There are reasonable things upon which informed, experienced and knowledgeable speculation or assumptions may be made. This accident is no different and many very good people who have engineering, mathematical, flight safety and airline operational and piloting experience have contributed freely and added to understanding. This includes a number of pilots who have flown this aircraft, some under similar weather conditions and who know this environment.
Along the way through these eight, possibly nine threads some exceptional thinking has been offered which has helped others who are less familiar with these aircraft and these operations but who nevertheless suspend judgement and comment, in favour of an abiding curiosity and thirst for knowing how others do this work.
In keeping with discussing what may be reasonably known regarding the displays available to the crew, post-event and so as to avoid leaving false impressions for others who are also reading here and studying this accident, that there was no flight information available to the crew other than the deck angle and the seat of their pants, the displays and all information provided by the two PFDs and NDs were almost certainly available with the exception of the airspeed and that only for a period of under thirty seconds.
The IRUs, DMC's and at least two FCPC's and the FCSC's were functioning, the aircraft was fully-powered, all the data needed for controlled flight was available and no primary system losses such hydraulics, engines or engine controls had failed.
A loss of airspeed data does not result in the loss of displays and there are no data indications, ECAM or ACARS messages indicating such a loss nor are there any indicated associated failures which would cause any or all screens to go dark.
Thus, attitude information (pitch & roll), IVSI, altitude and heading information were all available. On the Systems Pages all information would be available including flight control positions. The ISIS, a somewhat independent attitude, speed & altitude (but not VSI) system was also available except for speed for a short while.
In the thirty-six other similar loss-of-CAS events no screens were blanked nor was other information normally provided on the two PFDs and NDs lost to the crew.
I gave up reading this thread thinking everything had been discussed to death and that the primacy of the pilots in the accident had been fully understood. Unfortunately it refuses to die. All evidence and information points to a temporary malfunction which was compounded and turned into an accident by an inadequate response from the flight crew. This links into what I believe are relevant cultural issues at Air France particularly in the area of crew training. It also ties in with human reactions to unexpected situations and failures of CRM and lack of use of SOPs. But it is a human issue not a mechanical issue. As PJ2 has mentioned (nice to see you back by the way) this is not an issue with flaps or spoilers at all or with availability of information.
Re, "But it is a human issue not a mechanical issue. [As PJ2 has mentioned...] this is not an issue with flaps or spoilers at all or with availability of information."
Given what we have, (and it isn't unreasonable to doubt that what we have is all that is available), this is a performance accident. The far more critical aspect of this accident is "Why?" At present I think it is not complicated.
Re, "What did the pilots mean, then, when they reported to the Captain, that they had no displays?"
The only reference to displays is when the PF states, "We haven't got a good display...", "...of speed", and the PM states, "We've lost the speeds", (IR3 p29, p74, English version). No other references to loss of attitude, or altitude information is made. Contrarily, a number of references to altitude and pitch are made which indicate that the displays were functioning:
"Reading the three instruments (the two PFD’s and the ISIS), the PNF noticed that the airplane was climbing and asked the PF several times to descend." - IR3, p74 English Version
Regarding their contributions to the captain's understanding and the captain's responses:
"In the absence of relevant information from the copilots, reading the information available on the screens (pitch attitude, roll, thrust, vertical speed, altitude, etc…) was not sufficient in itself for the Captain to become rapidly aware of the airplane’s situation. He did not then ask questions that could have helped him to understand the sequence of events." - IR3, p76 English Version
Re, "And when did the displays return?"
The displays did not disappear. But the CAS indication did and it reappeared just under 30 seconds after the initial UAS event:
"At around 2 h 10 min 34, the speed displayed on the left side became valid again and was then 215 kt; the speed on the ISIS was still incorrect.". - IR3, p74 English Version
...and from IR3, p75:
"At 2 h 11 min 06, after several attempts to call, the PNF was anxious again about the absence of the Captain. This anxiety probably increased the stress for the PNF who was faced with a situation that he didn’t understand.
A second later, the speed on the ISIS became valid again. ADR 3 being selected on the right side PFD, the speed for the PF also became valid again. It was then 183 kt and the three displayed speeds were consistent. This brought no comment from the crew." - IR3, p75, English Version
I am well aware of the underlying assumptions behind these tentative conclusions but from experience with and knowledge of the airplane they are not unreasonable.
Re, "Later, after the aircraft was stalled, the CVR could indicate that other informations were temporarily unavailable, including vertical speed, attitude on the PFDs, altitude."
Yes, I can believe that. Under full stall conditions, a number of sensors, and therefore their downstream services, would not be working correctly. The NCD messages/indications and the "intermittent" stall warning are but two examples.
