 In the definition of load factor, the lift is not simply that one generated by the aircraft's wing, instead it is the vector sum of the lift generated by the wing, the fuselage and the tailplane, or in other words it is the component perpendicular to the airflow of the sum of all aerodynamic forces acting on the aircraft.The lift in the load factor is also intended as having a sign, which is positive if the lift vector points in, or near the same direction as the aircraft's vertical axis, or negative if it points in, or near the opposite direction.Excessive load factors must be avoided because of the possibility of exceeding the structural strength of the aircraft.