Definition
A turn at half the rate of a standard rate turn, producing a heading change of 1.5 degrees per second, or a complete 360-degree turn in four minutes. It is commonly used at higher airspeeds where a full standard rate turn would require an excessive bank angle.
Plain English
A gentler turn than the normal one used for instrument flying. Instead of turning all the way around in two minutes, you take four minutes — so the airplane is banking less and changing heading more slowly.
Context Anchor
Seen in instrument flying and on electronic flight displays when using turn-rate or trend information to judge how fast the airplane is turning.
Derivation
“Standard rate” refers to the commonly used instrument turn rate of 3 degrees per second. “Half-standard” means half of that rate, so the airplane turns at about 1.5 degrees per second instead of 3.
Why Pilots Care
Produces smoother heading changes that reduce the chance of overshooting a desired course or altitude during instrument flight.
Intuition Check
Half-standard does not mean using half of a normal bank angle. It means the airplane’s heading is changing at half of the standard turn rate.
Example Sentence 1
Cruising at 250 knots, the captain used a half-standard rate turn to intercept the airway without exceeding 25 degrees of bank.
Example Sentence 2
Trend indicators helped the pilot hold a steady half-standard rate turn while intercepting the localizer.