Radar Cross Section (RCS) is the equivalent effective area of a given target intercepting a radar wave. In other words, RCS is a measure of how detectable a solid is with radar. For the past years, several electromagnetic numerical codes were used to calculate the RCS of aircrafts including the well known and commonly used Finite Element Method (FEM), Finite Difference Time Domain (FDTD) and Method of Moments (MoM). An incident planar wave is used to simulate the radar signal. Today a hybrid method known as Finite Element Boundary Integral (FEBI) solves a RCS model using the advantages of both FEM and MoM. This paper shows a series of RCS benchmarks listed in the literature comparing the results and performance of FEM, IE and FEBI. In order to show the state of the art of electromagnetic numerical codes and a more realistic analysis, several RCS of aircraft models are presented using FEBI and a true radar source.