When a calm wind shears into a headwind, what is the effect on airspeed?

When calm wind transitions into a headwind during an approach, airspeed effectively increases for the aircraft. This phenomenon occurs because headwinds reduce the ground speed required to maintain a particular indicated airspeed (IAS). As the aircraft encounters a headwind, the relative airflow over the wings increases.

This increase in relative wind enhances lift, which is crucial during the landing phase when pilots need to maintain a certain airspeed to ensure safe control of the aircraft. The pilot’s indication of airspeed, or IAS, will not change directly due to the headwind; rather, the aircraft's ground speed decreases in response to the headwind while still maintaining the necessary airspeed to keep the aircraft in controlled flight.

This behavior emphasizes the importance of understanding wind conditions and how they affect flight performance and handling, especially during landings and approaches.