French crash investigators said on Saturday that the Air France jet which plunged into the Atlantic had speed monitors that had often failed on other planes and were due to be replaced.
The head of the air accident investigation agency said the missing Rio to Paris flight, which crashed on Monday with the loss of all 228 people on board, had suffered multiple systems failures in its final moments.
Automatic error messages broadcast by the A330 jet just prior to the crash showed that its autopilot had cut out after it received conflicting speed readings, BEA director Paul-Louis Arslanian told reporters.
"There is a programme of replacement, of improvement," he said, adding that planes that have not yet had the replacement are not necessarily dangerous, and that in other cases pilots had been able to regain control.
Yesterday, Airbus urged all pilots of its jets to review a warning issued in July 2001 on the procedures to follow if speed indicators give conflicting readings and force the autopilot to cut out.
Investigators seeking clues to what had caused flight AF 447 to crash so suddenly have so far had to rely on the automatic messages as salvage crews have been unable to locate the wreckage in deep Atlantic waters.