When a plane is struck by lightning, it often sparks curiosity or concern. Modern aircraft are designed to handle this well-understood phenomenon safely. Robust engineering and operational procedures ensure that lightning strikes, while sometimes startling, rarely pose a significant threat to flight safety.
How Lightning Interacts with Aircraft
Aircraft can act as a trigger for lightning, especially when flying through areas with high electrical fields, such as within or near thunderstorms. The aircraft’s presence enhances ambient electric fields, completing an electrical circuit. When a lightning strike occurs, the electrical current typically enters the aircraft at one point, often an extremity like the nose, a wingtip, or the tail.
The current then travels along the plane’s outer skin, designed to conduct electricity, and exits from another extremity. Lightning attachment points can move along the aircraft’s surface, creating “swept strokes.” This conduction path ensures electrical energy remains on the exterior, protecting the interior and occupants.
Aircraft Protection Systems
Aircraft are constructed with advanced protection systems to manage lightning strikes. The primary defense is the “Faraday cage” principle, where the aircraft’s conductive outer skin, typically made of aluminum or composite materials with embedded conductive foils, directs the electrical current safely around the cabin. This design prevents the high voltage electricity from penetrating the interior, shielding passengers and sensitive electronic equipment.
Beyond the conductive skin, aircraft incorporate other protective measures. Lightning diverters, often found on non-metallic parts like the radome (nose cone) and winglets, attract lightning and guide its energy to the conductive airframe. Critical systems, including wiring and fuel tanks, are also shielded and designed to prevent ignition or disruption from electrical surges.
Bonding straps connect various metal components to ensure continuous electrical paths. Static wicks on wingtips and tail help dissipate static electricity and can also serve as discharge points for lightning.
Passenger Experience and Post-Strike Procedures
Passengers inside an aircraft struck by lightning may experience a bright flash of light and hear a loud bang. There might also be a temporary flicker of cabin lights. Despite these sensory experiences, passengers are unaffected by the strike due to the aircraft’s protective design.
Following a suspected lightning strike, pilots perform a systems check and make a logbook entry. Upon landing, the aircraft undergoes a thorough inspection by maintenance crews to check for any minor cosmetic damage, such as small burn marks or pit marks, particularly at the entry and exit points of the strike. This mandatory inspection ensures the aircraft remains airworthy.
Frequency of Strikes and Overall Safety
Lightning strikes on commercial aircraft are more common than many might assume. On average, a commercial aircraft is struck by lightning at least once or twice a year, or approximately every 1,000 flight hours. These strikes most frequently occur during takeoff or landing, between altitudes of 5,000 and 15,000 feet, where planes often pass through electrically charged clouds.
While pilots endeavor to avoid thunderstorms, encountering lightning is a routine and expected part of aviation. The robust design and rigorous testing standards for aircraft ensure a strong safety record concerning lightning strikes. Serious incidents directly caused by lightning are exceedingly rare, with the last major commercial plane accident attributed to a lightning strike occurring in 1967. These protection systems and post-strike protocols contribute to the safety of air travel, making lightning strikes a manageable event for modern aircraft.