Slats were retracted at time of impact. That is known from DFDR recorded data, ... That is a fact.
The only fact I can see is that none of the traces for slat position and flap lever position is published.
Originally Posted by PJ2
The NCD messages/indications and the "intermittent" stall warning are but two examples.
It is interesting to note that the vertical speed trace never reaches the NCD status, but still the PF seems to indicate that he totally lost his V/S reading. As long as the V/S was selected from IR the V/S trace was making sense, when the V/S was selected from ADR the V/S trace was becoming somehow erratic. We may wonder why the V/S was occasionally selected from ADR (A33Zab said something on that, I have to find it back) does it have anything to do with the IRs capability ... what could be the consequences on the PFD's attitude display ?
The best that can be said regarding a slat/flap extension theory is, it is possible that such a selection was made at some point but improbable that it actually was. I think this because that is a significant operational emergency decision and would be noted in the IR3 even if the parameter has not been provided. There is no mention of slats and only one technical mention of flaps in IR3.
As Turbine D has quite reasonably asked however, of what significance is this in relation to the accident?
Vertical speed is a baro-inertial calculation. Inertial and Air Data systems have different advantages in the calculation. IR calculation is better in dynamic maneuvers and ADR calculation is more stable over time, (no IR drift issues). Input is automatically selected in accordance with reliability. If ADR data is unreliable it returns an "NCD" status.
Perhaps this may explain comments regarding behaviour of the IVSI display, perhaps not. Various data-source selections were apparently made (can't recall what they were, and also FCPC was switched off/on as well IIRC) - as I mentioned, system behaviours in these circumstances are much less understood than in normal circumstances and, like the earlier examination and sorting out of the ACARS messages, a lot of permutations/combinations would have to be examined before a definitive sense of what was being displayed on the PFDs at any moment during the post-apogee phase. The crew does comment on (loss of) altitude and rate of descent during this phase so something was displayed.
Perhaps due to my lack of advanced technical knowledge, but I have never been able to get my mind around the idea that they thought they were in OS. Why not? Because of the highly unusual deck angle. How in the world could anyone suspect OS when tipped back like that???????????????????????????? I ask you.
A very kind and knowledgeable list-member has privately educated me on this (link my choice, not his). They didn't know WTH the airplane was doing unless the instruments were reliable on all counts.
That is what instruments provide. Life itself. It is uncomfortable, but very occasionally one must utterly reject what one's senses say, and rely totally on gadgets.
And that is why Flaps and slats (spoilers) are important, and why a few of us are pisssed off at BEA for witholding data. As I said, the Captain had to climb the aisle to re-enter the cockpit. Note his first comment? "Er....what are you doing?"
A Frenchman does not confront another, generally, with such a terse comment.
There is a gob of very pertinent data simply missing from the releases, end of...
...a few of us are pisssed off at BEA for witholding data.
There is a gob of very pertinent data simply missing from the releases.....
I'm waiting to get pissed-off/very disappointed if the final report is missing any data. In the meantime, I don't believe it's fair to accuse them of that. 'Interim' means just that. I do agree in general that there appears to be holes in it, but guessing is, IMHO, pointless! Might you be what they call a loose cannon?
The excellent link you have provided discusses important aspects of pilots who are non-instrument-rated flying in, or into poor visual conditions. One must believe the instruments at all times because the alternative under some conditions is a loss of control.
You are right, most pilots are indeed familiar with these things...it's drilled into all pilots from very early on in ab-initio training/testing/licencing process.
Some may recall the John Kennedy Jr. accident in which control was lost at dusk, a time of day when the horizon is poorly defined.
Put bluntly (but not overly-dramatically), a non-instrument-trained or rated pilot who enters cloud or continues to fly in deteriorating visual conditions, once entered, has about a minute-and-a-half before the spiral dive develops. The way out is to immediately level the wings but if one has no horizon and doesn't know how to read the artificial horizon instrument or attitude information is missing (displays blanked), the dive will not be stopped.
Not among the accidents listed in your link is the Gulfair A320 loss-of-control accident at Bahrain in 2000. Of particular interest is the "Appendix E, Perceptual Report". Also not listed among these accidents is the Afrikiyah A330 accident at Tripoli which some have discussed these same phenomenon. But we'll probably never know given both political and infrastructural problems which began with the recent civil war in Libya around the time of the accident.
In considering the notion that has been expressed regarding AF447 that all displays were blank, (no information displayed to the crew and not just a missing speed indication for a half-minute), almost certainly the result of loss of attitude, altitude, vertical speed, airspeed, heading etc (on a cloudy, moonless night) would have been a high-speed spiral dive and an extremely high speed impact with the sea. We know that such is not the case.
