WORLD> America
Brazil: Crash probe looks at sensors
(Agencies)
Updated: 2009-06-05 09:48

Meteorologists said the Air France jet entered an unusual storm with 100 mph updrafts that acted as a vacuum, sucking water up from the ocean. The incredibly moist air rushed up to the plane's high altitude, where it quickly froze in minus-40 degree temperatures. The updrafts also would have created dangerous turbulence.

The jetliner's computer systems ultimately failed, and the plane broke apart as it crashed into the Atlantic on a flight from Rio de Janeiro to Paris Sunday night.

Independent aviation experts said it is plausible that a problem with the external probe - called a "pitot tube" - or sensors that analyze data collected by the tube could have contributed to the disaster.

Related readings:
Brazil: Crash probe looks at sensors Brazil recovers 1st Air France jet debris
Brazil: Crash probe looks at sensors Air France: No hope of survivors in Atlantic
Brazil: Crash probe looks at sensors China mourns victims onboard crashed Air France jet
Brazil: Crash probe looks at sensors Air France jet likely broke apart above ocean
Brazil: Crash probe looks at sensors New Air France debris found, explosion unlikely
The tubes have heating systems to prevent icing. But if those systems somehow malfunctioned, the tubes could quickly freeze at high altitude in storm conditions, said the other industry official, who also was not authorized to discuss the investigation.

Other experts outside the investigation said it is more likely that the sensors reading information from the tubes failed.

"When you have multiple system failures, sensors are one of the first things you want to look at," said John Cox, a Washington-based aviation safety consultant and former crash investigator for the Air Line Pilots Association.

Jetliners need to be flying at just the right speed when encountering violent weather, experts say - too fast and they run the risk of breaking apart. Too slow, and they could lose control.

"It's critical when dealing with these conditions of turbulence to maintain an appropriate speed to maintain control of the aircraft, while at the same time not over-stressing the aircraft," said Bill Voss, president and CEO of the Flight Safety Foundation in Alexandria, Va.

France's accident investigation agency has established that the series of automatic messages gave conflicting signals about the plane's speed, and that the flight path went through dangerously stormy weather. The agency warned against any "hasty interpretation or speculation" after the French newspaper Le Monde reported, without naming sources, that the Air France plane was flying at the wrong speed.

Two buoys - standard emergency equipment on planes - were spotted Thursday in the Atlantic Ocean about 340 miles (550 kilometers) northeast of Brazil's northern Fernando de Noronha islands by a helicopter crew, which was working off a Brazilian navy ship.