Which indicator is not affected by blocked static pressure?

The turn coordinator is an indicator that is not influenced by blocked static pressure. It operates based on the aircraft's motion and orientation rather than atmospheric static pressure readings. The turn coordinator measures the rate of turn and provides a representation of the aircraft's coordination during flight. This information is derived from the movement of the aircraft through space and is not affected by external pressure changes such as those that would occur if the static source were blocked.

In contrast, the airspeed indicator, altimeter, and heading indicator rely on static pressure input for their function. For example, a blocked static source will prevent these instruments from providing accurate readings, leading to erroneous data that can affect flight operations and decisions. In particular, a blocked static port would cause the airspeed indicator to freeze at a certain value and would not reflect actual speed changes, while the altimeter would fail to provide an accurate altitude reading.

Understanding the specific functionalities and dependencies of each instrument is crucial for effective flight management, especially in scenarios where static pressure issues may arise.