Definition
A turn rate of 1.5 degrees per second, which is half of the standard-rate turn of 3 degrees per second. A turn at this rate completes 360 degrees in four minutes. Half-standard rate is typically used at higher airspeeds where a full standard-rate turn would require an excessive bank angle, and is commonly indicated by a dedicated half-standard-rate index on the turn coordinator or turn-and-slip indicator.
Plain English
A gentler turn — half as fast as the normal instrument-flying turn. The aircraft takes four minutes to go all the way around instead of two.
Context Anchor
Seen in instrument flying when using the turn coordinator or turn-and-slip indications to control how fast the aircraft is turning.
Derivation
Standard rate' refers to the agreed-upon reference turn rate used in instrument flying (3°/sec). 'Half-standard' simply means half of that reference. The phrase exists because pilots needed a recognised slower turn rate for higher-speed flight where a full standard-rate turn becomes impractical.
Why Pilots Care
Allows smoother, lower-workload turns that maintain precise timing without requiring steep bank angles.
Intuition Check
Half-standard rate does not mean half the usual bank angle. It means half the usual rate of heading change: 1.5 degrees per second instead of 3 degrees per second.
Example Sentence 1
Above 250 knots, the pilot used a half-standard rate turn to keep the bank angle reasonable during the course reversal.
Example Sentence 2
Using half-standard rate during the approach kept the bank shallow and the workload low.