Print from Airliners.net discussion forum
http://www.airliners.net/aviation-forums/general_aviation/read.main/5505035/

Topic: BEA Final Report AF447: July 5, 2012
Username: BEG2IAH
Posted 2012-07-04 17:17:54 and read 30135 times.

Folks,

It seems the AF 447 final accident report is due tomorrow. I hope BEA will come up with some good recommendations. Still hard to believe three years passed already.

http://www.bea.aero/en/enquetes/flig...f.447/pressrelease30may2012.en.php

Topic: BEA Final Report AF447: July 5, 2012
Username: Independence76
Posted 2012-07-04 19:11:08 and read 30060 times.

I've waited for this day for 3 years.

Hopefully we can truly peer through the eyes of the pilots for the first time with all the answers in front of us. I do not mean to sound overdramatic (I apologize if I do), but this may go down as the landmark example of "the true danger of automation with an inexperienced flight crew" within the aviation community.

The Airbus Fly-By-Wire system is incredible and I admire it greatly. However, for this flight crew sitting in front of 200+ people not immediately realizing the first sign of trouble is, to me, a distressing scenario in the practice of pilot training. Alternate Law 1 & 2 are virtually "page 2" material of Airbus flight characteristics.

I'm somewhat indifferent on the proposition of altering the side stick and throttles to be backdriven, but it would be of a greater benefit to pilots in my honest opinion, and this accident potentially may not have happened if they were. One could argue that making them backdriven would assist in CRM awareness, but this is a debate I'm willing to let the BEA settle.


I will be eagerly awaiting the final report.

[Edited 2012-07-04 19:11:34]

[Edited 2012-07-04 19:12:27]

[Edited 2012-07-04 19:12:35]

Topic: BEA Final Report AF447: July 5, 2012
Username: justloveplanes
Posted 2012-07-04 19:41:38 and read 29983 times.

It is a tough call to make. The other side of the coin is how many crashes has the Airbus system avoided? Thousands of times more I am will to bet. So one must be careful about throwing out the baby with the bathwater.

Best solution is better training an pitot tubes that don't ice up IMHO.

Topic: BEA Final Report AF447: July 5, 2012
Username: LH707330
Posted 2012-07-04 21:54:08 and read 29829 times.

This will be an interesting read, I'm most curious to see what the human factors group comes up with. Hopefully they will have something more material than "pilot error: they failed to execute the checklist" as the probable cause. Maybe they will mention personality issues between flight crew members, etc. Who knows....

Topic: BEA Final Report AF447: July 5, 2012
Username: JoKeR
Posted 2012-07-05 01:14:24 and read 29521 times.

Quoting justloveplanes (Reply 2):
It is a tough call to make. The other side of the coin is how many crashes has the Airbus system avoided? Thousands of times more I am will to bet. So one must be careful about throwing out the baby with the bathwater.

Exactly my thought! If there was a serious flaw, 330s would be dropping out of the sky at regular intervals, thank Lord that's not happening.

I suspect human factor, inadequate training and poor communication will be the main culprits, though fingers will probably be pointed left, right and backwards. Really hope that the families find peace and closure after this report - sadly nothing that this report says will bring back their loved ones or take away the pain they have endured.

Topic: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-05 06:40:13 and read 28842 times.

So I took a look at it, and it's a pretty interesting read, but it's pretty much confirming the initial report, with faulty airspeed readings causing pilot errors. I hope that this doesn't happen again.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: DrColenzo
Posted 2012-07-05 06:43:19 and read 28811 times.

Quoting PHX787 (Reply 5):
I hope that this doesn't happen again.

Following that point, I saw that they made an additional 25 further recommendations on the top of the ones issued previously and are pursuing a manslaughter investigation against Airbus and Air France.

I cannot look too deep right now as I am working, but do you have any details on what the recommendations and accusations are?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 06:43:38 and read 28815 times.

News agencies are reporting that the report is out, though I can not yet find it on the BEA web site.

The news are quoting the main investigator who believes the crash was due to "pilot and technical failure".

See, for instance:

http://www.bbc.co.uk/news/world-europe-18720915
http://www.france24.com/en/20120705-...-blames-pilot-error-faulty-sensors

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-05 06:46:59 and read 28746 times.

Quoting DrColenzo (Reply 6):
I cannot look too deep right now as I am working, but do you have any details on what the recommendations and accusations are?

I was looking at the quibbits from USAToday

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: N14AZ
Posted 2012-07-05 06:47:00 and read 28744 times.

Quoting PHX787 (Reply 5):
So I took a look at it

Where did you find it? I scanned the BEA webpage but couldn't find it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: motif1
Posted 2012-07-05 06:49:25 and read 28688 times.

Quoting PHX787 (Reply 5):
So I took a look at it

A link would be appreciated. Thanks!

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-05 07:02:13 and read 28485 times.

http://www.usatoday.com/news/world/s...5/Air-France-crash-2009/56024902/1
http://avherald.com/h?article=41a81ef1/0080&opt=0

Press conference to discuss more of the details.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 07:16:59 and read 28295 times.

Quoting motif1 (Reply 10):
A link would be appreciated.

AvHerald says:

Quote:
The summary of final report will be summarized as soon as the report has been released a few hours after the end of the press conference and processed as usual.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-05 07:18:38 and read 28260 times.

Quoting AirlineCritic (Reply 12):
Quote:
The summary of final report will be summarized as soon as the report has been released a few hours after the end of the press conference and processed as usual.


I could've been reading the AVherald wrong

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: N14AZ
Posted 2012-07-05 07:27:41 and read 28141 times.

In th past, BEA made available the interim reports on their webpage directly after the press conference (please correct me if I am wrong but that's what I remember).

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: TeamAmerica
Posted 2012-07-05 07:32:50 and read 28117 times.

BEA final report is here:
http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 07:39:32 and read 27980 times.

Quoting Independence76 (Reply 1):
Hopefully we can truly peer through the eyes of the pilots for the first time with all the answers in front of us. I do not mean to sound overdramatic (I apologize if I do), but this may go down as the landmark example of "the true danger of automation with an inexperienced flight crew" within the aviation community.

Is the problem any larger than an inexperienced crew without automation?

I would say no, even to the contrary.

A crucial lack of experience is always dangerous and unacceptable.

Quoting Independence76 (Reply 1):
I'm somewhat indifferent on the proposition of altering the side stick and throttles to be backdriven, but it would be of a greater benefit to pilots in my honest opinion, and this accident potentially may not have happened if they were.

It would have changed absolutely nothing, since the pilots were made aware by the systems that they were going into a stall already and yet they reacted incorrectly to that.

The backdrive would have stopped as well when the systems lost forward speed again during the stall, so it would not have been of any use.

