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

AF 447 Thread No. 5

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

AF 447 Thread No. 5

Old 1st Aug 2011, 13:53
  #1221 (permalink)  
 
Join Date: Jan 2005
Location: W of 30W
Posts: 1,916
Likes: 0
Received 0 Likes on 0 Posts
Visibility of pf actions

Originally Posted by Indarra
I would like to take up more explicitly the suggestions that a few others have made about the visibility of PF actions with the sidestick. I do think care needs to be taken in considering this factor. Unfortunately, it perhaps has become a taboo or “jump over” issue because of unproductive AB vs Boeing arguments, and it has tended to be quickly dismissed in this forum. Similarly I do not see it picked up in explicitly in the BEA reports.
From 318 to 380, Airbus is doomed to the technology it has imposed to all - Very early on, common sense complains were formulated though.

Never, ever, BEA would address such topic.
Only AAIB has openly commented on it.
CONF iture is offline  
Old 1st Aug 2011, 14:10
  #1222 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes on 0 Posts
Hi GarageYears,
Originally Posted by GarageYears
The point of my post and the original mention by HarryMann was an attempt to understand the PF's comment regarding "crazy speed"... I do have some concerns that he may have thought the opposite - i.e. crazy LOW, but that would not agree with the use of the Speedbrakes.... so it has to be crazy as in 'fast'? But then you wouldn't select TO/GA in that case.
This expression "une vitesse de fou" is crystal clear. It always means, related to speed, "extremely high". A more correct grammaticale expression would be "une vitesse folle", exact same meaning, but here, "fou" is related to somebody: it is a metaphore meaning that only a crazy man (le fou) would go that fast.
takata is offline  
Old 1st Aug 2011, 14:10
  #1223 (permalink)  
 
Join Date: Dec 2006
Location: Melbourne
Age: 51
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Stall and horizontal stabiliser

Back to basics here if you don't mind... a conventional a/c pitches ND at stall because the horizontal stabiliser is still flying.

Some have referred to PF's glider training. In a glider stall even if you hold full back stick, the nose drops and a/c recovers (before stalling again if you continue) because the HS is flying and there is not enough elevator authority (at ~30 kt) to keep the nose up.

Of course the situation under discussion here is vastly different, but can elevator and power together really maintain a NU attitude in the A330 with a stalled wing and a flying HS?

At the extreme AoA eventually reached, wouldn't the HS have also then been stalled?
tmadam is offline  
Old 1st Aug 2011, 14:11
  #1224 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 64
Posts: 7,153
Received 352 Likes on 219 Posts
Old Carthusian
With respect, your resort to a false dichotomy in your response to me is an error. There was indeed something wrong with the aircraft, AND there looks to be something wrong in the handling of that malfunction, which falls in the realm of human factors.

Hand Solo's later point affirms that the hand flying issue need not lead to loss of control, certainly.

Others have likewise commented, which is why a point I also raised was training in Air France. See also Hand Solo's follow on comment:
"Train your crews right and the captain should have no problem leaving the cockpit during ITCZ transit."

My point in response to Dozy had to do with his FALSE statement that there was nothing wrong with the aircraft. YES, there was, the pitot tubes iced up, and that is a fundamental system for any aircraft in flight.

As has been noted for two years on these forums, that by itself need not result in a crash, but it was the triggering event that was the first in the sequence of things going awry until impact with the surface. It is also a contributing cause (from a human factors standpoint) or what looks to be at least one pilot not trusting instruments related to air mass inputs:
Airspeed (which was unreliable at various points)
Stall Warning
VErtical speed

Note, these aren't pure pitot tube inputs, but with AoA not readable, you have to infer something about AoA from your airspeed and attitude, as that's what you've got. Stall speed is what it is for various conditions, thus, if speed is unreliable, might one of the crew think that Stall Warning is spurious? (Then again, the pitch and power chorus will once again sing their usual in three part harmony ... )

There is a known remedy for the sub standard pitot tubes that hadn't been undertaken for that particular hull. To repeat for clarity: not a matter of either or, it's BOTH.

Insofar as the manufacturer is concerned, I am not sure they are clear from related fault (AF looks to get hit with a lot of fault here for the above) since manufacturer's input on training, airworthiness, and documentation is non trivial.
-----
HazelNuts: many thanks for post 1110. http://www.pprune.org/tech-log/45687...ml#post6609124
From this I understand that turbulence did increase the challenge for hand flying, somewhat, if your analysis is correct.
-------
For anyone: (from the CVR) Does this mean the PNF is taking controls in the left seat, or he wants the PF to roll left?

