Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF447 Thread No. 3

Tech Log The very best in practical technical discussion on the web

AF447 Thread No. 3

Old 7th Jun 2011, 01:33
  #1521 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Machinbird
Well, seems to me that when various facts of the case become public knowledge, it becomes very hard to doctor them to suit an agenda.
Erm, that is true. However, are there unintended side effects such as premature finger pointing?

If the data gets altered those altering it face a problem. Secrets are not normally very well held, especially in this age of Wikileaks. There are enough people watching the physical hardware containing the data and the extraction of the data that pushing out forged data will be a very high risk behavior.
JD-EE is offline  
Old 7th Jun 2011, 01:46
  #1522 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Likes: 0
Received 0 Likes on 0 Posts
Wallybird, if I may brag a little in turn, when I left college and entered industry I had experience far beyond that of the usual graduate. (Which seemed to piss off some of my peers no end.) I entered industry as an electronics engineer in the communications electronics field with an MS degree. I had already been designing and modifying radios for over a decade on my own. I had a very good idea what those silly little electrons I was pushing around could do.

I continued to learn. And I pushed around ever larger batches of electrons. (Then I literally got bored and moved over into the software realm - partly by "long story" accident.)

And I was an exception with two things in my favor, the self taught experience I had and a strong affinity for communications electronics and software. I was emotionally committed to my job.

It sounds like you were to. And I hope you have continued to learn. I presume you are not quite so naive today as you were straight out of your first flight training. And maybe you've learned some practical things about what you're flying now that were not taught in any schools.

However, there is evidence on the ground that people who are not highly committed to their job, in love with it as it were, who get into pilot training and somehow come out the other end with their piece of paper entitling them to be a member of a transport aircraft's cockpit crew. Just off hand 9/11 comes to mind right off.

I am very distrustful of somebody who comes out of training of any sort as a know it all or thinking he knows it all. Generally they don't. And their overconfidence, their hubris, can lead to a fall. (It is not inconceivable something on the CVR that has been released may implicate PF of having a fatal case of hubris.

I had the good sense, when I hit industry, to realize I knew a lot, had a near intuitive feel for what electrons would do, and anticipated I still had a things to learn that would be fun having learned them. (I admit to bitching about the learning process.)
JD-EE is offline  
Old 7th Jun 2011, 01:48
  #1523 (permalink)  
 
Join Date: Aug 2005
Location: fl
Posts: 2,561
Likes: 0
Received 0 Likes on 0 Posts
We got in a low speed buffet in an MD 80 when my captain decided to get clear of turbulence by climbing faster seeing the blue sky above in the clouds and his speed got slow. I told him he was too slow so he hit alt. hold at 365 climbing to 370 but it was too late and even with max power we couldn't get out of it. I told center we needed a lower now but we had opposite direction traffic 12 oclock 5 miles so they couldn't clear us lower. The opposite direction traffic was at 350 1500 ft below us so we never had legal separation back then in the 80's. We selected 500 fpm descent to keep from going into a deep stall with the plane buffeting even with the 500 fpm descent. I figured we needed 20 seconds to pass him in the clouds so once we were clear ATC let us continue our descent to got full control back.

I hope when the final reports come out we will understand what made the PF think he had to pull back instead of push forward. If we had pulled back we knew what the results would be. A deep stall and total loss of control. I am not proud of what we did that day because that is the only time in my life I felt out of control of our aircraft because we weren't paying close enough attention. It never happened again and that was over 15,000 hrs ago.
bubbers44 is offline  
Old 7th Jun 2011, 01:49
  #1524 (permalink)  
 
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes on 0 Posts
Thanks PJ2,

I would suspect the -80E would be similar.

I would think the CFM's on the A-340 would be working very hard at Mach 0.83 and 35K, pushing the edge of their capability, could have used a slightly larger fan along with an additional LPT stage with more modern airfoil aerodynamic efficiencies that are now available.
Turbine D is offline  
Old 7th Jun 2011, 02:27
  #1525 (permalink)  
 
Join Date: Jul 2003
Location: An Island Province
Posts: 1,252
Likes: 0
Received 0 Likes on 0 Posts
S_Ed, (#1581) I don’t know, but your question could be added, or even associated with these:- http://www.pprune.org/tech-log/45283...ml#post6492274 #1305

And what about the IRU aspects too?

