Thread: AF447
View Single Post
Old 12th Jun 2009, 03:27
  #1222 (permalink)  
Join Date: Mar 2009
Location: on the ragged edge
Posts: 80
Thank you "Safety Concerns" for that important post. I have to question a comment my colleague made which said:

The reason for such caution is, among other reasons, the fact that the ACARS is a maintenance reporting and messaging system, not a flight data analysis tool. The granularity of the data is very high, (stating the obvious).
While a good point, I'm not sure what he means by "granularity." I was under the impression that the most, if not all of the data path is digital, not analog on it's way up to the satellite. This means it is of a highly accurate and known behavior: we know the program, the version number and the data error bit checking subroutines that will not report the message if it is fragmentary (unlike micorsloth products which are not allowed in flight.) Error reporting of LMU items is very reliable stuff AFAIK: FAULT: The component experienced a subroutine shortcomming or a lack of signal that it needs to do it's thing. A fault occurred (not necessarily a complete failure or even a power loss). Some faults cause other faults in units that were depending on data from the upstream unit. This is my understanding of the process.

Mr Faser's attempt to delve into the aerodynamist's world of high speed, high altitude aerodynamic cause and effect sequences is ill-advised imho. These things do not have probable outcomes, even for a supercomputer. This is why most of the designs are scrapped at Edwards and Dryden after flight testing concludes, that for unknown reasons, the airfoil section when introduced on this particular airframe in this way behaves differently.

On the Rudder at altitude: whether or not a Yaw damper function was involved, or the pilot was involved is impossible to say. Airbus posters here suspect that yaw damping was available since in that alternate law mode it is still supposed to provide protection from dutch roll. My earlier comments were in the context of complete loss of yaw damping. I don't feel that's the problem now that Alternate Law has been explained to me.

All we should say for sure is that it appears the forward bolt hole of the VS yielded and the next two attach points did not, as evidenced by the attached lug carry though hardware. I wouldn't expect the VS/Rudder assembly to survive this way, attached and in good shape, if it was still attached to the airplane at sea level. But strong circumstantial SITA (french product for ACARS) data indicates it was attached at 0214z since the HF antenna coupler did not fault. (The SATCOM however, likely had it's own integral GPS for acquiring lock, I'm told, so this is no longer plausible evidence for an IRU platform available: hence ATT info.)

Seeing the same components faulted on other a330 mishaps is strong evidence. AB emphisizing unrelable airspeed preparedness is very suggestive that they feel this is the problem. Reportedly, the CEO said he doesn't think it's the pitot tubes. I don't either. Even though I think they all iced up, I suspect it's really the A330's interpretation of a complete loss of all air data that caused this accident. I had a number of accidental thrust latches on the FMA on the A310, where the AFS took the wrong action and required us to disconnect it.

Unfortunately, it appears I have sired a number of Captain experts with a total of one post. While they could have been banned for taking unpopular positions in the past, their posts suggest they have no experience flying in weather at altitude. I would suggest that from now on, that anybody with the title of Captain in his screen name is automatically suspect.

Yes including me. Feel free to challenge me on anything.



All the above, is only my opinion only, and I could be wrong.
Captain-Crunch is offline