The crew was confused, beginning with their failure to execute the mandatory checklist on the loss of airspeed indication. And they made multiple crucial errors of judgment after that as well, actively keeping the aircraft stalled against aerodynamic forces.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: nomadd22
Posted 2012-07-05 07:53:22 and read 27796 times.

Quoting Klaus (Reply 16):
Is the problem any larger than an inexperienced crew without automation?

The theory is that the inexperience was aggravated , or caused by a too automated flight system. The more planes go toward push button flying, the less experience pilot have at truly flying them. To put it in vague terms, they can lose the "feel" for the operation. It sounds like the AF crew had the indicators they needed, but failed to put them together into a coherent picture of what was happening, aggravated by a breakdown of cockpit discipline.

Automation has surely prevented more loss of life than it's caused. It just has it's downsides too.
It's not just flying planes. It's something that's happening in fields everywhere. Many people don't need to understand how machines work at the most basic levels anymore as they get more complex and automated. It's a problem when that automation fails.

[Edited 2012-07-05 07:54:07]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 08:54:14 and read 27269 times.

One word of warning to folks reading the BEA report and various news articles

Nothing in English can be taken as exact or the final word.

The pilots were speaking French and the official report is in French.

We've seen in the earlier reports and the CVR transcripts that many things which seemed crucial in the English translations do not mean what we thought in the original French.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-05 09:38:42 and read 26702 times.

The report references the CVR transcript in its list of appendices, but doesn't include it. Peculiar - anyone know if it's available?

Quoting Klaus (Reply 16):
The backdrive would have stopped as well when the systems lost forward speed again during the stall, so it would not have been of any use.

   The sudden lack of it may have even made things worse.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 10:02:46 and read 26299 times.

Quoting nomadd22 (Reply 17):
The theory is that the inexperience was aggravated , or caused by a too automated flight system. The more planes go toward push button flying, the less experience pilot have at truly flying them. To put it in vague terms, they can lose the "feel" for the operation. It sounds like the AF crew had the indicators they needed, but failed to put them together into a coherent picture of what was happening, aggravated by a breakdown of cockpit discipline.

They never had control of the situation right from the get-go: Failing to even execute the unreliable airspeed checklist leaves no doubt about it.

Automation or not was not the problem there.

Inexperience and a lack of competence in general has nothing to do with automation. That's mostly a phantom debate in this context.

Quoting Mir (Reply 19):
The report references the CVR transcript in its list of appendices, but doesn't include it. Peculiar - anyone know if it's available?

Wasn't it in the interim report already?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 10:06:38 and read 26254 times.

Some interesting points as I keep reading through the report. This part is in 1.16.2, a study of previously happened unreliable speed incidents. The study found that:

Quote:

With regard to the crews’ reactions, the following points are notable:
The variations in altitude were contained within about one thousand feet. There were five cases of deliberate descent, including one of 3,500 feet. These descents followed a stall warning;
Four crews did not identify the unreliable airspeed situation: in two cases, the crews concluded that there was an inconsistency between the angles of attack; in the two other cases, the crew considered that the speeds were erroneous rather than unreliable.
For the cases studied, the recorded flight parameters and the accounts given by the crews did not reveal any application of the memory items from the unreliable airspeed procedure, nor the procedure itself:
The reappearance of the indications of flight directors on the PFD suggests that no disconnection inputs were made into the FCU;
The durations of engagement of the thrust lock function indicate that no attempt was made to rapidly disconnect the autothrust followed by a manual adjustment of the thrust to the recommended value;
There was no attempt to command display a pitch attitude of 5°.

I find it amazing that other crews (not just AF447) often did not identify the unreliable speed situation. And more interestingly, apparently none of the crews performed the unreliable airspeed procedure.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: flood
Posted 2012-07-05 10:10:09 and read 26179 times.

Quoting Mir (Reply 19):
The report references the CVR transcript in its list of appendices, but doesn't include it. Peculiar - anyone know if it's available?

The listed Appendix 1 / CVR transcript is in the report itself, starting p.87

edit: apologies, that's p.87 in the interim report  



Appendix 1 can be found separately here:
http://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01.en.pdf


[Edited 2012-07-05 10:15:37]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-05 10:14:27 and read 26085 times.

Quoting flood (Reply 22):
The listed Appendix 1 / CVR transcript is in the report itself, starting p.87

I didn't see it there, but it's okay, since it's available at this link:

Quoting TeamAmerica (Reply 15):
BEA final report is here:
http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 10:16:51 and read 26061 times.

Quoting Mir (Reply 19):
The report references the CVR transcript in its list of appendices, but doesn't include it.
http://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01.en.pdf

Quoting Klaus (Reply 20):
Quoting Mir (Reply 19):The report references the CVR transcript in its list of appendices, but doesn't include it. Peculiar - anyone know if it's available?
Wasn't it in the interim report already?

A more complete CVR transcript is available on the BEA page linked above - with many comments in different English words than the interim report version.

It appears to me that this translation does a better job of conveying the 'flavor' of the pilots words - based on the more accurate cultural translations from the French we've had on past threads.

This CVR transcript makes it clear that both the PF and the PNF felt they had to climb and were trying to make the aircraft climb as it fell in the deep stall.

But as cautioned in the CVR forward - the CVR transcript cannot viewed as a complete description of what happened in the cockpit - the FDR data has to be linked to the CVR to have a more complete view.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 10:21:38 and read 26878 times.

Quoting AirlineCritic (Reply 21):
I find it amazing that other crews (not just AF447) often did not identify the unreliable speed situation. And more interestingly, apparently none of the crews performed the unreliable airspeed procedure.

The passage you quoted emphasises the need for better, more focused training.

We've wondered why this crew alone seemed to have failed to follow procedure. Now we know that other crews also failed to follow procedure. Those crews just apparently did not make a serious initial wrong command input.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 10:33:20 and read 26768 times.

Quoting rfields5421 (Reply 24):
This CVR transcript makes it clear that both the PF and the PNF felt they had to climb and were trying to make the aircraft climb as it fell in the deep stall.

They were constantly pulling deep into a stall, but they were not in a deep stall!



[Edited 2012-07-05 10:51:48]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: canoecarrier
Posted 2012-07-05 10:38:01 and read 27331 times.

Quoting rfields5421 (Reply 24):
A more complete CVR transcript is available on the BEA page linked above - with many comments in different English words than the interim report version.

As you say, the transcript in this final report is much more comprehensive than the one they released in the Interim Report. Previously there were gaps in the transcription over 3 minutes in length. This appears to be a nearly complete version of the CVR transcript.

As has been discussed here in the past, BEA has done a very thorough job of investigating the root causes of this event. For example, shortly after the initial disappearance of the aircraft and failure to find the crash site, BEA put together an international working group to aid in finding lost aircraft in areas of the world without radar coverage. That included an analysis of triggered transmittal of CVR/FDR data in the event of an emergency.

That work found its way into the recommendations in this final report on the crash.

