Consider this ... let's say both engines are spooling down for whatever reason (supercooled water droplets accumulating in the engine core - read more here ... http://www.georgehatcher.com/Ice_Cry...To_Engines.pdf) - due to the simple fact that both engines were (potentially) exposed to the same weather effect they might be spooling down one after the other without too much delay. Now I would presume, that the ACARS error message for engine flameout would be triggered below a certain N1 value.

It remains to be calculated what would happen sooner - both engines failing (thereby shedding the AC1 electrical bus and cutting off ACARS) or cabin pressure loss (no clue how much pressure is lost due to imperfect seals and a "normal" outflow valve position) amounting to cabin alt rising those 150 ft that would trigger the CABIN ALT warning.

It would be very helpful if BEA would release the position of both MLGs and both engines in the debris field - might give a good clue if the east-west orientation of the debris field is significant. Why am I so hung up on this? Simply - if the aircraft was heading east-west (or west-east for that matter) at the point of impact, yet as the material analysis shows it hit the water near wing-level it would mean that the pilots were in control of the aircraft. Unfortunately that would open new questions again :/

PS: Apologies for typos ... half asleep :/

Just to clarify. The RAT would (as far as electrics go) only power the AC ESS and DC ESS buses, so the ACARS subsystem would remain unpowered.

CPC
 

PJ2;

HN39 has already asked the question regarding valid ADR info to the CPCs. In the circumstances surrounding the various ACARS messages, e.g. NAV ADR DISAGREE, and it appears that at least PRIM 1 and PRIM 2 were switched off, possibly in an attempt to reset. Do you believe that in the probable circumstances at 0214, that the CPCs were receiving valid ADIRU data?

I'm thinking that in the fail safe situation that the pressure relief valves, once triggered could possibly be configured to also initiate the Cabin Vertical Speed Advisory. Any thoughts?

Evidences might only be found in the deep of the ocean; we'll only see some evidence once the recorders will be recovered and analysed. But it is exactly the same as for any other explanation so far (deep, spiral, flat, spin stall, vertical stab loss, one, two or three upsets, crew asleep, turbulences, updraft, downdraft...)

All we've got is very few facts and hints that we can try to put together:
a) attitude at impact.
This aircraft impacted the sea without any external sign of an upset attitude beside the loss of forward speed. If, at impact time, it was outside its flight enveloppe, it is mostly due to this lack of forward speed. Consequently, the lack of thrust can not be ruled out.

b) Impact time.
Determining the time at impact is only based on the probability of the ACARS sequence stopping between 0214:26 and not later than 0215:14; on the other hand, a dual-engine flameout after 0214:26 would have caused exactly the same effect: a dual-engine flameout = EMER ELEC re-configuration, and in this case, the SATCOM become inoperative and no more ACARS would be sent if the engines do not recover.

c) ACARS.
Something very serious was still in progress: F/CTL PRIM1 and SEC1 faults at 0213:45 and 0213:51, with a spacing of 6 seconds between both ACARS, mean that it happened simultaneously. Such a reset of both flight computers -primary and backup simultaneously- is not possible without an associated fault which was never transmitted. It certainly was not due to the crew manual reset as it is contrary to the basic safety rule: never reset both fligth computers at the same time => you'll be left with those mechanical flight control only (trim, not even direct law). Then I think it was likely due to some change in the power supply configuration, and those ACARS which should have followed in the later sequence might have been interrupted by the lack of SATCOM once in EMER ELEC.

d) Indirect ACARS hints.
There is plenty of ACARS linked to the ADRs faults but none about the engines state. If the aircraft departed and stalled during 5 minutes, this is very unlikely that none of the engine will suffer any failure, due to this (low speed?) stalled flight attitude, while none was ever transmitted all along the sequence. No flameout, no engine stall detected. Nothing about the powerplants which were running in manual thrust and were also feeded by the same corrupted air data.

e) Ice and rain.
At FL350, the presence of ice particules is clearly demonstrated by the pitot icing. If we still can not be sure of the real weather encountered at this level along F-GZCP path -she can fly above or between active cells like in many other cases of pitot icing recorded in tropical atomosphere- this is pretty sure that down below her, there was both ice and rain (beside any possible turbulence level). Now, her powerplants could also have encountered troubles with ice and rain, as demonstrated by many other events with similar engines mounted in various airframes.

