The frequency of lightning strikes that an airplane experiences is affected by several factors, including the geographic area where the airplane operates and how often the airplane passes through takeoff and landing altitudes, which is where lightning activity is most prevalent. More jet airplane lightning strikes occur while in clouds, during the climb and descent phases of flight, than any other flight phase.
The reason is that lightning activity is more prevalent between 5,000 to 15,000 feet (1,524 to 4,572 meters) altitude. Airplane components made of ferromagnetic material may become strongly magnetized when subjected to lightning currents.
Large current flowing from the lightning strike in the airplane structure can cause this magnetization. While the electrical system in an airplane is designed to be resistant to lightning strikes, a strike of unusually high intensity can damage components such as electrically controlled fuel valves, generators, power feeders, and electrical distribution systems.Most of the external parts of legacy airplanes are metal structure(Faraday Cage) with sufficient thickness to be resistant to a lightning strike. This metal assembly is their basic protection.
The thickness of the metal surface is sufficient to protect the airplane’s internal spaces from a lightning strike. The metal skin also protects against the entrance of electromagnetic energy into the electrical wires of the airplane. While the metal skin does not prevent all electromagnetic energy from entering the electrical wiring, it can keep the energy to a satisfactory level.