In most cases, nothing – except a slight flickering of cabin lights and a few milliseconds of interference that the cockpit instruments experience. Modern passenger aircraft’s skin is made primarily of aluminum which is a good conductor of electricity. Inside, there is adequate insulation, so most of the current flows through only the exterior framework of the aircraft. In the case of some modern small aircraft which have an outer skin made of non-conductive or less conductive composite materials there is an embedded layer of wires or mesh which allow the lightning current to pass through. Since the fuel tanks are properly sealed with a thick layer of insulation the lightning bolt having entered one extreme like nose or wing exits from another extreme such as the tip of the aircraft’s rudder.
The last known and recorded incident occurred in 1967 when lightning struck a plane carrying passengers. Unfortunately, the fuel tanks exploded, causing the plane to explode mid-air. Since then, much has been researched about lighting and how airplanes can be made safer. Today, planes such as Boeing 787 and Airbus A350 are made with a higher composition of composite materials such as carbon fibers, resulting in a reduced electrical conductivity of wings and fuselage. By adding more metal wiring to the composite material, good electrical conductivity is ensured on the aircraft’s exterior.
Furthermore, weather forecasting systems have progressed to the point where they can predict sudden changes in weather even before a plan is about to take off. This allows air traffic controllers to suggest different routes to the pilots to avoid heavy clouds, rain, and lightning. In most cases, neither the pilots nor the passengers will feel anything because the lighting will strike the nose or tail and will travel through the body of the plane and exit from the opposite end. However, minor electrical damage may occur but not enough to bring down the plane.
Planes are protected against lighting in two ways: Conductive meshes and Avionics and flight control systems.
Avionics and flight control
If avionics and flight control systems are not designed properly, there are chances that a spike could occur due to a lightning strike. Today, these systems are installed in airplanes with surge protection devices and shield wiring throughout the aircraft. Wingtip lights that are installed on the exterior frame of the airplane are also properly grounded to prevent excessive voltage from flowing in the wiring inside the wing.
The second way to protect airplanes from lighting strokes is conductive meshes. These are installed in the composite skin that helps minimize damage to the surface and prevent the buildup of electrical current in one area. Manufacturers construct the main shell out of carbon fiber that actually forms the fuselage and then coats it with an extremely thin corrosion-resistant layer of fiberglass.
On top of that, aluminum or copper mesh is installed. This is as fine as a window screen and is made to perform two jobs: It spreads the current to minimize damage to the skin of the aircraft when it is stuck in one location and keeps the current on the fuselage’s exterior. As a result, this reduced the voltages that otherwise might be induced inside the airplane causing damage to the electrical systems.
All in all, airplanes are pretty safe today when it comes to getting hit by lightning. Safety aspects of airplanes have progressed to the point where it is almost impossible to bring down a plane. Even if the engines give up and the pilot is competent, the plane could be safely landed without any casualties. An airplane is most vulnerable when it is taking off. This is a moment where everyone holds onto their breath, but thanks to the impressive technology and safety features, casualties and serious damage is highly unlikely.