What is the critical angle of attack?

The critical angle of attack is defined as the angle at which the airflow begins to separate from the upper surface of the wing, resulting in a stall. At this point, the wings can no longer produce sufficient lift to maintain flight, regardless of the airspeed. When an aircraft exceeds this angle, the smooth airflow over the wings is disrupted, leading to an abrupt decrease in lift. Understanding the critical angle of attack is crucial for pilots, as it helps them avoid stall conditions by recognizing and maintaining safe flight parameters.

The other options refer to different aspects of flight performance. For instance, the angle necessary for takeoff is specific to a particular aircraft's configuration and conditions but does not define the critical angle of attack. The angle that maximizes lift relates to the optimal lift-to-drag ratio, which is different from the critical angle. Lastly, the angle at which a pilot must pull back on the yoke to gain altitude is more related to control inputs rather than the aerodynamic concept of critical angle of attack.