What is wind shear and why is it dangerous during takeoff and landing?

• A. A sudden gust that only affects ground speed.
• B. A rapid change in wind speed/direction with height; can cause loss of airspeed and control.
• C. A persistent wind blowing parallel to the runway that aids takeoff.
• D. A low-altitude weather phenomenon causing turbulence only above clouds.

Answer: (B)

Wind shear is a rapid change in wind speed and/or direction over a short distance in the vertical column of air. During takeoff and landing, the aircraft is close to the ground, at low airspeeds, and has limited time to respond to these sudden changes. If headwind drops abruptly or a tailwind increases, the airplane’s indicated airspeed falls, reducing lift. That drop in lift near the ground can lead to a stall or a loss of control just when you’re trying to climb away or settle onto the runway. Wind shear can also bring strong vertical motions (like gust fronts or microbursts), which disrupt the flight path and further complicate maintaining the proper airspeed and attitude. Pilots mitigate these risks with vigilant winds awareness, appropriate airspeed management, and go-around decisions when wind shear is evident or suspected.