What can cause a shifting CG during flight?

A shifting center of gravity (CG) during flight is primarily influenced by factors like fuel burn and the movement of cargo or passengers. As fuel is consumed, the weight decreases, and if the fuel tanks are located away from the aircraft's centerline, this can cause a change in CG. Furthermore, the repositioning of cargo or passengers can alter the distribution of weight within the aircraft. For example, if a passenger moves from the front to the back of the aircraft, it shifts the CG aft, potentially affecting the aircraft's handling characteristics.

While engine failure, the position of the pilot, and weather changes can impact flight dynamics and performance, they do not directly cause a shift in the CG. Engine failure primarily affects thrust and aerodynamics, while the pilot's position typically remains static in relation to the structure of the aircraft, and weather changes do not alter the mass distribution of the aircraft. Thus, the movement of fuel and cargo or passengers is the key cause of changes in CG during flight.