What occurs when an aircraft exceeds the critical angle of attack?

When an aircraft exceeds the critical angle of attack, it enters a stall. The critical angle of attack is the point at which the airflow over the wings can no longer remain smooth and starts to separate from the wing surface. This results in a significant loss of lift because the wings are no longer generating enough aerodynamic force to support the aircraft's weight.

In a stall condition, the aircraft may experience a rapid decrease in lift and may start to descend, potentially resulting in a loss of control if not recovered properly. Understanding this concept is crucial for pilots, as it emphasizes the importance of maintaining appropriate angles of attack during flight to ensure safe and effective handling of the aircraft.

The other options do not accurately describe the situation when an aircraft exceeds the critical angle of attack. For instance, adverse yaw is a phenomenon associated with differential drag during turns and is not directly linked to exceeding the critical angle of attack. Gaining altitude and increasing speed are also not outcomes of exceeding the critical angle, as such actions would typically require controlled lift and thrust, which are compromised during a stall.