Travel: Simon Calder's column

Can aircraft be struck by lightning? Yes!, thundered our postbag.

In last week's column Time Off's editor, Harriet O'Brien, wrote that she'd been assured planes were safe from lightning strikes because of the absence of an electrical earth. Almost immediately, phone lines crackled and e-mails sparked.

"Of course aircraft can be struck by lightning", writes Norman W Foster of Cambridgeshire, a member of the Royal Aeronautical Society. Hugh de Lacy of Ipswich corrects the widespread misconception that all lightning travels from the sky down to the Earth. "In fact, a lightning strike can occur between any two points in the atmosphere where a sufficiently high potential difference has built up, and many lightning discharges take place from cloud to cloud ("sheet" lightning). It is quite possible for an aircraft near such a potential difference to be struck by lightning; the sharp edges on aircraft structures tend to concentrate an electric field and provide a preferential path for the discharge."

So what are the likely consequences? Could passengers be fried? Mr Foster again: "Except in the case of total loss, harm to occupants is virtually non-existent as they are protected by the same principle which protects car occupants from lightning, where the surrounding metal structure acts as a Faraday cage."

Harriet did not look thrilled when I showed her the line about "total loss". Several pilots, present and past, joined the debate. From Redhill, Geoff Allan reports: "I was captain of an aircraft struck by lightning while descending into Bergen. We lost our navigation aids and compass system and relied on radar to get us in ..." Mr Allan says, however, that lightning strikes are now relatively rare - "not because there is less lightning, but because modern aircraft spend most of their time above clouds".

In the Fifties, writes a former pilot signing himself only "John", the risks were higher: "Twice in one week I was flying at night in a Lincoln, an improved version of the Lancaster bomber. On the first occasion, over the Bay of Biscay, the damage consisted of a hole in the starboard wing leading edge, large enough for the crew chief to get his head in (after we had landed), and the radio aerials were burnt off. Later, over the North Sea, the rear gun turret was struck; the cone-shaped flash eliminators on the machine guns were left drooping like melted candles."

Tom Dewis of Powys says that in a flying career of almost 40 years he had "more strikes than I would like to count. One was a case of ball-lightning, where a ball of apparent fire rolled through the cabin." Mr Dewis helpfully adds how you will know if you are in a plane caught in a thunderstorm and don't happen to see that ball of lightning roll past: "You may hear a hollow-sounding bump, followed by a slight smell of ozone. You've had a lightning strike! That's all."

Not quite all, writes Ronald Savage of Liverpool. "On our round-the-world tour in 1992, upon leaving Tokyo on a United Airlines DC10 we had just entered the clouds when there was a hell of a crack and flash shaking the aircraft somewhat (me with crossed legs). The pilot then confirmed we had been struck, but as there was no damage we could continue our flight to Bangkok."

Back to Harriet's fear of flying course; Mr Foster signs off with a PS: "Frozen chickens are not fired into test engines; dead ones yes, but not frozen. Live birds in the sky may be bloody cold, but they are not stiff and solid." And the semi-anonymous John offers an equally chilling postscript: "My best wishes to Harriet. I was going to mention that some years later I was one of only two survivors in a mid-air collision of two jets in cloud - but I don't want to scare her."