I haven't had a chance to fully read the new report, but I did notice it made some further recommendations related to SAR operations and ATC that weren't in the Interim Report.

edit: I'll be interested to get Kaiarahi's input on part of the report that discusses the Human Factors Working Group (1.16.8) and if Mandala can glean any more information from the more complete transcript included in the Appendix to this report for his spreadsheet.

[Edited 2012-07-05 10:41:46]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: DrColenzo
Posted 2012-07-05 11:00:33 and read 26914 times.

Quoting rfields5421 (Reply 25):
Quoting AirlineCritic (Reply 21):
I find it amazing that other crews (not just AF447) often did not identify the unreliable speed situation. And more interestingly, apparently none of the crews performed the unreliable airspeed procedure.

The passage you quoted emphasises the need for better, more focused training.

With the 'zero tolerance' approach to failure in the industry, surely the replication of the similar reactions to similar situation suggests a wider problem that needs to be addressed? The correct changes will happen as a result of the AF447 tragedy but I personally find it intriguing that such a disastrous chain of events occurred after decades of industry improvements in control systems and training. Even before AF447, AA587 demonstrated how incorrect training can lead to a horrific crash and I am wondering out loud whether an industry wide audit and indeed reassessment of training method needs to be undertaken to find potentially catastrophic problems that are not apparent in day-today operations.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 11:52:03 and read 26127 times.

Example of the CRM and decision procedures in the crew (Section 2.1.1.2):

Quote:

In fact, the risk associated with the crossing of the ITCZ was discussed several times by the crew. In particular, from 1 h 45 to 2 h 00, the Captain and the PF noticed that they were entering the cloud layer and discussed the strategy to adopt. To avoid flying in the cloud layer while crossing the ITCZ and therefore to limit flight in the turbulent conditions that he mentioned several times(20), the PF wanted to change flight level and fly above the cloud cover, while recognising that it was not possible for the moment to climb two levels. He made several allusions or suggestions on the flight levels and the temperature from 1 h 35 min 20 onwards. He even considered requesting a non-standard level 360. His various interventions in the minutes that preceded the autopilot disconnection showed a real preoccupation, beyond the simple awareness of an operational risk. Some anxiety was noticeable in his insistence. The Captain appeared very unresponsive to the concerns expressed by the PF about the ITCZ. He did not respond to his worry by making a firm, clear decision, by applying a strategy, or giving instructions or a recommendation for action to continue the flight. He favoured waiting and responding to any turbulence noticed. He vaguely rejected the PF’s suggestion to climb, by mentioning that if “we don’t get out of it at three six, it might be bad”.


and choice of relief pilot (Section 2.1.1.3.2):

Quote:

The investigation was not able to determine if the Captain had clearly defined the roles between the two co-pilots during flight preparation and in anticipation of his absence during his in-flight rest time. He did however implicitly designate as relief pilot the co-pilot in the right seat and PF, but did so in the absence of the second co-pilot, just before waking him. If this distribution of roles probably contained no ambiguity for the persons concerned, being in line with the principle in the Operations Manual (co-pilot as relief Captain and PF on the right), it was not however free of difficulty.


[Edited 2012-07-05 11:56:36]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: canoecarrier
Posted 2012-07-05 12:27:22 and read 25671 times.

This part is a little interesting. We've talked about how the crew ignored (or seemed to ignore because they didn't comment on it) the stall warning(s) that went on for some time. The report has a section (1.16.8.3) on that:

"Numerous studies have been conducted on insensitivity to aural warnings and they showed that the aggressive nature, rarity and unreliability of these warnings may lead operators to ignore these signals [1, 2]. In particular, in the event of a heavy workload, insensitivity to aural warnings may be caused by a conflict between these warnings and the cognitive tasks in progress. The ability to turn one’s attention to this information is very wasteful as this requires the use of cognitive resources already engaged on the current task. The performance of one of these tasks (solving the problem or taking the warning into account) or of both would be affected."

Additionally, they compare the response of the AF 447 crew to other crews that had similar conditions (1.16.8.4).

"A comparative analysis of reports and statements by other crews based on seventeen events that occurred in similar conditions to those of AF447, two of which are studies in 1.16.2, brought to light the following trends:

1) Analysis of the situation by crews appears difficult
2) Calling on the « unreliable airspeed » procedure was rare
3) Some crews mentioned the difficulty of choosing a procedure bearing in mind the situation (numerous warnings)
4) Others did not see the usefulness of applying this procedure given that in the absence of doubt about the unreliability of the airspeeds, their interpretation of the title of the “unreliable airspeed “ procedure did not lead them to apply it
5) Some gave priority to controlling the pitch attitude and thrust before doing anything else, and
6) The triggering of the STALL warning was noticed. It was surprising and many crews tended to consider it as inconsistent."


#2 is interesting because that is a memory item. #6 may be relevant because it appeared the AF 447 crew ignored the "STALL" warning. So, to some extent there is a common denominator with many of the other events. Perhaps the initial climb, initiated by the PF was the one factor that made this one so much different than the other events.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 13:01:43 and read 25166 times.

Quoting DrColenzo (Reply 28):
surely the replication of the similar reactions to similar situation suggests a wider problem that needs to be addressed?

The initial BEA report was 'shocking' to the industry - in that about 3 dozen similar events were identified quickly. Such super-cooled icing at altitude was thought to be incredibly rare, hardly worth wasting training time upon the possibility - we learned it is much more common.

1) The review of past possible similar incidents was not comprehensive. Several airlines which fly the A330 / A340 refused to provide data to the BEA of possible incidents. So we know 3 dozen is the low threshold. There are very likely many more which were not included in the analysis.

2) Only Air Caraibes pushed Airbus about the way the crew and aircraft responded to UAS incidents at cruise - i.e. checklist, warnings, etc. And that airline had increased focus on air crew training. Other airlines only began to change some of their training after AF447 and the various interim reports. I have to wonder if anyone but folks deeply involved in avaition safety would have known of the Northwest Airlines incident had AF447 not recently occured.

3) While much has been made of the Thales probe and that the aircraft had not received the newer Goodrich probes - a couple points need to be remembered. Even the Goodrich probe has been shown to be vulnerable to such icing. Also - the really big problem with the Thales probes was in the A320 aircraft series - where there were many, many more icing failures - because those aircraft fly in known icing much more often than the A330/A340 family. That is due to their higher number of cycles on average, and more ascents/ descents through bad weather. Air France was agressive in replacing the probes on that series of aircraft, with the A330/A340 family next in line.

Quoting DrColenzo (Reply 28):
I am wondering out loud whether an industry wide audit and indeed reassessment of training method needs to be undertaken to find potentially catastrophic problems that are not apparent in day-today operations.

To me the report - what I've read so far - points to need for a fundamental change in the thoughts behind simulator and flight training. Basically, much more time in training.

