Buffeting in an airplane is caused by?

Buffeting in an airplane is primarily caused by unsteady airflow resulting from turbulence. This phenomenon occurs when the smooth flow of air over the wings and control surfaces is disrupted, often due to the presence of high angles of attack or airflow separation. When the airflow becomes turbulent, it can lead to rapid oscillations of the aircraft, which are felt as buffeting. This effect can decrease the effectiveness of control surfaces and may signal that the aircraft is approaching its performance limits.

In contrast, the other options address different concerns. Excessive weight and balance issues can lead to instability but do not directly result in the rapid oscillatory motion characteristic of buffeting. Poor aerodynamic design might lead to reduced overall performance but does not specifically cause the turbulent flow that leads to buffeting. Similarly, incorrect control surface settings can lead to handling difficulties but are not the primary source of the airflow disturbances that create buffeting. Thus, recognizing that buffeting is fundamentally linked to the unsteady airflow from turbulence is essential for understanding this aerodynamic phenomenon.