PAX in75, '68'
alf5071h is offline  
Old 7th Jun 2011, 02:35
  #1526 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Likes: 0
Received 0 Likes on 0 Posts
Tactile feedback

MurphyWasRight and others, I'd propose a tactile feedback to the other side from that which last pressed the I've got it button. Then the PNF can feel what is going on. Once he takes over there's either no feedback (which should be the fail safe condition) or there is simple stiffness feedback as gums seems to say existed in military aircraft.
JD-EE is offline  
Old 7th Jun 2011, 04:02
  #1527 (permalink)  
 
Join Date: Jun 2009
Location: somewhere
Posts: 451
Likes: 0
Received 0 Likes on 0 Posts
Tactile feedback

JD-EE:

In normal situations the 'feedback' will be noticed by PNF.
If PF SS input is 1G climb (ANU), PNF will experience a 1G climb and knows PF pulled the stick (not to the max).

What you are suggesting is an interconnection with both SS (Bus bar or by Electric synchronisation) and in abnormal situations you want to disconnect this synch.

A lot of engineering ahead for a feature which will be of -no use- most of the time.

There is a visual indication of resultant SS inputs on PFD on ground.

mm43 post: http://www.pprune.org/tech-log/45283...ml#post6497401
A33Zab is offline  
Old 7th Jun 2011, 04:29
  #1528 (permalink)  
 
Join Date: Nov 2006
Location: SoCalif
Posts: 896
Likes: 0
Received 0 Likes on 0 Posts
What you are suggesting is an interconnection with both SS (Bus bar or by Electric synchronisation) and in abnormal situations you want to disconnect this synch.

A lot of engineering ahead for a feature which will be of -no use- most of the time.
The same could be said for Stall Warning and a lot of other basic items that are required by regulation on a normal airliner.

There is a visual indication of resultant SS inputs on PFD on ground.
Lotta' good that does at FL 350.

The yoke in your gut on a normal airliner tells you the other pilot is pulling hard. You don't have to look at a display or at his hand, or a Trim in Motion alert. Does the A330 have a Trim in Motion alert?
Graybeard is offline  
Old 7th Jun 2011, 05:04
  #1529 (permalink)  
Thread Starter
 
Join Date: Jan 2005
Location: W of 30W
Posts: 1,939
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by MWR
No need for mechanicall movement to keep PNF aware of the control inputs, a vector display would work well. Lenght and direction of vector (line from a central "0" dot) would show the inputs.
mm43 made also a kind of similar proposal … but No please !
Not another PFD item you need to concentrate on and add to the scanning - soon we'll need 5 pairs of eyes to collect all those direct visual targets ...


Originally Posted by Lazerdog
Have not seen much mention if any of whether altimeter data was available. It appears to me from looking at the releases that it should have been there, and would have been unreeling downward and would have been part of the instrument cross-check.
That’s a good point. The BEA note mentions a few altitudes but the source is not specified and neither if all recorded altitude data were consistent …


Originally Posted by JD-EE
He was apparently sitting on the right hand side and the RHS sensors were not recorded the way Air France had the FDR setup.
Question : Is the FDR settable at the airline request ?

On the media side, above all the news media formates … must be a reason why newspapers are in free distribution at airports.


Originally Posted by DozyWannabe
Airbus aircraft do retain a degree of artificial feel to allow the pilot to know what the *aircraft* is doing, but what CONF and the others are banging on about is the fact that on the Airbus you can't directly feel what the other *pilot* is doing.
Do I have ever said anything like it … Please quote !
MWS has well tried to explain but you don’t seem to hear …
CONF iture is offline  
Old 7th Jun 2011, 06:14
  #1530 (permalink)  
 
Join Date: May 2011
Location: US
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Thanks JD-EE, Well said.

If that turns out to just be a media invention, reported in so much mainstream European media, that's pretty shameless, especially included in the timeline as a direct quote.

