Plain English Meaning
The airplane is actually climbing — going up — and the instruments confirm it.
Full Definition
An indication that the airplane is gaining altitude, confirmed by the vertical speed indicator showing an upward value and the altimeter showing increasing altitude.
Context Anchor
Used during stall recovery and takeoff procedures, often before raising flaps or landing gear.
Derivation
Positive comes from the idea of being above zero. In this phrase, it does not mean “good”; it means the climb rate is greater than zero, so the airplane is gaining altitude.
Why Pilots Care
Confirms the airplane has enough energy and performance to the safely before retracting flaps or raising the nose further.