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

AF 447 Thread No. 7

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

AF 447 Thread No. 7

Old 22nd Nov 2011, 09:45
  #441 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Likes: 0
Received 0 Likes on 0 Posts
I can barely read a DFDR trace, and as such I'm certainly not going to attempt to second-guess the PF's thought process, but whatever it was, the overriding theme seems to have been to keep the nose up at all costs. The reason I mention the "rocketship approach" is because I wonder if he'd got it into his head that as long as he had the nose above the horizon and TOGA set, he was safe.

While the sim was being set up, I used the time to try out various different grip techniques on the sidestick. No matter how hard I gripped or whether I was moving with the elbow or wrist I could not get more than a fractional deviation in the pitch channel when moving it stop-to-stop in the bank channel without trying to add pitch input deliberately. This is not to say it didn't happen to the PF, but I don't think it's as easy as Machinbird thinks it is.
DozyWannabe is offline  
Old 22nd Nov 2011, 11:12
  #442 (permalink)  
 
Join Date: Jul 2009
Location: The land of the Rising Sun
Posts: 171
Likes: 0
Received 0 Likes on 0 Posts
If we speculate on the PFs mental state (always a dangerous thing) I think we have to assume that he had only one thing in mind. All other information which might have contradicted this view was ignored or excluded. Sadly, the planes behaviour was not a factor in his actions. Evidence in similar situations tends to indicate fixation on one thing not a variety.
A study of cultural issues here would also yield dividends. Korean Airlines experience in the 80's and 90's is highly relevant with supposedly better trained military pilots messing up big time. It is also interesting to note the lack of CRM prevalent during that period. It is not where the pilot is from that is important but the culture and environment he/she operates in.
AS TTex600 notes past accident history does not indicate that things were necessarily better. But as accidents have gone down with better technology and more reliable aircraft, human factors have become more visible. Whilst a case can definitely be made that training is being neglected the airline culture has a more significant role.
Old Carthusian is offline  
Old 22nd Nov 2011, 11:30
  #443 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by TTex600
I personally believe the cause is much deeper than the pilot not knowing how to get out of a stall.
Could you elaborate a little? I know you're talking about people you're actually meeting on the line here, but as far as this thread is concerned I don't think anyone has suggested that "Cause is pilot error, and we're done". Pilot error itself has myriad contributing factors including rest time, training, airline culture and human psychology.

As far as the airframe is concerned, it appears that recovery is relatively straightforward at the apex of the zoom climb, and becomes progressively more difficult as the aircraft sinks further into the stall. From the point they pass about 30,000ft on the way down it's impossible to know whether any airframe could have been recovered other than by using techniques which your average line pilot would not know, and in any case, from the moment they actually stalled they were in test pilot territory to start with.
DozyWannabe is offline  
Old 22nd Nov 2011, 14:08
  #444 (permalink)  
 
Join Date: Jun 2009
Location: VA, USA
Age: 58
Posts: 572
Received 0 Likes on 0 Posts
As I posted previously and reenforced by TTex600 there seems to a problem with training and the overall approach. First as I noted and then again by TTex600, the simulator training syllabus for most carriers (all?) seems to have frozen in time, something like 25-30 years back - there is a lot of engine out/engine fire/engine fell-off type stuff, but little related to high altitude/UAS/near-upset. Does the current training regime match the real world as it stands now? My opinion is engines are very much more reliable than might have been experienced 30 years back, so are all these engine out situations worth the sim time? You tell me - I'm not a pilot, but I build sims, and model all kind of engine malfunctions, but nothing at all related to stall buffet cues... (at least in the sound department, may be the vibration boys do?).

Secondly, I know of several simulators that can be rapidly reconfigured to alternate aircraft - the cockpit representation is generic, but can be set-up as a twin jet, twin turboprop, light-prop, well in fact pretty much whatever. Further though, the flight modeling includes extended envelopes, up to and beyond stall - since some of the types modeled can be flown into and recovered from such an upset. So my question for the gallery is: "Would such a simulator be seen as an important adjunct to the existing FFS Level D devices?". You might say, "why bother? Put the pilot in a real plane and do the same thing." But I can very quickly see the finance department jumping up and down at the cost - the sim can run near 24/7 (ok, 20/7 with maintenance downtime), but doesn't eat fuel or cost much to run (versus any aircraft) and doesn't run the risk of falling out the sky.... The cost of that sim, well depends on a lot of details, but it should be on the right side of $5M, maybe quite a bit below that if smart choices are made.

