Definition
A flight instrument that shows the rate at which the airplane is turning (yawing) and whether the turn is coordinated. It uses a gyroscope to drive a needle that deflects left or right to indicate turn rate, and a curved tube containing a ball in liquid to show slip or skid. When the ball is centered, the turn is coordinated; when the ball is off-center, the airplane is slipping or skidding through the turn.
Plain English
An instrument with a needle and a ball. The needle tells you how fast you are turning. The ball tells you whether your feet and hands are working together properly during the turn.
Context Anchor
Seen on the instrument panel, especially during basic instrument flying and when checking whether a turn is coordinated.
Derivation
‘Turn’ refers to the airplane changing heading. ‘Slip’ comes from the older flying sense of the airplane sliding sideways through the air rather than turning cleanly. The instrument is named for the two things it shows you at once.
Why Pilots Care
It helps the pilot maintain coordinated flight, preventing slips or skids that waste energy and reduce control effectiveness.
Intuition Check
Do not assume this instrument shows bank angle. It shows rate of turn and whether the airplane is sliding sideways in the turn.
Example Sentence 1
During the climbing turn the student watched the turn-and-slip indicator and added right rudder until the ball recentered.
Example Sentence 2
When the ball in the turn-and-slip indicator stayed centered, the instructor confirmed the turn was properly coordinated.