Flightglobal:

French investigators have this morning confirmed that automatic messages transmitted by the Air France Airbus A330-200 lost four days ago show that the aircraft was experiencing conflicting airspeed information from its on-board sensors....

Author: Kieran Daly

Date: 05 June 2009

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It is time to ground these planes until a complete, reliable explanation of what is happening with their electronics is available, and corrections made.

I think you are jumping to wild conclusion here and mixing up cause and effect - the fact that the ACARS was sending system failure / error messages suggests that something was causing this , rather than these being the reason the aircraft was lost. Until the flight recorders are recovered  and if we a very lucky some parts of the aircraft this investigation has little way to move forward . This loss maybe nothing to do with the aircrafts avionics systems , it could be structural , a bomb , a cargo door opened , cargo came loose in the turbulence and caused serious damage , Icing or even crew error .  We don't know and grounding all A330s and A340s won't give us the answer -get real.

I disagree with comments by Seat 1A. Yes the electrical failures, ADIRU and ISIS failures etc are clearly a cascade effect and secondary to the cause but clues to the cause are found in the Chronological sequence of faults reported by ACARS and require a little imagination to join the dots. 

For the same reason I also disagree with BEA criticism of public speculation. Participation of public and pilots alike in various online forums debating the facts as they came to light has worked like a supercomputer performing an Ockham's Razor analysis in record time. 

The prospect of a bomb and lightning were evaluated and discarded quite quickly. This intense speculation has actually helped to narrow focus on super cooled water ingestion by the pitot tubes and subsequent blockage by ice formation blinding aircraft sensors.Indeed at 0210Z one of the very first failures reported was loss of pitot ports, followed by rudder limit failure, indicating potentially that the autopilot and subsequently the crew were already unable to fly at correct attitudes.

Autopilot did not disengage until 0211 according to ACARS and ADRIU/ISIS failure followed loss of static ports. 

Questions will now have to centre on weather crew selected pitot heat prior to entry into the CB cloud ?

Some questions will naturally devolve on the very wisdom of flying into such a system when an Iberia flight took significant avoiding action, whilst AF447 did not ? 

My belief is that very quickly after losing static ports the aircraft first assumed an attitude which over stressed the wings and cabin perhaps contributing to some of the noted failures and shortly after the aircraft began to tumble and broke up. That seems a logical sequence. 

 

 

Seat1A:

...This loss maybe nothing to do with the aircrafts avionics systems , it could be structural , a bomb , a cargo door opened , cargo came loose in the turbulence and caused serious damage , Icing or even crew error .  We don't know and grounding all A330s and A340s won't give us the answer -get real.

 

I don't agree with the theory of a bomb, a structural failure etc. An avionics failure obviously has played a role in this crash. One of the clues we have is one out of a total of 24 automatic failure messages sent by ACARS to some ground station, indicating a data inconsistency between airspeeds of the 3 ADIRUs. On the other hand, meteorologists describe the crash area as significantly convective, which could also has caused ACARS itself to malfunction. Even though ACARS messages are non-investigative, the human factor should also be taken into account. The aircraft was flying in cruise, meaning that it’s very likely that the Autopilot was engaged. A data inconsistency between the ADIRUS leads to AP disengagement. In this case the pilots have short time to analyse the situation and respond correctly (remember Birgenair crash in 1996) . This, combined with the assumed de-pressurisation of the cabin could have led to the catastrophe. Once is sure, a single fault could never have led to the crash

 ?? what are the potential effects of lightning & or static electricity on a carbon fibre composite airbus ??

"Some questions will naturally devolve on the wisdom of flying into such a system when an Iberia flight took significant avoiding action, whilst AF447 did not ?" You're dead right, Simon. Then, who was flying when they entered this highly convective area? This is a long-haul night flight and rest period is usually allocated among the three flt deck crew. True, they had the radar to guide them, but this was a squall line and the CB"s were in formation closed to one another. A small hole in between the CB's was no guarantee that they would pass through it as if the squall line was static. Eventually, they got caught amidst severe turbulence and icing which unhinged and shut down their automated systems. How do you hand fly this aircraft out of this vortex and live to tell all about it?

It is interesting to read in Simon_G's comments about the reported rudder limit failure, especially after the pictures of the amost completely intact vertical fin was found floating in the Atlantic. I wonder if the FDR of the A300 that lost its fin before crashing in New York indicated a rudder limit failure? That was turbulance too.

Captn Tommy