Definition
A gyroscopic flight instrument that displays the rate at which the airplane is turning (rate of turn) and whether the turn is coordinated (ball centered) or uncoordinated (ball deflected to one side). The needle indicates direction and rate of yaw; the inclinometer ball shows the balance between yaw and bank.
Plain English
An instrument with two parts. A needle shows how fast the airplane is turning and which way. A ball in a curved tube shows whether the turn is smooth and balanced, or whether the airplane is slipping or skidding through it.
Context Anchor
Seen in engine-inoperative flight and instrument-scan discussions, especially when checking that the airplane remains coordinated during a one-engine-inoperative climb.
Derivation
The name describes what it shows: a turn (the needle) and the bank quality of that turn (the ball). It does not show bank angle directly — only whether the bank is correct for the rate of turn.
Why Pilots Care
In an engine-out climb, using the instrument to stay coordinated preserves climb performance and prevents unnecessary drag or loss of directional control.
Intuition Check
Do not read “bank” here as money or as a riverbank. In this term, bank means the airplane’s wings are tilted, while the instrument mainly shows turn rate and coordination, not exact bank angle.
Example Sentence 1
After securing the failed engine, the pilot used the turn and bank instrument to hold a small amount of bank toward the operating engine and keep the ball slightly displaced for best climb.
Example Sentence 2
The instructor had the student watch the turn and bank instrument while practicing shallow turns on one engine to confirm coordination.