Which I fear will not occur. Some training sessions will be modified to include this type incident - but then other important training will be deemphasized, or even skipped completely.

Because the bottom line is that implementing such recommendations will result in noticably higher costs for the airline. And the airlines are going to do everything they can to not only keep from increasing training costs, but decrease such costs.

Quoting canoecarrier (Reply 30):
#2 is interesting because that is a memory item.

Maybe the reality is that memory items are becoming like high school students studying for standardized tests. People learn to memorize the answers, but don't learn how to apply the answers to real world situations.

[Edited 2012-07-05 13:02:15]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Pihero
Posted 2012-07-05 14:02:57 and read 24287 times.

A long awaiterd document anrd really worth the wait .
For those who don't understand french doc presentation, the final report in English is Here
and the list of appendices is also entry for the respective document : Click on the check mark in the column of the language you'd favour.
This is also long reading and , although we studied this accident at length, there are still some surprises :
- the similarities between AF447 and the other incidents is quite enlightening. A lot more will come from this part of the document as it is too important in terms of ergonomics and CRM, not even talking about SOPs.
- About the crew : the LHS was found in the "stored position. It can only mean that PNF had been in the process of giving up his seat to the captain... How long had the seat been in that position ( it prevents the pilot to have any meaningful input to the flight controls) ?.

I need to read the whole report before making any meaningful input.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Semaex
Posted 2012-07-05 14:04:15 and read 24149 times.

Quote:
For the cases studied, the recorded flight parameters and the accounts given by the crews did not reveal any application of the memory items from the unreliable airspeed procedure, nor the procedure itself:

Oh how I wished I did not have to learn the memory items for my flight training in the PA28. They were annoying, consumed valuable study time and I never used them anyways. Here's the reason why I still learned them... because they are of vital importance.
If the pilots are unable to recall memory items, then how can you not put (part of) the blame on them? When undergoing pilot training, the company must ensure that pilots are (1) capable of coping with abnormal amounts of stress and (2) that pilots are eager to train for and maintain a set value of internal standards and procedures. I can't see how AF cannot be held responsible for this accident, or at least the way the pilot reacted to a system malfunction.

Quote:
The investigation was not able to determine if the Captain had clearly defined the roles between the two co-pilots during flight preparation and in anticipation of his absence during his in-flight rest time.

"Laissez-faire". It's just as destructive in aviation as an autocratic flight deck. Does AF not use the concept of Captain / Senior First Officer / First Officer on long haul? I find it hard to see where the roles and ranks of those three are disputable if such a regulation is strictly enforced by the company!


I am very dissapointed in the way AF treats this issue after 228 passenger have died, largely due to the misjudgement of the crew. If only it were the confusing indications in the cockpit or the abnormal leadership style, but the fact stays that they flew right into a massive thunderstorm, which by all means every pilot knows to avoid.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Colombia
Posted 2012-07-05 14:22:37 and read 23879 times.

Quoting Klaus (Reply 20):
They never had control of the situation right from the get-go: Failing to even execute the unreliable airspeed checklist leaves no doubt about it.


I think Klaus has a good point here. More than automation the point is the lack of training, in many airlines this maneouvre is performed only until the memory items are done, so the rest of the checklist is not finished.

Hopefully after this it might become a mandatory sim maneouvre

Regards,
Daniel

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 14:24:29 and read 23860 times.

In section 2.1.2.3 the reports notes:


"It would also seem unlikely that the PNF could have determined the PF’s flight path
stabilisation targets. It is worth noting that the inputs applied to a sidestick by one
pilot cannot be observed easily by the other one and that the conditions of a night
flight in IMC make it more difficult to monitor aeroplane attitudes (pitch attitude
in particular)."

I pointed this out in earlier threads and was told that the other pilots inputs were
"easily" observed.....I guess not. This is particularly significant, especially as though
it appears that the 330 is neutrally stable in Alt 2B law. I wonder if the pilots were
trained for and understood this. I didn't see...or missed...that. I would think knowing
what the other pilot is doing with his joystick would be a great asset....I guess not.

That idea of having tracking joysticks is entirely independent of what the airplane is
doing....even sitting on the ground. One moves...the other tracks....exactly like yokes.
I can't envision any reason...other then cost why this would not be desirable.

Having the way the aircraft responds to joystick inputs, especially suddenly and
while the plane is flying in the coffin corner seems very undesirable to me, but maybe
unavoidable with the loss of airspeed inputs.

Altogether, I thought the report was extremely well researched, documented, and
presented.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: railker
Posted 2012-07-05 14:25:54 and read 23878 times.

One thing I noticed, and correct me if I'm wrong here ... but reading through the CVR transcript which included all the sounds, it was already pointed out that the stall warning sounded unacknowledged some 70+ times.

Another one that caught my attention that started sounding in between the crickets and stall warnings was one that was noted on the CVR as "SV [synthetic voice]: dual input". Which is where the problem of establishing PIC admist the disaster, and that the pilot on the right (as it's hard to determine PF/PNF in my opinion when R/H pilot gives up controls and then takes them over again without saying) ...

Anyhow, how does the 'dual input' alarm relate to this incident, and the all too late realization by the rest of the crew when the R/H pilot stated he'd been pulling back on the stick the whole time?

Though with the mentions in the report about ignoring the stall warning, the one about dual input (assuming it means what it sounds like) might have just blended in with the rest of the noise and confusion in the cockpit, and thus gone unnoticed until the pilot mentioned the fact aloud that he'd been trying to climb the aircraft...

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 14:28:00 and read 23846 times.

Airbus has flown test flights to determine buffeting levels in configurations corresponding to AF 447 (Section 1.16.5):

Quote:

Additional analyses were conducted with Airbus to determine if this phenomenon could correspond to buffet. The identification of this phenomenon is complicated by the fact that the concept of buffet is defined as accelerations at the level of the pilots’ seats and not at the centre of gravity.

Airbus subsequently flew special flights to collect more accurate data at high angles of attack and with an aircraft configuration close to that of the accident (mass, flight level, Mach, etc.). These tests made it possible to refine the preliminary correlations and to establish that the level of buffet was considered to be a deterrent by the test pilots when the angle of attack was about 10°, corresponding to normal acceleration amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10 min 57 s during the accident flight.

Thus, the stall warning was triggered at 2 h 10 min 51 at an angle of attack corresponding to the theoretical threshold for the measured Mach value. Two seconds later, vibrations that might correspond to buffet appeared. The intensity of vibration probably reached the deterrent buffet level at about 2 h 10 min 57 s.

Apparently, ECAM was not very helpful to the crew (Section 2.1.2.4):

Quote:

Once the first actions in response to the perceived anomaly is executed (returning to manual piloting following AP disconnection) and the flight path stabilisation ensured, the philosophy of both the manufacturer and the operator is for the crew to look for additional information necessary to understand the problem and take action. Three seconds after the autopilot disconnection, the ECAM displays no information that is likely to point to a speed indication problem

The ECAM mentions a maximum speed that should not be exceeded but does not mention a minimum speed. This could lead crews to suppose that the main risk is overspeed. In the absence of any reliable speed indication, this might lead to a protective nose-up input that is more or less instinctive.

