Why You Shouldn't Worry If Lightning Strikes Your Plane
According to the National Weather Service, commercial planes are struck by lightning once or twice per year on average. Since airplanes are hit daily by lightning all over the world, why don't we hear more about it? Simply put, we don't hear about lightning hitting planes because it's just not that big of a deal. In fact, the last time a U.S. commercial airplane crashed directly due to lighting was in 1967.
Although lightning hits planes more than most dare imagine, planes aren't dropping out of the sky, and there's a reason. To pass safety certifications, commercial aircraft undergo a litany of lightning tests to ensure the plane can withstand lightning strikes. Due to a modern engineered design and construction, lightning just doesn't affect airplanes — at least not their ability to fly or the plane's passengers. In fact, if you've ever been in a plane hit by lightning, there's a good chance you never even noticed.
Lightning currents pass around the plane
Lightning strikes typically occur during take-off and landing, as lightning activity increases between 5,000 and 15,000 feet. In the majority of incidents, the plane actually triggers lightning as it flies through highly charged clouds. When the current doesn't originate from the plane, lightning often hits protruding parts, such as the nose and wing tip. Once lightning hits, the voltage travels through the plane. However, the plane's fuselage acts as a Faraday cage, protecting the inside of the plane while the current moves around the exterior.
Engineers construct airplanes specifically to ensure the voltage travels quickly through the exterior of the plane. The "skin" of commercial planes consists mostly of aluminum, which is one of the best conductors of electricity. Although less-conductive composite materials are also used on some modern aircraft, engineers embed a layer of conductive materials, such as copper foil, to direct the electrical currents of lightning.
Safeguards protect sensitive electronics
The skin of the plane also works to protect the sensitive interior components of the plane. Modern jetliners feature miles of wiring and critical computers that control everything from the engines to plane headphones. In addition to safeguarding the exterior of the plane, engineers also ensure that sensitive wiring and electrical instruments are protected from surges and interference.
When lightning hits a plane, it can cause "lightning indirect effects," which can send currents to sensitive equipment of the plane. However, engineers create safeguards to shield and surge protect this equipment. The Federal Aviation Administration (FAA) sets regulations for manufacturers of this circuitry and equipment to protect these components from lightning effects.
As stated, you probably wouldn't even notice if your plane was hit by lightning in most cases. One exception would be a cloud-to-ground lightning event, in which the lightning passes through the plane and hits the ground. Besides possibly a loud bang, which you would commonly associate with lightning hitting the ground, even these types of lightning strikes are over in a flash. Although flying through inclement weather is never fun, lighting hitting your plane just isn't something you need to worry about.