Air France says it has been acting expeditiously and with forethought on the issue of upgrading pitot tubes on its A330 and A340 widebodies.
Speed sensors are getting close attention in the crash investigation of AF 447, because automatic alerts sent out by the A330-200 in the last minutes of the flight indicate there was disagreement between the three speed sensor channels, triggering a fault warning.
However, AF 447 had not been upgraded at the time it went down.
In a statement defending its actions, Air France says only since May of last year has it seen increased loss of air speed data associated with icing in the pitot probes on A330s and A340s.
The airline says it upgraded pitot probes on A320 narrowbodies following Airbus’s advice in September 2007 to do so; it didn't do so on the Airbus widebodies because at the time water ingestion did not appear to be a problem and no recommendation had been made to do so.
Air France insists it asked for a fix once it started seeing anomalies on its A330s and A340s, but that Airbus at first said the A320 issue was different; only this year did Airbus let it be known that the A320 improvement could also benefit from the A330 and A340, the airline asserts.
Air France adds that it took the decision to start upgrading the pitot tubes on its Airbus widebodies and did not wait for the aircraft maker to issue a recommendation for such an action.
Here is the full Air France statement on the issue.
Following the many questions which have appeared in the media on the issue of the Pitot probes in its fleet (the Pitot probe is an instrument which measures the air speed of the aircraft), Air France wishes to make the following clarifications:
1) Malfunctions in the Pitot probes on the A 320 led the manufacturer to issue a recommendation in September 2007 to change the probes. This recommendation also applies to long-haul aircraft using the same probes and on which a very few incidents of a similar nature had occurred.
It should be noted that a recommendation from the manufacturer gives the operator total freedom to apply the corresponding guidelines fully, partially or not at all. Should flight safety be concerned, the manufacturer, together with the authorities, issues a mandatory service bulletin followed by an airworthiness directive (AD).
The recommendation to change the probes was implemented by Air France on its A320 fleet where this type of incident involving water ingress had been observed. It was not implemented on the A340/330s as no such incidents had been noted.
2) Starting in May 2008 Air France experienced incidents involving a loss of airspeed data in flight, in cruise phase on A340s and A330s. These incidents were analysed with Airbus as resulting from pitot probe icing for a few minutes, after which the phenomenon disappeared. Discussions subsequently took place with the manufacturer. Air France asked for a solution which would reduce or eliminate the occurrence of these incidents. In response to these requests, the manufacturer indicated that the probe model recommended for the A320 was not designed to prevent such incidents which took place at cruise levels, and reiterated the operational procedures well-known to the crews.
In the first quarter of 2009 laboratory tests suggested, however, that the new probe could represent a valuable improvement to reduce the incidence of high altitude airspeed discrepancy resulting from pitot probe icing, and an in service evaluation in real flight conditions was proposed by Airbus. Without waiting for the in service evaluation, Air France decided to replace all its probes and the programme was launched on 27 April 2009.
Without making any assumptions as to a possible link with the causes of the accident, Air France speeded up this programme and reminded its pilots of the current instructions issued by the manufacturer to cope with the loss of airspeed data.