Hi Graybeard,
It seems that I missed your post here:
Originally Posted by Graybeard
Originally Posted by Graybeard
Airspeed and altitude are separate and unique functions within the ADR, except at low speeds, and their output data bus words are separate and unique. An ADR may flag or put out erroneous airspeed without affecting altitude output.
Takata replied:
Each ADIRU module is separated in two: ADR+IR. If you are turning OFF the faulty ADR part because of unreliable airspeed, you will also reject all the associated static and AoA probes. Hence, if all three are rejected, you are only left with your standby instruments.
Do you really know the fault logic of the ADIRU, Takata? You're saying that faulty airspeed is turns off all air data and AOA outputs from the ADR?
You should read again what I wrote and your question will be answered: when an ADR is declared faulty, an amber fault signal will pop up on the panel. Now, can you tell me how the hell one can only turn off the captain's pitot probes without turning off all the other chanels of ADR 1 (TAT, AoA, Static pressure, barometric altitude)?
There is only two separate parts: ADR & IR, as I said, and one may only turn off the complete Air data output from a faulty ADR.
Originally Posted by Graybeard
I think you have confused ACARS report with reality. The ACARS report is to aid the tech at destination in troubleshooting to the level of the offending LRU, Line Replaceable Unit.
I think that you may be the one confused here: what is then the purpose of sending cockpit effect messages without associated fault? Do you really think that "AUTO FLT AP OFF" or "AUTO FLT A/THR OFF" are only send because the tech will have to replace both autopilot and autothrust once landed?
Originally Posted by Graybeard
Arinc 700 design was finalized in the late 1970s... bla bla bla.
Irrelevant as it is about A330 systems here: how its Air data are managed and integrated in flight and not about the general principles of ADIRs unit integrated in other flight systems.
Originally Posted by Graybeard
BEA stated that the TCAS Fail on 447 was due to its internal monitoring of altitude. That altitude comes from the transponder. BEA doesn't explain why there wasn't also ATC Fail. There should have been, if the altitude it received from the ADR was faulty.
Yes, my knowledge and experience suggests BEA was mistaken on its assessment of the TCAS Fail.
No. Altitude values comes from the ADRs, via the transponder, but may not follow the same logic. In particular, the transponder may work without altitude imputs (which is not displayed in this case) while the TCAS is also feed with Radio Altitude and may need a valid and precise barometric altitude to continue to work without faulting. It is all about the internal functions of each particular system and its test boundaries. Moreover, the BEA is not supposed to explain all the details of every possible "no failure case sent" as it could lead to a never ending process. If Airbus told them that it was likely due to a TCAS altitude function failure (considering what elements they have on hand), then it is very likely the reason.