Certified Flight Instructor - Flight Instructor Airplane Practice Exam

As the center of gravity (CG) moves aft, how does aircraft stability change?

1. It becomes less stable but easier to control.

2. It becomes more stable and controllable.

3. It becomes less stable and less controllable.

4. It has no effect on controllability.

The correct answer is: It becomes less stable and less controllable.

As the center of gravity (CG) moves aft, the overall stability of the aircraft decreases, which has significant implications for its handling characteristics. An aircraft with an aft CG has a tendency to become less stable because the aerodynamic forces acting on it have a greater leverage, making it more sensitive to pitch changes. This can lead to a reduction in the natural stability provided by the tail and can result in situations where the pilot may need to exert more effort to maintain level flight. When the CG is located further back, the aircraft may exhibit a tendency to pitch up or down more easily, often making it more difficult to control, particularly during certain maneuvers. This means that as the CG moves aft, the pilot may find the aircraft is less controllable and may require more input to manage attitude changes effectively. In contrast, a forward CG generally enhances stability and controllability, as the aircraft resists changes in pitch and requires less pilot input to maintain stable flight.