What Actually Happens When Lightning Strikes an Airplane in Flight? (It Happened to Me)

What Actually Happens When Lightning Strikes an Airplane in Flight? (It Happened to Me)

In fact, it's probably happened to you, too: It's common, and it's not as dangerous as you might think.

By Eric Rosen

The weather outside the plane window was stormy. My Qantas flight from Los Angeles to Melbourne had made an unexpected landing in Sydney to refuel since it looked like we would have to circle our final destination. Weather all over the southeast of the Australia was a mess and we’d been caught right in the middle of it.

Not that the descent into Sydney had been too rough. We were on a Boeing 747 jumbo jet with two decks and four engines. What could be safer than that?

As we sat on the ground in Sydney, though, the weather rolled in, blanketing the airport in dense clouds and driving rain. Lightning flashes flicked in the distance.

Nonetheless, our captain came on the PA system to announce we’d be taking off momentarily for the final short leg to Melbourne. We lumbered down the tarmac to the head of the runway. The engines revved for the long takeoff run and the ascent, the plane’s nose lifting ever so slightly as we left the ground.

Everything seemed fine for the first few moments, but then there was a sharp flash of pink light that illuminated the cabin, followed quickly by a dull "pop" like someone had loosed a champagne cork. Then silence.

As passengers, myself included, looked around, bewildered, the plane leveled off. No one was talking, and no announcements were made. Had we been hit by lightning? The storm still seemed to be in full force and we were pushing our way through leaden clouds. I could barely see the engines on my side of the plane from my window, but they seemed to be all right. What now?
Fortunately, we didn’t have long to wait to find out. About five minutes after it happened, the captain was back on the PA system explaining what we had witnessed. The plane had indeed been struck by lightning, which in itself wasn’t worrying, he said. But they had to go through various safety procedures and remain within the vicinity of the airport. Once they had ascertained that their instruments were functioning properly and the engines were unharmed, we were back on our way to Melbourne.

That was the first and only time I’ve ever been in an airplane that has been struck by lightning… that I know of. The truth is, given the amount I travel (literally hundreds of flights per year), it’s probably happened before and almost certainly will again. And chances are it’s happened to many of you, whether you’ve known it or not.

"Planes are hit by lightning more frequently than you might expect," explains aviation expert, founder of the site Ask The Pilot and author of Cockpit Confidential, Patrick White.

By some estimates, each commercial plane flying in the U.S. is hit by lightning at least once a year. If that seems like a lot, consider that Weather.com estimates there are about three billion lightning bolts on the earth each year (Florida is the most active region in the country). Like Doc Brown tells Marty McFly in Back to the Future, your typical lightning strike can generate 1.21 gigawatts, or over one billion volts. A flash of lightning can also heat the surrounding air to about five times the temperature of the surface of the sun. 

Kind of scary, right? But after a lightning strike to Pan Am flight 214 over Maryland in 1963 caused a wing explosion and the plane to crash, killing all 81 people aboard, the government and aviation industry quickly acted to make flying as safe as possible. There hasn’t been a commercial plane crash attributed specifically to lightning in 50 years.

So what exactly happens when a plane is struck by lightning, and how safe are you? White explains: "The energy does not travel through the cabin electrocuting the passengers; it is discharged overboard through the plane’s skin."

Essentially, planes are like giant conductors. Lightning hits them at one extremity, usually the tip of a wing or on the nose (their shapes tend to cause electrical fields to concentrate in those places anyway), and the current travels through the aircraft’s exterior and shoots off another part like the tail. The plane’s metallic shell functions as a Faraday cage, isolating the electrical charge on its surface and preventing it from entering the interior of the aircraft.

While the aluminum used in many plane exteriors is very conductive, and hence conducts the current easily, many newer aircraft like the Boeing Dreamliner are constructed using carbon-fiber composites, which are not conductive. Newer planes have a metal mesh (typically copper or aluminum) embedded into their surfaces specifically to conduct the electrical currents caused by lightning strikes and to isolate the charge from the rest of the plane.

Critical electrical equipment on the airplane is shielded from the exterior to make sure that lightning doesn’t interfere with operations. Planes undergo extensive testing to make sure that they will not be affected by static electricity either, which builds up on planes whether they’re hit by lightning or not. Planes also have static dischargers, or static wicks, installed on their trailing edges specifically designed to dissipate the electricity that accumulates around them.

White says that after a lightning strike, "The first thing would be to check the instrument panels and look for any caution lights, warning lights, or other signs of a system acting abnormally. If lightening has damaged something internally, the cockpit indications would likely be pretty obvious. " 

The other danger is that a spark will ignite the fuel in the plane’s tank. To prevent that, fuel tanks are given extra shielding, and all the fuel lines, access valves, caps and vents connected with the fuel system are built to withstand a direct lightning hit. Speaking of fuel, in recent decades, jet fuel has also been engineered to be much less explosive and flammable than in the past.

"Once in a while there’s exterior damage," says White. "A superficial entry or exit wound, or minor injury to the plane’s electrical systems. But a strike typically leaves little or no evidence."

If it does cause damage, it is usually limited to a tiny hole or burn mark on the fuselage. After a confirmed strike, ground crew will inspect the jet and make any repairs that might be necessary.

So although it might be scary to the folks inside the plane, lightning is no longer a major danger to flights. That said, pilots still tend to avoid thunderstorms when possible to avoid other hazards like wind shear, turbulence, and hail. The added benefit is that, by doing so, they’ll hopefully avoid lightning as well.

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