In a headwind to tailwind shear, what happens to the aircraft's airspeed?

In a headwind to tailwind shear, the aircraft experiences a significant change in wind direction and speed. When transitioning from a headwind (wind coming from the front of the aircraft) to a tailwind (wind coming from behind), the effective airspeed can decrease initially due to the change in relative wind direction impacting lift and thrust.

During this transition, if the aircraft is still maintaining a constant true airspeed, the indicated airspeed experienced by pilots can appear to drop due to the sudden increase in ground speed caused by the tailwind. However, when accounting for aerodynamic principles, the reduction in relative wind can lead to a decrease in the performance of the aircraft, such as in lift generation, which pilots must manage carefully. Therefore, the initial decrease in performance and effective airspeed experienced during this shear event typically results in a decrease in airspeed for the aircraft, which aligns with the selection of this answer.

Understanding this concept is crucial for pilots during critical phases of flight, particularly during takeoff and landing, as they must be prepared for variations in airspeed which can affect the overall handling and safety of the aircraft.