Lightning strikes are relatively common occurrences, particularly for larger commercial aircraft, and in most cases they are relatively harmless thanks to technology designed to protect airplane passengers in the event of a strike. After a commercial flight in 1967 was brought down by lightning, the aviation industry permanently changed aircraft design to make lightning strikes a virtual non-event.
Though direct lightning strikes may have a mild impact on an airplane's electrical system, causing flickering lights and temporary equipment disturbance, planes have been designed to conduct a lightning strike's electricity across and off the exterior of the aircraft. An airplane's exterior skin may be either made of a highly conductive metal such as aluminum or may include conductive cables that give the lightning a path to travel on.
Though this is a relatively safe system, if the protective skin has any gaps or breaks, it may allow the lightning's electricity to penetrate into the aircraft. However, essential equipment inside the aircraft is given additional layers of protection to avoid any serious incidents resulting from lightning strikes.