The probability to lose an A330 from cruise level in the middle of the Atlantic was considered much more than pretty slim before this event. Nevertheless, one was lost.
Anyway, concerning a possible engine dual-flameout, see my post several pages back citing an Airbus to customers communication.

1. French government monopoly 2. Captain in control
 

I am very surprised that there is not more concern in this forum about the fact that French government entities have control over the recovery and analysis of the wreckage. They have already been far too elusive about the mapping and identification of the debris field. I have only seen one rather oblique reference (sorry, can't recall where) to the tail section of the plane, and therefore the CVR and FDR, being in the debris field. If images of the tail section were released, it may create expectations about the condition of the recorders and the likelihood that their data will be intact. It concerns me that those images have not been released and that no statement has been made about the damage or lack of damage to that part of the plane. It leads me to wonder if the French government does not want there to be any expectation about the integrity of the data. In this forum it has been stated that the French court will have control of the recorders as sealed evidence. How do we know this?

Point 2: I have never piloted a powered aircraft but my issue here concerns commonsense rather than piloting skills. When there is an accident there is more often than not some sort of human error involved. As a regular paying passenger I have to say that I have faith in the technology but grave suspicions about the people up front. Many correspondents to this forum will be flight crew and may like to comment on my concerns, which are as follows: to me it is almost inconceivable that a captain would take a nap during the time at which the plane is traversing the tropical convergence zone, where it is known by all that there is elevated risk. Surely commonsense would dictate that the captain take the precaution of being in control at the time. If anyone believes that it is okay for the captain to take a nap during a period of the flight when there is a risk of an upset, doesn't that suggest that some pilots have become far too complacent about their responsibilities?

HN39, you're welcome...as I say, some meandering thoughts which may strike chords with others and take us forward. I'm keeping in mind that the ADRs themselves haven't failed but are receiving erroneous pitot data which the ADRs are rejecting, and the SDAC (or FWC) is creating the disagreement message. I'm not sure if ADR data transmission stops because of this, or downstream users are "told" that the data is bad, or that any further error detection and use of data downstream would be made independent of the ADRs with the equipment responding with error messages of its own.

Without further research, I would have to say that the ADR static pressure data would still be valid and providing the ADR pushbuttons remained ON, available for use downstream of the ADRs, but it's a question I can't answer. I'll keep looking.


mm43, Just to be sure, the PRIMs don't send data to the CPCs. I'm not sure if recycling the PRIMs would have any effect but I doubt it.

Understand the thinking on the safety valves. As I see them at the moment, they appear to be mechanically driven, (spring-loaded poppets) by differential pressure, (positive, and negative - the negative pressure relief valve mentioned earlier is additional, due to the volume of the fuselage), with electronics monitoring position for the CMC. There is no description of, nor does there appear to be any other mechanism which would drive the valves open through other means, (in either direction).

Translation of Update on 2010/04/11 meeting between BEA and family representatives
 

Good mmorning all,

With reference to post #3325/11 april by auv-ee pse find hereunder a revised translation of the french article published in "Tour Hebdo".

Thierry Mariani, Secretary of State for Transport and Jean-Paul Troadec, Director of the Enquiries and Analysis Office (BEA) for the safety of the civil aviation, met today with the AF 447 Rio-Paris victims families information commitee together with the representatives of the Gendarmerie's Air Transport section and the Gendarmerie Nationale's criminal investigation institute.

The families and the BEA were able to discuss the organisation of the recuperation of the wreckage, one week after having been located. The ship " Ile de Sein", belonging to the french Group Alacatel Lucent in charge of the recuperation of the wreckage, will depart Cap Verde on 21 April without any families representative on board so as to "not affect the judicial procedure".

