An Air France pilots' union accused French and European air safety bodies of failing to prevent the crash of flight AF447 by ignoring warnings about faulty speed probes, in a letter published on Wednesday.

Speculation has swirled on the speed sensors which fed inconsistent readings to the cockpit just before the Airbus A330 plunged into the Atlantic on 1 June, with investigators saying they were a "factor", if not the cause of the crash.

The SPAF union wrote to France's DGAC aviation authority and the European Aviation Safety Agency (EASA), accusing both of ignoring a string of incidents involving defective airspeed, or pitot probes.

"For years the crews of A330/340 aircraft have been reporting cases of loss or variation of airspeed data in severe weather conditions," SPAF head Gerard Arnoux said in the letter.

"Appropriate measures" from either agency would have "helped prevent the sequence of events that led to the loss of control of the aircraft," which crashed en route from Rio to Paris killing 228 people, he charged.

Arnoux said it was the "responsibility" of both agencies to "force the manufacturer Airbus to make the necessary changes" to the defective sensors.

Contacted by AFP, the DGAC agency declined to respond to the charges. The EASA was not immediately reachable for comment.

The SPAF letter mentioned a presentation made to the EASA in September 2007 as proof the agency was aware Airbus pitot probes had suffered "a significant number of operating incidents linked to icing over or heavy rain."

According to an internal report seen by AFP in the wake of the crash, Airbus jets at Air France experienced at least nine incidents in which airspeed sensors, or pitot probes, iced over in the past year.

Air France decided on 12 June to upgrade all pitot probes on its long-haul fleet after protests from pilots, but neither the DGAC nor the EASA have asked Airbus or airlines to replace the sensors.

Conflicting airspeed data can cause the autopilot to shut down and in extreme cases lead the plane to stall or fly dangerously fast, causing a high-altitude break-up.

The French bureau leading the investigation into the AF447 crash, the BEA, said in a report last week that the airliner's defective speed sensors were a "factor but not the cause" of the accident.

The BEA also said that the plane did not break up in mid-air, explaining that it hit the water belly-first while moving at strong "vertical" speed.

AFP

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