Which of the following instruments is NOT a gyroscopic flight instrument?

The altimeter is not a gyroscopic flight instrument, which is why it is the correct answer. Gyroscopic flight instruments rely on the principles of gyroscopic motion to provide essential flight data. These instruments include the directional indicator, artificial horizon, and turn coordinator, all of which use a spinning gyroscope to maintain a stable reference for navigation and attitude control.

The directional indicator, for example, helps pilots navigate by indicating heading based on the stable reference provided by a gyroscope. The artificial horizon, or attitude indicator, shows the aircraft's orientation relative to the earth's horizon, aiding in understanding the aircraft’s roll and pitch. The turn coordinator provides information about the rate of turn and helps pilots ensure a safe and coordinated turn.

In contrast, the altimeter measures altitude based on atmospheric pressure changes and does not incorporate gyroscopic principles. Therefore, it does not function as a gyroscopic instrument like the others mentioned.