This master thesis focuses on modeling, control and trajectory tracking of a hexacopter UAV (Unmanned Aerial Vehicle) used in fire-detection missions. A set of non-linear dynamic equations describing the motion of the hexacopter were derived. These equations were then implemented in Matlab/Simulink, which became a good simulation environment for further studies. A PID controller was successfully implemented in simulation; a linear model was used to tune the parameters of the inner PID controllers.