Modern aircraft make use of several electronic systems; some of these systems have functions that are critical for flight safety. The aerospace community is aware that strong radiated signals, like those generated by telecommunication or air traffic control systems may be so severe that could be able to upset these flight safety critical systtems. So, aircraft manufacturers must provide means to reduce the amount of RF power that can penetrate the aircraft systems, and then minimise the probability of disasters caused by high intensity radiated fields.Thus, certification of aircraft in HIRF is a challenge to modern mobility engineering. The certification test in HIRF is so complex and expensive that its repetition os prohibitive. Furthermore, this kind of test is only appliable during final developing phases of a new aircraft model. So, the designers must include effective HIRF protections to critical systems.On the other hand, from the design quality point of view, it is very important that HIRF protections of an aircraft are correctly sized to not overload the vehicle with cost or weigh. Thus, it is desirable to have a reliable set of design factors to help the choice of the HIRF protections.The purpose of this paper is to present the efforts of the electromagnetic compatibility tests team of EMBRAER to develop a simplified test procedure able to obtain this design factors in order to help the development of new air craft models.