Terrorism or design failure?

French crash investigators have revealed that the Air France flight which killed 228 people en route between Brazil and Paris on July 10 did not break up mid-air but fell vertically into the Atlantic.

At a press conference in Le Bourget to make public their initial findings, investigators said Flight 447 dropped out of the sky in a remote area outside radar coverage but without the black boxes, the cause may remain a mystery.

Alain Bouillard, from the Bureau d’Enquetes et d’Analyses (BEA accident investigation body said: "The plane was not destroyed while in flight. The plane appears to have hit the surface of the water in flying position with a strong vertical acceleration."

According to the initial report, life vests found with the wreckage around 930 miles from the Brazilian mainland were not inflated, suggesting there was no time to implement emergency measures for a sea ditch.

They stated that a flurry of automatic messages sent out by the aircraft’s computers before it fell provided little detail on position and that now, as the black box signals will start to fade, a full diagnosis may not be possible.

There has been widespread speculation that the automatic messages emitted by the Air France plane indicated it was receiving incorrect speed information from its external monitoring instruments, which could destabilise control systems.

Some experts raised the possibility – and examples of past incidents – in which these external monitors, known as pitot tubes, may have iced over.