Air France will immediately replace on all of its long-haul Airbus aircraft the external speed sensors that possibly could be involved in the deadly crash of one of its planes, a pilots' union said on Tuesday.

"Air France has provided us with an extremely proactive and very accelerated replacement program," said Erick Derivry, a spokesman for the SNPL union, the main union for Air France pilots.

Investigators are considering crash theories that include the possibility that the monitors, called Pitot tubes, iced over and gave dangerously false readings to cockpit computers during a violent thunderstorm.

The L-shaped metal tubes jut from the wing or fuselage of a plane and are heated to prevent icing. The pressure of air entering the tubes lets sensors measure the speed and angle of flight.

Air France Flight 447 plunged into the Atlantic early on June 1 about four hours after taking off from Rio de Janeiro to Paris, killing all 228 people on board. Twenty-four bodies have been recovered so far, Brazilian authorities said Monday.

Paul-Louis Arslanian, director of France's air safety investigation agency, said some problems with "inconsistent messages" have been detected with the Pitot tubes on the Airbus A330.

There have been a number of incidents involving malfunctioning Pitot tubes on A330s and A340s, according to interior Air France records.

French investigators say it is too early to pinpoint any causes for the crash because of too few clues.

Air France said it began replacing the Pitot tubes on the Airbus A330 model on April 27 after an improved version became available, and would finish the work in the coming weeks. The monitors had not yet been replaced on the plane that crashed last week.

(Xinhua News Agency June 10, 2009)