Every so often, we see images going around the internet of airplanes being struck by lightning. Yes, they look dramatic, and some of those pictures are truly incredible. But don’t be scared: lightning strikes don’t happen to every flight, but they aren’t uncommon, with the standard industry statistics suggesting that on average each plane gets struck once every two years or so.
The good news is that every plane you’re flying has been engineered with some really clever science to be absolutely fine during and after the lightning strike, and to get you safely to your destination.
It’s not as movieworthy as Back To The Future’s 1.21 gigawatts being conducted down to Doc Brown’s DeLorean —but it’s pretty interesting stuff.
Older aircraft, the kind made of metal, are essentially large Faraday cages, which you might remember from a school physics class. Essentially, with metal around the outside, and reinforced by a specially engineered mesh material within the skin of the plane, the lightning passes harmlessly around you and continues on its electrifying way to wherever it’s going.
It’s the same principle as in a car, and if you live in a lightning prone area you’ll be used to being told that being in an automobile is one of the safest places to be during a thunderstorm. Around sensitive parts of the aircraft, like fuel tanks and electrical systems, shielding gives an extra layer of protection.
And protection it needs: the US National Weather Service says that the temperature of a bolt of lightning approaches 30,000°C, which is — I am reliably informed — very hot indeed.
But, you may be asking, aren’t newer jets made of lightweight composite materials that aren’t metallic, so how do they conduct the lightning? Well, you’re right —the Boeing 787, for example, uses carbon fibre reinforced plastic — and so airplane manufacturers use a special foil to get the Faraday cage effect back.
Technically, it’s called Electrically Conductive Expanded Metal Foil, and it’s part of the sandwich of material layers that makes up the outer skin of the aircraft. This sandwich of layers includes the composite, the foil, and layers to protect the metal foil from moisture and thus corrosion.
Just like a metalframed airliner, the lightning passes swiftly through the foilwrapped tube and along the wings and leaves the plane.
If you’re on a plane that gets struck by lightning, you’ll be entirely safe, and you’re unlikely to even be delayed. But if you’re on that plane’s next flight, you might be a little bit late taking off. There are extra safety and security checks mandated by the government agencies that regulate flying, just to make sure that all the electrical systems are working properly— and even that there aren’t any scorch marks, which usually suggest that some closer inspection is required.
Maintenance technicians will examine the entire aircraft, focusing on the sections that lightning is known to usually enter and exit the aircraft if it’s struck, which include the nose, wings, tail, various sensors, antennas, radomes, lights and the landing gear doors. You might hear a bang and get a surprise — but your plane will get you safely on the ground and be back in the air faster than you might think.