Regions of command refer to which relationship?

• A. The relationship between altitude and thrust
• B. The relationship between drag and lift
• C. The relationship between turn rate and bank angle
• D. The relationship between speed and the power required to maintain or change that speed

Answer: (D)

Regions of command describe how airspeed is governed by power. It’s about the link between speed and the power required to maintain that speed or to change to a different speed. For a given altitude, the speed you hold is determined by the balance between power available and power required; increase power and you accelerate until you reach a speed where power required equals power available, decrease power and you decelerate to the speed where power required again matches the power you’ve chosen. The important takeaway is that speed is controlled through the power setting, and the power required curve shows how much power is needed at each speed to maintain flight or to change speed. Other options describe different relationships that aren’t about how speed is commanded via power.