Definition
A turn rate of 1.5 degrees per second, which is half of the standard-rate turn of 3 degrees per second. At this rate, an aircraft completes a 360-degree turn in four minutes. Half standard-rate is typically used at higher airspeeds (generally above 250 knots) where a full standard-rate turn would require an excessive bank angle.
Plain English
A gentle turn that takes twice as long as a normal instrument turn. Instead of completing a full circle in two minutes, a half standard-rate turn takes four minutes.
Context Anchor
Seen in instrument flying and turn rate indicator discussions, especially when interpreting how fast the aircraft is changing heading.
Derivation
"Standard-rate" refers to the FAA-defined benchmark turn rate of 3 degrees per second. "Half" simply means one-half of that benchmark, so 1.5 degrees per second. Knowing the term is built off the standard-rate turn helps anchor it as a related, slower variant rather than a separate concept.
Why Pilots Care
Provides a controlled, predictable turn rate that reduces workload and keeps the aircraft within protected airspace during instrument flight.
Intuition Check
Half standard-rate does not mean half the normal bank angle. It means half the normal rate of heading change: 1.5 degrees per second instead of 3 degrees per second.
Example Sentence 1
Climbing through 18,000 feet at 280 knots, the pilot used half standard-rate turns to keep the bank angle manageable.
Example Sentence 2
During the approach briefing the instructor called for a half standard-rate turn to align with the final approach course.