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AF 447 Thread No. 9

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AF 447 Thread No. 9

Old 8th Jul 2012, 19:46
  #181 (permalink)  
 
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JD96

One thing I haven't seen mentioned on here (only reading the latest thread), is that it took 40 seconds to call the captain after autopilot kicks off, and another minute for him to arrive. I'm not a pilot, but it seems it should be policy for the captain to be called immediately in that circumstance
Call him/her back if you must and only when it's safe to do so, but:

1. You should have two type rated pilots at the controls who are capable of handling the aircraft, with or without the autopilot and with or without the captain being on the flight deck.

2. Calling the captain (via "phone" or similar) would take one of the pilots "out of the loop", albeit briefly, at a time when both pilots should be firmly focused on flying the aircraft.

3. In any event dependant on crew rest facilities, sleep patterns and umpteen other things you may not get the captain back onto the flight deck in a matter of seconds, it will possibly/probably take several minutes, which is the reason for point 1.


AF may have failed on at least one of those points.......

Last edited by wiggy; 8th Jul 2012 at 19:48.
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Old 8th Jul 2012, 20:57
  #182 (permalink)  
 
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There seems to be some departure from 'actual' parameters in that sim (as expected), as you describe a pitch down below the horizon with full THS and power. 447 managed to hold a high nose attitude in that situation. How much stick effort was required to hold the nose down against the thrust couple? Full forward, half
@PJ2
I share that concern. PF achieved a higher pitch attitude and stalled at lower speeds, mainly due to the fact that some ND SS and or reducing th NU SS input led to some g- reduction below 1.0 g without effectively reducing the pitch rate (see the Nz graphs of the respective time frame). TOGA application at that point (2nd StallWarning) and SS NU input forced a further increase of pitch without solving the speed and AOA problem. Thus when the stall finallly occured, pitch was a lot higher and speed was slower than what you describe in your sim exercise. With the nose lower like that gods g (gravity for the nonflyers) works a lot earlier than it would have for AF447, and the speed would be back in flying parameters a lot quicker.
Presently on leave on my iphone, therefore no further comments on the report.

Last edited by RetiredF4; 8th Jul 2012 at 21:00.
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Old 8th Jul 2012, 22:25
  #183 (permalink)  
 
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Looking back at one of HN39's graphics on post stall recovery, I was reminded of an earlier debate over "super-cooled" water. The matter has not been cleared up by the BEA as their conclusions include:-
The precise composition of the cloud masses above 30,000 feet is little known, in particular with regard to the super-cooled water/ice crystal divide, especially with regard to the size of the latter.
The equatorial areas of the Atlantic and the western Pacific are the spawning grounds for sometimes large tropical revolving storms. The mechanisms associated with these maritime environments and their affect on the upper atmosphere is still not fully understood.
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Old 9th Jul 2012, 06:31
  #184 (permalink)  
 
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Originally Posted by jcjeant
If this video exist .. maybe this will be seen on the judicial process ...
Enough of that pseudo transparency ...
Video animation of selected recorded data is basic stuff - Where is it ?
Full data are not available to all in the judicial process - Why is that ?

Originally Posted by Clandestino
Since the stakes are pretty high, I bet video will leak, as will CVR track, eventually.
How naive you can be ...
There was no such thing as a CVR track leak, there was intentional release of deformed data in order to format the opinion :

According to Amedeo from Le Figaro, the AF447 captain had stated :
On ne va pas se laisser emmerder par des cunimbs

But now the last CVR transcript from the BEA is :
On n’a pas été emmerdé par les cunimb hein

Completely different meaning.
I can explain if you need help.

What connection between Le Figaro and Airbus ... I let you guess.

It appears also that Fabrice Amedeo is the same guy that took part in this other piece of propaganda where the Airbus Chief Pilot himself was generously interviewed from the impressive A380 flight deck.



