When considering air travel, many people wonder about the effects of a lightning strike on an aircraft. While the thought of a plane being hit by lightning can seem alarming, such incidents are a relatively common occurrence and modern aircraft are designed to withstand them safely.
Frequency of Lightning Strikes on Aircraft
Commercial airplanes are struck by lightning more often than many realize, typically once or twice per year, or about every 1,000 flight hours. Aircraft often act as conductors, initiating strikes when flying through electrically charged thunderclouds or areas with high electrical activity.
Most lightning strikes occur at intermediate altitudes, often between 5,000 and 15,000 feet, rather than at cruising altitudes. This is because planes are frequently in or near cloud formations during takeoff and landing, where lightning activity is more prevalent. The aircraft itself can enhance ambient electric fields, effectively attracting a strike.
How Aircraft Withstand Lightning Strikes
Aircraft are engineered with multiple layers of protection to safely manage lightning strikes. The primary defense is the Faraday cage principle. The aircraft’s conductive outer skin, typically made of aluminum alloys or composite materials with conductive fibers, allows electricity to flow harmlessly around the cabin. This design ensures the electrical current travels along the exterior surface, preventing it from entering the interior where passengers and sensitive electronics are located.
Beyond the Faraday cage, aircraft incorporate specific components to manage lightning. Lightning diverters, metal rods or strips on the nose, wingtips, and tail, are strategically placed to guide the strike away from sensitive areas, especially composite radomes. They create a path of least resistance, allowing the lightning to flow onto the aircraft’s main conductive skin. Fuel tanks are reinforced with thick skins and tightly designed structural joints to prevent sparks from igniting fuel vapors. Sensitive avionics and electrical systems are equipped with surge protection devices and shielded wiring to prevent damage from electrical surges.
What Passengers and Crew Experience
When lightning strikes an aircraft, passengers and crew typically experience a sudden, bright flash of light. This is often accompanied by a loud bang or pop, which can be startling. Some individuals might also perceive a jolt or vibration throughout the cabin.
While unsettling due to visual and auditory effects, the event is generally harmless to those inside. Passengers are shielded by the aircraft’s design, and the loud noise is due to the rapid expansion of air along the lightning channel. Pilots are thoroughly trained to handle such occurrences and maintain control of the aircraft, ensuring continued safe flight. Occasionally, there might be a temporary flickering of cabin lights or brief interference with some instruments, but critical systems remain operational.
Post-Strike Safety Measures
Following a suspected lightning strike, a mandatory post-flight inspection is conducted upon landing. This check ensures the aircraft’s continued airworthiness and identifies any potential damage. Maintenance personnel examine the entire surface for minor damage.
Common findings include small burn marks, pitting, or discolored paint at the points where lightning entered and exited. Components like static wicks or antennas may show signs of damage and require replacement. While these checks are precautionary, they can sometimes lead to flight delays as the inspection process can take several hours. Flight crews make a logbook entry detailing the event, providing maintenance teams with information for inspection and necessary repairs.