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Lightning is a high voltage and high current phenomenon and it originates by build up of electrical charge in the air or, more commonly, in clouds. It is constituted of an electric current peak of short duration (0,5 ms) and high intensity (200 kA), followed by a low intensity (400 A) but high duration (1s) periods. The lightning effects in aircraft can be divided in two groups: direct effects (physical effects such as melting, rupture, damage of surfaces and structures due to conduction of lightning current or high power magnetic force) and indirect effects (electromagnetic fields generating levels of transient voltage and current on interconnecting wiring and cable leads within the equipment circuits eventually damaging internal components).

In the past, civil aircraft were assessed for electromagnetic compatibility in terms of the ability of onboard systems to coexist without incompatibility problems. However with the advent of electronic into safety critical systems on a new generation of civil aircraft, the aviation authorities became concerned about the potential interference effects of High Interference Radiated Fields (HIRF). The HIRF is generated by emission groups located in aircrafts, airports, ship/boat, such as antennas, radar, navigation/communications instruments, transmitters, among others. The results of interaction of the external electromagnetic fields with aircraft structure and electric-electronic systems herein installed can be generate a high intensity of voltage and current transients, occasioning hazard to electronic equipments and operational reliability.