What happens when an aircraft exceeds its critical angle of attack?

When an aircraft exceeds its critical angle of attack, it enters a stall condition. The critical angle of attack is the angle at which the airflow begins to separate from the wing's upper surface, resulting in a significant reduction in lift. Once this angle is surpassed, the wing can no longer generate sufficient lift to support the weight of the aircraft.

In a stall, the aircraft's ability to maintain level flight is compromised, and control can be lost temporarily. The aerodynamic principles governing lift and drag are altered, leading to an inevitable decrease in lift. Understanding this phenomenon is crucial for pilots, as recovery from a stall generally requires specific actions to regain control.

The other options do not accurately describe the implications of exceeding the critical angle of attack. For example, increasing speed is typically related to maintaining lift, not a consequence of reaching the critical angle. Similarly, gaining more lift contradicts the very nature of exceeding this angle, since it leads to a reduction in lift. Lastly, while becoming uncontrollable may be a potential outcome of a stall, it is not the precise or immediate effect that occurs upon exceeding the critical angle of attack.