Definition
A turn rate of 1.5 degrees per second, which is half the standard rate of 3 degrees per second. At half standard rate, a complete 360-degree turn takes four minutes instead of the two minutes required at standard rate.
Plain English
A gentle turn that changes the airplane's heading at half the speed of a normal instrument turn. It takes four minutes to make a full circle instead of two.
Context Anchor
You may hear this during a radar approach, especially when a controller is giving turn instructions to guide the airplane toward the runway path.
Derivation
Literally half of standard rate. Standard rate is the reference turn rate used in instrument flying (3 degrees per second), so half standard rate is exactly that — half of it.
Why Pilots Care
Produces smoother course corrections that reduce overshoot risk on final approach and improve passenger comfort in instrument conditions.
Intuition Check
Half standard rate does not mean half your airspeed or simply half your usual bank angle. It means half the standard turn rate: about 1.5 degrees of heading change per second.
Example Sentence 1
Above 250 knots, the controller asked for half standard rate turns to keep the bank angle reasonable.
Example Sentence 2
The pilot used half standard rate turns while being vectored to avoid overshooting the localizer in the turn to final.