...

Thus, having identified the loss of airspeed information, the PNF turned his attention
to the ECAM, undoubtedly in an attempt to refine his diagnosis and to monitor any
actions displayed. He started to read the messages, and consequently called out the
loss of autothrust and the reconfiguration to alternate law. The successive display of
different messages probably added to the confusion experienced by the crew in its
analysis and management.

...

The symptoms perceived may therefore have been considered by the crew as
anomalies to add to the anomaly of the airspeed indication, and thus indicative of
a much more complex overall problem than simply the loss of airspeed information.

How the crew may have missed the stall warning (Section 2.1.3.3):

Quote:

The crew never referred either to the stall warning or the buffet that they had likely felt. This prompts the question of whether the two co-pilots were aware that the aeroplane was in a stall situation. In fact the situation, with a high workload and multiple visual prompts, corresponds to a threshold in terms of being able to take into account an unusual aural warning. In an aural environment that was already saturated by the C-chord warning, the possibility that the crew did not identify the stall warning cannot be ruled out.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-05 14:30:28 and read 23795 times.

Having read this report, one glaring issue seems to point to a lack of handling experience, both in non-normal operations and manual flight. It states that the PNF (the senior copilot) had last performed a manual landing over two months before the accident flight - surely this is unacceptable?? More pressingly, I believe the whole issue of simulator based training needs completely tearing down and starting again from square one. The whole V1 cut/single engine go around/Non precision instrument approach refresher seems just so predictable - and doesn't really reflect real world flying. What pilots should get is a wide variety of failures, encompassing different systems at all stages of flight - but without any briefing of any sort. Surely this would help them to prepare mentally for the shock and surprise of situations such as this - which seemed to almost be the last hole in the cheese.  

Anyway, RIP to all on board, especially the crew who clearly tried as hard as their situational awareness would allow to save their aircraft, right until the very end.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-05 14:31:09 and read 23788 times.

Quoting canoecarrier (Reply 30):
#6 may be relevant because it appeared the AF 447 crew ignored the "STALL" warning.

If the crew believed the initial stall warning was faulty (and they certainly had reason to - we know it was driven by corrupted input from the air data sensors), then it's quite likely the subsequent stall warnings were ignored, either consciously or unconsciously. What's curious, though, is that the captain, who wasn't around when the problems began, wouldn't have reason to believe that the warning was faulty, yet he didn't ask about it. Perhaps the actions of the other two, who didn't appear to be focusing on it, led him to the incorrect conclusion that it was faulty and should be ignored.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 14:31:22 and read 23786 times.

.....an additional thought.

Because the report says that recovery was unlikely once they fell back through 35,000 feet, I'm not sure
they had time between the initial autopilot disconnect and falling through 35,000 to read and use any
check list. That's why we have the "memory" check list to stabilize the situation. This is where they
failed for whatever reason...training, misreading instrumentation, etc.

[Edited 2012-07-05 14:35:17]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 14:37:36 and read 23649 times.

Quoting airtechy (Reply 35):
That idea of having tracking joysticks is entirely independent of what the airplane is
doing....even sitting on the ground. One moves...the other tracks....exactly like yokes.
I can't envision any reason...other then cost why this would not be desirable.

System complexity would go way up and reliability would take a significant hit (right down to canceled flights on malfunctions), which doesn't seem like a very good tradeoff when it would have benefits only in the rare and already near-catastrophic situation of a total CRM breakdown as in the case of AF447.

The way Airbus FBW works it would not have any flight-control-related benefits, because the constant spring is already a correct reflection of what effect a movement of the stick will have in normal law (and outside of normal law it sounds even more dubious to engage a backdrive system when parts of the systems are already unreliable).

And whether it would have had any benefit for AF447 is questionable, since neither of the pilots seems to have been aware that they were in a stall all along.

Quoting Mir (Reply 39):
If the crew believed the initial stall warning was faulty (and they certainly had reason to - we know it was driven by corrupted input from the air data sensors)

I may mis-remember, but I don't think that is true. The unreliable airspeed indication lasted only for a few tens of seconds and became stable again afterwards. The stall warning depends on it, too, so as far as I'm aware it only sounded when the airspeed indication was reliable again. And was later interrupted only when the PF pulled the aircraft so deep into the stall that airspeed dropped too low to be measured any more, without fault of the sensors at that point.

[Edited 2012-07-05 14:45:42]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-05 14:40:56 and read 23721 times.

Quoting AirlineCritic (Reply 21):
I find it amazing that other crews (not just AF447) often did not identify the unreliable speed situation. And more interestingly, apparently none of the crews performed the unreliable airspeed procedure.

If your in the cruise, all you need to do initially is to turn the flight directors off and manually maintain the pitch attitude and thrust setting in response to unreliable airspeed. There is no rush to dive into any checklist or procedure, this is for any aircraft type.

Most cases of unreliable airspeed these days are picked up by the system automation well before the crew does, and self resolve in under 10 seconds. In the old days I suspect they just were never picked up, as those aircraft flew pitch attitude and thrust setting, they just self resolved.

Over reaction to many events in aviation can cause more problem than the original event.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-05 14:59:53 and read 23353 times.

Quoting Klaus (Reply 41):
I may mis-remember, but I don't think that is true. The unreliable airspeed indication lasted only for a few tens of seconds and became stable again afterwards. The stall warning depends on it, too, so as far as I'm aware it only sounded when the airspeed indication was reliable again.

But it did sound, in conjunction with the loss of air data indications. That's enough to link the two in the back of your mind, and if you don't realize that you've got valid air data afterward (and I don't believe they did), it's very possible to assume that any stall warnings are invalid as well.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 15:04:34 and read 23329 times.

Quoting zeke (Reply 42):
If your in the cruise, all you need to do initially is to turn the flight directors off and manually maintain the pitch attitude and thrust setting in response to unreliable airspeed. There is no rush to dive into any checklist or procedure, this is for any aircraft type.

...

Over reaction to many events in aviation can cause more problem than the original event.

And that makes a lot of sense. Thanks, Zeke. I also think that is the general idea with the unreliable speed procedure:

http://www.bea.aero/fr/enquetes/vol.af.447/imageshr/figure.73.jpg

Paraphrasing a bit, it essentially tells you to turn off the FD/AP and hand-fly the aircraft in the sensible way. Which should come naturally for pilots... I had hoped, at least. You should be aware of your altitude, pitch, power settings... even if the FD/AP takes care of it under normal circumstances. Not that I have to tell you this, obviously. Just making a point that it matches what you said is the natural reaction.