The ship is due to come back mid-june. The priority will be given to the technical enquiry and, if found, the recuperation of the flight recorders. The families have also been advised that attempts will be carried out to recuperate some victims bodies in order to meet the judicial enquiries. If it is at all possible to recuperate them, they will be identified in France and given back to their families asap.

"The operator's schedule given today can be modified if the recuperation operation requires more time", said Thierry Mariani. During this meeting the Secretary of State presented Philippe Vinogradoff, new ambassador for the relations with families, appointed by the government in order to be the sole interlocutor between the victims families and the various authorities of the concerned countries.

Re: Bleeding Speed Fast
Svarin, are you hinting at a Vmo/Mmo caused pitch up? I believe we discussed that a while back and came to the conclusion that we would need the black boxes to validate that concept. The information available presently is not sufficient to say yes or no, but the concept is not ruled out. At least it could account for some of the time before AF447 started down like a falling safe.

It's been over five months since I've posted on pprune. Been regularly reading some forums and threads of course; this one for professional interest, and JB for therapy. ;)

I shan't comment on any technical aspects regarding the upset and loss of AF447, as there are others who continue to do a much better job of that than I could. What I will advance is the postulate that the action (or inaction) of the flight crew likely had a great deal to do with the initial upset (as opposed to the intial upset being a direct result of technical factors).

There are certainly indications that the crew were (for reasons yet unknown) not being proactive during the 30 minutes or so leading up to the departure from controlled flight (lack of position reporting or other communications from the flightdeck, for instance). Human behaviour research tells us that if such was the case, then a reasonable assumptive progression from that goes one of two ways: 1, The crew were too busy with other duties, or 2, they were also not being proactive in other areas also for whatever reason(s).

There is no reason to suspect that the crew were overwhelmed with other activites in the half hour prior to the first ACARS, therefore postulate 2 is more likely. So, the suggestion that the crew did not take any action to address a deteriorating situation is worth discussion. Remember that the conditions that we are aware of on the flight deck (through ACARS) tell us there were significant events but none significant enough to explain the loss of the aircraft).

There is strong (circumstantial) reason to believe the Captain was not on the flight deck. Additionally, as all flight crew members know, there are a variety of reasons why:
1 There may have been only one flight crew member up front for ten minutes or more
2 There may have been two crew members up front but only one actually "in the loop".
3 There is even the possibility (documented in past occurrences) that there was no functioning crew member up front (nodding off, severe turbulence causing injury, etc).

I am not suggesting a specific reason for the lack of action (as there is clearly no evidence yet to do so) but I am suggesting that to be overwhelmed, such that the aircraft is lost, points to being caught way off guard. Which in turn points to an environment on the flight deck that was, shall we say "less than SOP".

Such a situation may also provide clues to why the passenger cabin seems to have been unprepared for whatever occurred.

Simply sharing thoughts...

HazelNuts39, if it was the satellite to the west that would be the one at 53° West. That would increase the angles to maybe the 3dB or half power points on the antenna pattern. That might be enough to prevent a message getting through. But it'd leave footprints of the attempt.

Chris Scott, I believe it's pretty clear the VS was with the plane until impact or very nearly to impact (15 seconds or less). The is no reason for the plane in a level attitude to lose contact with the satellite as long as it had power.

If the plane was in the last 15 seconds of its flight with the VS still attached, please describe how it came off before impact.

If the engines flamed out at altitude I suppose it is possible for the plane to sink in a power lost condition to the surface at that time. But, how does the CPC malfunction to provide the messages received BEFORE the engines flamed out? It seems messages would be a different order in that situation. (Recent discussion has me believing a double flame out would cause loss of power to the ACARS system. But, this would not be a total loss of power to the aircraft. I believe CPC and controls are the last items to go as power reserves and the aux generation capabilities on the aircraft die.)

Regardless, obsessing over VS falling off the plane because God swatted at it is not meaningful. That was not the beginning of the chain of events that ended AF447's flight prematurely. It would be an effect rather than a cause.

