exceeds its critical angle of attack.

(As explained in the aerodynamics video about stalls, the airflow starts to disrupt at a particular moment: when the critical angle of attack is reached. While the traditional wisdom dictates that this happens at slow airspeed, when the nose of the aircraft is high, this can happen at any speed. If you apply abrupt pitch-up controls, the angle of attack can reach the critical number where the airflow separates and the aircraft stalls. Remember also that the angle of attack is the difference between the chord line and the relative wind (or direction of motion of the aircraft). When the aircraft reaches maximum speed, the wing will still produce lift, but structural failure can occur (the aircraft wouldn’t be strong enough to go that fast).  If the aircraft exceeds its maximum allowable operating weight, structural damage or failure is also a possibility.  See “Stalls” video for more information.)