(eng): Tiltrotor aircraft are complex, highly nonlinear systems which offers distinct operational advantages due to their unique Vertical Take-Off and Landing (VTOL) capabilities. Hovering a piloted tiltrotor in the helicopter flight condition is one of the most challenging tasks for pilots. Therefore, automatic control of the tiltrotor is always desired. Classical automatic linear control techniques fail to provide an adequate performance guarantee. In comparison, the application of nonlinear control techniques offers a potential alternative. Thus, in this paper modelling and hover control of a BELL XV-15 tiltrotor aircraft is presented. The MATLAB/Simulink based dynamic model of the BELL XV-15 tiltrotor aircraft is validated with respect to FLIGHTLAB model. In addition, a nonlinear hierarchical control strategy is adopted to provide automatic hover control of the tiltrotor aircraft. The results show a good hovering performance of the tiltrotor aircraft with small position tracking error.