Note:
We may be able to establish a little bit more. If both engines flame out does that affect (or effect) oxygen mask deployment. (Would lack of power prevent deployment or would its loss cause automatic deployment?) Is there anything we can infer regarding presence or absence of power on the plane by the fact that the masks had not deployed?

Quoth takata: One can infer, however, that until the end of the ACARS transmissions less about 10 seconds or less the VS was still attached. Therefore one can also infer that a VS detachment did not doom the plane as it was already doomed at the earliest possible time for its departure form the plane.

That, in itself, says a lot, I believe.

Hi Grizz. Good to see you again.

I agree that there the human factors are likely to have been very important. Possibly more important than the hardware.

At some stage, did both pilots drift off too sleep. We have all drifted off to sleep without meaning to. It shouldn't happen when flying a plane, but it has many times. Middle of the night, apparently routine flight, and disrupted circadian rhythm. All the ingredients are there.

If we get useful information from the CVR/FDR then all these questions will be answered. If we do not however, then we will be left with the following:
1. All the knowledge we had prior to discovery of the plane, which was inconclusive and fitted numerous theories
2. The location of the wreck. This is pretty close to the impact point. It would have sank fairly quickly and the subsurface currents are not that strong. The the wreckage is a very close approximation to the impact point.
3. The wreckage - which has already confirmed not a high speed impact with the water, which most people had accepted already.

So the only new piece of information to incorporate into existing theories will be the location.

Based on existing knowledge and an impact close to KNP, how does the following scenario sound?
1. Both pilots drifted off to sleep. Didn't avoid weather. And missed some radio calls (although there are other explanations for this, these explanations don't incorporate the failure to deviate around weather).
2. Pilots suddenly wake due to turbulence. Confusion about what has happened, concern about the present situation of the aircraft, and also concern about the implications for them. None of this makes for clear thinking in a hurry. Not difficult to imagine almost a panic situation.
3. Radar looks very threatening ahead.
4. Thinking "at least we came through what is behind us", and so a decision to perform major change in heading. 90 degrees or possibly even more.
5. Sudden upset, loss of control, and inability to recover.

This explains lack of preparation of cabin - CC seats not occupied, and lots of unrestrained pax.
A significant course deviation (reversal) may also explain the location close to LKP, and where all that energy (both kinetic and potential) went.

Again, we all hope the recorders will reveal all. If they can't be recovered (or if data can't be recovered from them), then we will be left with the best theory that fits all the knowns. And the location will be one of those knowns.

Having recently experienced severe probe icing while avoiding CB at high altitude I can understand how the AF crew would be struggling to understand what was happening and might have been distracted from their avoidance of active CB tops. I would be interested to know more about the A330 radar control panel as fitted on this aircraft. Does it have an auto tilt function? If not, failure to reset the tilt manually to a cruise setting at top of climb might have meant that CB radar returns were not seen or correctly presented. An inadvertent CB penetration while coping with probe icing problems could easily lead to a big upset.

Grizzled,
 

A330 fleet has logged 18.000.000 flight hours since its entry into service back in 1993 with only two hull losses (AF447 and the Afriqiyah one in Tripoli) with casualties.
Of course, it will have been better for all the poor souls on board those two flights that they did not occur.
Anyway, with such figures, we can surmise that this particular A/C type is basically safe.
We all know in this business that today accidents involve more and more human factors, including of course the interactions between pilots (one type of culture) and systems designed by engineers (one other and very different type of culture).

Therefore, it seems logical to come back (as other posters have done already) to the behaviour of the pilots during this flight.

Even if I am not as radical as you regarding this behaviour (I think they were alert due to the forthcoming crossing of the ITCZ), since some weeks after the accident, I have been musing over the following lines :
- either the pilots took the wrong decisions / actions as they were misled by corrupted data / information coming from the (in)famous iced pitots,
- or the pilots were overwhelmed by the volume of information to be dealt with (not lucky enough to have five brains in the cockpit as in the QFA A380 last November) and were not able to take the good decisions / actions on time.

