Plain English Meaning

Aircraft have two airspeed zones that behave differently. In the upper zone, things work the way you'd expect: more power equals more speed. In the lower zone, things flip: flying slower actually requires more power, not less, because of how drag changes at low speeds.

Full Definition

A concept describing two distinct ranges of airspeed in which an aircraft behaves differently with respect to power and drag. Above the speed for minimum drag (L/Dmax), the aircraft is in the region of normal command, where adding power increases speed and reducing power decreases speed in the expected way. Below that speed, the aircraft is in the region of reversed command, where more power is required to fly at a slower speed because induced drag rises rapidly as airspeed decreases.

Context Anchor

Used in instrument flying when discussing pitch, power, , and slow-speed .