If an aircraft is operating at CLMAX AOA, the aircraft is stalled.

When an aircraft is operating at the maximum lift coefficient angle of attack (CLMAX AOA), it is not necessarily stalled. The maximum lift coefficient represents the highest amount of lift that an airfoil can generate at a given speed before airflow separates from the wing surface. At CLMAX AOA, the wing is producing the maximum lift but still has the potential to generate more lift before stalling takes place.

Stall occurs when the angle of attack exceeds the CLMAX, leading to a significant decrease in lift due to airflow separation. Therefore, when the aircraft operates at or below this critical angle, it is generating the maximum lift efficiently without stalling.

The other answer choices imply conditions under which stall might occur, but they do not accurately reflect the definition of stall relative to CLMAX AOA, reinforcing the understanding that operation at this angle can still be in a controlled, non-stalled flight condition.