Please bear in mind that none of these possibilities is from my point of view an attack on the professionalism / competencies of the two pilots in the cockpit (whether the Captain was there or not).

And that's why I am much more interested in the CVR than in the DFDR ... hoping anyhow that both will be found and decoded.

Again with the fin!
 

Ok everyone seems convinced that the fin departed on impact with the water. I still ask - why? Most of the claimed evidence seems to be of the sort "nothing else could so tear up the supporting structure" - but do we know that? Composite materials fail explosively as the tremendous locked-in stress energy of the layered and bonded materials is released - so there is plenty of energy around to do a lot of damage. Also - there are no scores, scuffs, or other marks on the fin to indicate it collided with any of the rest of the disintegrating structure - why? We would have maybe the only case ever of complete destruction of an airframe without significant exterior damage to one of its largest members.

Perhaps I am being dense, but I fail to see how everyone can be so certain.

edit: yes I am aware of the notch taken out of the lower end of the rudder - something to be expected if the fin departed rearward in flight! Of course that will show on the tail cone should it be found.

Without getting into the examination of the damage done to the Vertical Stabilizer's mounting hardware, the rhetorical response is, "Please explain why the V/S would not suffer any exterior damage if it had fluttered down on its own from altitude?"

That's easy, we have an example with AA587, whose fin was torn off by aero-forces and fluttered into Jamaica Bay. The rudder was lost, but otherwise the fin looks as good as new (from the attach points upward).

Indeed, the question arises in my physicist's muddled head, what is the maximum possible impact speed that will leave a fin in shiny new condition? And surely this speed will be gentler on the rest of the airframe than the evidence suggests.

777fly;
A lot has been said on this and the other two AF447 threads on radar.

Information provided airline crews on radar systems and effective use is at best parsimonious and at worst, ineffective. I wrote about this on the now-locked thread a few days after the accident, wondering if it was as simple as that and all the rest were details.

I'm not sure what you mean by "auto-tilt". In all radar installations I'm familiar with, stabilization is provided by the ADIRS; -at zero tilt the antenna is always oriented to the horizon regardless of pitch attitude.

Typically for those new to it, understanding radar begins with the idea of a flashlight and it's beam width and what it will and won't light up at various distances.

Most FCOM's don't tell crews how to use radar. Many here will know this, but for those who haven't used radar, (from the manufacturer) the beam width for the A320 and A330 is typically 2.84deg, (1.42deg above, and below, center).

One uses the 1:60 rule to determine how far below or above one's FL the returns are and judges passage through a line such as the one seen that night, appropriately. The bottom of the beam at a two-degree down-tilt at 60nm is at 2 x 60 x 100 = 12,000ft below aircraft level, approximately!, (and the top is about 5000ft above the horizon!)

A 2.84deg beam is always 17,000ft wide at 60nm, (2.84 x 60 x 100), double that at 120nm, and remember the beam is weaker. At zero tilt, one is scanning about 8500ft above and below the horizon. So one has to scan up and down to learn what's ahead.

In other words, one doesn't leave the tilt set but, using the above simple information, scans up and down, using small tilt adjustments and even using manual gain for a few sweeps to understand what's ahead. One knows about blanking, about where turbulence will be found, about what does and does not show up in the returns, etc.

Unless things have changed in the last few years, none of this is taught or even mentioned formally. One has to seek the knowledge out and then put it to use and learn. Dave Gwinn (RIP) had a great course on radar at one time. I know there are others now.

damirc:

"ust to clarify. The RAT would (as far as electrics go) only power the AC ESS and DC ESS buses, so the ACARS subsystem would remain unpowered."

I appreciate that a RAT wouldn't power ACARS - but it would provide hydraulic and electrical power to continue control of flight control surfaces.

To date; we don't have evidence of dual-flameout, but we do have evidence that the sensor system delivering airspeed, altitude and AoA data to the pilot suffered from icing and was unreliable.

