Aerodynamic Dilemma Faced by Aviators: Wind Shear
Wind Shear, a meteorological phenomenon, poses a significant risk to aircraft during landing and at low altitudes. This sudden change in the horizontal and vertical direction and strength of the wind can be a few feet thick, with winds reaching 80 knots and a 90-degree change in direction, making it one of the most dangerous weather events for aviation.
Pilots and air traffic control (ATC) work together to detect and avoid wind shear during landing. Pre-flight and en-route weather forecasting and alerts play a crucial role, with pilots reviewing weather reports and forecasts that indicate the likelihood of wind shear. SIGMETs or convective activity alerts are common examples of such warnings.
Onboard wind shear detection systems, such as radar and sensors, provide real-time warnings to identify and react to wind shear, particularly during approach and landing phases. These systems are complemented by ground-based detection tools like the Low Level Wind Shear Alerting System (LLWAS) and Terminal Doppler Weather Radar (TDWR).
The LLWAS uses a network of anemometers located around the airport to detect rapid changes in wind speed and direction at low altitudes, providing alerts of low-level wind shear hazards close to the runway environment. The TDWR, on the other hand, uses Doppler radar technology to detect wind shear phenomena such as microbursts and gust fronts within terminal areas, enabling timely warnings to ATC and pilots.
Microbursts, a dangerous type of wind shear, occur below CB clouds during thunderstorms. They are characterized by strong, downward air flow that can cause sudden and great damage. Dry microbursts, which lack rainfall, are more challenging to predict and detect due to their evaporation before rainfall.
Reports from pilots of double-flight aircraft can also provide reliable information about wind shear, including location, altitude, and intensity. An example of a pilot wind shear report is "moderate wind shear at the 4 miles on final approach for runway 35 at 400 feet".
Despite efforts to detect and avoid wind shear, its dynamic nature makes it difficult to determine with high precision. However, with the combined use of onboard and ground-based detection systems, pilots and ATC can take necessary precautions to ensure safe landings, including vigilance, airspeed control, increased thrust, and if necessary, go-arounds to avoid accidents linked to wind shear.
Technology plays a significant role in detecting and managing wind shear during landing and takeoff, with onboard wind shear detection systems such as radar and sensors providing real-time warnings. Weather reports and forecasts also play a crucial part, including SIGMETs and convective activity alerts, offering pilots information about the likelihood of wind shear events.
