The coupling of lightning fields into aircraft and cables

The current distribution in the skin of an aircraft struck by lightning is described and the effects of airframe resonance are noted. Nearby strikes produce initially an electromagnetic pulse which is scattered by the aircraft, creating circulating currents in the skin: this process is considered. The magnetic fields at the surface diffuse into the skin, and significant currents flow on the interior after a time lag dependent on the skin resistivity. In addition, the surface fields couple directly into the interior through breaks in the conducting skin or through insulating panels. Methods of calculating the magnetic and electric fields in the interior of the aircraft are discussed, and the effects on electrical and electronic systems described. The screening of internal cabling is reviewed.