This paper presents development of non-linear six-degree-of-freedom model for a large UAV and simulation of its dynamics during its landing phase. A non-linear six-degree-of-freedom aircraft model was developed using the block available in the Aerosim Aeronautical Simulation Blockset in MATLAB / SIMULINK environment. The aircraft parameter data for a large UAV was taken. The developed model could be used for simulating the dynamics of the UAV with single piston engine and fixed pitch propeller. The following controllers were tuned using the above model to simulate its landing phase. ‘Bank to Aileron’, ‘Airspeed error to Pitch command’, ‘Pitch error to Elevator deflection’, ‘Engine rpm error to Throttle’. The first approach was by conventional techniques using PI and PID controllers. In the next stage fuzzy logic controllers were designed for the above cases. All fuzzy controllers were designed using Mamdani inference system.