Definition
A flight instrument, often called the turn-and-slip indicator or turn-and-bank indicator, that displays two things at once: the rate at which the airplane is turning (shown by a needle) and whether the turn is coordinated (shown by a ball in a curved liquid-filled tube). The needle indicates direction and rate of turn; the ball indicates whether the airplane is slipping or skidding through the turn.
Plain English
A cockpit gauge that tells you how fast you're turning and whether the turn is smooth and balanced. The needle shows the turn; the ball shows whether the airplane is sliding sideways through it.
Context Anchor
Seen during maneuver practice, instrument scanning, and steep-turn training when the pilot checks whether the airplane is turning smoothly and in control.
Derivation
The name describes its two functions: the 'turn' part (the needle showing rate of turn) and the 'slip' part (the ball showing whether the airplane is slipping out of a coordinated turn). 'Slip' here means the airplane is sliding sideways through the air rather than tracking cleanly around the turn.
Why Pilots Care
Confirms the turn remains coordinated to avoid altitude loss, increased drag, or disorientation.
Intuition Check
Do not read turn-and-slip as just “a turn plus a mistake.” In this context, it means a specific instrument indication used to judge the turn and whether the airplane is sliding sideways.
Example Sentence 1
During the steep turn, she glanced at the turn-and-slip indicator and added a touch of rudder to center the ball.
Example Sentence 2
When the turn-and-slip indicator showed a skid, the pilot applied opposite rudder to correct.