I wonder when the report said that the other crews had not followed the unreliable speed procedure, did they meant that the crews had not explicitly mentioned this procedure, or that they did something inappropriate for the situation? Based on the text, it seems that some crews at least neglected to turn off the PD. But maybe it wasn't necessary in their situations, if the aircraft was still flying the right way. Those crews may have had the situational awareness that AF 447 crew lacked.

[Edited 2012-07-05 15:15:28]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-05 15:13:05 and read 23265 times.

Quoting AirlineCritic (Reply 44):

Read the first line, "if the safe conduct of the flight is impacted", that is not the cruise. You are already level, above MSA.

This is the problem when members of the general public get access to such information, they do not how to use it. You do not do the boxed memory items in such a situation.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 15:19:03 and read 23122 times.

Quoting zeke (Reply 45):
Read the first line, "if the safe conduct of the flight is impacted", that is not the cruise. You are already level, above MSA.

Ah, yes. Thanks. Question: Does this also cover not necessarily turning off PD/AP, if the crew can observe that they are not immediately causing a problem?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-05 15:45:07 and read 22851 times.

Quoting AirlineCritic (Reply 46):

The checklist is 5 pages long, it is broken up in different phases of flight. The initial part of the checklist which you posted is designed for the initial phase of flight, where it talks about thrust reduction altitude, that is typically 1500' above the runway. It is covering the possibility for example a bird strike that hits the pitot probes. It tells you what thrust setting and pitch attitude to fly to get above terrain to level off and sort it out, we typically fly 15 degrees NU or greater after liftoff, so the attitude is not uncommon for that phase of flight. It is a memory item, as you are too close to the ground to be distracted with a qrh checklists.

Below that entry point, they have another, and in that section you also turn the autopilot and flight directors off, as well as autothrust. It gives you tables of thrust and pitch setting in order to level off. If you are in the cruise, one already knows the pitch and thrust setting, all one needs to do is maintain it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-05 15:50:48 and read 22721 times.

The a.net discussions have often looked at the role of the stall warnings that were no longer continuous after some time had passed and the aircraft angle of attack was too great. The report states something interesting about this (Section 2.3.3):

Quote:

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. However, it was doubtless already too late, given the aeroplane’s conditions at that time, to recover control of it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: huxrules
Posted 2012-07-05 16:11:14 and read 22490 times.

I have a quick question. The report says that for low altitude stall recovery the suggested method is 12.5 deg and TOGA throttle. It goes on to say that the PF might have remembered this procedure and used it (the plane was near 12 deg pitch up for most of the time and TOGA for some of it). My question is - how is low level stall recovery 12 deg nose up? I thought stall recovery is always descend or be level.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rcair1
Posted 2012-07-05 16:57:50 and read 21991 times.

Quoting justloveplanes (Reply 2):

It is a tough call to make. The other side of the coin is how many crashes has the Airbus system avoided? Thousands of times more I am will to bet. So one must be careful about throwing out the baby with the bathwater.

You are connecting items that are not connected. The fact that a system, any system, works most of the time does not mean that it cannot be improved. Safety is incremental - the whole purpose of investigations like this is to identify changes that can be made to improve something. Nobody (rational) is saying scrap the entire system. They are say - can we take a very capable system and make it better. BTW - the system is the aircraft + pilots, not the aircraft or pilots.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ricknroll
Posted 2012-07-05 17:01:27 and read 21990 times.

Quoting AirlineCritic (Reply 21):
I find it amazing that other crews (not just AF447) often did not identify the unreliable speed situation. And more interestingly, apparently none of the crews performed the unreliable airspeed procedure.

Unbelievable. It's a testament to the plane there weren't more crashes, if there was such incompetence and lack of adherence to procedures.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirCalSNA
Posted 2012-07-05 17:14:51 and read 21554 times.

I would hope that this accident prompts Airbus to rethink its over-reliance on computerized flight control, which, consistent with the use of joy sticks, relegates pilots to peripheral status except when the sh** hits the fan. This is a basic human-factors design flaw.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 17:21:56 and read 21496 times.

Quoting ricknroll (Reply 51):
if there was such incompetence and lack of adherence to procedures.

The information tells me that it is not incompetence.

Rather there is a training, and systems issue, in properly identifying unreliable airspeed in modern aircraft (a B777 is one of the aircraft identified in the BEA study where the crew did the same thing as the A330/A340 crews - so it is not an A vs B issue)

One reason I can see for the difficult in identifying UAS is the number of other things that can cause almost identical symptoms and instrument readings.

There are eight (8) different things that might indicate UAS listed in Annex 6.

Another is that the majority of UAS occur during climb or descent through bad weather in 'known icing' conditions, not at cruise. Heck, I trained to fly with the airspeed gauge covered in primary training. But I certainly could not even begin to identify air speed failure in a big jet.

It was easy for us to sit back, look at the messages transmitted to the maintenance computer and say this looked like the pitot tubes froze. It is also clear from the BEA report and from the investigation of other cruise level incidents - that it is not so clear or easy to diagnose correctly in a cockpit in real time.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 17:39:15 and read 21404 times.

Quoting AirCalSNA (Reply 52):
I would hope that this accident prompts Airbus to rethink its over-reliance on computerized flight control, which, consistent with the use of joy sticks, relegates pilots to peripheral status except when the sh** hits the fan. This is a basic human-factors design flaw.

That's a prejudiced knee-jerk judgement which is simply not covered by the investigation.

If anybody was "over-reliant" on anything, it was Air France with their training and the pilots of AF447 as a possible result of that.

If there was anything to what you're claiming, Airbus planes would be falling out of the sky all the time.

They just don't, however.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: jollo
Posted 2012-07-05 17:58:48 and read 21314 times.

In the english version, at page 201, the last in the list of factors believed to explain the (to me, still incredible) failure of the flight crew to take into account the prolonged stall warnings reads:

Quote:
The difficulty in recognizing and understanding the implications of a reconfiguration in alternate law with no angle of attack protection.

Putting this as last point in a long list looks reasonable: factors such as "failure to identify the repeated lack of application of the required unreliable airspeed procedure/checklist" and "absence of any training in manual handling at high altitude with unreliable airspeed indications" stand out as much more poignant. Still, the degraded protection mode the a/c was flying with since the (transient) pitot freeze event didn't help (hell, full AoA protection would have prevented this disaster), so I guess they just had to mention it as a factor.

But it wasn't just put in last: if I'm not mistaken, it's also one of the very few contributing factors that aren't adressed by any recommendation.

Your thoughts?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ltbewr
Posted 2012-07-05 18:15:37 and read 21407 times.

