One of the essential conditions for the safe and effective operation of aircraft is that the weight and center of gravity (C of G). The aircraft manufacturer determines the basic weight and C of G of each aircraft. However, these values may change in service as a result of modifications, repainting, replacement of major components, or structural repairs.

Compliance with the weight and balance limits of any aircraft is critical to flight safety. Operating above the maximum weight limitation compromises the structural integrity of an aircraft and adversely affects its performance. Operation with the center of gravity (CG) outside the approved limits results in control difficulty.