It's possible the airplane didn't hit the water intact. But so far, from the scraps of clues we have (lack of a red cab alt warn, tight debris dispersal pattern if that is the case), tends to discount the likelihood that it came apart at hight altitude.
Because of the ACARS transmission requirements and characteristics and need for normal ships power, I feel it's safe to say that the airframe was intact at the time of the last transmission 0214z. Whether that Amber ECAM Advisory was a Cab decent advisory, or, an amber "Excessive Cabin V/S" has not been answered yet completely to my satisfaction by the techs here and other places in an affirmative fashion. They suspect that that's what it is; but the jury is still out even when they are referencing the 330 TSM and AMM's. It's not a red warning however imho.
Again, I don't see any acars evidence that a complete loss of cabin pressure occured prior to 0214z. (Maybe later in the dive at breakup.) But there is evidence of a severe loss of full flight control protections at 0213z caused most likely by loss of Air Data Computer function caused by loss of pitot air sensor data a few minutes earlier. (caused by, if previous airbus accidents reports are any guide: probe icing.)
Disclaimer: I have not flown the A330 and am unfamiliar with FBW.
But considering their wx and weight, a loss of control (jet upset) seems likely. Once you dive tens of thousands of feet in the dark like Adam Air did, high G's in the pull up are going to guarantee that things start coming off the airplane, (Cowlings and Fairing are the first to leave: we had two crews do this) likely followed by major structural damage of the forward and aft main spars in the wings and horizontal stabilizer. If you lose the rudder, then you're in bad trouble. But if you lose the vertical stabilizer (as was floating in the water), the game is completely over. I have examined airliners (as just a line pilot) after evasive flight control deflections, and the counter weights come off the control horns of elevators and large sections at the tips break off (if the stab is designed properly).
Some flyers brought the subject back up of Dutch roll at altitude. Unfortunately, airbus training that I've been in, doesn't demonstrate how to counter the effects of dutch roll if all yaw damper function is lost (the: that's never going to happen mentality). If line pilots try to use the rudder to right the aircraft, they will loose control even if all the flight controls are working properly. The correct way to keep flying at altitude is so tricky with the roll spoilers only (opposing every roll motion AFTER the roll is at it's zenith), that you are strongly advised to slow down and descend to a lower altitude immediately, like say FL290. This is sadly, going to put you is the bad weather were you don't want to be. But if you don't do it, I'm afraid not even old Mr. Neil Armstrong could save this one. Maybe at Edwards on a nice day, but not in the dark, in a storm with failing flight controls and failing instruments at the same time.
If all yaw damp function was lost, this would have quickly become a compound emergency that 90% of line pilots could not control even if they were "sticks".
My experience with rudder limiters is that it is expected that it will fail in its present mode. For example, if it fails at FL350, in high speed/low travel mode, you will loose rudder travel capability at low/slow altitude. If it fails in low speed mode, and now you're indicating fast, you could break the tail off with even normal rudder inputs. The problem is, with AF447, nobody knows at 350 in cruise what mode it failed in with the airspeed all over the place.
Right?
CC
The above, as all my posts are, are just my opinions only.
Last edited by Captain-Crunch : 9th June 2009 at 07:17.
Reason: added disclaimer
I declare my amateur status, just another seeker after information.
I would think, in view of the importance of Pitot tubes, that they should be at least of different types so that a common failure did not cause them all to fail at the same time.
Dissimilar components cause as many problems though. If you want to rely on being able to compare the outputs, then the components have to be practically identical. In particular, you're forced to design to at least the same specification, and perhaps the actual same design details (in the case of a pitot probe, geometry for example). So the same extreme conditions which will disable probe A will quite likely also disable probes B and c anyway. meanwhile you have to deal with the nuisance of 2 or 3 suppliers for one part, carrying more spare parts in the maintenance pool, and so on.
