Lightning Protection of Aircraft

Lightning strikes pose a significant risk inside airplanes, where lightning incidents frequently occur. Unfortunately, in the past, four major accidents have been caused by lightning strikes. Considering that even the Earth’s surface experiences frequent lightning strikes, we can infer that airplanes flying tens of thousands of feet are at serious risk. On average, a commercial airplane is struck by lightning about once a year. This significant rate highlights the importance of protecting airplanes from lightning.

Lightning strikes on airplanes cannot be prevented, but airplanes can be easily protected from them. Today, airplanes are increasingly made of composite materials for lighter weight and fuel efficiency. Since these materials have low electrical conductivity, they can pose a risk in case of a lightning strike. Therefore, the upper surface of the airplane is covered with very good conductors. The incoming lightning is safely redirected back into the atmosphere by the highly conductive surface of the airplane. It is crucial that conductivity is maintained throughout the entire airplane. As shown in the image below, materials with high conductivity such as Expanded Metal Foil (EMF) are embedded into the composite to ensure the required conductivity. Lightning strike tests are conducted annually on airplanes.

Boeing 787 composite structure.

Protection Against Static Electricity

Another hazard in airplanes is static electricity. As airplanes encounter ice, clouds, and other masses, they accumulate static electricity due to friction. This static electricity must be safely discharged back into the atmosphere. For this purpose, “dischargers” are installed on the wings.

Static electricity is discharged through rods installed on airplane wings.