What is one detrimental effect of icing on aircraft performance?

Icing on an aircraft's surfaces has a significant detrimental effect on its performance, particularly by increasing stalling speeds. When ice accumulates on the wings, tail, or other parts of the aircraft, it disrupts the smooth airflow over these surfaces. This disruption alters the lift characteristics of the wings, leading to a higher angle of attack being required to maintain flight. Consequently, the aircraft reaches its critical angle of attack sooner, which can result in an increased stalling speed.

In practical terms, this means pilots must maintain higher speeds during takeoff and landing to avoid stalling, making operations in icy conditions more challenging and potentially dangerous. The other options are misrepresentations of how icing affects aircraft; for instance, icing does not improve fuel efficiency, increase lift, or decrease drag, as those would all lead to enhanced aircraft performance rather than the negative impact caused by ice accumulation.