A quick costs calc: ($5M/(10 years*365*20))=$68/hr purchase cost... (assumes sim lasts 10 years, runs 365 days/year/20 hours a day)

- GY
GarageYears is offline  
Old 22nd Nov 2011, 14:26
  #445 (permalink)  
 
Join Date: Jul 2009
Location: DFW
Age: 61
Posts: 246
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DozyWannabee
Could you elaborate a little? I know you're talking about people you're actually meeting on the line here, but as far as this thread is concerned I don't think anyone has suggested that "Cause is pilot error, and we're done". Pilot error itself has myriad contributing factors including rest time, training, airline culture and human psychology.

As far as the airframe is concerned, it appears that recovery is relatively straightforward at the apex of the zoom climb, and becomes progressively more difficult as the aircraft sinks further into the stall. From the point they pass about 30,000ft on the way down it's impossible to know whether any airframe could have been recovered other than by using techniques which your average line pilot would not know, and in any case, from the moment they actually stalled they were in test pilot territory to start with.
You've already acknowledged the source of my statement. I was talking about the way some other pilots regard the cause of this accident. The lack of airline pilot participation in this very forum is a good indicator of the overall lack of interest I see in my fellow pilots. Most airline pilots I speak to about AF447 have only a passing familiarity with the details, they don't have the interest to go deeper than "the pilot stalled it and didn't know how to recover". I'm not a psychologist, so any conclusion I draw from their attitude is pure speculation, but I think that most Airbus drivers I talk to don't want to accept that the airplane is partly at fault because that would mean that it could happen to them. Very few human beings want to believe that some event could overwhelm them, I believe it is called "denial".
TTex600 is offline  
Old 22nd Nov 2011, 15:34
  #446 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Likes: 0
Received 0 Likes on 0 Posts
Well, they can't say the aircraft was entirely blameless because of the issue with the pitot tubes for starters, but are you saying you believe there's another issue at play?

I think you'll find a lot more pilot participation in the non-public areas of the forums, by the way.
DozyWannabe is offline  
Old 22nd Nov 2011, 16:38
  #447 (permalink)  
 
Join Date: May 2007
Location: MXP
Age: 64
Posts: 4
Likes: 0
Received 0 Likes on 0 Posts
pilot interest

Hi there,
We as pilots are very interested in this forum despite all the comments.
I personally fly an A 330 last model and i feel confident with this bird.
I flew Boeing planes too and i believe is all the same job.
What we need is to fly more manually and train people to do it.
My Navy time told me that the checklists are written with the blood of others like this case
Best Regards
Alcalde
alcalde is offline  
Old 23rd Nov 2011, 01:11
  #448 (permalink)  
 
Join Date: Jul 2009
Location: The land of the Rising Sun
Posts: 171
Likes: 0
Received 0 Likes on 0 Posts
TTex600
Once again it comes down to human factors - know your machine and how to deal with issues. This was lacking. No aircraft is perfect and despite the current machines being far superior to previous machines they can still go wrong and have their foilbes. Pilots need to understand this and to be able to react correctly when it happens. Those that don't crash. You mention denial and this is certainly a factor but the very fact of denial is rooted in the mind of the denier. You are right that pilot error is far too 'glib' an explanation for the accident but it was a recoverable problem if the pilots had been able to react in the correct way.
Old Carthusian is offline  
Old 23rd Nov 2011, 02:15
  #449 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Once again it comes down to human factors - know your machine and how to deal with issues. This was lacking. No aircraft is perfect and despite the current machines being far superior to previous machines they can still go wrong and have their foilbes. Pilots need to understand this and to be able to react correctly when it happens. Those that don't crash. You mention denial and this is certainly a factor but the very fact of denial is rooted in the mind of the denier. You are right that pilot error is far too 'glib' an explanation for the accident but it was a recoverable problem if the pilots had been able to react in the correct way.
OC, Human Factors?

How well trained were the AF447 crew to handle UAS at altitude. Judging from the horrible example we have been puzzling over the last 2+ years, they were not adequately trained for the successive situations that they encountered. Whatever the emphasis of the training program, it did not prepare them for what they encountered.