2 h 11 min 38
PNF: Commande à gauche ("Controls to the left")

BOAC: it appears we are thinking similarly here.
------
Caveat: what follows involving CVR excerpts is based on partial translation a few pages back, and edited to shorten this long post. Do not take this as gospel, please, gentle readers.

This just struck me:

PF: "I have a problem it's that I no longer have vertical speed"

Does this mean ... VSI (source, static and inertial) on PF display is gone wrong, he doesn't trust it, the value makes no sense to him, or his scan has broken down?
---------------------------
When I read from the Captain "it's not possible" I had a chill go down my spine.

2 h 12 min 33 There I'm going up ok so let's go down
2 h 12 min 34 VS : « Stall, stall » + cricket incomplet
2 h 12 min 39 ok, we're in TOGA
2 h 12 min 40 VS : « Stall, stall Stall alarm starts [continues until 2 h 12 min 46]
2 h 12 min 42 PF: In alti[tude] we're at what, here?
2 h 12 min 44 CAP: It's not possible
{Was "how far below the assigned altitude" or "we are stalled" not possible ... }
Two minutes before impact, the Captain appears to have to overcome the denial stage of dealing with an inflight malfunction. (Human factors issue, how people respond to malfunctions and emergencies. Granted, he was trying to catch up to a situation in progress ...)
---
PNF: Là tu descends oui You're going down now, yes
CAP: hey you ... you're in ... put put the wings level
PNF: Mets les ailes horizontales Put the wings level
PF: That's what I'm trying to do
**** Question on crew training is: why doesn't PNF take the stick now?*****
Thought, not fact, follows:

At this point in the event, (two minutes before impact) the aircraft may have been saveable with wings level, nose down, and fly out of the stall and then pull up to break descent. Does not look as though PNF's scan was working in the direction that would have led to this course of action. I don't think he realized that the stall warning was not spurious.)

CAP: Put the wings level
2 h 12 min 59 PF: I'm at the limit of the stick... to the left
CAP: Rudder pedals
2 h 13 min 23 : VS : « Dual input »
(PNF is on the controls, but doesn't take over the controls. ???)

A minute and a half previously he said
2 h 11 min 38 PNF:
Commande à gauche ("Controls to the left")
2 h 13 min 25
PF: What is... how come we're continuing to descend so fast?
***From CVR, it seems that neither the PNF nor Captain responds with "we are stalled." Ouch.
2 h 13 min 28
PMF: Try to see what you can do with your controls up there. The primaries etc
2 h 13 min 32
PF: At level 100
2 h 13 min 36
PF: 9000 feet
2 h 13 min 38
CAP: Easy with the rudder {PF Still trying to get the wings level?}
2 h 13 min 39
PNF: Climb climb climb climb (remonte / "climb back up")
2 h 13 min 41 :
VS : « Dual input »
2 h 13 min 43 :
VS : « Dual input »
2 h 13 min 45 :
VS : « Dual input »
2 h 13 min 47 :
VS : « Dual input »
2 h 13 min 40
PF: But I've been pulling to the back stop for a good while
CAP: No no no don't climb back up
PNF: Alors descend
2 h 13 min 45
PNF: So give the me controls. I have control

About two minutes and 20,000 feet (lost) after.. 2 h 11 min 38 PNF: Commande à gauche ("Controls to the left")
(assumes ~ 10,000 fpm decsent average rate ...)

NOTE: If "controls to the left" means at this point in his talking to PF "roll left" then some of my analysis is bogus.
---------------------------------------------------------
@ Owain: Post # 1161, thanks.

@T54: I fear you are too close to right, in re psychology.

@Gonebutnotforgotten:
It seems the BEA are wondering whether reappearances of the FD bars might have had an influence, but if they did, this merely shows how the poor fellow seemed unable to 'look through the bars' to see and assess the underlying attitude.

There may be good explanations for this behaviour, but I am struggling to find them. On the face of it, the question for Air France is whether this skill level is typical (in which case they have a humongous training problem to resolve) or unique to this co-pilot (in which case checking and evaluation needs attention).
I used to hear something about "HUD cripples" who were forced to fly on regular instrument scans ... but won't digress.

@ HarryMann: posts #11778. Thanks, clears up a few things.

