For many travellers, seeing lightning outside an aircraft window is unsettling enough. Add the thought of the aircraft being struck, and it’s easy to understand why passengers become concerned. Yet, the reality is far less dramatic than it would seem.
Commercial aircraft are struck by lightning surprisingly often. In fact, the average plane is hit approximately once every 1,000 flight hours, which works out to roughly once or twice every year over the course of normal airline operations. Despite this, lightning-related accidents are exceptionally rare thanks to decades of engineering.
The History of Lightning Protection on Planes
Lightning has always posed a challenge to aviation. In the early days of flight, aircraft were built primarily from wood and fabric, materials that offered very little protection against lightning. As aviation developed through the 1920s and 1930s, metal airframes became increasingly common. While these proved much better at conducting lightning safely around the aircraft, they also highlighted the need for engineers to understand exactly how lightning interacted with aircraft structures and onboard systems.
The importance of dedicated lightning protection became even clearer as commercial aviation expanded after the Second World War. Aircraft were flying higher, further and more frequently, while carrying larger numbers of passengers. Several lightning-related accidents during the 1950s and 1960s, including fuel tank explosions thought to have been triggered by lightning, prompted significant research into aircraft protection. One of the most notable was the 1963 crash of Pan Am Flight 214, a Boeing 707 that was struck by lightning near Elkton, Maryland.
Following accidents such as this, aircraft manufacturers, regulators and researchers developed much stricter lightning protection standards. Fuel systems were redesigned, electrical bonding was improved, electronic equipment was shielded, and large-scale laboratory lightning simulations were conducted before the aircraft entered service.
Today, every commercial aircraft must demonstrate that it can safely withstand lightning strikes before it is certified to fly. Modern airliners are therefore designed with lightning in mind from the very beginning.
What Happens During a Lightning Strike?
Most lightning strikes occur while an aircraft is climbing or descending through storm clouds, rather than while cruising at high altitude. Lightning will usually strike a point near the nose, wingtip or engine nacelle before travelling safely across the aircraft’s outer skin and exiting via the tail. The electrical current remains on the outside of the aircraft, effectively treating the fuselage as a giant Faraday cage, which protects everyone inside.
If you’re onboard during a strike, you may notice a very bright flash outside the window, followed almost instantly by a loud bang or sharp crack. Some passengers also report seeing a brief flicker of the cabin lights as electrical systems automatically switch between power sources.
What they don’t feel is the electricity itself. The current does not pass through the cabin or the passengers. In many cases, people don’t even realise a lightning strike has occurred until the flight crew announces it after the event.
How Are Aircraft Protected?
Traditional aluminium frames naturally conduct electricity around the aircraft’s exterior. Newer composite aircraft, such as the Boeing 787 and Airbus A350, incorporate fine copper or aluminium mesh beneath the outer surface to provide the same conductive path.
Critical electronic systems are also shielded against electromagnetic interference, wiring is protected, fuel tanks are designed to prevent ignition, and sensitive equipment must demonstrate compliance with rigorous lightning certification requirements before an aircraft can enter service.
During aircraft certification, manufacturers subject aircraft to simulated lightning currents in laboratories to verify that both the aircraft structure and its electronic systems continue to operate safely. Once an aircraft enters service, there is no fixed annual “lightning protection test” like those carried out on buildings. Instead, airlines inspect aircraft as part of routine scheduled maintenance and perform detailed inspections after any known or suspected lightning strike. Engineers look for entry and exit marks, structural damage, degradation of protective materials and any signs of system faults before the aircraft is returned to service.
Although the environments are completely different, the principle remains the same. Whether protecting an aircraft travelling at 35,000 feet or a building standing on the ground, the objective is not to stop lightning, but to provide a controlled path for the enormous electrical current while protecting the people and systems inside. It is this combination of intelligent design, rigorous testing and ongoing maintenance that allows both aircraft and buildings to withstand one of nature’s most powerful forces.
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