By Nashwa Abdel-Tawab INVESTIGATORS into Air France's A330 crash are considering the possibility that the speed sensors on Flight 447 may have iced up. Air France said it had begun the switchover of speed sensors, known as pitot tubes, five weeks before the crash, but only after disagreeing with Airbus over the manufacturer's proposal to carry out tests before replacing them. So far, six bodies have been recovered from the plane, which crashed on its way from Rio de Janeiro to Paris killing all 228 people on board. France has also sent a nuclear- powered submarine to search for the black box flight data recorders that will be crucial to understanding why the modern plane fell from the sky as it passed through storms. Investigators believe the pilots may have set the aircraft at a dangerous speed because they were relying on faulty speed readings. "Signals sent by the plane before disappearing showed its autopilot was not on," said Paul-Louis Arslanian, the head of the French agency leading the investigation into the crash. Arslanian said it was not clear if the autopilot had been switched off by the pilots or had stopped working because it received conflicting airspeed readings. The agency said the A330 had sent out 24 error messages in four minutes including one indicating a discrepancy in speed data. It said similar problems had happened before. He added that investigators were searching a zone of several hundred square miles for the debris. "It is vital to locate a beacon called a "pinger" that should be attached to the cockpit voice and data recorders, now presumed to be deep in the Atlantic," he said. Air France said it had first noticed in May 2008 that ice in the sensors was causing lost data in planes like the A330, but that it failed to agree with Airbus on steps to take. According to the airline, Airbus offered to carry out an in-flight test on new sensors this year but the airline decided to go ahead and started changing them anyway from April 27. The plane manufacturer Airbus says the investigation found the flight received inconsistent readings from different instruments as it struggled in a massive thunderstorm.
