Modern aircraft are specifically designed to safely manage lightning strikes, a common natural electrical discharge. Engineers incorporate advanced protection systems and materials to ensure the safety of both the aircraft and its occupants.
Frequency and Nature of Strikes
Commercial aircraft experience lightning strikes regularly, typically once or twice a year for an individual plane, or approximately every 1,000 flight hours across a fleet. The aircraft often triggers the lightning strike when it flies through a region with a high electrical field, especially within clouds during climb or descent. The lightning current usually attaches to one point on the aircraft, such as the nose or a wingtip, and then travels along the conductive outer skin before exiting from another extremity, like the tail.
Aircraft Protection Mechanisms
Aircraft are engineered with sophisticated mechanisms to withstand lightning strikes. A primary defense is the “Faraday cage” principle, where the aircraft’s conductive outer skin, often made of aluminum or composite materials with embedded conductive meshes, allows the electrical current to flow around the fuselage. This design prevents the high-voltage current from entering the aircraft’s interior, protecting passengers, crew, and sensitive electronic equipment. Modern composite aircraft, which are less naturally conductive than older aluminum designs, incorporate expanded metal foils or interwoven wire meshes beneath the paint to replicate this protective effect.
Electrical bonding ensures continuity between metallic components of the aircraft, such as the airframe, wings, and control surfaces. This equalizes electrical potentials and reduces the risk of arcing.
Static wicks, small metal rods located on the trailing edges of wings and other surfaces, help dissipate static electricity that builds up during flight. While their primary role is to prevent interference with communication systems, they can also serve as points for lightning to discharge into the atmosphere.
Fuel tanks are also protected through design; they are positioned in areas less prone to strikes, and their structures are built to prevent any arcing or sparking within the tank that could ignite fuel vapors.
Experience During a Strike
When lightning strikes an aircraft, passengers and crew typically experience a bright flash of light outside the windows, often accompanied by a loud bang or clap, similar to thunder. There might also be a slight jolt or vibration felt throughout the cabin. The aircraft’s internal systems, including navigation and communication, are generally unaffected due to extensive shielding and protective measures.
Post-Strike Procedures and Safety Record
Following a confirmed or suspected lightning strike, aircraft undergo thorough inspections by maintenance personnel. These inspections check for visible damage, such as minor scorch marks, burn spots, or small pinholes at the lightning’s entry and exit points. While cosmetic damage can occur, the aircraft’s structural integrity is designed to remain intact. Maintenance procedures may include a quick release inspection for minor events or a more comprehensive standard inspection, depending on the severity and location of the strike.
The safety record of modern aviation concerning lightning strikes is strong. Aircraft are designed with robust protection, and serious incidents are rare. The last major commercial airline accident directly attributed to a lightning strike in the United States occurred in 1963. This long safety record underscores the effectiveness of current aircraft design and maintenance protocols in mitigating the effects of lightning.