What can cause unsafe flight conditions concerning airfoil performance?

The presence of slight frosting or icing on the wing can significantly impact airfoil performance, leading to unsafe flight conditions. When ice forms on an airfoil, it alters the smooth airflow over the wing's surface and can increase drag while reducing lift. This disruption can result in a stall at airspeeds that would normally be safe, seriously affecting the aircraft's handling and performance. In particular, even a small amount of icing can create a substantial decrease in the wing's effectiveness, especially during takeoff and landing phases when precise control is critical.

While heavy winds can present challenges, they do not directly affect the aerodynamic performance of the airfoil itself in the same way that icing does. High temperatures can influence air density and performance but are less immediately critical compared to the direct aerodynamic consequences of ice on the wings. Low humidity also does not significantly impact airfoil performance under most circumstances. Therefore, the unique problems posed by frost or icing on the wing make it the most critical factor in terms of unsafe flight conditions regarding airfoil performance.