A Turn and Slip Indicator or a Turn Coordinator is a gyroscopic aircraft instrument, essentially a second Attitude Indicator. The instrument combines a rate of turn indicator and a slip/skid indicator into one unit, providing both the rate of turn and roll information. It is designed to be mounted in a single gimbal with its spin axis parallel to the lateral axis of the aircraft, helping pilots assess the quality and coordination of a turn.
Despite its historical significance, the rate-of-turn indicator is no longer as useful as an instrument which gives both horizontal and vertical attitude information. Because a second Attitude Indicator can replace a Turn Coordinator, some now argue that turn coordinators are obsolete.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
Is a turn coordinator required?
Yes, a turn coordinator is required if the flight is filed IFR. 14 CFR 91.205 lists a gyroscopic rate-of-turn indicator as required equipment for IFR flight. The turn coordinator needle satisfies that requirement because it is a rate-of-turn indicator. The same regulation also keeps the balance (slip/skid) indicator mandatory, so the inclinometer portion of the turn coordinator must be installed and working even though an attitude indicator and heading indicator are already required.
For VFR operations neither the rate-of-turn gyro nor the slip-skid ball is required, so a turn coordinator will be left inoperative or removed provided the aircraft remains in approved minimum equipment configuration.
Can you fly without a turn coordinator?
Yes, you can fly without a turn coordinator under certain conditions. FAR 91.205 lists required equipment, yet the turn coordinator is not on that list for VFR-Day flight. An attitude indicator, a heading indicator, and a VSI is not required for VFR-Day flight. A pilot can fly for hours without noticing turn coordinator nonfunctioning, and the slip-skid information is still available because the inclinometer provides slip/skid information. If the turn coordinator is inoperative, FAR 91.213 allows certain Part 91 operators to fly an aircraft with inoperative instruments, provided the equipment is not required and does not constitute a hazard. A mechanic must deactivate or remove inoperative equipment before flight. For IFR flight the attitude and heading indicator is required, yet the turn coordinator itself is waived if the Minimum Equipment List permits certain equipment inoperative or if the aircraft is operated under an approved MEL that allows operation with specific inoperative equipment under approved procedures.
I realize that certain older aircraft are qualified for flight with only a turn-and-slip device, so a turn coordinator is not legally required everywhere. A trained aviator can do without one, yet piloting without it feels like steering a complicated track with a sightless section. The turn coordinator's additional attribute of indicating the speed of change of direction gives a direct and natural image of how the aircraft is performing. When the skyline vanishes into fog or fades into blackness, keeping accurate control is vital .I would feel assured in a high-workload area with that tiny device as my main indication to the aircraft's position.
Jim GoodrichPilot, Airplane Broker and Founder of Tsunami Air
