An aircraft that encounters a headwind of 40 knots, within a microburst, may expect a total shear across the microburst of:

The correct answer is 80 knots, which accounts for the total wind shear experienced by the aircraft when encountering a microburst combined with a headwind. In a microburst scenario, a sudden downdraft of air can occur, followed by an outward spread of wind, which can dramatically change the wind components an aircraft is facing.

When an aircraft flies into a microburst, it first encounters the headwind component of 40 knots. Following this encounter, the microburst typically adds significant downdraft and horizontal wind change that contributes to the overall wind shear. A microburst can create an additional wind component that might be as strong as 40 knots in the opposite direction, which combines with the existing headwind to yield a total shear.

Thus, when you account for the headwind of 40 knots plus the additional shear of 40 knots due to the microburst, the total shear experienced would be 40 knots + 40 knots, leading to a total of 80 knots. This is critical for flight safety, as understanding how wind shear affects the aircraft’s performance is essential for proper dispatch and operational planning.