FAA Instrument Rating Airplane (IRA)Flight Instruments and SystemsMedium
A student pilot asks how a turn coordinator differs from a turn-and-slip indicator in the information each provides to the pilot. Which statement correctly describes this difference?
- AThe turn coordinator senses both roll rate and yaw rate, while the turn-and-slip indicator senses yaw rate only
- BThe turn coordinator displays only bank angle and provides no turn rate information
- CThe turn coordinator operates on static pressure while the turn-and-slip indicator operates on vacuum pressure
- DThe turn-and-slip indicator is always electrically powered while the turn coordinator is always vacuum powered
Show answer & explanationAnswer & explanation
Correct answer: A. The turn coordinator senses both roll rate and yaw rate, while the turn-and-slip indicator senses yaw rate only
The turn coordinator's gimbal is canted, allowing its gyro to sense roll rate in addition to yaw rate, giving an earlier indication of a turn's onset, while the older turn-and-slip indicator only senses rate of yaw about the vertical axis.
Why the other options are wrong
- B. Both instruments provide turn rate information; the turn coordinator adds roll sensitivity, it doesn't eliminate turn rate data.
- C. Neither instrument's fundamental sensing principle is based on static pressure; both are gyroscopic instruments typically electrically powered.
- D. Power source is not a fixed rule; both instruments are commonly electrically driven in modern aircraft.
Turn Coordinator vs Turn-and-Slip Indicator
The turn coordinator's canted gimbal allows it to sense both roll and yaw rate, giving an earlier indication of turn entry, while the turn-and-slip indicator senses only yaw rate.
- Turn coordinator symbol often depicts a miniature airplane
- Both use a ball to indicate coordination (slip/skid)
- Both are typically electrically powered gyroscopic instruments in modern aircraft
Memory trick: The coordinator 'feels the roll before the yaw catches up.'