Contained within the OnPoint Program is the real time diagnostic program. There are two levels, Standard or Comprehensive, the Comprehensive can be custom designed to whatever the aircarrier would like. For what we would be interested in, the Standard program will show fault alerts, exceedance alerts and would notify the aircarrier of "critical" detected anomalies. The Comprehensive program would do the same as the Standard program but also would diagnose (diagnosis done by GE) the fault alerts and would detect all anomalies. So the data transmitted by each engine to GE & AF would depend on which program AF selected.
The data sent in either case would show all the key engine operating data, N1 and N2 speeds, oil quantity & temperatures, EGT readings, fuel consumption, air pressure entering the combustor, high vibrations, etc. The detected critical anomalies would include high EGT, flame out/compressor stall conditions, fire, commanded engine thrust levels outside normal operational conditions, etc.
I don't know what AF signed up for, but the data is very comprehensive and dates to the very first flight of the engine sending the data.
Sorry for the delay, but we have had bad weather here today...
Assuming AF447 was intact on hitting the Ocean surface, could you explain the disparate condition of the floating wreckage by considering that the Ocean surface was not flat but instead had large wave action?
The BEA thinks there was low forward velocity, but a fuselage hitting a line of waves could cause multiple impacts, and various breaks and ejection of components under varying impact loads.
There was wx in the area, so presumably the Ocean wasn't smooth as silk that night??
All of us that have flown into CB's or had a pitot-static ice problem and simply held attitude and didn't chase speed or altitude until we figured out our problem. Keep wings level and a semblance of level attitude.
No, QF72 upset was not related to Unreliable Airspeed Indication.
jcjeant has a very valid question : Which event was identified to justify the publication of the AD 2010-0271 and the related red OEB called Loss of AP and A/THR associated with alternate law reversion ... ?
The procedure outlined in machaca's post seems very reasonable. And I doubt that the AF crew re-engaged the autopilot if it had kicked off for whatever reason, especially in turbulence.
Many of us on this forum have experienced turbulence beyond the definition "moderate", heh heh. Last thing we did was have "otto" try to "help". I tend to go with the FBW systems, as they seem to avoid huge control surface movements, but apply the commands much quicker than we humans. The Viper felt about like a F-111 down low on a bumpy day. Nice soft ride for a "light" jet.
it is obviously difficult for most internet-age people to read beyond a few lines of text with any effectiveness
With all due respect, I don't think this is really fair. All of us have been generous with our time and contributed what expertise we have in order that we may collectively understand what happened here.
Naturally, we will all tend to focus on different aspects and different phases of this disaster - depending on our area of special interest or expertise. When all you have is a hammer......
Clearly you have detailed understanding of the flight control systems and the ACARS stuff - areas that are pretty much meaningless to me. Others have displayed very detailed understanding of radio capabilities and satellites. It is not that I am disagreeing with any of these people, or not bothering to read their posts (interesting even if beyond my understanding). I am simply talking about something different.
So I am not disputing your proposed explanation - I can't. Rather, I am proposing that there are likely to have been additional significant human nature issues prior to the upset, and that these may have played a contributory role.
The fact that this scenario has never happened previously despite many hundreds of thousands of operation of this model aircraft, and the fact that we still don't really know what has happened despite thousands of posts and countless thousands of hours of speculation means that the exact sequence of events is likely to be complex and non-intuitive. There is likely to be a complex interplay of factors (aircraft and personnel) that combined on this particular occasion to produce a unique outcome.
Please, this is not a pissing contest. Nor should it be seen as an opportunity to denigrate others. Surely that is disrespectful to those that lost their lives, as well as to those here seeking to advance our collective knowledge. When (if) we know all, then it may appear to have been somewhat arrogant or naive to believe that there was one single factor (to the exclusion of everything else) responsible here.
BEA report no.2, after analysis of thirteen events of losses of or temporary anomalies in indicated speeds, states:
In seven cases, the autopilot was reconnected during the event. In two of them, the re-connection occurred when the two speeds were consistent with each other but were erroneous;
The reappearance of the flight directors on the PFD when two air speeds will be calculated that can lead the crew to rapidly engage the autopilot. However, these speeds, though of the same order, can be erroneous and weak and thus lead the autopilot to command movements of the flight control surfaces that are inappropriate for the real speed of the airplane.
The failure has AFS (Auto Flight System) as its identifiers. AFS is Airbusese for Autopilot. But wasn't that A/P OFF at the beginning of the sequence ? And it was turned OFF by the aircraft itself, following Pitot probes failure. And now we find it as the identifier in an FMGEC fault, which means AFS detected a fault in FMGEC1. Who turned the A/P back ON and reactivated it ?
Good catch !!
Obviously this message never received the attention it maybe warranted..
