Few clues from downed Air France jet's 24 messages

Other News Materials 13 June 2009 22:27 (UTC +04:00)

With black boxes yet to be found from the Air France jet that crashed into the Atlantic Ocean, investigators are struggling to draw conclusions from physical evidence and a burst of 24 automatic messages sent from the plane in the minutes before it disappeared, AP reported.

A full transcript of the messages provides some new insight, but no answers.

An aviation industry official with knowledge of the Air France investigation told The Associated Press that the transcript - found on http://www.eurocockpit.com and first reported by The New York Times on Saturday - was authentic but inconclusive.

"There is a lot of information, but not many clues," the official said, speaking on condition of anonymity as he was not authorized to discuss the matter.

The official said jets like the Airbus A330 that crashed automatically send such maintenance messages about once a minute during a plane's flight. They are used by the ground crew to make repairs once a plane lands.

The first error message on the transcript indicates a problem in one of the plane's bathrooms at 2245 GMT (7:45 p.m. local time; 6:45 p.m. EDT) May 31 - an error that wouldn't raise much alarm. But a burst of 14 messages all sent at 0210 GMT June 1 (11:20 p.m. local time May 31; 10:20 p.m. EDT May 31), is where the trouble began, the industry official said.

Investigators have focused on the possibility that external speed monitors - called Pitot tubes - iced over and gave false readings to the plane's computers.

"The messages that came in (at 0210 GMT) include the problem with conflicting speed readings," the aviation industry official said. "Everything that happens from there results from the failure of the Pitot tubes."

Air France ordered the tubes replaced on the long-range Airbus planes on April 27 after pilots noted a loss of airspeed data in a few flights on Airbus A330 and A340 models.

Another message indicated a fault with the "rudder limiter," a mechanism that limits how far the plane's rudder can move. It is one of the few messages directly tied to physical evidence investigators have. The nearly intact vertical stabilizer - which includes the rudder - was fished out of the water earlier this week by Brazilian searchers.

If the rudder on the Airbus A330 were to move too far while traveling fast, it could shear off and take the vertical stabilizer with it - which some experts theorize may have happened based on the relatively limited damage to the stabilizer.

The industry official, however, said the error message pertaining to the limiter didn't indicate it malfunctioned, but rather that it had locked itself in place because of the conflicting speed readings.

"When that fault kicks in, the limiter locks into place based on the last known 'good' speed," he said. "It doesn't mean there was something wrong with the rudder."

Airbus has said one of the automatic messages showed a change of cabin pressure equal to an altitude change of more than 1,800 feet (548 meters) per minute, but that the company did not yet have enough information to interpret this yet.

The search for bodies and debris from Air France Flight 447 took on renewed urgency, meanwhile, as experts questioned how much longer efforts would prove fruitful, even as six more bodies were pulled from the Atlantic.

Almost two weeks after the crash, Brazil's military said that June 25 has been set as a tentative date for halting efforts and that starting Monday officials will meet every two days to evaluate when to stop the search, depending on whether they are still recovering bodies or debris.

Finding the plane's flight data and cockpit voice recorders - whose locator signals begin to fade after 30 days - is key to determining how and why the Airbus A330 went down en route to Paris from Rio de Janeiro, possibly after breaking up in the air. Debris and bodies from the jet also contain crucial clues, and warm water temperature affects the length of time a body floats and remains visible to searchers.

According to the Brazilian military, the water temperature in the areas they are looking is averaging about 82 F (28 C) - warm water that speeds up the process of a body surfacing, floating and then sinking once again, said William Waldock, who teaches air crash investigation at Embry-Riddle Aeronautical University in Prescott, Arizona.

"At this point, it's not really surprising you are hearing them (the Brazilian military) talking about an end to the search," Waldock said.

In water temperatures like those in the search area, he said, an intact body could likely float for two or three weeks - Air France Flight 447 went down May 31 with 228 on board. Those warm waters also mean there is a lot of marine life in the area and "they'll break a body down faster," Waldock said.

Navy Vice Adm. Edison Lawrence said the Brazilians "have information" that a French ship had found six more bodies, which would bring the total to 50. It was not clear when the bodies were recovered; Lawrence said he thought it was either Thursday or Friday. It wasn't immediately possible to verify the information with French officials.

Medical authorities examining 16 bodies already brought onto land in Recife have refused to release information about the state of the corpses.

Meanwhile, military ships and planes continued to struggle in worsening weather looking for more bodies and debris.

The plane's recorders - perhaps the best hope of definitively learning what went wrong - remain elusive. A French nuclear submarine is scouring the search area in the hopes of hearing pings from the black boxes' emergency beacons. The first of two U.S. locator listening devices won't arrive until Sunday.

Weather in the mid-Atlantic was bad and getting worse. Rains reduced visibility for ships, and cloud cover blocked satellite imagery.

So far, there is no evidence of an explosion or terrorist act, but a number of clues that describe systemic failures on the plane.

Experts have said the evidence uncovered so far points to at least a partial midair breakup of the Airbus A330.