Air France 447 - Confusion Over Debris Complicates Search for Plane

PARIS — Brazil’s military forces said that the only piece of the debris they recovered thus far from the Atlantic Ocean on Thursday did not belong to the Air France Flight 447 that disappeared Sunday night on a flight from Rio de Janeiro to Paris, throwing the investigation into confusion and angering the French government.

Although the discovery is a setback — and calls into question early theories on why the plane disappeared — Brazil says that it earlier in the week has spotted other debris it thought was from the plane and will now try to retrieve those pieces to confirm where they came from. Locating wreckage from the plane would help investigators determine where it went down and aid in their search for the black boxes containing data and voice recorders.

And finding these black boxes is an urgent concern for investigators because the signal the boxes emit will begin to fade after 30 days. Without substantial physical clues, the data and voice recorders would likely provide the only explanation for the crash.

Late Friday, France’s military said it was sending a nuclear submarine to try to help detect signals from the black boxes.The Brazilian military had not initially recovered the other debris spotted by search planes, including what they thought was an airplane seat and life jacket, because it was concentrating on finding survivors.

But as aviation experts have tried to construct theories of what happened to the plane, an Airbus A330, on the basis of a slender set of facts, the discovery that the 8-foot-long structural support piece found Thursday was not from the plane destroyed a key piece of evidence for the theory that the plane broke up at high altitude. Some aviation experts had thought that because a large part had been found closer to Rio than other debris, that meant the plane came apart at high altitude, allowing the parts to spread widely.

In a news conference at the investigation’s base in Recife Friday morning, the military said that it still believed the debris spotted Tuesday in a 2-mile stretch belonged to the Air France plane and that it was doubling back to recover the pieces while battling rain and poor visibility in the area.

The new uncertainty over the disaster came after a warning fromAirbus, the manufacturer of the missing jet, the timing of which may indicate one focus of the investigation. Airbus issued the warning on Thursday to all its customers to follow established procedures when pilots suspect airspeed indicators are not functioning properly. The bulletin appeared to be the first hint that malfunctioning instruments indicators might have played an important role in the crash that Air France said had killed all 228 onboard.

In radio interviews on Friday, France’s transportation minister, Dominique Bussereau, urged “extreme prudence” about judging the source of any debris that is recovered until it could be properly analyzed. “The main objective is to get our hands on the black boxes, the flight data recorders,” Mr. Bussereau said.

“French authorities have been saying for several days that we have to be extremely prudent. Our planes and naval ships have seen nothing.”

He said it was “bad news” that the Brazilian teams had been mistaken about the large piece of debris. “We would have preferred that it had come from the plane and that we had some information.”

On Friday, the Paris prosecutor’s office said it had opened its own criminal investigation of the crash, a routine legal procedure whenever a French national dies abroad. Of the 228 passengers, 61 were French citizens.

With the setback in the investigation and no definitive answers concerning the plane’s final whereabouts, friends and relatives of the passengers have been struggling with their grief.

“Yesterday I thought it was over but this morning when I heard the debris were not from the plane, I didn’t know what I should think,” said Élodie Grandvalet, a close family friend of Isabelle Hochabaeff, 41, and her husband Yvan, 44, two of the victims from France.

The confusion started when the Brazilian military said on its Web site Thursday that it had recovered an 8-foot long structural support piece, a pallet, used in the cargo area of airplanes. But by Thursday night, the military had retracted that and said that the pallet — wooden — did not, in fact, belong to Flight 447.

The Airbus statement on airspeed indicators, approved by French investigators, said that the message had been sent “without prejudging the final outcome of the investigation,” but clearly it pointed to the possibility that mismanaging the plane’s speed could have been one step in a cascade of on-board failures, leading to the crash northeast of Brazil on Monday.

The message noted that “there was inconsistency between the different measured airspeeds” in the Airbus 330 that crashed, one of several error messages that were sent by the plane’s automatic systems to an Air France maintenance base.

Airspeed on jets is measured by the combination of a tube that faces forward, called a Pitot tube, and an opening on the side of the plane known as a static port. The plane’s speed is determined by comparing the pressure in the Pitot tube that is created by the oncoming wind with the pressure from the static port.

The model that crashed, an A330, has three pairs of tubes and static ports. But other instruments can also be involved in calculating air speed, and the notice to airlines, called an Accident Information Telex, did not specify the nature of the inconsistency.

The message went to airlines that operate all Airbus models, from narrow-body A318 models to the double-decker jumbo A380.

Failure to manage an inconsistency properly has been cited in several crashes of big jets from various manufacturers. In 1996, a Boeing 757 taking off from the Dominican Republic crashed because the airspeed indicators of the captain and the first officer disagreed, and the crew mismanaged the problem. Mud wasps had nested in one of the Pitot tubes.

A plane that flies too slow can lose lift and crash; too fast and it can break up in the air.

The Airbus notice referred to the Quick Reference Handbook and the Flight Crew Operating Manual, which is a more detailed volume that is also kept in the cockpit. For all the models, however, the advice is the same: keep the plane level and keep the throttle setting in place while troubleshooting. The ability to fix the problem in flight would depend, of course, on its source.

With only limited information available, and without the flight data recorder or cockpit voice recorder, experts around the world could not do much more than speculate. A series of system failures could be set off by an on-board fire, by a failure that allowed ice buildup on a critical instrument, or by a variety of other causes, experts said.

The Airbus notice pointed out that the airplane was crossing an area of multiple thunderstorms at the time of the accident early Monday. Severe thunderstorms can cause crashes, although it is not clear whether the conditions that the flight encountered, on its planned route from Rio de Janeiro to Paris, were unusual.

At AccuWeather.com, a commercial weather service, forecasters calculated that thunderstorms in the region of the crash could have generated updrafts in the range of 100 miles per hour, although Daniel G. Kottlowski, a senior meteorologist, conceded that this was not unusual weather.

He noted that one message sent out automatically by the plane indicated the cabin had depressurized, and he suggested perhaps this had forced the crew to descend into breathable air — and a more intense part of the storm.

Nicola Clark reported from Paris, Matthew L. Wald from Washington and Liz Robbins from New York. Andrew Downie contributed reporting from São Paulo, Brazil and Sergio Peçanha from New York.