What Happens When Lightning Strikes a Plane?

How Often Does It Happen?

Lightning strikes to commercial aircraft are surprisingly common. The average commercial airliner is struck by lightning approximately once or twice per year, translating to roughly one strike per 3,000 flight hours. Globally, the commercial aviation fleet is struck thousands of times annually. Despite this frequency, the last commercial aviation accident in which lightning was the primary cause occurred in 1967 (Pan Am Flight 214, 1963; one of the last cases involving unprotected fuel tanks).

This remarkable safety record is not accidental — it is the result of deliberate engineering that has made aircraft essentially immune to the effects of direct lightning strikes.

The Faraday Cage Effect

Metal-skinned aircraft act as Faraday cages — conducting enclosures that distribute electrical charge across their outer surface without allowing significant current to flow through the interior. When lightning strikes an aluminum-skinned aircraft, the 200,000-ampere current pulse travels across the external skin from the strike attachment point (typically a wing tip, nose radome, or vertical stabilizer tip) to the exit point, bypassing the interior and its occupants entirely.

The aircraft skin must be sufficiently conductive that this distribution occurs without creating dangerous voltage gradients across any accessible surface. Bonding straps and conducting mesh ensure electrical continuity across all panels, doors, and access points. Every component of the aircraft's external structure is bonded to the same electrical potential, preventing spark discharge in fuel areas.

Composite Aircraft Challenges

Modern aircraft like the Boeing 787 and Airbus A350 use carbon-fiber-reinforced polymer (CFRP) for the majority of their airframe. Carbon fiber is conductive, but the fibers are embedded in epoxy resin that can limit current-carrying capacity. If unprotected, lightning current could arc through the structure, creating heat and potentially igniting fuel vapors.

Both Boeing and Airbus address this through several means:

• Expanded copper foil mesh: A thin copper mesh layer is embedded in the outer composite plies, providing a conductive surface layer comparable to aluminum skin in current-carrying capacity.
• Aluminum layer on critical areas: Especially around fuel tank boundaries and near structural joints where arcing would be most dangerous.
• Zone-based protection: Areas of highest lightning attachment probability (tips and extremities) receive enhanced protection; lower-probability zones receive lighter treatment.

The result is that CFRP aircraft have demonstrated essentially the same lightning resistance as aluminum aircraft in service.

Fuel Tank Protection

Fuel tanks represent the greatest fire/explosion risk in a lightning event. Regulatory requirements (FAA AC 20-53) mandate that no ignition sources can be present within the fuel tank under any lightning scenario. This requires:

• All wiring in or near fuel tanks to be shielded with lightning-rated shielding
• Fuel tank fasteners to be sealed with lightning-resistant coatings to prevent sparking at panel joints
• Fuel vent caps and probes to be designed to prevent ignition of fuel vapors outside the tank
• Fuel quantity probes to operate at voltages too low to ignite vapors even if their insulation fails

The 1996 TWA Flight 800 accident (fuel/air vapor ignition in center wing tank from non-lightning electrical source) led to comprehensive fuel tank flammability reduction requirements that also benefit lightning protection.

Passenger Experience During a Lightning Strike

Passengers who experience a lightning strike may notice a loud bang, a bright flash through windows, and a brief smell of ozone. The aircraft may yaw slightly. Rarely, passengers seated near windows report a mild tingling sensation. Cabin lights may flicker briefly. What they will not experience — thanks to the Faraday cage effect — is any electrical shock through their seats, armrests, or seat-back screens.

After a lightning strike, crews inspect the aircraft per standard procedures. Minor scorching or burn marks at attachment and exit points are common and require inspection. Avionics are tested for any anomalies. In the overwhelming majority of cases, the aircraft continues its flight or completes its rotation with no maintenance action required beyond documentation of the event.