Former US Airways pilot Cpt. Sully Sullenberger, best known for the 'Hudson River Miracle', is now an aviation and safety advisor/commentator for the CBS TV network. Prior the the final report on AF 447 later in the day Thursday on CBS's Morning Show, he commented on the anticipated report and his thought on some problems leading to the cause of the crash of AF 447. This is a link to this article: http://www.cbsnews.com/8301-505263_1...howDoorFlexGridLeft;flexGridModule

Using an A-320 simulator (similar to the A330 and the A320, a plane Cpt. Sullenberger was very experienced with) and a B-747 simulator, he noted what he sees as critical differences and issues. As the linked article notes, he thinks the 'joystick' design of A's does not give you enough status or feel of your flight position, while B's 'wheel' design shows more obviously your flight position. He also notes that the A's joysticks of the pilots are not interconnected so a mistake by one will not be understood immediately by the other flight officer.

As others have noted and the final and prior reports noted, the failure of the pitot tube from icing, CRM issues, confusion from the instruments, the computerized systems using compromised and conflicting data were all factors. This brings up a point: are their design flaws in Airbus' design of how pilots control the aircraft vs. Boeing's that may have contributed to this crash, and if so, what can be done ?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirCalSNA
Posted 2012-07-05 18:47:11 and read 21123 times.

Quoting Klaus (Reply 54):
If there was anything to what you're claiming, Airbus planes would be falling out of the sky all the time.

Given the amount of time and money that have gone into understanding what went wrong with AF447, it seems that even one accident like this is enough for most people to be deeply concerned.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: dfambro
Posted 2012-07-05 18:49:51 and read 21103 times.

Quoting rfields5421 (Reply 31):
Such super-cooled icing at altitude was thought to be incredibly rare, hardly worth wasting training time upon the possibility - we learned it is much more common.

rfields, thanks for your great work on help on understanding the report and issues around the accident. To nitpick, though, the BEA does not believe this represents super-cooled icing. Instead, they believe the cause of the obstruction was a high density of ice crystals in the air.

They draw this conclusion from the CVR (2 h 09 min 46) and analysis of the meteorological data. On page 46, section 1.7.1, 4th paragraph, they discount the supercooled water idea, writing "the presence of super cooled water at FL350 is not very probably and would necessarily have been limited to small quantities."

1.6.9.6.1 (pg 40) goes into detail on ice crystal blockage.

Notably, Airbus was already of aware the ice crystals were a problem. On 1.17.1.5.3.2 (pg 123), it interesting to read that (refering to past unreliable airpseed problems with the 330/340 fleet)
"Air France asked Airbus for information about
the cause of these events and the solutions to implement, and also asked if the Thales
C16195BA probe could resolve these problems. Airbus replied that the cause of the
problem was probably probe obstruction by a rapid accumulation of ice crystals, and
that the Thales C16195BA, developed to address the issue of water ingestion during
heavy rainfall, was unlikely to improve the performance in an ice crystal environment."

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 19:01:19 and read 21050 times.

Quoting AirCalSNA (Reply 57):
Given the amount of time and money that have gone into understanding what went wrong with AF447, it seems that even one accident like this is enough for most people to be deeply concerned.

The amount of concern is beyond doubt and directly related to the extent of the tragedy.

Where I think you're going wrong is by leaping to a conclusion that's just conveniently in line with pre-existing prejudices.

The reports make it rather clear that the sequence of events was not that trivial, and given the almost total confusion of the crew right from the beginning of the sequence of events, it is not at all clear nor does it even look very plausible that a different type of aircraft would have made all the difference here as you seem to believe.

You're judging from an already fixed conclusion, not from the actual facts.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: canoecarrier
Posted 2012-07-05 19:03:01 and read 21037 times.

Quoting Mir (Reply 39):
What's curious, though, is that the captain, who wasn't around when the problems began, wouldn't have reason to believe that the warning was faulty, yet he didn't ask about it. Perhaps the actions of the other two, who didn't appear to be focusing on it, led him to the incorrect conclusion that it was faulty and should be ignored.

I'll have to go back and check our timeline from the previous threads, but didn't the Captain enter the cockpit just as the last stall warning was sounding and it ceased shortly afterword?

I think the Captain never had an understanding of what was going on from the moment he entered the cockpit to the time they hit the water. Understandably so. The plane was already outside the flight envelope at that point.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 19:50:25 and read 20899 times.

Quoting AirCalSNA (Reply 52):
I would hope that this accident prompts Airbus to rethink its over-reliance on computerized flight control,

You believe that even though the report identifies several Boeing aircraft accidents due to near identical source events, and very similar crew reactions. I guess you must be unhappy with Boeing's "over-reliance on computerized flight control" in the B727. (Sarcasm implied).

You should also note that new military fighters, military cargo and patrol aircraft for the past couple decades and Boeing aircraft such as the B777, B787 and B747-800 all are as heavily computerized as the Airbus birds.

Quoting dfambro (Reply 58):
To nitpick, though, the BEA does not believe this represents super-cooled icing. Instead, they believe the cause of the obstruction was a high density of ice crystals in the air.

I hadn't got to that point in the report yet when I made the initial post. However, such icing was ruled even more 'impossible' than super-cooled water icing right after the crash of the aircraft by many experts.

Quoting canoecarrier (Reply 60):
but didn't the Captain enter the cockpit just as the last stall warning was sounding and it ceased shortly afterword?

According to the Annex 1 - CVR transcript

Captain first words upon re-entering are at 2:10:42.5

The Stall warning continues to sound on and off until the aircraft is near impact the water at 2:12:43. The "cricket" alarm is also sounding near continuous during this period and the 'C-Chord' alarm is also sounding frequently.


One thing I see in the report is that with three alarms sounding - going on and off several time a minute most of the time - picking out which is important and which is not important would be extremely difficult.

The report also adds something I haven't seen before.

Neither the PNF, nor the PF, turned off the Flight Director. During the course of the event - several times the very highly visible FD cross hairs disappeared and appeared on the PFD of the pilots. And it always showed the aircraft should be pitched up. The correlation of the FD with the stall warnings sounding may have helped lead the PF and PNF to decide the stall warnings were an error.

The report also mentions prior studies that visual indications/ warnings are more important than aural indications

While the AT automatically turn off, I'm think the FD turnoff should also be automatic, not a manual checklist item.

The BEA mentions several times the FD display and that the PF control inputs could be following the FD. Also the FD is much more visible than the indications of stall on the PFD - which also might have contributed to the PF not realizing the aircraft was in a stall.

One final item I want to mention from the report. The BEA is very explicit - aircraft certification does NOT include entering and then recovery from a full stall - only the approach to a stall and recovery from that state.

Some have asserted that the certification process does include entering fully developed stalls - and recovery. It does NOT.

WARNING - I've read the report and the annexes twice so far - which means I have not thoroughly studied the details. My impressions at this point might be subject to change.

[Edited 2012-07-05 19:52:02]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 19:53:32 and read 20876 times.

