What impact does even a few millimeters of ice or frost have on an aerofoil?

The presence of even a few millimeters of ice or frost on an aerofoil negatively affects its performance by increasing drag and reducing lift. This occurs because the smooth airflow over the wing is disrupted, leading to less efficient lift generation and a higher stall speed. As a result, the aircraft requires a longer distance to reach the necessary speed for takeoff.

Given this information, the impact of ice or frost increases both the takeoff distance and the necessary speed for the aircraft to safely lift off. These changes can significantly compromise the aircraft's performance, especially at lower speeds during takeoff and landing phases. Therefore, it's crucial for pilots to ensure their aircraft is free of any ice or frost before takeoff to maintain optimal aerodynamic efficiency.