Air France has disclosed that it initiated a programme to change pitot probes on its Airbus A330/340 fleet five weeks before the loss of flight AF447, after concluding that a new version could offer improved performance in high-altitude icing conditions.
It also states that it has "accelerated" this replacement, although the carrier emphasises that this does not imply any direct connection to the loss of its A330 over the South Atlantic on 1 June.
Air France says that, from May last year, it recorded a number of incidents of information loss during cruise on A330 and A340 aircraft. Analysis indicated that this was linked with pitot probe icing.
The carrier had already opted to switch probes on its Airbus A320 fleet, but not its long-haul aircraft, in the wake of a manufacturer recommendation in September 2007.
Air France points out that it was not obliged to follow the recommendation, and states that it had experienced pitot water ingestion only on the A320s at low altitudes.
"It was not implemented on the A330/340s as no such incidents had been noted," says the airline.
© Air France/Ph Delafosse
But after last year's emergence of A330/340 incidents, the carrier says it held a series of technical discussions to seek a way of "reducing or eliminating" the problem - adding that the updated probe adopted for its A320s was "not designed" to prevent occurrences at higher cruise altitudes.
Laboratory tests in the first quarter of this year indicated that a new pitot probe "could give a significant improvement" to the problems associated with icing, and Air France ordered a switch to the new component on 27 April. The carrier says it implemented the change ahead of in-flight trials by Airbus.
Presence of ice crystals or water exceeding pitot probe specifications has previously been linked by the French civil aviation administration to airspeed fluctuations on A330s during flights through extreme meteorological conditions.
Evidence of inconsistencies in airspeed has already been identified in data transmissions from AF447 but investigators have yet to confirm its significance.
Air France states that, throughout, it has been reiterating instructions to crews on procedures to deal with loss of airspeed information.