Which of the following is a consequence of ice accumulation on an aircraft?

The consequence of ice accumulation on an aircraft is an increase in stall speed. When an aircraft accumulates ice on its wings and control surfaces, it disrupts the smooth airflow over these surfaces. This disruption leads to a decrease in the lift generated at any given speed, effectively necessitating a higher airspeed to achieve the same lift. As a result, the stall speed—the minimum speed at which the aircraft can maintain level flight—increases. Pilots must be aware that the presence of ice requires them to fly at a higher speed to avoid stalling, thereby directly impacting flight safety and aircraft handling characteristics.

In general, the other options are incorrect because ice accumulation does not lead to increased fuel efficiency, nor does it improve aircraft performance. Instead, it degrades performance and can make handling more difficult. Additionally, it does not decrease stall speed; rather, it leads to the opposite effect, thus underscoring the critical importance of understanding ice effects in aviation safety.