This may well not be common failure - in the sense of the probes being at fault - it may be the case that the environment was too much for them.
Suppose you wish to drive your car quickly, and put high speed-rated tyres on all 4 wheels, but to "be safe" you go for one Michelin, one Goodyear, one Bridgestone and one (someone else). Then you drive at 20mph over the rated limit for all the tyres anyway. The fact that they are dissimilar sourced won't do much good, in all likelihood. You're pushing them all outside their design spec anyway.
Quote:
I understand three pitot tubes and three ADIRUs. Do A330s also have a steam ASI? If not I can imagine that all three pitot failure would be very difficult at high altitude, turbulence, even moderate, and in the dark.
ISIS is the "integrated standby" for when the main three systems fail - but it still has to source pressure from outside, so again, the environment could well be the issue. Not the aircraft components.
Quote:
Is/are AoA indicators part of the pitot tubes?
No, different component. Some a/c use measured AoA to correct the measured air data - I don't know if this is the case for A330 or not.
Quote:
Are the Pitots electronic, ie, are there sensors in the pitot heads or are there still air pressure tubes back to the ADIRUs. Are the static heads duplicated for each pitot head, do alternate static cut in automatically, by electric switch or (like mine) by pulling a plug/ turning an air cock? (Or am I being naive assuming there is alternate static?)
Air pressure lines to the ADIRUs, I believe. Most large a/c will have duplicate (left/right) statics for each pitot, to balance sideslip effects; again, I expect that to be the case here. The back-ups are through the multiple ADIRUs and ISIS - I doubt the crew can reconfigure the system beyond selecting which ADIRU they can display data from.
I'll remove my speculative statements if/when someone more knowledgable comes along
You then wrote; 1 ) asking for any proof of a " turbulence encountered " message, again the link I provide has the list of received messages -and sure enough , there is NOT a" turbulance encountered" message. ( Voice, ACARS or keyboard..)
I don't think so. A message about turbulence is NOT going to be sent on that list to maintenance. Don't you understand this? Those are all AUTOMATED messages sent within miliseconds of the computer detecting the comparator disparities to the MECHANICS.
A human hand on the keyboard is likely to send a turbulence report to????????
Flight Operations! Assuming he pushed the right ACARS MESSAGE DEST button in turb!
CC
Last edited by Captain-Crunch : 9th June 2009 at 06:45.
The F/CTL computers will report faults if they get enough bad air data info
Been through the FCOM3, and no where does it indicates that an ADR failure (or all of them for that matter) would fail the PRIMs or SECs?
They do receive information from they ADRs, but as the the fault was recognised by the PRIM, (the ADR DISAGREE fault was announced, indicating only two ADR were being used by the PRIMs and these ADR disagreed), ALT LAW would be latch and it would appear to be the end of it. Would you care to explain a bit more?
I didn't get the impression that either dani's post or lomapaseo's were referring directly to you or your posts. In dani's case he wasn't at all swatting at flies; he was making (what I thought at least) was an accurate and appropriate comment re some of the speculation of the past day. It seems to me that Lompaseo was doing the same thing.
Grizzled
Thanks for that.
Typically if I intend to counter a single post idea I will quote it. If I intend to offer a rebuttal directly to a person's individual opinion then I will include their name to avoid any other attribution.
PJ2 posts are quite capable of standing on their own and eloquently expressed. I might be adding my own tint of color from time to time on the subject just to broaden the readers outlook
All my posts regarding a theory where an exploding oxy bottle (located in the avionics compartment, where all the computers are located, and very near all the probes as well) would be the root cause of the accident (QF had an oxy bottle explode a few months ago, resulting in a huge hole in the fuselage) have been deleted!! Even the post where I ask what happened with my previous posts has been removed.
Is this thread being censored?
Yes. Posts which speculate on causes not backed up by the facts are being deleted by the moderators, I believe.
There is no reason to suppose any such explosion. There was no explosive decompression indicated.
