What defines the back side of the power curve?

The back side of the power curve, often referred to as the "region of reverse command," is defined as the point where drag exceeds thrust. In this region, as an aircraft slows down, more power is required to maintain level flight due to increased induced drag. The relationship between airspeed and power required to maintain level flight becomes counterintuitive in this area; generally, a higher angle of attack is needed to generate enough lift, resulting in increased drag. Consequently, the aircraft must trade power for altitude when operating in this region, which is critical for pilots to understand, especially during approaches and go-arounds where operating at low airspeeds can lead to undesirable flight characteristics.

Understanding this concept is important for avoiding situations like an inadvertent approach to stall, which can occur if a pilot does not recognize that increased power is necessary to maintain altitude as airspeed decreases. Hence, being aware of the dynamics of the back side of the power curve can significantly enhance safe piloting practices.