Definition
Gyroscopic instruments that sense and measure the rate of rotation about a single axis rather than maintaining a fixed reference in space. Their output is angular velocity (degrees per second), which is then used to drive rate-based instruments such as the turn coordinator and turn-and-slip indicator, and to feed angular rate data into an Attitude and Heading Reference System (AHRS).
Plain English
A rate gyro is a small spinning sensor that measures how fast the aircraft is turning around one axis, not which way it is pointing. It tells you the speed of the rotation, like saying 'turning at three degrees per second' instead of 'banked twenty degrees.'
Context Anchor
Seen in instrument flying discussions of attitude and heading reference systems, especially when explaining how electronic flight displays sense aircraft motion.
Derivation
Gyro' comes from the Greek gyros, meaning 'circle' or 'turn.' A rate gyro is named for what it measures: the rate of turning, not the position.
Why Pilots Care
Accurate rate information lets pilots execute smooth coordinated turns and maintain control during instrument flight when outside visual references are unavailable.
Analogy
A rate gyro is like a sensor in a phone that notices how quickly you twist or tilt the phone. By itself, it senses the motion; the system uses that motion information to update the display.
Intuition Check
Do not read “rate” here as a general performance number like climb rate. In this term, it means the speed of rotation around an axis.
Example Sentence 1
The turn coordinator is driven by a rate gyro, which is why it shows rate of turn rather than bank angle.
Example Sentence 2
AHRS units combine data from rate gyros with accelerometers to compute continuous attitude changes.