What effect does clear ice have on aircraft performance?

Clear ice accumulation on aircraft can have a significant impact on performance primarily by blocking airflow over the wings and other surfaces. This disruption in airflow can lead to an increased stall speed, making it more difficult for the aircraft to maintain controlled flight, especially at lower speeds.

As ice forms, it changes the shape of the airfoil, which is critical for generating lift. The smooth surfaces typically associated with an airfoil become irregular due to the presence of ice, leading to turbulence instead of smooth airflow. This results in a higher likelihood of stalling as the aircraft approaches its critical angle of attack, which is the point at which lift is lost.

The other options do not accurately represent the effects of clear ice. For instance, ice does not increase lift; in fact, it tends to decrease it due to the degradation of the airfoil shape. Additionally, ice adds weight to the aircraft, which is counterproductive to flight performance, and it clearly does not have no significant effect, as the presence of ice is a serious concern for pilots. Understanding the consequences of clear ice is essential for maintaining aircraft safety and performance in adverse weather conditions.