Definition
The band of airspeeds in which an aircraft is intended to be flown during routine operations in smooth air, shown on the airspeed indicator as a green arc. It extends from the stalling speed with flaps up and gear up at maximum gross weight (the bottom of the green arc) to the maximum structural cruising speed (the top of the green arc), which is the highest speed permitted in normal operations and may only be exceeded with caution.
Plain English
The range of speeds you should normally fly in. On the airspeed indicator it is the green arc — fly inside it during everyday flying in smooth air.
Context Anchor
Seen on the airspeed indicator and in aircraft limitations discussions, especially when learning the color markings on the airspeed gauge.
Why Pilots Care
Operating outside this range risks either a stall or structural overload even in smooth air.
Analogy
It is like the normal-use zone on a machine gauge: below it may be too low, above it may need extra caution, and the marked band shows the ordinary operating area.
Intuition Check
“Normal” does not mean every speed that feels safe or every speed the airplane can reach. Here it means the specific approved green-arc range shown on the airspeed indicator.
Example Sentence 1
After leveling off in smooth air, the pilot trimmed for cruise well within the normal operating speed range.
Example Sentence 2
Turbulence encountered above the normal operating speed range can cause structural damage even when the airplane is below maneuvering speed.