Definition
On the turn-and-slip indicator, the needle is the vertical pointer driven by a rate gyro that deflects left or right to show the direction and rate of turn of the aircraft. A standard-rate turn (3° per second) is indicated when the needle is deflected to a calibrated index mark, commonly called a 'doghouse' or standard-rate mark, on either side of center.
Plain English
The needle is the pointer on the turn indicator that swings left or right to show which way you are turning and how fast you are turning. When it lines up with the mark, you are turning at the standard rate of 3 degrees per second.
Context Anchor
Seen during instrument flying when checking the turn indicator as part of the instrument scan.
Derivation
Needle comes from an old word for a small, pointed tool. That helps here because many cockpit instruments use a thin pointed marker, like a needle, to show a reading.
Why Pilots Care
The needle gives a direct readout of turn rate, which is essential for timed turns, holding patterns, and maintaining standard-rate turns under instrument conditions. If the attitude indicator fails, the needle becomes a primary reference for controlling bank.
Analogy
It works like the pointer on a car speedometer: the pointer itself is not the speed, but its position tells you what is happening.
Intuition Check
Needle does not mean a sewing needle here. It means the instrument’s moving pointer that shows the airplane’s turn.
Example Sentence 1
She rolled into a left turn until the needle settled on the standard-rate mark, then started her timer for the procedure turn.
Example Sentence 2
The pilot watched the needle center again as the airplane rolled out on the new heading.