Last edited by Lonewolf_50; 1st Aug 2011 at 15:32.
Lonewolf_50 is offline  
Old 1st Aug 2011, 14:27
  #1225 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by "Lonewolf 50
For anyone: (from the CVR) Does this mean the PNF is taking controls in the left seat, or he wants the PF to roll left?
2 h 11 min 38
PNF: Commande à gauche ("Controls to the left")
The PNF announced to the PF that he was making himself an imput to the left (which can be seen at the same time on the track recorded).
This happened when aircraft departed to the right, despite the PF already applying full stick deflection to the left.
takata is offline  
Old 1st Aug 2011, 14:34
  #1226 (permalink)  
 
Join Date: May 2011
Location: Australia
Age: 63
Posts: 200
Likes: 0
Received 0 Likes on 0 Posts
PF lost his scan, panicked,overcontrolled and zoom climbed whilst experiencing somatogravic disequilibrium, and it took them more 20,000 feet of confused high AoA stall at massive ROD to get anwhere near "I have the aircraft".

From reading the transcripts, i'd say PNF was their best chance.
Mimpe is offline  
Old 1st Aug 2011, 14:40
  #1227 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 64
Posts: 7,153
Received 352 Likes on 219 Posts
takata, thanks for that. If the PNF was on the controls at that point, this has me very puzzled.

(IIRC, PNF was senior man in the cockpit before captain returned).

If you have to come onto the controls, to correct a flying issue by the other pilot, the standard CRM I am familiar with is that you make a control change (you take controls) and you fly until it's right.

Not sure what one would find in Air France SOP in that situation.

I just had a weird thought:

The PNF was wondering "why is captain not back in the cockpit?" at some point. Perhaps, on his way back to his rest station, he had to visit the lavatory, and when the recall came he was finishing up the business, or in the middle of it. This might explain "delay in response" that had the PNF concerned ...
Lonewolf_50 is offline  
Old 1st Aug 2011, 14:52
  #1228 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes on 0 Posts
Hi Lonewolf,
Originally Posted by Lonewolf 50
IIRC, PNF was senior man in the cockpit before captain returned.
Well... no!
That's the part missed by almost everybody about "command of the flight" and it is also part of BEA comments (and concerns) about the flight deck management.
In fact, the captain left his command to the PF -the younger F/O. It is the sense of captain question about jr. F/O licence; he is checking if the jr. F/O can take "command" during his rest.
Air France doesn't make any distinction between F/Os seniority (both are presumed competent).
SOP is that the F/O "in command", when captain leaves the FD, should be the one flying: hence here, it is the PF who is in "command", not the PNF. This should be formalized by a captain annoucement about who is taking the command until his return, but there was no such a formal "passassion of command".
Air France changed that after AF 447. Today, the pilot "in command of the flight" would be the F/O PNF in left seat.
But it was not the case at this time.
takata is offline  
Old 1st Aug 2011, 15:09
  #1229 (permalink)  
 
Join Date: Jul 2011
Location: USA
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
prend la priorité

To repeat my dumb question (possibly overlooked because of the delay before my post with the CVR + VS appeared)...

From page 99 of the report in French,

2 h 12 min 16
Le pilote en place OPL prend la priorité.

2 h 12 min 17
VS: « Priority right »

According to the key on page 89, "OPL" is the PF:
Copilote en place droite (PF) pilotant avec le manche OPL

Was the "PF" (sitting in place OPL) not actually the one with "la priorité" up until that moment??
gpc62 is offline  
Old 1st Aug 2011, 15:18
  #1230 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Lonewolf 50
I just had a weird thought:

The PNF was wondering "why is captain not back in the cockpit?" at some point. Perhaps, on his way back to his rest station, he had to visit the lavatory, and when the recall came he was finishing up the business, or in the middle of it. This might explain "delay in response" that had the PNF concerned ...
This is based on something said by the PNF, I presume. But it is not the meaning I understood myself from the context:
- 2 h 11 min 06 : (…) il vient ou pas
The French pronom "il" is undefined, it may be related to something or someone. But all the discussion between pilots is about aircraft control up to this point and after this point. PNF wanted the PF to control his pitch during the climb. It is obvious that he is irritated by PF way of flying and slow corrections. PNF is very authoritative and PF seems quite stubborn.

