Just a word to clarify that ISIS doesn't receive "attitude from internal gyros", it receives inputs from ADIRU1 and 3.
Someone please clarify.Is the ISIS a mini PFD or a genuine standby instrument?This is at the heart of the matter.Forget wreckage,concentrate on what the crew had available to them in the last minute.This will tell the story.
This is what I could gather :
at 0210Z : from bottom to top :
- AUTO FLT AP OFF
-F/CTL ALTN LAW
- FlAG ON Capt PFD
- FLAG ON F/O PFD
- AUTO FLT ATHR OFF
- NAV TCAS FAULT
- FLAG ON CAPT PFD
- FLAG ON F/O PFD
- F/CTL RUD TRV LIM FAULT
- EFCS2...1..EFCS1...AFS
- EFCS1...X2..EFCS2X
at 0211Z :
- FLAG ON CAPT PFD
- FLAG ON F/O PFD
at 0212z:
- NAV ADR DISAGREE
- ISIS ....ISIS
- IR2...1,EFCS1X, IR1, IR3
at 0213Z :
- F/CTL PRIM1 FAULT
- F/CTL SEC1 FAULT
- AFS 1 FMGEC1
at 0214z:
- MAINTENANCE STATUS
- ADVISORY.../...
Above is ACARS summary from Lemurian.
Question(s) for Airbus pilots:
a)data for triple pitot heat failure is surely relevant here;not what happened but it amounts to the same thing.In that case,what it says is that one of the ADR's should be turned off to trigger the ECAM "ADR DISAGREE".If icing anticipated,turn off 2 ADR's?Why?Does it not follow that the 02:12 ACARS message "NAV ADR DISAGREE" was in response to pilot action?ie pilot de-selects ADR(s) OFF.If the multi-pitot failure/blockage theory is correct,theres nothing for the computer to find disagreement with.Theyre all three plain wrong.So the pilot must intervene to generate the ECAM warning.Is this correct?
b)It mentions it again for dual pitot heat failure;the inherent risk is that the computer will lock out the one remaining good ADR.So the pilot must turn off one of the faulty ADR's and trigger the NAV ADR DISAGREE which in turn will lead to ADR CHECK procedure.
So NAV ADR DISAGREE warning can either be computer-generated OR pilot-action generated(Pilot switches OFF faulty ADR).Correct?
d)Now that one ADR has been disabled and the ECAM warning generated what next?For ALT LAW to kick in,there must be disagreement between 2 remaining ADR's,either speed or AoA.If speed disagrees in the remaining two ADR's,crew fly unreliable airspeed procedure.If speed does not disagree,AoA is culprit,and crew ignores spurious STALL warnings(Air Caraibe).Is that about right?
e)The ECAM message in the Air Caraibe incident was FCTL ADR DISAGREE,not NAV ADR DISAGREE.What does this indicate?How telling is it that both 447 and Caraibe began with AP/FD disconnects?
f)In ALT LAW roll control is same as for Direct?Please enlighten.Sensitivity issues?
g)With a CAS of say 90 knots on all 3 ASI's at time of RUD TRAVEL LIMIT warning,could rudder deflection of 31 degrees been mandated by the computer as the limit?
h)What is the QRH procdure(2.20) for flight with all 3 ADR's out.ECAM apparently only covers single ADR op?Would 3 ADR's out=Direct Law?
I know Im out of my depth(never piloted/travelled on an Airbus) but no-ones asking questions that relate to what the crew had available to them in the last minute.What did they see??