What performance impact occurs from loading an airplane with the CG aft of its aft limit?

When an airplane is loaded such that the center of gravity (CG) is aft of its aft limit, it leads to general pitch instability. The reason this occurs is that an aft CG position results in reduced static stability, making it more difficult for the aircraft to return to its original attitude after a disturbance. This instability affects the aircraft's handling characteristics and can lead to a tendency to pitch up or down uncontrollably under certain flight conditions.

Essentially, the aircraft becomes less responsive to control inputs due to the reduced leverage exerted by the tail in stabilizing the aircraft. This can manifest during various phases of flight, particularly takeoff and landing, where pitch control is critical for maintaining safety and performance.

The other options, while representing aspects of aircraft performance, do not directly address the specific consequence of operating with the CG beyond its aft limit in terms of handling and stability. For instance, while the longitudinal axis may be influenced by loading changes, and some degree of control authority could be involved, the most critical issue resulting from an aft CG is indeed the loss of pitch stability.