind Shear is defined as a sudden change of wind velocity and/or direction in either the vertical or horizontal planes. At low level, i.e. when aircraft are departing from or landing at an aerodrome, wind shear can present a severe risk to flight safety. Therefore, timely warnings are essential to help pilots respond appropriately. Low Level Wind Shear Alert System (LLWAS) is a ground-based system used to detect wind shear and associated weather phenomena, such as microbursts, close to an airport; especially along the runway corridors. This information can then be passed, in real-time, to warn pilots and aerodrome services.

A standard LLWAS consists of a number of anemometers strategically placed around, and within, an aerodrome, and a data processing system. The aim of the system is to provide visual and audio alerts to ATC so that they can pass on information and warnings about wind shear and microbursts to pilots and other aerodrome services and customers. In order to increase the detection area of a wind shear, Doppler Weather Radar and Wind LiDAR are incorporated with anemometer based LLWAS system. LiDAR Radar increases the detection range up to 10 km in clear air and light rain. Doppler Weather Radar increase the detection range more than 20 km in rainy weathers