I'd like you to think (way?) back to when you were learning to fly. Did you ever get in way over your head? Do you remember that feeling? Did the instructor steady things up for you and allow you to resume control? Were you lucky (if solo) and puzzle things out for yourself?

These guys got in way over their heads. There was no one there to punch the freeze button and explain what went wrong. To their credit, they kept on trying to the end. Unfortunately they did not understand that which is perfectly clear to us using our retrospectiscope.

The purpose of training is to keep us from getting in over our heads. As you fly, you will periodically find little things you didn't know or did not properly understand. Some of these are of minimal import. A few can be life threatening.

When training departments decide what to emphasize, there is a risk assessment of some type used to allocate training effort. Most accidents seem to occur in the takeoff and landing phase. Very few in the cruise phase. This accident unfortunately occurred in a less emphasized phase of flight. Furthermore, the system failure, UAS, had only recently begun to be visible in the safety radar scope, so training in that subject had to displace other training to be included in the time-limited training syllabus.

To sum up, the crew of AF447, particularly the two co-pilots were not ready for the UAS emergency that they encountered. They handled that emergency about as well as you would handle a night landing aboard an aircraft carrier.
Machinbird is offline  
Old 23rd Nov 2011, 04:15
  #450 (permalink)  
 
Join Date: Jul 2009
Location: The land of the Rising Sun
Posts: 171
Likes: 0
Received 0 Likes on 0 Posts
Machinbird
I totally agree with what you say and I hate to think what a mess I would make of a night landing. However, training or lack of it is part of the human factor equation. As you mention getting in over one's head is part of learning to fly. But we should learn from that and emerge wiser and more aware. At first it seems so easy and then suddenly it isn't but after the experience we have more respect for the environment and the aircraft. I would hope that pilots flying the big jets would be aware of how to troubleshoot and deal with the issues they face. However, some are not and the whys and wherefores are what make up the human factors. Reading the accident report on Korean Airlines Flight 6316 is instructive. One crew dealt with the instrument problem successfully, the next crew did not and crashed the aircraft. Once again there were all sorts of human factors involved such as CRM (or lack of it) and lack of communication and training. Certainly training for UAS needs to be improved and it needs to be taught as a recogniseable issue. But the fact remains that there was a procedure availaible and a checklist to follow at the time. Maybe not clear but it did exist. It wasn't used and there seems to have been no attempt to troubleshoot the issue professionally. This is cultural as well as a gap in training.
Old Carthusian is offline  
Old 23rd Nov 2011, 05:35
  #451 (permalink)  
 
Join Date: Jul 2009
Location: DFW
Age: 61
Posts: 246
Likes: 0
Received 0 Likes on 0 Posts
Old Carthusian, one can't "know his machine" when the machine is Dr. Jekyll or Mr. Hyde.

From what we presently think we know, the pilots dealt poorly with the UAS which lead to an upset. Once upset, they were faced with control harmony different than normal. How is the crew to "know the machine" when the machine isn't consistent?
TTex600 is offline  
Old 23rd Nov 2011, 05:41
  #452 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 4,569
Likes: 0
Received 0 Likes on 0 Posts
How is the crew to "know the machine" when the machine isn't consistent?
it's consistent in that it does what the pilot commands it to do. It's the pilot who is not consistent in knowing what commands to apply
lomapaseo is offline  
Old 23rd Nov 2011, 06:40
  #453 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by TTex600
If the airplane consistently does what it is commanded to do, how do you explain "auto trim"? When does the pilot command trim?
To offload pressure on the primary flight surfaces, exactly the same as autotrim does. Autotrim is a way of solving the problem of not having the surfaces transmit the pressure through the primary flight controls - nothing more, nothing less.

Why does it wander around the selected speed? (for you Boeing , Embraer, Canadair, Douglas drivers - the bus will vary by ten or more knots below 10Kft when fully automated. It trims for flight path, not for speed)
I'm sure that other airframes also "wander" to some degree, and always have, because even calm air is never 100% calm - it may not have been as apparent in the steam-gauge days due to the analogue nature of the instruments.

