What is low-level wind shear and why is LLWAS important?

• A. A rapid change in wind speed/direction near the surface; LLWAS detects it to improve safety on approach and takeoff.
• B. A system for measuring air traffic density.
• C. A system for visual landing guidance.
• D. A satellite-based weather forecast.

Answer: (B)

Low-level wind shear is a rapid change in wind speed or direction in the lowest part of the atmosphere near the surface. The LLWAS, or Low-Level Wind Shear Alert System, is designed to detect these hazardous changes by monitoring winds at multiple locations around an airport and sounding alerts when a dangerous wind gradient is detected. This early warning is essential during approach and takeoff, when aircraft are close to the ground and small shifts in wind can significantly affect airspeed and lift, potentially leading to a hard landing or loss of control. The system helps pilots and air traffic control make timely decisions to adjust speed, flight path, or configuration, or to execute a go-around if needed. The other descriptions refer to tasks unrelated to wind-shear detection—measuring air traffic density, providing visual landing guidance, or offering satellite-based forecasts.