[Ref Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 5-3]
What’s Critical AoA?
Critical AOA = stalling AOA ≅ CLmax point ;
Critical AoA is the AoA angle in which the wings have reached CLmax point.
After reaching Critical AoA, any further increase AoA will result in the wing stalling.