In this scenario, how would you explain that radio was not used for MAYDAY
Good Question Philpop,
Since you asked respectfully, unlike Christy, I'll answer.
It takes a good number of seconds via any means to get a message off, no matter is it's HF, (high freq), ACARs (even longer) or even VHF on guard.
If the chit hits the fan, and you start fooling around looking for your hand-mike, screaming for people thousands of miles away to help you, then you will die. This wasn't a small thing that happened (Full Pinball TILT). The automation went haywire. The train came off the track. If you start spinning sideways in your car and decide right then, that you need to call for help on your CB..... guess what? Better hope that Channel 16 is the Coroner!
The first thing you must do, at all costs, is Hand Fly the Machine, while the other guy (let's hope he wasn't in the head) gets the train back on the track by restoring Air Data that the autopilot will accept. If you waste even a few seconds scratching your head at 500mph, it's adios controlled flight!
But these poor guys had 3-4 minutes of shear terror to deal with. And it's clear they never got back under control.
Aviate (get it under control, using hand flying and partial panel skills not taught anymore)
Navigate (radar cell avoidance)
and lastly, if you don't have enough to do already with the HAL-9000 going "DingDingDingDingDing"
Communicate.
CC
(see? It's not the Bermuda Triangle out there. It's over-reliance on automation imho.)
Last edited by Captain-Crunch : 9th June 2009 at 06:54.
Reason: omitted nuts, cleaned it up
Been through the FCOM3, and no where does it indicates that an ADR failure (or all of them for that matter) would fail the PRIMs or SECs?
They do receive information from they ADRs, but as the the fault was recognised by the PRIM, (the ADR DISAGREE fault was announced, indicating only two ADR were being used by the PRIMs and these ADR disagreed), ALT LAW would be latch and it would appear to be the end of it. Would you care to explain a bit more?
Perhaps the IR2 FLR immediately before the two F/CTL warnings in the ACARS list?
No ACARS messages were received after 0214, suggesting a catastrophic airframe failure shortly thereafter. The vertical stabilizer probably sheared off then, either causing the loss of control and break-up, or, more likely, as a consequence of detrimental airloads during departure from normal flight.
Airspeed calculation and indication depends on valid altitude calculation. Altitude calculation does not need airspeed, except for fine trimming. If icing the pitot tubes clogged them up, there is no logical reason to kill their companion static data outputs, as appears to have happened with this plane. It would seem to take a lot more icing to clog the static ports at the same time.
The Air Data boxes must have condemned the validity of their altitude outputs as well as airspeed, or the TCAS would not have flagged failed. TCAS does not have an airspeed input. Hence, if the "Pitot tubes are defective" is true, the Air Data boxes are also lacking necessary partitioning in their outputs.
By design, faulty airspeed computation/indication should not affect altitude computation/indication.
If clogged pitot were a not so rare phenomenon, altitude, attitude and ground speed would be used to simulate airspeed, using the last valid airspeed as baseline. But more than one pitot failing at a time is "too rare to consider."
Just because they have found the fin doesn't make it the prime suspect. There is nothing that indicates when it detached and very little to suggest why.
The speculators are out in force today. We had hot air bubbles 2 days ago and it's airbus composit material failure today. If they find an engine next are we going to blame that?
You should actually read what I posted, I suggested that the state of the vertical stabiliser was the evidence, it did not appear to have been subjected to the extremely destructive forces of impact, suggesting it seperated in flight.
The radar system they are using to discover these components is a very sensitive one. Visual range of the MK1 eyeball is very limited. These large pieces are most likely being discovered by radar. This suggests that is is unlikely they will find anything larger. I know these facts from my experience as a naval air controller, none of it is speculation.
If you wish to make non-constructive comments and wait for the final report I suggest you don't post.
The fact is, we know from previous experience and from Airbus admission that the fin is very sensitive to excessive sideloads.