2 options for the families of the AF447 pilots :
Either they accept what's on the menu right now and try their best to resume 'normal' life.
Either they fight the system in research of the full story ...
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Old 9th Jul 2012, 09:29
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How naive you can be ...
There was no such thing as a CVR track leak, there was intentional release of deformed data in order to format the opinion :

According to Amedeo from Le Figaro, the AF447 captain had stated :
On ne va pas se laisser emmerder par des cunimbs

But now the last CVR transcript from the BEA is :
On n’a pas été emmerdé par les cunimb hein

Completely different meaning.
I can explain if you need help.
Yes indeed ...
But all this is weird for me (made sens .. or not)
Indeed this sentence (cunimb) is called when the plane is near Natal (the captain announces that he sees Natal just before pronouncing the sentence about cunimbs)
passing RUMBA
0 h 44 min 45
We can see Natal
ahead

0 h 44 min 49
We weren’t hassled by
cumulonimbus eh
It does cunimbs they met on "en route" .. Rio-Natal ?
Curious to see a meteo graph on this route .... (I see nothing special in the TEMSI appendix 12)
Or the sens is ... "it was no cunimbs between Rio-Natal" ?
It's usual to have cunimbs between Rio and Natal ?

Last edited by jcjeant; 9th Jul 2012 at 09:45.
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Old 9th Jul 2012, 10:56
  #186 (permalink)  
 
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And with 1783 fatalities in its history, according to a tally compiled by the Swiss-based website "Aircraft Crashes Record Office", Air France has been the second most deadly airline for passengers after Russia's Aeroflot.

Oops, that's harsh....
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Old 9th Jul 2012, 11:58
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Hi DozyWannabe,
but in the second case, even with +6000fpm selected, the FDs engage with an actual VS in excess of that. In that case, would the FD have commanded nose down?
Please see page 98 of the final report.

Apart from the first 20 seconds or so when PF pulled the nose up whilst trying to keep the wings level in ALT LAW, subsequently the FDs were reasonably closely followed.

From time 02:10:50 until 02:11:40, whilst the stall warning is sounding, the FDs are commanding nose up from 7.5 degs up to 20 degs.
It would be far less confusing if the FDs had remained out of view until reselected by the pilots, or if they reappear automatically then park at zero pitch and wings level command until a pilot manually "sync"ed them to a mode they want.
If the FDs had remained locked onto ALT FL350, then they would have commanded a nose down.

I fail to see the logic of this design.

Last edited by rudderrudderrat; 9th Jul 2012 at 16:55. Reason: spelling syntax
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Old 9th Jul 2012, 13:24
  #188 (permalink)  
 
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The flight tests did not go beyond approach to stall. The presenters opined that recovery from the developed stall is out of the envelope and that recovery is highly doubtful, even with proper actions. i.e. certification does NOT require recovery from a developed stall.
What Owain has theorized tells me that "doubtful" is a dubious vedict. He pointed out that from the data available, THS and elevators still had lift and authority. That supports the idea that recovery is possible, but what isn't certain is the altitude penalty paid to recover. (Though some estimates can be made). As note previously, they became, once stalled, two test pilots not well briefed on what they were testing ... and didn't know they were now in that role.
It seems as if the FDs, when 'valid', were reacting to the existing rates which is not the way I expect - ie 'Flight Followers' rather than 'Flight Directors'.
Confuses me as well. Makes sense to me that FDs are to be selected OFF when UAS is encountered. Back to flying attitude and power ... old school flying.
Correct. This is probably the most confusing part about the FD logic. The FDs are withdrawn automatically during unreliable airspeeds and the FMA modes are lost. If two airspeeds erroneously agree, then the FDs will reappear with present HDG and instantaneous VS. In the confusion of the moment, it appears to me that this crew then followed these new FD modes.
The first line of the Memory items of the "Unreliable speed Indication / ADR Check Proc" AP/FD .... Off was never accomplished.
It doesn't help to solve the problem when the FDs keep reappearing with erroneous guidance.
Arrrgggh!

For PJ2, since you've spent some time actually training AB3xx pilots:
You seem skeptical that the instrument scan of the two pilots on the flight deck at the time, heavily dependent upon the FD. Do you find very many pilots who go through your training sessions to be what I might call "FD" dependent? Do the training scenarios give you the latitude to find out where their scans are strong, and where they are weak?

It would appear that if one pilot is too heavily dependent on the FD, (PF in this case), that increases the problem the other pilot has in helping the PF get back into the game. (If I am making comments to him based on a scan of nose and wings, and he is following his FD, maybe we have a chance for confusion?)
If that "FD boresight" were in progress (guessing) then my understanding of some "why did they do that" is somewhat improved.
But only partly.
PNF appears to have maintained something of an instrument scan, in re altitude at least, as he was working (in vain) to correct PF's various errors. (Note: seems that he'd have helped more by making sure the memory item of disconnecting FD was accomplished).
What many of us are saying is that FD 're-enable' should either be inhibited without a deliberate selection by crew OR, less desirable, it should re-engage in 'acquire selected altitude' mode, although this latter could cause problems if slow and below that altitude.
Seems that the former is the more desirable.

