Which gyroscopic instrument is NOT found in a Cessna 172?

The speed indicator is not a gyroscopic instrument, which is why it is the correct answer. In a Cessna 172, the speed indicator, or airspeed indicator, is a pitot-static instrument. It measures airspeed based on the difference between the static pressure and the dynamic pressure caused by the aircraft's movement through the air.

On the other hand, the attitude indicator, heading indicator, and turn coordinator are all gyroscopic instruments. The attitude indicator uses gyroscopic precession to display the aircraft's orientation relative to the horizon. The heading indicator serves as a directional reference, utilizing a gyroscope to provide accurate heading information. Similarly, the turn coordinator indicates the rate of turn and can also show the coordination of the turn through its gyroscopic function. These instruments are critical for maintaining control and situational awareness during flight, especially in conditions where visibility may be limited.

Understanding the functions and categories of these instruments is essential for pilots, as it directly relates to their ability to interpret data crucial for safe flight operations.