It isn't direct evidence of course but given the way these things go it is again a reasonable support for the view that the PFD/NDs were displaying most if not all their information except for the CAS.
"In considering the notion that has been expressed regarding AF447 that all displays were blank, (no information displayed to the crew and not just a missing speed indication for a half-minute), almost certainly the result of loss of attitude, altitude, vertical speed, airspeed, heading etc (on a cloudy, moonless night) would have been a high-speed spiral dive and an extremely high speed impact with the sea. We know that such is not the case. "
With great respect, Sir.
From BEA Interim Report Number 3
"At 2 hr 12 min 02 the Pilot Flying said: 'I have no more displays......'
The Pilot not Flying then said: 'We have no valid indications....' "
Now that's from page ten, and the statements are made 17 seconds after the Captain has re-entered the cockpit. Further dialogue? I would wager so...
Re the wager, being a pilot I don't bet on things but thank you for reminding me of the information (on page 10!).
The loss of the VS parameter & displayed information is a possibility that I discussed in a previous post in re the "baro-inertial calculation and if supplied by a malfunctioning ADR, could return "NCD" and not be displayed. From the IR3, Appendix 1, p94:
The vertical speed is no longer
calculated by the IR (Inertial
reference) but by the ADR. It is
about -10,000 ft/min.
This is coincidental with four ACARS messages indicating events occurring at 02:11:45, (and recorded/time-stamped between 5 & 29 seconds later) which also coincides with the disruption, as discussed above, of a number of parameters including the VS traces:
02:11:45 FLR/FR0906010210 34111506EFCS2 1,EFCS1,AFS,,,,,PROBE-PITOT 1X2 / 2X3 /1X3 (9DA),HARD 02:11:45 FLR/FR0906010210 27933406EFCS1 X2,EFCS2X,,,,,,FCPC2 (2CE2) /WRG:ADIRU1 BUS ADR1-2 TO FCPC2,HARD 02:11:45 FLR/FR0906010211 34220006ISIS 1,,,,,,,ISIS(22FN-10FC) SPEED OR MACH FUNCTION,HARD 02:11:45 FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2 (1FP2),HARD 02:11:55 WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV 02:11:58 WRN/WN0906010211 341201106FLAG ON F/O PFD FPV 02:12:02 PF states “I don’t have any more indications”; PNF, “We have no valid indications” Thrust levers to IDLE; N1s @ 55% 02:12:17 PF makes ND inputs; AoA decreases, speeds become valid again, stall warning sounds again 02:12:47 WRN/WN0906010212 341040006NAV ADR DISAGREE 02:13:32 PF: “we’re going to arrive at level one hundred”
When the PF says (likely to the captain), "I have a problem it's that I don't have vertical speed indication" and "I have no more displays" I do not think he means that his entire PFD is blank. From his comments, he still has attitude & altitude information and the altitude information is unwinding at a thousand feet every three seconds or so at that point in the stalled descent.
The overarching point, to which I am addressing my comments, that the displays were blank prior to the apogee and during the entry into the stall, and are somehow causally linked to the ensuing loss-of-control, stall and descent, is incorrect. Post full-stall and at high-pitch/high-descent rate, any number of indication & system anomalies are likely going to occur, which may lead a crew who may be continuing to believe that the aircraft (the wing) is still flying, to significant cognitive dissonance and an inability to construct a model of aircraft behaviour such that the way to a recovery could be seen. These are CRM as much as SOP matters, a subject which I expect to be dealt with in depth when the final report is issued.
from Interim Report #3 F-GZCP. Downloaded and copied from my Apple ipad.
At 2 h 12 min 02, the PF said, “I have no more displays, and the PNF “we have no valid indications”. At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning triggered again.
//////Interim Report n°3 On the accident on 1st June 2009 to the Airbus A330-203 registered F-GZCP operated by Air France flight AF 447 Rio de Janeiro - Paris Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile Ministère de l’écologie, du développement durable, des transports et du logement//////
Old Carthusian. Thanks, you are right, and I would include the text on the page from which this comments arrive, also. It describes a a/c severely in UPSET, but from which a recovery is made. Also, the PF's side of the panel is not recorded, as you can see, and I do not doubt him, PJ2 has inferred proper displays as you have. That is fine, but let's not forget that we have actual evidence, in the two pilot's actual voices.
jcjeant what pages are you copying from #3? Are there different iterations of the report? Mine is of 114 pages long, downloaded some while ago. Do not tell me it has been altered/modified?
Lyman I am not sure of the relevance of your comments here. The phrases you quote are taken out of context and should be read in conjunction with the rest of the transcript (further on in the report p94-96). From the comments made it is clear that the instrument displays were providing information.