Why Airbus, Air France were convicted on appeal in 2009 Rio-Paris crash

Why Airbus, Air France were convicted on appeal in 2009 Rio-Paris crash
The two aviation giants were convicted of manslaughter in the accident of flight AF447, which killed 228 people on June 1, 2009. Both companies had previously been found not guilty at the first trial. They are now filing an appeal with France's highest court.