Definition
The ratio of the total aerodynamic load supported by an airplane's wings to the actual weight of the airplane and its contents. Load factor is expressed in multiples of normal gravity (G), where 1G represents the airplane's weight in straight-and-level unaccelerated flight. During maneuvers, turbulence, or pull-ups, the wings must support more than the airplane's weight, producing load factors greater than 1G.
Plain English
How many times the airplane's own weight the wings are currently being asked to hold up. Straight and level, the wings carry exactly the airplane's weight (1G). In a steep turn or sharp pull-up, the wings may have to carry two, three, or more times that weight.
Context Anchor
Pilots encounter load factors when learning about steep turns, maneuvering speed, turbulence, stalls, and airplane structural limits.
Derivation
"Load" comes from Old English meaning a burden or weight being carried. "Factor" comes from Latin factor, meaning "one who makes" or, in math, a multiplier. Together, load factor is the multiplier applied to the airplane's weight to get the actual load on the wings.
Why Pilots Care
Exceeding published load-factor limits can overstress the airframe, cause structural damage, or lead to an inadvertent stall.
Grounding Statement
In a steep turn or sudden pull-up, the airplane may still weigh the same on the ramp, but in flight the wings and structure may have to carry much more than that weight.
Intuition Check
Do not confuse load factors with how much baggage, fuel, or cargo is in the airplane. Here, “load” means the extra force placed on the airplane in flight, not the items loaded into it.
Example Sentence 1
In a level 60-degree banked turn, the load factor is 2G, meaning the wings must support twice the airplane's weight.
Example Sentence 2
The pilot stayed inside the airplane's load-factor envelope while practicing steep turns to avoid overstressing the wings.