AF447 Investigators Prep for A330 Wreck Recovery, Question Previous Searches

 - April 15, 2011, 10:15 AM
Search teams found large pieces of the wreckage of Air France Flight 447 at the bottom of the South Atlantic off the coast of Brazil on April 3. Photo credit: BEA

Investigators from the French BEA (Bureau d’Enquetes et d’Analyses) are preparing to recover the wreckage of Air France Flight 447, the remains of which search crews found on April 3. All 228 aboard the Airbus A330-200 flying from Rio to Paris died when it crashed on June 1, 2009.

The Ile de Sein, a ship supplied by Alcatel-Lucent Submarine Networks (ASN) and equipped with a remotely operated vehicle provided by Phoenix International, will leave Cape Verde to start the recovery phase of the operation on April 21. The BEA will give priority to finding and recovering the flight data and cockpit voice recorders. “Phase 5” might last until mid-June.

The Alucia ship, which launched the small Remus 6000 submarines that spotted the A330’s remains, left the area on April 9. The fourth search campaign started on March 25 and yielded positive results one week later. For once during the search effort, the BEA can consider itself lucky. The aircraft, scattered over a rectangle measuring 650 by 2,000 feet, lies 13,000 feet below the ocean’s surface on a flat part of the seabed in an otherwise mountainous area. Some debris have partially sunk into the sand.

Search crews found large aircraft subassemblies off the Brazilian coast, quickly identifying the engines, wing pieces and a landing gear. They also found human remains. The Remus 6000s carried on and mapped the debris area using 2,000-foot-range side-scan sonars and cameras.

Last week, it emerged that the “black box” pingers should have transmitted when search teams tried acoustic detection within their range, in 2009. “The reasons why the pingers were not detected will be investigated,” the French minister of Transports said.

Moreover, a new analysis attributed a high level of probability of finding the wreckage to various areas around the last known position. Facts confirmed the theory this time.

The search previous attempt, in April 2010, relied on sophisticated drift simulations that suggested looking for the aircraft wreckage relatively far north of the last known position. That approach yielded only disappointment. Soon after, in June 2010, the BEA dropped buoys in the region and followed them by satellite over a few weeks in an effort to confirm the reliability of the predictive drift models. It turned out that vortices in the ocean render forecasts problematic.

So far, BEA investigators have attributed the accident partly to icing of pitot speed probes. However, they insist that any such problem had to combine with other factors to cause an accident. The BEA now has reasonable hope to find and recover the cockpit voice and flight data recorders. Help may also come from the quick-access recorder and some systems’ memories.