FAA Instrument Flight Instructor (FII)Instruments and SystemsMedium
A student pilot asks their CFII to explain the key functional difference between a turn coordinator and a turn-and-slip indicator. The correct explanation is that the turn coordinator
- Adisplays bank angle directly, while the turn-and-slip indicator displays only heading
- Bsenses only yaw, while the turn-and-slip indicator senses both roll and yaw
- Csenses both roll and yaw, while the turn-and-slip indicator senses only yaw
- Duses a vacuum-driven gyro, while the turn-and-slip indicator is always electric
Show answer & explanationAnswer & explanation
Correct answer: C. senses both roll and yaw, while the turn-and-slip indicator senses only yaw
The turn coordinator's gimbal is canted so the gyro responds to rotation about both the roll and yaw axes, allowing it to indicate the onset of a roll earlier than a turn-and-slip indicator, which is gimbaled to sense yaw only and shows rate of turn about the vertical axis alone.
Why the other options are wrong
- A. Neither instrument displays heading; both show rate/direction of turn, not bank angle directly.
- B. This reverses the correct relationship between the two instruments.
- D. Both instruments are typically electrically powered in modern aircraft, so power source is not the distinguishing feature.
Turn Coordinator vs Turn-and-Slip Indicator
The turn coordinator's canted gimbal senses roll and yaw, showing the onset of a roll, while the turn-and-slip indicator senses only yaw about the vertical axis.
- Turn coordinator gimbal is canted about 30°
- Displays a miniature aircraft symbol showing roll rate
- Turn-and-slip indicator uses a needle showing yaw rate only
- Both use the inclinometer ball to show coordination
Memory trick: Coordinator feels the roll AND the pull — the slip needle only feels the pull.