Last edited by Lonewolf_50; 9th Jul 2012 at 13:32.
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Old 9th Jul 2012, 16:59
  #189 (permalink)  
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Hello Lonewolf_50;

I'm on the road at the moment and need some time to compose a response, as well as respond to RetiredF4's observations.
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Old 9th Jul 2012, 20:35
  #190 (permalink)  
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The flight tests did not go beyond approach to stall

Certification requirements have varied over the years. One always needs to check the certification basis for a given aircraft and, even then, it is not guaranteed that a variation wasn't agreed upon during the program.

As I recall, the 744 may have traded on the basis of the earlier models.

As to what the OEM ought to investigate, over and above the Standards, might be another matter.
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Old 9th Jul 2012, 22:15
  #191 (permalink)  
 
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The flight tests did not go beyond approach to stall
Makes me wonder why I did 3 QTG's recently that encompass 'the stall', as validated by IAS, buffet onset, stall AOA, and VSI break? QTG's come from flight test data.

There is a big difference between 'the stall' and a 'developed' (better word, aggravated) longer term condition.

One always needs to check the certification basis for a given aircraft...
as JT says.
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Old 9th Jul 2012, 22:39
  #192 (permalink)  
 
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Wondering why we are talking about "pitch rate" command versus "pitch" command. Can't command a rate directly, nor pitch itself, so to get a "pitch" value you must hold the stick fore or aft to get there, then adjust because the 'fuser is still trying to command a gee value - nominal one gee corrected for pitch attitude. Am I reading the manual wrong?

That being said, what in the hell are the pilots doing trying to follow the FD's? That's one theory out there on the streets, from what I have read.

I have always felt that a constant nose down attitude and some power to gradually fly out of the stall that the jet experienced would have been possible. 5 degrees, 10 degrees, no matter. Very glad a few have tried it in the sim or calculated the required maneuver. The jet does not have a pitch coefficient moment as we had in the Viper at 40 or 50 degrees AoA that prevents a nose down pitch moment using elevators and the THS.

If there is one thing about our primitive FBW system, it was a force transducer versus a position transducer for pitch and roll commands. So to hold a pitch attitude other than what Otto was trying to achieve to meet the gee command ( trim gee not a default of one gee), we had to exert "x" pounds. Releasing the stick commanded Otto to resume the trim command we could set. The 'bus does not allow the pilot to command a trim gee. So the pilot has to hold the stick fore or aft to get away from that one gee default trim condition. This feature was rather intuitive, despite lack of movement. To fight nose up trim we had to push forward, and vice versus.

This is still a great thread for discussion, and I am honored to be able to bitch and moan and contribute amongst all the commercial pilots here.
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Old 9th Jul 2012, 22:50
  #193 (permalink)  
 
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Lonewolf_50;
... seems that he'd have helped more by making sure the memory item of disconnecting FD was accomplished.
In that context, "We've losts the speeds" doesn't appear to have had any relevance to "IAS doutuese", and as that item wasn't sought in the QRH (at least no mention made), the PNF became concerned with -
(a) how the aircraft was being handled;
(b) the necessity to get the Capt back ASAP.
Unfortunately, the whole episode can be placed into similar categories -
  • Lack of training in high altitude UAS procedures
  • Lack of training in high altitude handling
  • Lack of CRM training.
Having said that, I and others have noted that a deviation would have resolved any issues, and we would have all continued on blissfully unaware that this accident was still waiting to happen.
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Old 10th Jul 2012, 00:58
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Until they passed 10,000 ft. there appears to have been no comment on their direction of travel... DOWN.

This was indicated ( and recorded). But it was not NOTICED by the pilots.

The presentation of this information might be improved.

( Seeing the hands of my old "Sensitive Altimeter" going round would have caught MY eye...)

( The lack of recognition of " STALL" has been discussed.)

Last edited by Jetdriver; 10th Jul 2012 at 03:12.
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Old 10th Jul 2012, 05:57
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The flight tests did not go beyond approach to stall. The presenters opined that recovery from the developed stall is out of the envelope and that recovery is highly doubtful, even with proper actions. i.e. certification does NOT require recovery from a developed stall.
Until they passed 10,000 ft. there appears to have been no comment on their direction of travel... DOWN.

