FAA Flight Instructor Airplane (FIA)Aircraft Systems and InstrumentsEasy
A student pilot asks why the turn coordinator's miniature airplane banks in response to roll rate while the attitude indicator does not use the same gyro orientation. Which statement correctly describes the turn coordinator's gyro?
- AIt uses a non-rotating pendulum mass to sense centrifugal force during turns
- BIt uses a gyro spinning in the vertical plane and canted approximately 30 degrees to sense both roll and yaw
- CIt uses a two-axis vacuum-driven gyro identical to the heading indicator
- DIt uses a gyro spinning in the horizontal plane to sense pitch and bank changes directly
Show answer & explanationAnswer & explanation
Correct answer: B. It uses a gyro spinning in the vertical plane and canted approximately 30 degrees to sense both roll and yaw
The turn coordinator's gyro is canted about 30 degrees from the horizontal plane, allowing it to sense both roll rate (rate of bank) and yaw rate, which is why it shows roll immediately when the ailerons are applied, unlike the older turn-and-slip indicator that only sensed yaw.
Why the other options are wrong
- A. This describes the inclinometer (ball), a separate instrument in the turn coordinator housing.
- C. The turn coordinator is electrically driven, and its gyro senses only rate, not attitude like a heading indicator.
- D. This describes the attitude indicator's gyro orientation, not the turn coordinator.
Turn Coordinator Gyro
An electrically driven rate gyro canted about 30 degrees to the horizontal, allowing it to sense roll rate in addition to yaw rate.
- Canted gyro axis (~30°) senses roll and yaw
- Electrically powered, not vacuum
- Displays rate of roll and turn, not bank angle
Memory trick: Canted gyro Catches both Roll and yaw