This article presents a simple method to calculate the angle of incidence and the slowness of P- and SV-waves from single 3-component set of data. The obtained slowness is used as the parameter to remove the free surface effect, such as phase distortion and amplification, and to recover the original incident wave. This method is derived from the calculation of ratios regarding the horizontal/vertical and the vertical/horizontal response for P-waves and SV-waves, respectively. From the comparison of the calculated ratios with the observed ones (estimated from data), the angle of incidence can be found. Synthetic data are first tested to prove their accuracy, and then, the first P- and SV arrivals of real data are analyzed. The results are compared with those evaluated from polarization analysis, and they appear to be quite consistent for synthetic P-waves.