Missing Air France flight: Investigation to probe freak weather conditions

Published on Tuesday 2 June 2009 11:03

INVESTIGATORS looking into the causes of the apparent loss of an Air France passenger jet over the Atlantic will want to find out if lightning and turbulence combined to bring the Airbus plane down.

But it may be some time before a cause for the plane's failure is known.

And if the Airbus A330's "black box" flight recorder is not recovered, investigators will find it even harder to pinpoint the reason for the disaster.

Stewart John, a fellow of the Royal Academy of Engineering and past president of the Royal Aeronautical Society said: "It is being reported that the pilot flew through turbulence, but that happens every hour of every day. These aircraft are designed to go through very powerful turbulence without being put at risk. Equally, they receive lightning strikes all the time, and the airframe is carefully designed to dissipate the electrical charge."

He went on: "This (the Airbus A330) is a 'fly-by-wire' aircraft – in other words it is completely dependent on its electronics to operate. But it has a huge amount of built-in-redundancy in terms of separation of wiring, back-up power supply etc.

"Whether the lightning and turbulence together caused a catastrophic fault on this occasion we won't know for some time."

Dr Guy Gratton, senior visiting research fellow in aeronautics at Brunel University in west London, said: "Reports indicate the plane had recently flown through thunderstorm activity. This implies cumulonimbus cloud, which most pilots will seek to avoid if they can.

"Conditions within or close to cumulonimbus include strong vertical air currents, severe turbulence, hail and lightning. While a modern airliner is designed to deal with all of these, none are desirable and aircraft damage is possible."

He added: "The A330 is equipped with multiple communications systems, so a complete loss of communications at the least means a major electrical failure of the aircraft – particularly given that all major electrical supply components are duplicated or triplicated in the aircraft. Such failures are very rare.

"Weather-related phenomena are likely to be a major part of any coming investigation."

Dr Gratton said that the black box accident data recorder (ADR) has a sounding device designed to help accident investigators find it even if has fallen into the sea.

The ADR records a large number of pieces of information including control positions and settings, engine condition, altitude and speed. There will also be a separate cockpit voice recorder, which should also be recoverable, and will include radio communications, any conversations between the captain and co-pilot, and any background noise in the cockpit.

Dr Gratton said that if the black box recorders are not found "a thorough investigation is still possible, but very difficult".

Experts looking for possible parallels have pointed to the crash involving a BOAC (later British Airways) Boeing 707 near Mount Fuji in Japan.

On a flight from Tokyo to Hong Kong, the plane ran into extreme turbulence and crashed near the mountain in March 1966.

All 113 passengers and 11 crew on board were killed and the subsequent inquiry found the probable cause of the disaster was that "the aircraft suddenly encountered abnormally severe turbulence which imposed a gust load considerably in excess of the design limit".

An automatic message from the Air France plane had indicated an electrical problem.

It was an electrical problem that led to a devastating fire which brought down a Swissair flight off Nova Scotia in Canada in 1998, killing all 229 people aboard.

Kieran Daly, editor of internet news service Air Transport Intelligence, said it was "absolutely imperative" that the black box flight recorder was found.

He went on: "If it's not recovered we may never know exactly what happened and the implications of this would be enormous.

"You would have had a state-of-the-art plane flown that has just disappeared over the Atlantic. Those involved in the search and investigation will move heaven and earth to make sure the black box is found."

Mr Daly said the chances of finding it were good and pointed to the fact that black boxes had been successfully located in the cases of the 1998 Swissair crash and in the TWA flight 800 crash in the Atlantic off New York in 1996.

Mr Daly went on: "We really know very little about what happened to the Air France flight. We know the plane flew through stormy weather and there was an electrical problem. But that sort of thing often happens.

"We have no evidence at all that the aircraft was struck by lightning. It really is leaping ahead quite a lot to say that the plane was brought down by lightning.

"That's why it is so important to find the black box and the wreckage. It's almost unheard of not to find wreckage."

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