In this paper, a novel version of six-degree-of-freedom nonlinear model for transport aircraft motion in cargo extraction is developed and validated by the theoretical mechanics and flight mechanics. In this model constraint force and moment reflecting the flight dynamic effects of inner moving cargo are formulated. A methodology for a control law design in this phase is presented, which linearizes the aircraft dynamics making use of piecewise linearization and utilizes robust control technique for interval system to achieve specified handling qualities with robustness to uncertainties.The simulations demonstrate adequate effectiveness and excellent robustness of the proposed controller.