So, I would interpret this sentence related to aircraft control, not to the captain: it sounds like an exprimed PNF concern about aircraft response time to imputs from the PF:
- have you got a response or not? (implying: I'm asking you to correct your pitch for a while but I can't see that we are going down)
takata is offline  
Old 1st Aug 2011, 15:23
  #1231 (permalink)  
 
Join Date: Mar 2010
Location: Sweden
Age: 87
Posts: 67
Likes: 0
Received 0 Likes on 0 Posts
Power and attitude

I have now read many statements that the correct action should have been "pitch and power" at cruise level. If this is really true can any of the knowledgeable posters explain to me why autopilot disconnect was so urgent when speeds started to become strange. Could it not have continued on by simply keeping pitch and power with some noisy kind of alarm to the pilots. They could then have chosen to keep it on or disconnect it at once. The same might be valid for the flight law change.
I am not a pilot so I am looking forward to good arguments from some of you
Diversification is offline  
Old 1st Aug 2011, 15:39
  #1232 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 70
Posts: 1,319
Received 24 Likes on 13 Posts
CAP: Là je sais pas là ça descend
I don't know we're going down

This was in reply to a question as to what should be done. Is the Captain's reply to be taken as 'I don't know why we are descending' ie that he accepted they were but couldn't figure out why - if so, not very encouraging to the PF, or that he didn't believe that they were descending ?
Mr Optimistic is online now  
Old 1st Aug 2011, 15:43
  #1233 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 64
Posts: 7,153
Received 352 Likes on 219 Posts
takata, thanks, to put it in words that make sense to me:

Even though in the "Captain's seat" (left), the PNF (who also has more time in this model of aircraft) is not the acting Captain (aircraft commander) for that leg. He is by role definition the co-pilot. This goes a long way to explain some of why he was trying to talk the PF back into level flight.

Does that fit what you said, or have I misunderstood you again?

This whole time, since the first discussion of CVR release, I have been under the impression that the PF (at A/P disconnect) was in the Right Hand Seat.

Is that incorrect?

Secondly, since this crash, AF has since changed policy so that the senior man on the flight deck is indeed the senior man on the flight deck.

Right?
Lonewolf_50 is offline  
Old 1st Aug 2011, 16:05
  #1234 (permalink)  
 
Join Date: Jun 2009
Location: Germany
Age: 71
Posts: 776
Received 3 Likes on 1 Post
DozyWannabe
@jcjeant - Nothing to do with any "protections" as such, travel limiters on hydraulic surfaces have been around for donkey's years (you don't want the same input:deflection ratio at cruise as you do at takeoff or on approach!). It looks to me like the limiters were functioning as they should have been - restricting surface travel while apparently in stable cruise phase and giving maximum authority when things started to go pear-shaped.
i had asked that question at least two times before, and your answer motivates me to try it a third time:

If the SS input to the flightcontrols, in this case to the elevators (and the THS???) is modulated according to speed, what speed source is used and is that a gradual change or a change of lets say 2 or three different datum values?


I think this question is very important, as we see a drastic drop of IAS after AP dropout while PF was (mis)handling the SS. If this new "false speed" changed the modulation of the SS input to the extreme low speed regime (wich at that time was not cosistant with the real speed), then the SS inputs of the PF would suddenly cause much greater flightcontrol deflections than moments before. It would explain part of the initial SS control problems and if THS travel is speed dependent as well we should look into THS travel to NU in relation to later (when speeds where valid again)THS travel ND also.
RetiredF4 is offline  
Old 1st Aug 2011, 16:07
  #1235 (permalink)  
 
Join Date: Jun 2009
Location: VA, USA
Age: 58
Posts: 578
Received 0 Likes on 0 Posts
Bear:

PF was in the RHS.

As for law:
2 h 10 min 22
PNF: Alternate law protections
Alternate law protections
Is clearly stated.

Where do you get the idea that the FCS will
"sort out" stick commands for best Flight Path? (NORMAL?)
That hardly includes waving the SS around in more or less the direction thought to be about right and have the "magic" figure out how to fly the airplane. You can go and read how Normal Law works.

Yet again I feel you are just throwing poop out there. The difference between considered opinion, extrapolated from the facts we have, and some of the imaginings you have blessed us with over the weeks is a large void. I am all for free thinking, but ever since you pestered all and sundry with your assertions of V/S loss in-flight things really haven't panned out for all your musings...
GarageYears is offline  
Old 1st Aug 2011, 16:11
  #1236 (permalink)  
 
Join Date: Mar 2006
Location: Choroni, sometimes
Posts: 1,974
Likes: 0
Received 0 Likes on 0 Posts
From 318 to 380, Airbus is doomed to the technology it has imposed to all - Very early on, common sense complains were formulated though.

