Instrument Rating Checkride Practice Test

How does icing generally affect an aircraft's performance?

1. Increases lift

2. Decreases drag

3. Increases stall speed

4. Reduces thrust

The correct answer is: Increases stall speed

Icing generally affects an aircraft's performance by increasing stall speed. This occurs because ice accumulation on the wings and control surfaces alters their shape and smoothness, leading to a disruption in airflow. As a result, the aircraft can no longer generate the same amount of lift at lower speeds, which means that the stall speed—the speed at which the aircraft can no longer maintain level flight—effectively increases. When ice forms on the wings, it adds weight and can create rough surfaces, leading to an earlier onset of stall conditions. Pilots must therefore be aware of how icing can impact their flight envelope, requiring them to maintain a higher airspeed to avoid stalling and to ensure safe operation. The other options do not accurately describe the main effects of icing on an aircraft's performance. While icing may change drag characteristics, it primarily leads to an increase in overall drag rather than a decrease. Additionally, thrust is typically reduced in icing conditions not because of icing itself, but rather due to the engine performance when operating in colder conditions or potentially due to additional weight.