Even looking at BEA's comment on this item reading a bit between the lines it becomes clear there might be something to it:
From BEA's second interim Report:
FMGEC1 (1CA1) (2 h 13)
ATA: 228334 Source: AFS Identifiers: - Class 1, INTERMITTENT
This message cannot be the trace of a reset which, in particular, excludes the possibility of a manual shutdown. This message could be the consequence of inconsistency between the two channels in the FMGEC (COM and MON). Such an inconsistency could be the consequence of erratic input parameter values. In any event, the effects of such a message could only be the disengagement of automatic systems, whose associated
cockpit effect messages had already been transmitted at 2 h 10. The “INTERMITTENT” nature of the message means that the problem lasted for
less than 2.5 seconds.
Between the lines I read that this indeed seems to indicate that automatic systems have been disengaged. Which in turn could imply they had been re-engaged before after the first disengagement which triggered the 210 ECAM's. The AD might indeed closely be related to this accident.
The ACARS message regarding Cabin Vertical speed is dated 1 min later than this. Which would mean that they were most likely not at CRZ altitude when the AFS was potentially re-engaged. This would point indeed to two upsets: Initial upset caused by UAS, recovered at an intermediate altitude (soemwhere between 10000 and 20000ft) which matches previous UAS incidents quite well btw. A subsequent upset caused by the AFS mislead by the still unreliable but now consistent speed. Question arising from this scenario: Down to which altitude could pitot icing be expected? Anyway, this scenario could explain the tragic difference to the previous incidents.
In any event, the effects of such a message could only be the disengagement of automatic systems, whose associated cockpit effect messages had already been transmitted at 2 h 10
To this should be added, from the same report, that a cockpit effect will only appear once in a given CFR/PFR. What we deal with is a CFR (Current Flight Report). I take it then that a A/P OFF message will not be repeated, since it was sent around 0210.
It is unfortunate that BEA would only give this item of information in that particular, obscure way. They essentially repeat themselves. However, reading between their lines would mean that A/P went OFF again without an ACARS message being transmitted (already done). So A/P had to be turned ON after 0210.
Another information hidden in this sentence from the report is that the list of cockpit effects produced by this failure is included in (but not necessarily identical to) all cockpit effects already sent from 0210.
In addition, would AFS catch a fault in FMGEC if it was still OFF (kicked off by the system itself). In other words, does the AFS as identifier positively ascertain that A/P was ON at the time the message was concatenated ?
My answer is yes, through all accumulated knowledge, but I do not have a positive answer, officially written in a book. I believe yes, it fits with all the rest (and I mean all the rest), but then... I am not defending that case in a court of Law, lucky me.
I would have expected BEA to answer that particular question, one way or the other. I guess they will do it now, and prove me wrong...
Been de-camping for last 48hrs, so now trying to catch up with this freight-train again... You've been discussing cabin crew activity/position.
Of course they MIGHT have been recently dealing with pax dinner. 0200z is 2200L at Rio. They were 3hrs30 into the flight, but it was a big load. If pax finished, crew dinner (cabin and/or flight-crew) might have been still under way.
[Just as an aside, I was once served dinner on an A320 and, as the steward lost his balance, the meal tray collided gently with the throttles. No harm done until he panicked and whipped the tray backwards, depositing its contents (including curry & rice) all over the centre pedestal!]
It can take the CC a long time, from the receipt of a command to secure the cabin, to complete the task. The most compelling evidence I've seen that they had not completed that task was the excellent picture posted by Shadoko, here, of one of the galley catering-cannister stowage units. The latches that must be closed to secure the cannisters are plainly open. Any proximate cabin crew member worth his/her salt would have secured them before sitting down, if severe turbulence was expected.
CS: OK, thanks. Seems clear on that point at least!
Edit: Though I wonder if that is consistent with the early best-fit scenarios with the weather, ie that the a/c was at the far end/about to exit a Cb. Suspect that can't be right as there would have been warning before the 'event'.
Last edited by Mr Optimistic; 24th Apr 2011 at 13:14.
Reason: Question on Cb
Thanks for the references from the BEA report, I didn't remember them. Still, I think the AD is more specific :
However, in some cases, the AP orders may be inappropriate, such as possible abrupt pitch command.
Are you aware of such specific concern among the 13 events ? Why that AD so late (DEC 2010) when the 13 events were already known for a while ? Any possibility for another ... event to justify the making of such AD ?
Originally Posted by 'PJ2"
I'm not sure what to make of "c", (in the sense that I would have expected not a pitch angle protection active, but an AoA protection active input.
I don't have an answer to that question, but that reminds me the 'Anti pitch-up compensation' which was partially responsible of the QF72 upset. Who was aware of that 'compensation' ... before it was mentionned in the ATSB report ? I had personaly never seen anything on it in any FCOM or other VACBI.
Just to say that there is so much unknown or/and untold on those airplanes ...
The 43-minute mission was nearing its conclusion when ice began forming on the X-31's pitot tube. The ice caused incorrect airspeed information to be sent to the craft's flight control computers, which were responsible for reconfiguring the aircraft for lower speeds. The result was a series of sudden, uncontrollable oscillations in all axes. The aircraft then pitched to 90 degrees angle of attack, and Lang was forced to eject as the X-31 crashed near the northern boundary of Edwards Air Force Base.