Data so far points to it being it more likely that the aircraft was stalled into the water under power, rather than a scenario where both engines flame out almost simultaneously (without fuel starvation) and auto re-light also failed. We know it wasn't a planned ditching attempt, since lifejackets were found in their containers and flaps were retracted.

deSitter:

"yes I am aware of the notch taken out of the lower end of the rudder - something to be expected if the fin departed rearward in flight!"

Are you aware of the compression damage to the bottom leading edge of the VS? That indicates that the VS rolled forwards. If you theorise that the VS came off in flight, you need to explain a scenario in which the VS would be rolled towards the front of the aircraft as it breaks away.

You can see the compression damage on the photos in the interim report.

A double engine flameout after 2:14:26 would have enabled the airplane to end up beyond The Circle. Evidently it didn't, so why theorize about that possibility?

sd666 - if you could point to something I might examine, I'd be grateful. The main point is - when composites fail under stress, they release enormous energy in the form of elastic shock waves into the surrounding structures. These would dissipate with distance and would be confined to the areas around the attach points. The effect would be explosive in every sense, and in fact the CVR of 587 recorded a very loud bang heard all the way on the other end of the aircraft.

Relevant both to the sort of problems mother nature can throw at us, and the amplifying effect of PIO on the rear vertical stabilizer...

The pprune thread http://www.pprune.org/rumours-news/3...urbulence.html here is unfinished but the official report Transportation Safety Board of Canada - AVIATION REPORTS - 2008 - A08W0007 shows how close it got to another AA587 incident - bank angles of +/- 55 degrees at FL360!

But the composite didn't fail. The mounts and parts of the fuselage structure were detached from the rest of the fuselage.

Intact Airbus composite fin was found floating of Perpignan after that crash, and there is eyewitness and black box evidence that it was still attached at impact.

The fin being found intact and floating is not evidence to back the detached-in-the-air theory - we know that this happens even in high-energy impact with water, with the fin still attached at impact.

"sd666 - if you could point to something I might examine, I'd be grateful."

Take a look at the interim report here:
http://www.bea.aero/docspa/2009/f-cp...90601e2.en.pdf

Point is - the composite part didn't fail. The (alloy) female lugs were ripped from the frames and are still attached to the stabiliser.

The report of the Working Group on Flight Data Recovery has a table of past underwater recovery operations (p. 12/13).
http://www.bea.aero/en/enquetes/flig...nal.report.pdf

For each of these accidents, it includes a column "tail floating?". (The reasoning being the proposal to place an additional set of flight recorders in the tail fin.) The table indicates "yes" only for AF447, a Kenya Airways A310 at Abidjan, and the A320 accidents at Bachrain, Sochi and Perpignan.

In all these four other accidents, the flight recorders were found, and the investigation showed that the cause of each accident had nothing to do with in-flight separation of the V/S.

In other words: Sometimes a cigar is just a cigar. And when a 'bus crashes at sea, the tail fin separates and floats. That's odd, but not a safety risk by itself.

And if the BEA report presents convincing evidence that the tail fin from AF447 separated on impact, too, there is no reason not to believe it.

Grizzled: I can't entertain the theory that two AF pilots could be asleep at the wheel at the same time. This seems a bit much. But I do agree that they were startled by something, possibly all the alarms going off and the various failures that we know of. I think this started a chain reaction of mistakes that led to the ultimate crash; but we are not sure that they were not following SOP's....something did happen that brought the plan down quickly, as you brought evidence of, and that something for now is a mystery.....:ugh:

Hello

I read in an update on the investigation by the BEA :
(source)
I understand that such tentative to connect ADS-C requires a crew action. Is that correct ?
If so, we can assume that (part of) the flight crew was conscient & proactive 9 minutes before the first ACARS message.
How much time before entering a cloud cell is the said cell visible on a weather radar ?

A cumulonimbus of the size they flew into should have been visible for a good 30-45 minutes before they flew into it. We will hopefully soon find out whether they were making judicious use of the weather radar.

AF447 in my point of view got a slow depressurization.
the plane flew down until impact with everyone already dead.

no need to be an expert!

