Study of Effects of Lightning Strikes to an Aircraft

In-flight statistics show that most strikes occurred 3-5 km above sea level, where the temperature is ~ 0C (Uman & Rakov, 2003; Larsson, 2002). There are two different types of lightning strikes to aircraft. The first type is that the aircraft initiates the lightning discharge when it is found in the intense electric field region of a thundercloud, and the second is the interception by the aircraft of an approaching lightning leader. The mechanism for lightning initiation by aircraft is often explained using the “bidirectional leader” theory (Clifford & Casemir, 1982; Mazur, 1989; Mazur et al., 1990; Mazur & Moreau, 1992), which describes the aircraft-initiated lightning process as a positive leader starting from the aircraft in the direction of the ambient electric field; this is followed, a few milliseconds later, by a negative leader developing in the opposite direction. This order of events is a consequence of the lower electric strength of air in the vicinity of a divergent (anode) field. The ambient thundercloud electric field measured under such conditions is typically in the range 50 100 kV/m (Marshall & Rust, 1991).