Instrument Rating Checkride Practice Test

Which type of icing can cause instruments to give inaccurate readings?

1. Induction Icing

2. Instrument Icing

3. Structural Icing

4. Clear Icing

The correct answer is: Instrument Icing

Instrument icing refers specifically to the accumulation of ice on flight instruments, which can obstruct readings and lead to dangerous situations. This type of icing can affect instruments such as the airspeed indicator, altimeter, and vertical speed indicator. When ice forms on these instruments, it can cause erroneous readings due to the obstruction of airspeed or pressure ports, leading to pilot misinterpretation of the aircraft's performance and position. The other types of icing mentioned, such as induction, structural, and clear icing, primarily affect the aircraft's performance or physical structure rather than the accuracy of instrument readings. Induction icing occurs in the engine's induction system, affecting engine performance; structural icing accumulates on the aircraft's surfaces, leading to weight gain and potential aerodynamic issues; while clear icing forms a smooth, glossy layer of ice that can also affect aerodynamics, but doesn’t directly impact instrument readings like instrument icing does.