[ELI5] Why are planes struck by lightning occasionally, and why is it seemingly not a problem for them?
In: Physics
They’re struck by lightning cuz they fly through thunderstorms sometimes.
And they don’t have issues with it cuz they are designed with metal channels separate from the planes controls and sensitive parts that allow the lightning to just flow through the plane and out the other side.
Because lightning doesn’t “want” to hit the plane, lightning “wants” to hit the ground, it just takes the easiest path to the ground, which is sometime through a plane.
Lightning probes many available paths to the ground, and the first one to make a sturdy connection receives the big jolt of electricity. Since the metal body of an airplane is way easier than air for electricity, it gives paths leading through it a “head start” and so these paths are more likely to make the connection. The result is that planes are decently likely to get hit by lightning.
The very thing that makes them prone to being struck makes them safe. That metal frame that acts like a free space for the electricity? It’s a free space that totally encloses the airplane and its occupants. The first path that makes contact with the ground will *never* go through the inside of the plane, because the metal shell of the plane is always going to be an easier path.
We use this effect in all sorts of places. People can wear chain mail suits and be struck by huge arcs of electricity for stage shows and be unharmed because the chain mail suit provides the same easy path for electricity.
This is due to something called the “Faraday Cage” effect. Imagine the airplane as a metal cage: when electricity hits it, the electricity flows around the outer surface but doesn’t penetrate inside. So, everything inside the plane, including passengers and all the electronics that make the plane work, remains safe and unaffected.
As for why, if they’re at the right place at the right time they’re the first thing that lightning bolt encounters.
If the lightning strikes a composite area it will be severely damaged. The glue holding the layers of material together will start delaminating. Many aircraft have lightning diverter strips embedded in large composite parts of the jet, allowing lightning to follow a conductive path.
Typically, when lightning strikes any part of the jet, it is on the extremities of the jet, far away from the electronics, and if it’s on the metal part, it allows the lightning to pass through. If the metal is thin, the current will burn through the metal so areas around the fuel tanks are typically much thicker. This doesn’t automatically mean lightning strikes on all metal parts of the aircraft are safe. All electronics are grounded to the aircraft structure; an unlucky strike could destroy certain electronic devices.
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