Definition
A category of aircraft instruments that measure either elapsed time or the rate at which something is changing. Examples include clocks and elapsed-time indicators (time), and vertical speed indicators, turn coordinators, and tachometers (rate).
Plain English
A grouping of cockpit instruments that either tell you how long something has taken or how fast something is changing.
Context Anchor
Seen in discussions of turn indicators, turn coordinators, and standard-rate turns during instrument flying.
Derivation
Rate comes from an older word meaning to reckon or calculate. In this use, it means how much something changes during a measured amount of time, which is why a turn can be described by time or by degrees per second.
Why Pilots Care
Correct interpretation prevents errors in flight planning, fuel reserves, and time-to-station estimates.
Intuition Check
Do not read this as ordinary clock time by itself. In this context, time and rate are two ways to describe the same turning motion.
Example Sentence 1
The vertical speed indicator falls under the time or rate category because it shows how quickly altitude is changing.
Example Sentence 2
When the chart listed time instead of rate, the pilot read the total duration directly for the climb segment.