In very extreme turbulence or in a loss of control situation, it is not unreasonable to expect such high loads on the vertical stabilizer.
It will be important to find out if the possible loss of the fin at altitude contributed to the accident or not.
Of course it could have remained attached until the airframe plunged in the water, but I find that option less likely. Time will tell.
In this scenario, how would you explain that radio was not used for MAYDAY
Human nature is at play here also. Whether it be as CC said, crew working too hard to make a call, or mind closing down by the reality of imminent death, I don't know, but aircraft have crashed with what seemed like ample time for the crew to holler something on the radio, but they did not. There's been grunts and groans on CVRs, but not much on the radio.
ACARS only transmits what it is told. It has no influence on any warning messages at all and acars does not time stamp them.
CFDS sends messages to ACARS for transmitting. CFDS also logs any ECAM warning without filtering. So for the real pilots out there can you now answer the following questions:
I have just tripped the A330 autopilot manually to off. Do I get a warning?
If yes acars will transmit it, if no acars cant transmit nothing?
Would the yaw damper remain operational following the air data disagreements?
IOW -- would it auto-disengage along with the AP and the downgrade to Alternate Law?
@Zeffy - there are reversion modes even in Alternate law where some yaw damping functions are retained. Also, even with a loss of ATT data from the ADIRUs, there are dedicated gyros to assist with yaw control on the A330.
I had earlier wondered the same thing when deciphering the ACARS messages and had been told (by an amused old fellow) and posted my answer earlier: An autopilot being switched off in the cockpit is nothing the Airbus CMS (Boeing acronym, sorry) will report home about.
To make it even clearer, logging and reporting to home base are two different functions and I have been told the choices of maintenance data sent can be airline-specific customizations.
A remarkable website of BEA, the French bureau of investigation and analysis for the safety of civil aviation.
No sign of a report on the alleged collision of F-GZCP with another airbus in late 2006, but they do have a report on a similar incident in 2002 between two Italian Airbuses 330 clipping each others wings on French territory. Mmm….
Anyhow, I came across another interesting BEA publication from August 2008, a fully fledged study on “turbulence and air transport”. In French only of course, but never mind. For those who like me want to have go at it, here is the link:
[url="http://www.bea.aero/etudes/turbulences.en.transport.aerien/turbulences.en.transport.aerien.pdf"]http://www.bea.aero/etudes/turbulences.en.transport.aerien/turbulences.en.transport.aerien.pdf URL]
The 34 pages of the report give a fresh reminder of the treacherous aspects of convective cells naturally also covered in the current PPRuNe thread. The report takes 48 occurrences between 1995 and 2007 with French registered, exploited or produced aircraft in France or abroad as a basis for study. Much more than half of the accidents and incidents have occurred in or next to Cumulonimbus, in which circumstances also the most seriously wounded were registered.
Despite a good flight preparation which includes in many cases an awareness of adverse weather conditions en route, it is stated that many pilots are nonetheless very surprised when they are actually confronted with turbulence. In particular for long distance flights the report points to the aids available to flight crews to stay alert and informed about actual and developing weather conditions en route. The on board weather radar is mentioned in terms of its vital importance, but also the challenges and even shortcomings of its optimal use. And more interesting and useful stuff.One final thing I would like to highlight has to do with the recurrent discussions in this thread about the supposed message that the AF 447 crew sent by ACARS to inform their company that they were experiencing severe turbulence. The report mentions explicitly that some French airline companies, in particular those that fly long distance routes, have dedicated departments that communicate via ACARS on updated weather situations en route. Where those departments are then specifically tasked with providing specific updates on weather to flightcrews. I would be surprised if AF would not have such a dedicated department. In that light an ACARS based exchange sounds very plausible. One of the questions in the AF447 case would then be why it was the pilot informing the dedicated department of the severe weather when they were experiencing it, and not the other way around so that avoiding action could have been taken.
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