Salute,

Good point, and so far, the best against this theory as, at first, I thought she might be found beyond the 40 NM circle or on its way back in the Southern part of it.
Hopefully, we'll see what is discovered once the recorders are found.

Unfortunately it has happened plenty of times Razoray. I guarantee you that many pilots would privately admit to you they had come close to nodding off. There have been several recent cases where it is understood this happened.

If this happened (if), it is not really the pilots fault. Humans are poor at overseeing things that mostly go right and require minimal intervention. Lack of mental stimulation, many hours of monotonous routine, night, chronic disruption to circadian rhythm.... Plenty of middle ages pilots will have obstructive sleep apnoea and chronic sleep deprivation. Honestly, it is amazing it does not happen more often (or maybe it does).

Sleep deprivation was cited as a significant contributing factor with Three Mile Island, Chenobyl, Bhopal, Exxon-Valdez.......

Falling asleep is the highest cause of single vehicle highway crashes at night. And driving requires a lot more effort (= mental stimulation) than flying. Plus these drivers are not driving 14 hours non-stop and coping with disrupted circadian rhythms.

By no means am I saying this is what happened. However it is certainly a possibility, and it does explain some issues prior to the crash. Therefore it is a possibility that must be considered unless it can be ruled out by the CVR.

VS (fin) and VS (vertical-speed)
 

'Morning JD-EE,
Normally an admirer of your arguments, I must admit your post #3346 leaves me nonplussed.

Quote:
"Chris Scott, I believe it's pretty clear the VS was with the plane until impact or very nearly to impact (15 seconds or less). The is no reason for the plane in a level attitude to lose contact with the satellite as long as it had power.
If the plane was in the last 15 seconds of its flight with the VS still attached, please describe how it came off before impact."

I happen to believe the BEA's finding that the "VS" (vertical stabiliser) was still attached at impact, but have never discussed the subject. Looking at my recent posts, what I have been discussing is "Cabin VS" (notional vertical-speed of cabin in terms of its air-pressure variations), in the context of the final ACARS message. Could the ambiguity of the term "VS" have caused your misunderstanding? If "vertical stabiliser" is too much of a mouthful, perhaps we could use the good old British term: "fin".

I've never discussed the conditions that might result in the ACARS antenna losing sight of the satellite. What I have discussed are possible reasons for failure of electrical power to the aircraft's ACARS system.
Are you mixing me up with someone else?

Quote:
"If the engines flamed out at altitude I suppose it is possible for the plane to sink in a power lost condition to the surface at that time. But, how does the CPC malfunction to provide the messages received BEFORE the engines flamed out?"

Agreed. I don't think there is any evidence that the CPC malfunctioned. I discussed the unlikely scenario of a double pack-failure (possibly caused by double engine-failure) in my post #3316, concluding:
"However, I would have expected double pack failure and double engine-failure both to be ahead of cabin VS in the ACARS message hierarchy..."

In other words, I think the shutdown of both air-conditioning packs would produce its own warning before the CPC noted the (resulting) cabin VS outside limits (cabin-altitude climbing). Like others, I think that the cabin VS warning was more likely created by a serviceable CPC noting the cabin-altitude suddenly descending at a VS outside limits; due to the aircraft descending rapidly through the cabin altitude of about 6000ft-7000ft, resulting in the opening of the inward-relief valve(s).

When proposing explanations for the final termination of ACARS messages, the latter scenario makes a complete loss of main AC-generation unnecessary prior to impact. At the suggested impact-VS of about 18000ft/min, there may have been fewer than 30 seconds of flight remaining at the time that last message was generated.

Sleepy Crew
 

AlphaZulu, I read this the same way you did. The crew had comm issues for 25 minutes up to 2:01, I would think this would have been enough stimulation to keep them awake for another 9 minutes.

WX Radar
 

From what I read early on in the first thread in this accident, the accident plane was using the same WXR-700X system it had when new. That means manual tilt control to scan down into the wet part of the storm, deciding possible diversion route by 80 miles, etc.

