Definition
The combination of airplane weight and center-of-gravity (CG) location that produces the worst-case handling and controllability when one engine is inoperative on a multi-engine airplane. For VMC determination, this is typically the maximum takeoff weight with the CG at its most rearward approved limit, because an aft CG shortens the rudder's moment arm and reduces its ability to counter the yawing force from the operating engine.
Plain English
The specific loading of the airplane — how heavy it is and where the weight sits along its length — that makes it hardest to control if an engine fails. For VMC testing, this is usually as heavy as allowed with the load placed as far back as allowed.
Context Anchor
Seen in multi-engine airplane discussions about how minimum control speed is determined and why the published value is conservative.
Derivation
“Unfavorable” means not working in your favor. “Center of gravity” comes from the idea of the single point where an object’s weight acts. Together, the phrase points to the legal loading condition where the airplane’s weight and balance work least in the pilot’s favor for control.
Why Pilots Care
The published VMC speed is based on this condition; any other loading results in a lower actual minimum control speed.
Grounding Statement
Picture the airplane loaded within its limits, but in the legal arrangement that gives the pilot the smallest control advantage after an engine fails.
Intuition Check
“Most unfavorable” does not mean an illegal or extreme loading outside the airplane’s limits. It means the least helpful loading condition that is still approved for the airplane.
Example Sentence 1
VMC is determined with the airplane at its most unfavorable weight and center-of-gravity position, so the published speed reflects the hardest case to control.
Example Sentence 2
With the airplane loaded to its most unfavorable weight and center-of-gravity position, directional control is lost below the published VMC if the critical engine fails.