Lightning bolts a risk for modern jets
Passenger jets are hit by lightning every 1,000 hours — on average twice a year — and experts say the risk from the bolts of electricity is growing.
But technical experts, astounded like everyone else by the disappearance of an Air France jet in the Atlantic.
Air France has said the A300-200 jet was probably hit by lightning as it passed through a violent storm on the flight from Rio de Janeiro to Paris.
But the airline’s chief executive Pierre-Henry Gourgeon said it suffered multiple technical failures before falling off radar screens.
“A succession of a dozen technical messages” sent by the jet showed that “several electrical systems had broken down” which caused a “totally unprecedented situation in the plane,” said Gourgeon.
“It is probable that it was shortly after these messages that the impact in the Atlantic came,” he added.
Nearly every commercial pilot has a tale of coming through a lightning storm. The French national office for aerospace study and research (ONERA) says that on average a plane is hit by lightning every 1,000 hours.
“Lightning could cause a mechanical problem, it could pierce the aircraft, but usually it can continue to fly,” said Vincent Fave, an expert airline accident investigator told AFP.
Yves Deshayes, of the French national airline pilots union (SNPL) said a lightning strike could damage a plane’s communications and navigation systems.
“But in a plane the systems are doubled, even tripled, so a lightning strike that threatens the security of a flight, and even the state of the aircraft, is extremely rare,” he said.
Deshayes suggested that a lightning strike could explain why there was no radio contact with the Air France plane, but nothing more.
“It is hard to imagine lightning hitting a plane and making it explode. It could cause a number of breakdowns, more or less serious, but to my knowledge there are no incidents of planes which were blown up by a lightning strike,” he said.
David Learmount of Flight International magazine said aircraft are designed to survive lightning strikes. But the disappearance of the Air France jet was a “chilling reminder that nothing is impossible, however unthinkable.”.
An expert on aircraft accidents, Francois Grangier, told AFP in a 2005 interview of his experience.
“In my career as a pilot I often experienced lightning as did all of my colleagues. It’s something which is often impressive, it makes a lot of noise in the aircraft and usually electrical power fails, but it’s just as if it happens at home: the fuses jump, you put them back and everything works.” Usually, the electrical impact spreads across the surface of the aircraft
“along the external skin, in aluminium alloy which is a very good conductor of electricity, and the fuselage and wings act as a Faraday cage.” Under the Faraday phenomenon any external metallic frame prevents lightning from traversing the structure.
However,
aluminium is giving way increasingly to composite materials based on carbon fibre and resin. Manufacturers are making increasing use of these materials because they offer weight, and therefore
fuel, savings.
For example, Boeing’s new generation 787 Dreamliner depends on extensive use of such materials.
But composite materials are less effective in deflecting lightning and manufacturers have turned to another way of providing a shield.
They use the ’metalisation’ of the aircraft: a kind of mesh is added, a superficial layer which acts as a
Faraday cage and in this way the aircraft is protected.
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Although the reason why Air France crash mid Atlantic is a milestone, media will not mention it: the end of the Faraday cage, the
drastic reduction of the space of the skies where the probability of a plane going bust could be neglected.
Milestone Air France crash mid Atlantic: end of the Faraday cage, drastic reduction 
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