In the waters around Fernando de Noronha, off Brazil’s northern coast, a grim task has begun in earnest.Search teams are attempting to retrieve wreckage from doomed Air France Flight 447 although French officials have warned that the mystery of why the jet crashed into the middle of the Atlantic, with 228 people on board, may never be solved. In Paris, the head of France’s air accident investigation authority said he was not highly optimistic that the Airbus A330’s black boxes would ever be found. Paul-Louis Arslanian expects the enquiry to be long and difficult. ‘We can’t allow ourselves to say just anything. We can’t allow ourselves to speculate,’ he told journalists. ‘It is essential that we check everything and when I say check, I mean: check, check and check again. We have to be sure that what we are saying is reasonably the truth, reasonably a fact.’ The French ship Pourquoi Pas is heading to the disaster zone, with mini-submarines able to go thousands of metres deep in the water.