Takata’s citation (post
2686) from the FCTM (Flight Crew Training Manual) would seem to be endorsing the theory put forward by UNCTUOUS at posts
2219 and
2412
Most failure modes of the airspeed/altitude system are detected by the ADIRS
and lead to the loss of the corresponding cockpit indication(s) and the triggering
of associated ECAM procedures. The fault sensing logic relies on a voting
principle whereby if one source diverges from the average value, it is
automatically rejected and the system continues to operate normally with the
remaining two sources. This principle applies to flight controls and flight
guidance systems.
However, there may be some cases where the airspeed or altitude output is
erroneous without being recognised as such by the ADIRS. In these cases, the
cockpit indications appear normal but are actually false and pilots must rely on
their basic flying skills to identify the faulty source and take the required
corrective action. When only one source provides erroneous data, a simple
crosscheck of the parameters generated by the three ADRs allows the faulty
ADR to be identified. This identification becomes more difficult in extreme
situations when two or all three ADR sources provide erroneous information. etc etc ...
From a private email: AF447 FPV & Ps data
Excellent piece of lateral thinking on the Static ports. I have been struggling to interpret the Flight Path Vector flag on the PFD (see ACARS PFR). Whilst the FCOM & FCTM make no reference to static pressure data as an input to the FPV I have in the past come across reference to the FPV being unusable when static pressure data is unreliable.
With detected erroneous static pressure data one expects airspeed/Mach, altitude, vertical speed, FPV, AP/FD and ATC altitude reporting to be affected. Setting the ultimate component aside, and noting the ACARS shows flags for the FD, shows an AP involuntary disengagement, shows PFD FPV flags, along with speed/Mach function for the ISIS and a variety of detailed messages regarding pitot-probes, one is at a loss* to explain the lack of reports for altitude and vertical speed.
Static isn’t just the hash detected by the ears. Obstructed/iced static lines may prove to be the glue that ties in all the AF447 esoteric failure indications. Read Takata’s entire FCTM citation and you get the impression that the safety factor afforded by
triple redundancy is more precisely a fallible fallacy foisted upon a gullible coterie of aviating automatons.
.