In this paper, a Nonlinear PID (NLPID) control design is proposed. The main idea consists of combining theclassical sliding modes approach together with the PID structure. Unlike the existing nonlinear PIDcontrollers in the literature, the coefficients are constant parameters in this work. Within this paper, weinvestigate the efficiency and the performance of this technique through an application to a small VerticalTake Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV). The NLPID based autopilot drives thevehicle toward the desired configuration in the space while stabilizing the roll and the pitch angles wherethe closed-loop system stability analysis is highlighted. The numerical simulations have shown satisfactoryresults using nominal model or disturbed one compared to the use of classic sliding modes technique only.Experimental tests are performed to validate the effectiveness of the proposed control approach.