FILE - In this Monday, June 8, 2009 file photo released by Brazil's Air Force, Brazil's Navy sailors recover debris from the missing Air France Flight 447 in the Atlantic Ocean. Geoff Dell, discipline leader of accident investigation at Central Queensland University, said if the black boxes of a missing Malaysia Airlines Flight MH370 were several kilometers (miles) deep, ships might need to be almost directly over them before the signal could detect them. If found in deep water, Dell expected that unmanned submarines would be needed to retrieve them. That’s how the black box from Air France Flight 447 was retrieved in May 2011, almost two years after the Airbus A330 crashed with the loss of 228 lives. (AP Photo/Brazil's Air Force, file) NO SALES