But this thread and the discussions here of what is actually known (and variations thereof) have all been very rich and useful. Thanks to everyone.
alex_brin is offline  
Old 7th Jun 2011, 06:14
  #1531 (permalink)  
 
Join Date: Jun 2009
Location: NNW of Antipodes
Age: 80
Posts: 1,330
Likes: 0
Received 0 Likes on 0 Posts
Originally posted by CON fiture ...
Not another PFD item you need to concentrate on and add to the scanning - soon we'll need 5 pairs of eyes to collect all those direct visual targets ...
Ok, that's what I wanted to hear..., from someone who actually flies the A332. But while on the subject, have you any personal ideas of how best to ensure that the PNF knows what the PF is doing with the side-stick?

There's another way of looking at this, i.e. as Captain you either have confidence in your F/O and can attend to the necessary if hand flying becomes essential, or you are caught with doing it (the flying) yourself. You may never know which until that time comes.
mm43 is offline  
Old 7th Jun 2011, 07:12
  #1532 (permalink)  
 
Join Date: Jul 2009
Location: France - mostly
Age: 84
Posts: 1,688
Likes: 0
Received 0 Likes on 0 Posts
AoA definition

Originally Posted by HarryMann
I think you might find a common definition of AoA is freestream vector Vs Wing Zero Lift Angle, not fuselage axis datum
or even, Vs Wing Chordline Datum
Not for the A330 or any swept-wing transport I know. See for example the Perpignan accident report for a definition of AoA and vane angle, Boeing's Performance Methods, or Airbus' 'Getting to grips'. Must be light aircraft thing.

The zero-lift AoA varies with flap and slat setting, spoilers, and cg. For the A330 in clean configuration it is about -2 degrees. For the airplane, 'trimmed' lift involves the wing, horizontal tail and fuselage contributions to lift and pitching moment.

Last edited by Jetdriver; 7th Jun 2011 at 12:24.
HazelNuts39 is offline  
Old 7th Jun 2011, 07:12
  #1533 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,483
Received 0 Likes on 0 Posts
CONF iture;
Question : Is the FDR settable at the airline request ?
Yes, it's possible but complicated.

The JARs, FARs and CARs, (Europe, USA, Canada), require mandatory data frames which record parameters at mandatory rates, (frames-per-second) on the FDR.

The regulatory standards are uniformly, pitifully, low when it comes to recording aircraft data. The schedules for mandatory parameters in the regulations are complicated, having to do with manufacturing and original aircraft certification dates. I'm working right now with aircraft which legally require about 30 parameters and that's exactly what they have and nothing more; later certification dates require up to 88 parameters.

The A332 which was operating flight AF 447 had about 1300 parameters. My bet is most of them are engine parameters, then system parameters, then flight parameters, (instrument, ILS, 'g', aircraft performance) and the fewest, if any, will be ECAM text, FMA text, GPWS and TCAS text parameters.

One of the motivations to have more than the minimum number of parameters beside flight safety is maintenance troubleshooting. Most aircraft systems today are self-reporting but often ACARS-type messages are not sufficient for complex troubleshooting. Engine monitors record enormous numbers of parameters separately from the FDR as do some other aircraft systems. We know this was the case with AF447.

Regarding the recording of parameters, (which really means designing a large data frame into which engineering data is placed, which is later changed into readable parameters by the DFDAU), that is a very complex process and piece of software which costs an enormous amount of money to construct. The work is almost always proprietary so there isn't any sharing of information done in the industry.

The thinking behind leaving out the RHS airspeed would likely be that there were "two" such parameters and so there was no need for "three". Much of this work is the victim of "statistical thinking"...that "averages" can actually tell a rich picture, when in fact they cannot; a clear example is the one we frustratingly have before us.

For many reasons, some historical, the kind of investigative work now being done using the FDR data is not, quite frankly, the primary consideration in building data frames which go beyond the legally required minimum parameters. It is cost-savings, usually through maintenance, not investigative capability, that is the priority, but that is changing.

To illustrate the potential for the number of parameters possible if the data frames were actually programmed and installed, the C-17 has about 40,000 parameters. Military FOQA however, is mission-oriented. Reliable dispatching is the priority though flight safety is part of MFOQA.

The B787 will be a remarkable aircraft in this regard. It will record thousands of "standard" parameters and leave many thousands off the record. Should trouble develop with a system however, the recording system will shift resources and storage to that system and begin recording those parameters which are related to the system providing a far more detailed recording for investigative work.

