What must be done to prevent instability during flight operations?

To ensure stability during flight operations, it is essential to correctly locate the center of gravity (CG) of the aircraft. The CG is the point at which the aircraft balances and it affects the aircraft's handling characteristics and performance. If the CG is too far forward or too far aft, it can lead to issues such as difficulty in controlling the aircraft, increased stall risk, and reduced maneuverability. Maintaining the proper CG within the specified limits allows for smoother flight and better response to pilot inputs.

The other options do not address the fundamental aspects of stability. Reducing altitude continuously does not inherently ensure stability and may actually induce further complications depending on the aircraft's design and load conditions. Increasing engine thrust continuously without regard to CG can lead to an unstable flight environment as well. Ignoring weight distribution outright will create imbalance issues, leading to poor aircraft performance and potential danger during flight. Thus, locating and maintaining an appropriate center of gravity is crucial for stabilization and safe flight operations.