The search for the black boxes of the Air France jet that crashed into the Atlantic Ocean will likely continue for at least another 16 days, even though their audio beacons are likely fading away, an American officer said Friday.
Brazilian and French searchers have recovered large chunks of debris and 51 bodies from Air France Flight 447, which disappeared with 228 people on board late May 31. Brazil on Friday said it was calling off its search for bodies and debris but that the hunt for the black boxes would continue.
"The reason for this is the impossibility of finding survivors or bodies, which has always been the main focus of our search efforts," Brazilian Air Force Col. Henry Munhoz said at news conference.
Experts say the black boxes may be key to deciding what brought the airliner down. And signals from the voice and data recorders begin to fade after about 30 days.
"We'll have a better idea July 1 on how much longer we'll go," said U.S. Air Force Col. Willie Berges, the Brazil-based commander of the American military forces supporting the search.
Berges said searchers were likely to keep going 12 to 15 days past the 30-day mark of the crash.
A French nuclear submarine and two French-contracted ships towing U.S. Navy listening devices are trolling a search area with a radius of 50 miles off Brazil's northeastern coast where it is believed the plane crashed.
The black boxes send out an electronic tapping sound that can be heard up to 1.25 miles away.
Airspeed monitors probed
With the recorders still missing, accident investigators have focused on automated messages sent by the plane minutes before it lost contact.
One indicates the plane was receiving incorrect speed information from external instruments, which could destabilize the plane's control systems. Experts have suggested those external instruments might have iced over.
Air France has now replaced the monitors, called Pitot tubes, on all its Airbus A330 and A340 aircraft.
On Thursday, U.S. safety officials said they were investigating two incidents in which airspeed and altitude indications in the cockpits of A330 planes may have malfunctioned. The aircraft are the same type as the Air France plane that crashed.
In both cases the planes landed safely, and no one was injured, the National Transportation Safety Board said.