Definition
Flight instruments that display the rate at which the aircraft is changing its attitude or direction, rather than its current attitude itself. The turn coordinator (or turn-and-slip indicator) and vertical speed indicator are the primary rate instruments — they show how fast the aircraft is turning or how fast it is climbing or descending.
Plain English
Instruments that show how quickly something is changing — how fast you are turning, climbing, or descending — instead of showing the current pitch or bank angle directly.
Context Anchor
Seen in instrument flying when using turn indicators, especially the turn-and-slip indicator or turn coordinator.
Derivation
Rate' comes from the Latin rata, meaning a measured or proportioned amount. In aviation, 'rate' refers to how much something changes per unit of time — degrees per second, feet per minute. A rate instrument therefore measures change-over-time, not a fixed position.
Why Pilots Care
They allow continued control of turns and climbs when attitude instruments are unavailable or unreliable.
Analogy
A car speedometer is a rate instrument: it shows how fast the car is moving, not where the car is. A turn rate instrument does something similar for the airplane's turn.
Intuition Check
Do not assume rate instruments show the airplane's exact position. Here, rate means how fast the motion is happening, not the final angle or position.
Example Sentence 1
During partial-panel practice, the pilot relied on the rate instruments to hold a standard-rate turn without the attitude indicator.
Example Sentence 2
With the attitude indicator inoperative, the pilot used rate instruments to maintain coordinated turns and a steady climb.