What is the ballast of an airplane?

An airplane must have a certain balance of weight, front to rear, to be stable in the air. The center of gravity must fall within a specific region for pitch stability. As fuel is burned, the center of gravity shifts in flight. Some aircraft require ballast weights to maintain this balance. Loading of passengers and cargo, as well as the installation of flight equipment, must also be carefully planned with "weight and balance" in mind. Aircraft logbooks contain specific information on which loading, fueling and ballast procedure should be followed.