A new, three-month hunt for the black boxes of a crashed Air France jetliner will begin in February, the head of France's accident investigation agency told relatives of crash victims on Saturday.
Jean-Paul Troadec, director of France's Bureau of Investigations and Analysis, said that locating the cockpit audio and data recorders is key to finding the causes of the June 1 crash that killed all 228 on board.
The briefing by Troadec relieved some tension among Brazilian family members who have said they are not receiving enough information about the investigation. But there were still complaints about how it is being carried out.
"They continue with their palliative talk," said Nelson Marinho, who lost a son on the flight and is president of an association of Brazilian victims' family members. "They say they're going to start the search again. Why did they stop in the first place if it is so important?"
The second and most recent search for the black boxes ended in August.
Maarten Van Sluys, also with the Brazilian family members' association, said a renewed effort to find the recorders is welcome, "but we cannot forget there are still 178 bodies _ among them Nelson's son _ that are at the bottom of the sea."
"We have expectations of recovering these remains and giving them a dignified burial," he said.
Troadec said the new search will include help from the U.S. Navy and the National Transportation Safety Board, along with accident experts from Britain, Germany, Russia and Brazil. Private companies also will help in the search, which will use submarines along with boats equipped with sonar gear.
Experts say the search for the black boxes of the Airbus A330 is one of the most challenging ever seen, as ocean depths where the plane went down reach nearly 23,000 feet (7,000 meters) and the sea floor is mountainous.
"To increase our chances, we have to limit in the most exact way possible the probable site of the accident," Troadec said. He said analysis of ocean currents may give investigators a better idea of where the main debris field is located.
Hundreds of pieces of debris were plucked from the Atlantic Ocean during the first two search operations, including a nearly intact tail, an engine cover, uninflated life jackets, seats and kitchen items. But they have not given investigators a clear cause for the accident.
Troadec said most of the automatic messages sent by the plane's computers just before it crashed are related to the plane receiving false speed readings from sensors known as Pitot tubes. Experts have said running into a violent storm at either too slow or too fast a speed would be dangerous.
Both the European Aviation Safety Agency and the U.S. Federal Aviation Administration ordered airlines flying Airbus jets like the Air France plane that crashed to replace their French-made Thales Pitot tubes. There have been a series of incidents related to the Thales sensors.
Despite that, Troadec said that the crash was likely caused by a series of failures and not just the Pitot tube.