French aviation investigators said Tuesday they are optimistic about finding the black boxes of Air France Flight 447, which crashed in the Atlantic last June en route from Rio to Paris, when a third phase of research begins in February.
All 228 people aboard the plane were killed.
Jean-Paul Troadec, chief of the French Accident Investigation Agency, said an international team of experts will reduce the search area for the black boxes to 2,500 square kilometers (965 square miles) — a fifth the size of previous efforts to recover them from the depths of the Atlantic Ocean.
That should make it easier to locate the debris from the plane, and the flight recorders.
“The scientists I have spoken to think that we have a good chance of finding the remains,” he said at a news conference outside Paris.
Lead investigator Alain Bouillard said he expects to be able to read the data stored in the black boxes, despite the amount of time they have likely rested on the sea floor.
The plane’s black boxes are believed to be nearly 23,000 feet (7,000 meters) under water. Without them, Troadec said investigators won’t be able to make a definitive report of what happened.
The second and most recent search for the black boxes ended in August. So far, investigators have located around 1,500 pieces of plane debris, Bouillard said.
Automatic messages sent by the plane’s computers just before it crashed show it was receiving false air 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 at high altitudes could be dangerous. Both the European Aviation Safety Agency and the U.S. Federal Aviation Administration ordered airlines flying Airbus jets like the one that crashed to replace their French-made Thales Pitot tubes.
The French Accident Investigation Agency said last week that the sensors are not certified to fly at temperatures below minus 40 degrees Celsius (minus 40 degrees Fahrenheit) and above 40,000 feet (12,000 meters), and recommended new international safety standards.
Investigators have insisted that the crash was likely caused by a series of failures and not just the Pitot tubes.
Troadec said that, while investigators are still working on the elements located so far, “we won’t go much further.”
“If we want to have a definitive conclusion then we think its necessary to find the flight recorders.”
A new, 60-day hunt for the black boxes will begin in February.
The U.S. Navy and the National Transportation Safety Board will help with the search, along with accident experts from Britain, Germany, Russia and Brazil. Private companies also will help in the search, which will use submarines and boats equipped with sonar gear.
Bouillard said that death for the 228 victims probably came about five minutes after Flight 447 ran into trouble.
He said a reading of the automatic messages emitted by the plane suggests that the plane hit the water around 5 minutes after the problem was alerted. The plane fell 35,000 feet (11,000 meters) in that time — 7,000 feet (2,000 meters) a minute — and the speed of impact means that it is unlikely anyone survived, he said.
In its second report, released last week, French accident investigation agency BEA said oxygen masks did not drop, and the plane did not depressurize. All the life vests found were still in their wrappers.