In a word, the answer to your question about airlines being able to "program" FDRs, is "yes". Anything can be recorded for a price. Designing the data frame and buying the license to use it from the manufacturer, whether a major one like Airbus or Boeing, or corporations like SAGEM and Teledyne who retain standard data frames for most aircraft types or others who have been hired to do the work themselves, is the way such capability is achieved. For changes and new installations for aircraft already in service there is always an STC involved and that can be extremely expensive and a very time consuming process to accomplish. Most airlines are so thinly resourced and working on such thin margins that getting such work done is very difficult.

The reasons that the #2 airspeed parameter and many others, (I suspect no ECAM messages are recorded), are not present requires a more lengthy explanation but essentially the reason involves cost.

A good link for some basic info in "CAP 731" is at http://www.ihst.org/portals/54/Attac...20L_CAP731.pdf . See especially, Appendix B.

None of this discusses the QAR, primarily used for flight safety analysis programs. These recordings are usually far richer, with many more parameters. Such recorders are not crash-protected, (the QAR unit on AF 447 was mounted in the 800VU rack brought aboard the Ile de Sein; hopefully the card survived and they can read it).

I'd be happy to exchange PMs for further, as it's a bit OT.

Last edited by PJ2; 7th Jun 2011 at 07:40.
PJ2 is offline  
Old 7th Jun 2011, 07:13
  #1534 (permalink)  
 
Join Date: Jun 2009
Location: somewhere
Posts: 451
Likes: 0
Received 0 Likes on 0 Posts
Normal airliner?

GB:

Quote:
What you are suggesting is an interconnection with both SS (Bus bar or by Electric synchronisation) and in abnormal situations you want to disconnect this synch.

A lot of engineering ahead for a feature which will be of -no use- most of the time.
The same could be said for Stall Warning and a lot of other basic items that are required by regulation on a normal airliner.

Quote:
There is a visual indication of resultant SS inputs on PFD on ground.
Lotta' good that does at FL 350.

The yoke in your gut on a normal airliner tells you the other pilot is pulling hard. You don't have to look at a display or at his hand, or a Trim in Motion alert. Does the A330 have a Trim in Motion alert?
Normal airliner?

-Visuals make no sense on FL350 but does when - normally - needed the most.

-As engineer i'm an outsider but do you really have eye in what the PF is doing with his yoke in such a mayham? Don't you have your own role by then?
Maybe you are right and they had better installed a yoke to become a normal airliner, but that doesn't change the FBW philosophy and in fact B is or will be as much flown by wire than A.

-Trim in motion alert: only visual for as I know....and that will be a proper enhancement: to make it audible too.
A33Zab is offline  
Old 7th Jun 2011, 09:32
  #1535 (permalink)  
 
Join Date: May 2011
Location: US
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
a footnote

Just a footnote here.

From this France Soir article:
Airbus, la descente infernale : Tout s

where the quote is part of the timeline:

"2 h 11 min 45 s. Tandis que toutes les vitesses redeviennent invalides et que l’alarme de décrochage s’arrête, le commandant de rejoint les deux pilotes dans le cockpit. « Je ne comprends rien », lâche l’un d’entre eux, affirme sur France Info Michel Polaco, pilote instructeur et ancien patron de la station. L’avion tombe alors à grande vitesse et il n’est pas sûr que dans la nuit, en pleine turbulence et au milieu des alarmes, les pilotes s’en rendent compte tout de suite."


It seems that this information is coming from French journalist Michel Polacco (name spelled with two c's), who seems to actually be a well-respected French journalist with French public radio, France Inter, specializing in defense and aeronautics reporting. (Please any French members correct me, because he seems well known.) He is himself licensed as a pilot and instructor and also flies helicopters. He has a blog called Le Ciel par Michel Polacco, (The Sky by Michel Polacco), www.polacco.fr which seems well-informed reporting about current aviation news.

I'm sure we'll know more when the BEA report comes out later this month.
alex_brin is offline  
Old 7th Jun 2011, 10:34
  #1536 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,810
Likes: 0
Received 0 Likes on 0 Posts
Cool

Hi,

A33Zab

-Trim in motion alert: only visual for as I know....and that will be a proper enhancement: to make it audible too.
Airbus FBW serie was conceived with the aim to make the flight safer and also to streamline the operation of the aircraft
One may wonder if the designers still had this goal when they decided:
Remove the beeper trim wheel movement
Inhibited alarm when the stall speed is below 60 knots
jcjeant is offline  
Old 7th Jun 2011, 10:38
  #1537 (permalink)  
 
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes on 0 Posts
Another media episode in this saga.

