In this paper, a new structure of the nonlinear proportional-integral-derivative (NPID) controller is proposed to control the air temperature at the outlet of the Computer-Aided Aerothermic System (CAAS). This technique is based on the main structure of the classical PID controller, in which the gains of the proportional, integral, and derivative actions vary at runtime according to the instantaneous error. The particularity of this method is to introduce a nonlinear function with each term of the classical PID controller. The objective of the proposed method is to stabilize the air temperature of the aerothermic system with a minimum of overshoot despite the presence of disturbances. Moreover, the proposed method is simple for practical implementation. The performance of the proposed controller (NPID) is evaluated, in terms of overshoot, settling time, and other performance indexes namely Integrated Absolute Error (IAE) and Integrated Squared Error (ISE). The simulation results are encouraging for practical implementation. The effectiveness of the proposed NPID controller is tested on a real laboratory system (CAAS). The experimental results obtained, in terms of tracking the input trajectory variation and rejecting the injected disturbance, show that the proposed technique has better performance and it is more suitable to control the system. In order to show the advantage of the new method over the others, a comparison between a conventional PID controller, a fuzzy logic controller (FLC), and the proposed controller (NPID) has been made. The results obtained indicate that the proposed technique is more effective in controlling the system (CAAS).