This was indicated (and recorded). But it was not NOTICED by the pilots.

The presentation of this information might be improved.
Get the feeling that BEA doesn't want to dwell to much on areas which could be the basis of claims against Airbus.
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Old 10th Jul 2012, 06:42
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i.e. certification does NOT require recovery from a developed stall.
Final Report section 1.18.1.1

Regulatory aspects The A330 meets the requirements of the regulations in force – that is to say JAR 25 changes 13 or 14 and the special conditions imposed by DGAC – at the time the type certification application was made.
JAR 25 Change 13

JAR 25.201 (c) (2) As soon as the aeroplane is stalled recover by normal recovery techniques
My emphasis. BEA were just stating the facts
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Old 10th Jul 2012, 09:28
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Originally Posted by Indarra
Get the feeling that BEA doesn't want to dwell to much on areas which could be the basis of claims against Airbus.
Where does this come from? The BEA pulled Airbus up on the certification of the pitot tubes and the SB rather than AD approach with which they were to be replaced. Airbus was served with notice of intended action for manslaughter along with AF.

The BEA are *not* interested in protecting Airbus (nor should they be) and never have been.
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Old 10th Jul 2012, 11:35
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Where does this come from? The BEA pulled Airbus up on the certification of the pitot tubes and the SB rather than AD approach with which they were to be replaced. Airbus was served with notice of intended action for manslaughter along with AF
OK. Doze, I’ve been a little too cryptic.

The stall recovery issue
A number of respected posters (such as PJ2 #127, #145, #165 and Owain Glyndwyr #148, #149 and there are others) have made a case for the possibility that the aircraft could have been recovered after the stall. BEA is in effect saying that it is only interested in what happened until departure from the flight envelope. It’s saying that while maybe or maybe not the aircraft would have been recoverable subsequently, the issue is, in effect irrelevant, because it didn’t cause the departure from the flight envelope.

What I want to say was the failure to attempt the stall recovery was another hole in the cheese, and logically shouldn’t be dismissed so easily by the BEA. Stall recovery surely is another part of the backup offered by having human pilots as the final resource. And just maybe, just possibly, the reason why the BEA is not interested is because it raises the question of the inverted stall warning. To have included a recommendation about the inverted stall warning could place Airbus Industrie under GREATER legal pressure.

The non-recognition of altitude loss
Similarly a couple of posters have expressed surprise that the BEA’s report does not particularly pick up the crew’s evident ignorance of the descent down to 10,000. Some have made the suggestion that they only noticed when one digit came off the digital display. Again, I am wondering, ever so gently, whether the failure to highlight this disadvantage of a digital altimeter versus an analogue one, was also influenced by a BEA desire to keep FURTHER pressure off Airbus Industrie.

Caveat
There are a lot of pages to read, and I haven’t had the time to absorb everything, but think the above thoughts, which seem to share something with JCJeant, might be worth injecting.
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Old 10th Jul 2012, 12:04
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The BEA does address the issue with the stall warning inhibition.

Originally Posted by BEA Final Report (English version) p.190
"A few seconds after the transition to alternate law, the stall warning sounded briefly, even though the PF’s inputs should have made this warning sound for several seconds. The reason for this is the drop in the measured airspeeds, some of which fell temporarily to below 60 kt, while the angle of attack reached 40°. Furthermore, the drop in measured airspeeds to values of less than 60 kt during the stall caused the repeated activation and deactivation of the warning which may have made it considerably more difficult for the Captain to effectively analyse the situation on his return to the cockpit."
The presentation also stated that while recovery at a later stage *may* have been possible if the crew had advanced handling training, the fact that none of them did rendered a recovery very unlikely.

Quite some time ago I stated a belief that the inhibition of the stall warning below a certain speed was very unlikely to be Airbus-specific. This is something I still believe quite strongly.

Last edited by DozyWannabe; 10th Jul 2012 at 12:06.
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Old 10th Jul 2012, 12:24
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Originally Posted by Indarra
To have included a recommendation about the inverted stall warning could place Airbus Industrie under GREATER legal pressure.
The recommendation is stated on page 214 of the Final Report:
When airspeeds are below 60 kt, the stall warning is no longer available, even though it may be beneficial for it to be available at all times.
Consequently, the BEA recommends that:
€€ EASA require a review of the conditions for the functioning of the
stall warning in flight when speed measurements are very low.
[Recommendation FRAN‑2012‑051]
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