Definition
The principle that an airplane's loaded weight and center of gravity (CG) location must fall within the manufacturer's approved limits — and within any narrower spin-specific envelope published in the Pilot's Operating Handbook (POH) or Airplane Flight Manual (AFM) — before intentional spins may be performed. A CG located near or aft of the rearward limit, or a loading that exceeds maximum gross weight, can make recovery from a spin slow, ineffective, or impossible, even when correct recovery technique is applied.
Plain English
Before you spin an airplane on purpose, it has to be loaded within the weight and balance limits the manufacturer specifies for spinning. Many airplanes have a tighter loading window for spins than for normal flight, and a tail-heavy or overweight airplane may not recover from a spin at all.
Context Anchor
Encountered during preflight planning for spin training, stall/spin awareness, and any lesson where intentional spins may be demonstrated or practiced.
Derivation
Weight comes from an old word meaning heaviness. Balance comes from the idea of a scale, where weight must be properly placed to stay under control. In aviation, the phrase points to both how heavy the airplane is and where that weight is located.
Why Pilots Care
An aft center of gravity increases the airplane's moment of inertia and can render normal spin-recovery inputs ineffective, turning a training maneuver into an unrecoverable spin.
Analogy
Think of a loaded shopping cart. If the heavy items are placed where they belong, it steers normally. If too much weight is piled at one end, it may still move, but it will not handle the way you expect.
Grounding Statement
For spin practice, the airplane must be loaded within the approved range before takeoff, not judged by feel after the maneuver begins.
Intuition Check
Do not assume “balance” means the airplane simply feels level in flight. Here, it means the airplane’s weight is located within the approved center-of-gravity range shown in the airplane’s manual.
Example Sentence 1
Before the spin lesson, the instructor and student recalculated weight and balance to confirm the airplane was within the spin-approved envelope listed in the POH.
Example Sentence 2
An aft loading that violated the weight and balance requirement related to spins caused the airplane to remain in a flat spin despite full recovery controls.