Never, ever, BEA would address such topic.
Only AAIB has openly commented on it.
Sad but true.
hetfield is offline  
Old 1st Aug 2011, 16:17
  #1237 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Lonewolf_50
Even though in the "Captain's seat" (left), the PNF (who also has more time in this model of aircraft) is not the acting Captain (aircraft commander) for that leg. He is by role definition the co-pilot. This goes a long way to explain some of why he was trying to talk the PF back into level flight.
Does that fit what you said, or have I misunderstood you again?
Well, concerning F/Os, they were both "co-pilots" for this leg. The one really acting as "co-pilot" during this leg was in fact the junior F/O, simply because he was the PF all along from take-off under captain command. At one point, captain ask him if he wants to take a rest, as he seems to be concerned by F/O long duty time. His answer was : "No, I don't feel tired".
When captain leaves, he could have picked the other F/O as "aircraft commander", but he didn't. He implicitely confirmed that "aircraft command" was on the hand of the PF.
I don't know the history of this crew. Was it usually composed of Captain + senior F/O? All we know is that the junior one was comming back from holiday. He certainly did not fly the previous leg with the same captain, but nothing says that the other F/O was also part of his usual crew.
Originally Posted by Lonewolf_50
This whole time, since the first discussion of CVR release, I have been under the impression that the PF (at A/P disconnect) was in the Right Hand Seat.
Is that incorrect?
Right, that's the only thing we knew for sure (we were guessing about who was flying, not from where). Now, we know also who was the PF, on the right hand seat.
Originally Posted by Lonewolf_50
Secondly, since this crash, AF has since changed policy so that the senior man on the flight deck is indeed the senior man on the flight deck.
Right?
It's not about seniority. Any F/O is still considered to be a possible choice for captain to pick for his replacement (should be determined pre-flight). It's about training for F/Os to perform the task as newly defined:
- Acting aircraft commander, PNF, left hand seat.
- PF, right hand seat.
takata is offline  
Old 1st Aug 2011, 16:23
  #1238 (permalink)  
 
Join Date: May 2000
Location: Glorious West Sussex
Age: 76
Posts: 1,020
Likes: 0
Received 0 Likes on 0 Posts
I think readers may find this significant...assuming my translation is correct from Page 78 of the report.

L’altitude maximale d’environ 38 000 ft a été atteinte à 2 h 11 min 10.
The maximum altitude of about 38,000ft was reached at 2 h 11 min 10.

Peu après 2 h 11 min 30, le PF dit deux fois qu’il a perdu le contrôle de l’avion.
Shortly after 2 h 11 min 30, the PF stated twice that he had lost control of the aircraft.

A 2 h 11 min 37, le PNF dit « commandes à gauche », prend la priorité et donne une action
brève en butée à gauche ; le PF reprend presque immédiatement la priorité sans aucune
annonce et continue à piloter.
At 2 h 11 min 37, the PNF said "controls to the left", took Priority, and give a brief control input left (?to the stop?)(en butee); almost immediately the PF took Priority back without any announcement and continued flying the a/c.

Technical note.. Airbus sidesticks have a "Takeover button" which when pressed disables the other sidestick. This is known as "Priority Left or Right". There are technical complexities but the important message is ...

RHS: I have lost control
LHS: OK I'll fly it
RHS: No I'll fly it anyway.......
TyroPicard is offline  
Old 1st Aug 2011, 16:28
  #1239 (permalink)  
 
Join Date: Jan 2008
Location: London
Age: 68
Posts: 1,269
Likes: 0
Received 0 Likes on 0 Posts
CAP: "Là je sais pas là ça descend"

in no way is this one single sentence. I was raised partly in French, the second "là" is out of place within one sentence. It suggests a second sentence, therefore:

Là je sais pas. Là ça descend

or to put it differently:

Là je sais pas .............. Là ça descend

Whatever the conclusion is, this sentence is crucial alongside the decisions or not of the PNF or the CDB (not) to take control
vanHorck is offline  
Old 1st Aug 2011, 16:28
  #1240 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 70
Posts: 1,319
Received 24 Likes on 13 Posts
Any particular significance to AoA sensor #1 consistently reading low ?
Mr Optimistic is online now  

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.