The WXR-2100 with auto tilt, etc., became available in 2003-4, IIRC. It even has automatic sensitivity adjustment for earth latitude.

Like most airlines, AF kept flying with the older generation (1982 design) radar, because it was still legal. In fact, I believe AF never opted for the new Wx radar for their newer A330, for economy of crew training. Common spares is also a big factor in discouraging upgrades for newer planes in the fleet.

UAL used to be the only airline in the US with decent Wx radar training, and they did away with that years ago. Does any airline provide more than the mandated minimum today?

deSitter, the airplane flying thingie would have told us it had lost the VS if it came off the plane at the beginning of this sequence. It did not tell us it got an owie on its tail feathers. Therefore, we can pretty well conclude its tail feathers were present until the pretty flying winged silvery cigar quit speaking to us either because of a fatal owie or a deep pout over losing its things what make it go.

Yes, Joanne IS getting tired of this.

deSitter: In point of fact it would have been loud enough that ACARS would have reported it. ACARS did not. Therefore one can safely infer that loud bang and the event you propose might have caused it did not take place.

ACARS

ACARS

ACARS

Please do consider it in your scenarios, particularly VS scenarios, guys.

Chris Scott, re "VS (fin) and VS (vertical-speed)" I must have misread your message once I saw "VS". I must admit that "VS", "Vertical Stabilizer", and other synonyms is becoming a bit of a trigger of late. My eyes must have glazed over at that point. Please accept my apology.

To the Thermal Couple
 

For Thermalsniffer: thank you for addressing the "what were they doing just before things went all wrong" vis a vis comms. I had forgotten than from the earlier threads. That series of transmissions puts the "nodded off crew" as unlikely, though it doesn't address a course change in progress when an upset occurs ...
For Thermaller:
Before we go further I will point out that if you are not familiar with what actually goes into flying, your attempt to apply "common sense" is an argument from ignorance.
Why would he do that, since the technology in which you have such great faith is in operation, and you have grave suspicions about said Captain? := You appear to have contradicted yourself, yes?

Of all the things I have faith in in the airline industry, and don't, the aircrew are the sole remaining element of the industry I haven't tossed up my hands and given up on. (Aside: Just in case you are unaware, it is my opinion that the airline industry has gone a very long way down the highway to hell (both on the commercial side and on the governmental side) and the air travel experience is being destroyed, one little bit at a time, by people who know no more of flying than they do of fornication ... to badly paraphrase General Patton. I am not of the industry, my flying and instructing (and mishap investigation) was undertaken as a military pilot. My experience as passenger had steadily degraded over time, to the point that I have in place a personal boycott of the industry unless I absolutely have no choice but to travel by air).

But back on topic of why the crew duties on long haul missions are broken up into pieces, the most dangerous elements of flying are the TAKEOFF / Departure phase, and Approach/LANDING phase, both of which you can call the terminal phases of flight. (Being at each end of a route). The enroute phases are statistically less dangerous. Check the history of fatal accidents if you doubt me. More of them happen during takeoff and landing.
EDIT for a correction: That would include "departure" and "approach" phase, which accounts for such things as bird strikes and midairs ...

Pilots know this, and so, dear sir, common sense dictates that the Captain must be alert for the most dangerous phases of flight, and on a very long haul route, like Rio to Paris, having him in crew rest during some of the cruise portion of the flight is a common, and effective, habit pattern used by numerous airline companies with generally good results. (A similar habit pattern is/was used by US Navy P-3 crews on long (8-14 hour) patrol missions).

For PJ2:

I am unsettled by your exposition on how weather radar training is sparse at best. For the modern all weather passenger liner, that radar is an important piece of kit that allows the aircrew to make critical safety of flight decisions en route, particularly when conditions change from "what we got in the weather brief" to "look at the size of that cell! :eek: "

However, I think this particular detail was raised in the earlier threads, and I'll leave elaboration on that discussion there. Your concise summarization and recapitulation is appreciated. :ok: