What is the critical angle of attack's significance in aviation?

The critical angle of attack is significant in aviation because it is the angle at which the airflow separates from the wing's upper surface, leading to a loss of lift and the onset of a stall. When an aircraft's angle of attack exceeds this critical threshold, the wings can no longer produce enough lift to sustain flight, resulting in a stall condition. This stall can compromise the aircraft's control and performance, making it crucial for pilots to be aware of and manage their angle of attack during flight—particularly during takeoff and landing phases where the margins for error are smaller. Understanding the critical angle of attack helps pilots maintain safe flight and avoid situations that could lead to a stall.