Experimental Studies of Lightning Strikes to Aircraft

Civil aviation transportation has been growing since the early forties and has become today a massive and unique transport system for people across continents and large countries. First age propeller airliners flew at low altitude and were often subjected to dangerous atmospheric and cloud hazards. Low visibility, heavy precipitation, severe turbulence, wind shear, icing and lightning are common weather hazards that are a challenge for flight safety. Among those weather hazards, lightning was the most unrecognized and misunderstood. Damages to aircraft due to lightning strike were frequently noticed; they range from arc spots on metal to centimeter-size holes in the fuselage, and dielectric radome and antenna destruction. Some cases of catastrophic events are directly attributed to lightning [1], [2]. Experimental in-situ studies were initiated no later than the early sixties [3], but the main in-flight research efforts were undertaken at the beginning of the eighties, when the perspective of a massive use of composite material in aviation was identified for a near future. Three major in-flight test programs were initiated in the USA and Europe by NASA, the Air Force, the FAA and the French Civil and Military Aviation Authorities, associated with Research Organizations. This paper is a review of the in-flight lightning strike experiments performed during that period. Information on aircraft missions, performances and  instrumentation is given. Available results and proposed interpretations are presented. The main outcomes of those experiments are emphasized and knowledge gaps and missing information are mentioned.