The stepwise regression is a well-established technique used to determine aerodynamic model structure from flight data. This paper discusses the application of stepwise regression to a nonlinear estimation method proposed previously by the authors, for model structure determination. The approach can also be used for updating aerodynamic database models in table look-up form. The current results obtained for model structure determination for a reference problem are compared against the results obtained using the well known least squares multivariate linear estimation. Simulated data of a transport aircraft is used to prove the concept. Finally, an application of the technique for the aero database update of a high performance fighter aircraft is discussed.