Definition
The highest value of the lift coefficient an airfoil can produce before it stalls. It occurs at the critical angle of attack — the angle just beyond which the airflow separates from the upper wing surface and lift drops sharply.
Plain English
The most lift a wing can make before it stops flying. Push the angle of attack any higher and the wing stalls.
Context Anchor
Seen on lift and angle-of-attack graphs, especially when learning why a wing stalls after reaching its maximum lifting point.
Derivation
CL stands for Coefficient of Lift — a number that expresses how efficiently a wing produces lift at a given angle of attack. MAX simply marks the peak value on that curve. So CL-MAX is the top of the lift curve, just before the stall.
Why Pilots Care
CL-MAX sets the limit for how slowly an aircraft can fly in level flight and directly determines stall speed in any given configuration.
Grounding Statement
CL-MAX is the top of the lift curve: beyond that point, more nose-up angle gives less lift, not more.
Intuition Check
CL-MAX does not mean the airplane can never make more total lift in any situation. It means the wing has reached its maximum lift coefficient for that airflow condition before stall begins.
Example Sentence 1
As the pilot raised the nose in slow flight, the wing approached CL-MAX and the stall warning began to chirp.
Example Sentence 2
A change in flap setting increases the value of CL-MAX and lowers stall speed.