Define wind shear and explain why it is hazardous during takeoff and landing.

• A. Wind shear is a rapid change in wind speed or direction with height or distance; it can cause sudden airspeed and altitude changes near the ground.
• B. Wind shear is a constant wind from a single direction
• C. Wind shear only affects weather radar readings
• D. Wind shear is the same as turbulence

Answer: (A)

Wind shear is a rapid change in wind speed or direction with height or distance, so the air flowing over the wings can change abruptly as you fly through it. That means the air mass around the airplane can suddenly speed up, slow down, or shift direction, which directly affects lift and airspeed.

This is especially dangerous during takeoff and landing because the aircraft is already operating close to its performance limits at low altitude. A sudden drop in headwind (or an increase in tailwind) near the ground can cause a quick loss of indicated airspeed and lift, making control more difficult and increasing the risk of a stall or a hard descent. Conversely, a sudden increase in headwind can cause a rapid rise in airspeed and a pitch or flight-path change that’s hard to manage right at the critical phases of flight. Because there’s little time and room to recover near the runway, wind shear can lead to substantial deviations from the intended flight path.

Wind shear is not merely constant wind, nor is it something only seen on radar; it’s an aerodynamic condition that can occur with or without visible weather and can accompany turbulence, though they’re not the same thing.