How such firm conclusions about pilot training can be reached on the basis of the massaged information that has already been released is beyond me - well actually it isn't beyond me as such, it is simply depressing.

I suspect that there are serious issues with the way the Airbus is to be operated in such a non-normal case.

According to some of our esteemed posters, the notion of stall warners that turn themselves off, overly sensitive controls, lack of multicrew coordination with regard to the flight control command and position, autotrim systems that leave the pilot with full aft trim and the alleged volume of contradictory warnings and cautions are as inexplicable as a design as the apparent actions of the pilots.

Also, does anybody remember this incident? The A330 radar that didn't paint a CB. This has probably been answered somewhere, but which radar configuration was fitted 447?
Sciolistes is offline  
Old 7th Jun 2011, 10:43
  #1538 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,810
Likes: 0
Received 0 Likes on 0 Posts
Cool

Hi,

It seems that this information is coming from French journalist Michel Polacco
M Polacco is indeed a journalist well know in the aeronautical press
Usually he is seen as conservative and not giving into sensationalism
Some comment that he is even too cautious.
It is therefore surprising that this time it will suddenly gives in the sensational

Also, does anybody remember this incident? The A330 radar that didn't paint a CB. This has probably been answered somewhere, but which radar configuration was fitted 447?
Apparently ... (from BEA report) the pilots seen something on the radar ... as they warned the cabin crew of some turbulences aera ahead their flight ....

Last edited by jcjeant; 7th Jun 2011 at 10:54.
jcjeant is offline  
Old 7th Jun 2011, 12:05
  #1539 (permalink)  
 
Join Date: Nov 2010
Location: FR
Posts: 478
Likes: 0
Received 0 Likes on 0 Posts
Hello

disclaimer : this thread moved along too quickly for me to be able to cath all ; apologies if what follows was already discussed, I don't think so as a search on the word "abnormal" didn't return any match.

Since the publication of the note by the BEA (btw, it's not a report, semantics matters here), I was wondering why the THS would have stayed @ 13° pitch up, even when the PF made nose down inputs on its side stick.

2 answers were possible :
- it's normal (per specification, not meaning it's sensible in 447 case) ; but why ?
- it's not normal, and indicates a failure / bug in the THS or its command chain .

It now seem to me that "it's normal", i.e. the aircraft managed the THS as its conceptors wanted it to do (= no failure).
Indeed, we have :
- the ALT 2 LAW which is load factor pitch / direct roll / auto-trim / ...
- the ABNORMAL ATTITUDE LAW which is ~ the same as ALT 2 LAW with the exception of the auto-trim being unavailable.

The ABNORMAL ATTITUDE LAW is triggered if (non exclusive list):
- the [mesured I presume] speed is below 60kt
- the AoA is above 30°
Per the BEA note, at each time after the beginning of the final descent, one of these two conditions was met.
So the ABNORMAL ATTITUDE LAW should have triggered, meaning the auto-trim was lost, hence the THS stayed "stuck" at 13° value.

My question for those in the know : Does the ABNORMAL ATTITUDE LAW activation also trigger a message indicating to the crew that the auto-trim is unavailable ?
I know the DIRECT LAW does that ("USE MAN PITCH TRIM" on the PFD), but what about the ABNORMAL ATTITUDE LAW ?

Thanks.
AlphaZuluRomeo is offline  
Old 7th Jun 2011, 12:19
  #1540 (permalink)  
 
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes on 0 Posts
Apparently ... (from BEA report) the pilots seen something on the radar ... as they warned the cabin crew of some turbulences aera ahead their flight ....
Apparently... a radar paints returns with varying degrees of severity and decisions are based on that. Clearly some returns were apparent, but that doesn't mean the convection was accurately painted or that the whole area was adequately painted.

Last edited by Sciolistes; 7th Jun 2011 at 13:30. Reason: Smelling and gramer
Sciolistes is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.