What happens when lightning hits an aeroplane?

It’s the moment you’ve never been waiting for. Tucked up under your airline blanket, nose in book, when, suddenly, a flash of bright light streaks through the aeroplane. You – well, the plane with you in it – has been struck by lightning. But do you need to panic, brace, or reach for a lifejacket?

So what actually happens when lightning hits an aeroplane, and why was it not seriously damaged?

Typically, a bolt will hit an extremity, such as a wing tip, or the nose, and the current will travel through the aeroplane’s metal shell before leaving from another point – the tail, for example. And, according to Patrick Smith, pilot and author of Cockpit Confidential, a book on “everything you need to know about air travel”, planes are hit by lightning far more frequently than you might think.

“An individual jet liner is struck about once every two years, on average”, and aeroplanes are designed accordingly. “Once in a while there’s exterior damage – a superficial entry or exit wound – or minor injury to the plane’s electrical systems, but a strike typically leaves little or no evidence.” You might not even notice it, he says.

Professor Mamu Haddad, professor and director at Cardiff University's Morgan-Botti Lightning Laboratory, which works on understanding lightning strikes on aeroplane construction materials, explains further.

Modern aircraft, he says, are made from lightweight carbon composite covered with a thin layer of copper – Dreamliners and Boeing Airbus A350s have this construction – and act as very good Faraday Cages, meaning that the space inside the metal (ie where you’re sitting) – is protected from electric currents.

Most important, he adds, is that the fuel tanks in the wings are not exposed to any lightning sparks – hence why the surrounding metal, structural joints, access doors, vents and fuel filler caps must be able to withstand any burning from a bolt of lightning, which can have temperatures of up to 30,000C.

“Lightning can be up to 200,000 amps – at a low current people might hear noise, or see a flash of light through the window, but they won’t feel anything," he said. "One effect on the aircraft body might be some local melting, where the lightning struck, but the aerospace industry is highly conservative, and testing so rigorous, that passengers aren’t at risk.”

Rare though they may be, there have been a few fatal incidents involving lightning strikes, however. In January, four charred bodies were reportedly pulled from plane wreckage in Indonesia after a light aircraft owned by Intan Angkasa Air was caught in a storm, hit by lightning and crashed. Bambang Ervan, an Indonesian transport ministry spokesman, confirmed to an Australian news site that all four people on board the aircraft were killed instantly.

http://www.telegraph.co.uk/travel/travel-truths/What-happens-when-lightning-hits-an-aeroplane/