Contrary to the spin (partisan positioning) you read here, the Airbus takes what you input, processes your input through its brain and outputs whatever it decides appropriate.
That's one way of describing it - another equally valid way is "gives you exactly what you ask for in a manner that is appropriate to the conditions". In terms of flight path stability (which is after all, what the manual combination of thrust, PFC input and trim were trying to achieve in conventional jets) it is relatively unmatched.

Imagine, if you will, the steering wheel on your automobile randomly varying tire steering angle for a given steering wheel angle. Fun, huh?
Except that is not a fair description in that it isn't "random". The whole point of the "graceful degradation" aspect of the design was that it gives you as close to Normal Law handling as possible despite the fact that some of the systems required to give you that handling are not functioning correctly. A fairer analogy would be a power steering setup that has a partial failure mode making the wheel half as heavy as it would be with power sterring out completely.
DozyWannabe is offline  
Old 23rd Nov 2011, 07:37
  #454 (permalink)  
 
Join Date: May 2011
Location: BOQ
Age: 79
Posts: 545
Likes: 0
Received 1 Like on 1 Post
How is it possible to quote someone on 22nd Nov 2011, 21:40 who doesn't post the quoted statements until 23rd Nov 2011 05:31??

Now that's spooky.

(HAL is at it again)

Last edited by OK465; 23rd Nov 2011 at 16:11. Reason: just to see what time it is
OK465 is offline  
Old 23rd Nov 2011, 07:53
  #455 (permalink)  
 
Join Date: Jul 2009
Location: The land of the Rising Sun
Posts: 171
Likes: 0
Received 0 Likes on 0 Posts
TTex600
I think that Jekyll and Hyde is a bit too much to describe an A330. I'm certain that it's not that bad. Iomapaseo sums the situation up excellently. Any airliner would have ended up in the same situation as AF447 if the pilots had performed the same actions. The accident wasn't platform related but crew related.
Old Carthusian is offline  
Old 23rd Nov 2011, 09:32
  #456 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Likes: 0
Received 0 Likes on 0 Posts
@chrisN - vBulletin uses server time as it's timestamp, otherwise threads would be unreadable. My guess is that the server was restarted at some point or there's been a database hiccup somewhere.

@Lyman - The sidestick is spring-centred, the PF does not have to "reindex it to neutral".
DozyWannabe is offline  
Old 23rd Nov 2011, 10:07
  #457 (permalink)  
 
Join Date: Feb 2001
Location: UK
Posts: 647
Likes: 0
Received 0 Likes on 0 Posts
DW, your post now numbered 457 has jumped in 2 above my 459, to which yours is a reply. You clearly did not send it at 09.32 UK time, so I wonder if your computer has defaulted to a non-UK time zone? The MS default is western USA or something might be worth you checking (it happened to me once).

Regards Chris
chrisN is offline  
Old 23rd Nov 2011, 11:13
  #458 (permalink)  
 
Join Date: Oct 2005
Location: 45 yards from a tropical beach
Posts: 1,103
Likes: 0
Received 0 Likes on 0 Posts
Without attitude display, PF was blissfully thinking he had only the ROLL to mitigate?
Lyman; perhaps I have missed someting, so please explain how the PF was without attitude display.
Neptunus Rex is offline  
Old 23rd Nov 2011, 11:15
  #459 (permalink)  
 
Join Date: Oct 2005
Location: 45 yards from a tropical beach
Posts: 1,103
Likes: 0
Received 0 Likes on 0 Posts
My post in reply to #465 has goe into 459!!! So here goes again;

Quote:
Without attitude display, PF was blissfully thinking he had only the ROLL to mitigate?
Lyman; perhaps I have missed someting, so please explain how the PF was without attitude display.
Neptunus Rex is offline  
Old 23rd Nov 2011, 12:54
  #460 (permalink)  
Moderator
Thread Starter
 
Join Date: Apr 2001
Location: various places .....
Posts: 7,129
Received 69 Likes on 50 Posts
Several posters have commented on the system's apparently putting posts out of order.

I can't claim to have much knowledge on how the system works in the background but my understanding is that posts are ordered by DTG.

Having said that we did have a period some time ago when the system went a tad strange and was logging incorrect DTG. Perhaps we are revisiting that situation again.

Either way, if you can tolerate the problem for the short term please and I'll refer it to the experts for attention.

Indeed, this post has been logged as having been made about 8 hours before it was made and posted in that incorrect DTG order - how quaint.
john_tullamarine is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.