Undoubtedly having tracking joysticks would add complexity to the Airbus control design. So does having multiple pitots, the ability to switch displays, and many other things that contribute to either safety or better and quicker information for the pilots. As such, saying they would add complexity would be accurate but totally irrelevant if in this case it would have allowed the PNF to see that the PF was stalling the aircraft. Wouldn't any competent pilot realize that having the yoke or joystick all the way to the aft limits would stall the plane...especially if held there? I still don't believe that the PNF realized that the PF was holding the joystick aft as he was busy trying to interpret the conflicting instrument displays.

It's seems someone with vast experience with the Airbus shares the same opinion. During my flight training, my instructor always kept a light hand on the yoke to get a feel for what I was doing or about to do.  
Quoting ltbewr (Reply 56):
Using an A-320 simulator (similar to the A330 and the A320, a plane Cpt. Sullenberger was very experienced with) and a B-747 simulator, he noted what he sees as critical differences and issues. As the linked article notes, he thinks the 'joystick' design of A's does not give you enough status or feel of your flight position, while B's 'wheel' design shows more obviously your flight position. He also notes that the A's joysticks of the pilots are not interconnected so a mistake by one will not be understood immediately by the other flight officer.

It is interesting that the ECAM was basically telling the pilots what the degraded flight mode was, but not the root cause for the degraded mode. The computers knew that all the pitots had failed and thus unreliable airspeed. Why did a simple message to this effect not appear. Example.... "UNRELIABLE AIRSPEED" . It could be argued that they would have been better off with the ECAM blanked.

I didn't see any mention in the report about any flags for the standby attitude indicator or the altimeters and the loss of pitots should not have caused flags on them. As other flight instruments were showing flags, why did they not use these to fly the plane?

Overall, it looks like the pilots were presented with conflicting/changing information, information that was not necessary to handle the immediate crisis, and the lack of credible information such as angle of attack that might have helped them realize they were stalled.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirCalSNA
Posted 2012-07-05 20:03:05 and read 20784 times.

Quoting Klaus (Reply 59):
The amount of concern is beyond doubt and directly related to the extent of the tragedy.

Where I think you're going wrong is by leaping to a conclusion that's just conveniently in line with pre-existing prejudices.

The reports make it rather clear that the sequence of events was not that trivial, and given the almost total confusion of the crew right from the beginning of the sequence of events, it is not at all clear nor does it even look very plausible that a different type of aircraft would have made all the difference here as you seem to believe.

You're judging from an already fixed conclusion, not from the actual facts

I understand but disagree with your point, and I'm not offering an expert opinion. Notably, however, my lay-person's concerns about Airbus echo those of recognized experts.

Interestingly the report, even as you characterize it, doesn't seem to refute that the "total confusion" of three experienced pilots in a structurally sound, flying plane was caused to a significant degree by the Airbus operating system on the A330. You proffer no reasonable explanation to the contrary, only speculation.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 20:06:18 and read 20830 times.

Quoting airtechy (Reply 62):
Wouldn't any competent pilot realize that having the yoke or joystick all the way to the aft limits would stall the plane...especially if held there?

In the B727 accident discussed in the report - both pilots held the yoke full aft and never realized the aircraft was stalling.

Also mentioned in the report - whenever the Flight Director display returned - it seemed to indicate on both PFD that nose up input was necessary. That and three competing alarms would have make identifying a stall very difficult.


However, I do expect that Airbus and other side stick controller companies will develop linked controls in a few years.

It might even be possible to develop such a system for aircraft types currently in production. However, retrofit of existing airframes will likely be impossible.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirCalSNA
Posted 2012-07-05 20:12:06 and read 20739 times.

Quoting rfields5421 (Reply 61):
You should also note that new military fighters, military cargo and patrol aircraft for the past couple decades and Boeing aircraft such as the B777, B787 and B747-800 all are as heavily computerized as the Airbus birds.

Interesting, but undoubtedly they all work in different ways. Have the other heavily computerized systems caused the same type of spectacular catastrophe as happened with AF447?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-05 20:15:54 and read 20823 times.

Quoting airtechy (Reply 62):
Wouldn't any competent pilot realize that having the yoke or joystick all the way to the aft limits would stall the plane...especially if held there?

It does not stall the aircraft, exceeding the critical angle of attack does. A stall can occur in any attitude and at any speed. What your theory does not explain is how aircraft with control columns have been crashed in similar scenarios with unreliable airspeed.

What you also do not mention, is that large aircraft with control columns normally have artificial feel built into them, if the airspeed is off, so is the artificial feel as it has an airspeed input.

Quoting airtechy (Reply 62):
It is interesting that the ECAM was basically telling the pilots what the degraded flight mode was, but not the root cause for the degraded mode.

ECAM is for systems, the flight control law changes are displayed on the PFD, along with attitude, airspeed, height, and heading. the PFD is the primary method for determine the aircrafts attitude in any stage of flight, not the control column. Any IFR pilot will tell you that.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 20:33:47 and read 20671 times.

Quoting rfields5421 (Reply 61):
You believe that even though the report identifies several Boeing aircraft accidents due to near identical source events, and very similar crew reactions. I guess you must be unhappy with Boeing's "over-reliance on computerized flight control" in the B727.

An interesting point. I would be interesting to know if the response to control inputs changes between the flight modes on the 777 as it seems to do on the Airbus. Not talking about protections or warnings...just the control response.

Section 1.1

"At 2 h 10 min 16, the PNF said “we’ve lost the speeds ” then “alternate law protections”.
The PF made rapid and high amplitude roll control inputs, more or less from stop to
stop. He also made a nose-up input that increased the aeroplane’s pitch attitude up
to 11° in ten seconds"

"The aeroplane was subject to roll oscillations to the
right that sometimes reached 40 degrees. The PF made an input on the side-stick to
the left stop and nose-up, which lasted about 30 seconds"

Section 2.1.2.3

"When the autopilot disconnected, the roll angle increased in two seconds from 0 to
+8.4 degrees without any inputs on the sidesticks. The PF was immediately absorbed
by dealing with roll, whose oscillations can be explained by:

ˆˆ - A large initial input on the sidestick under the effect of surprise;
ˆˆ - The continuation of the oscillations, in the time it took to adapt his piloting at
high altitude, while subject to an unusual flight law in roll (direct law)."

"Following the autopilot disconnection, the PF very quickly applied nose-up sidestick
inputs. The PF’s inputs may be classified as abrupt and excessive."

This sounds like either a case of unstable/high gain control response or a lack of training in flying the plane in ALT 2 law at high altitudes.

I find this little titbit very interesting.

2.2.5 Aeroplane behaviour in reconfiguration laws

"When there are no protections left, the aeroplane no longer possesses positive
longitudinal static stability even on approach to stall. This absence specifically results
in the fact that it is not necessary to make or increase a nose-up input to compensate
for a loss of speed while maintaining aeroplane altitude. This behaviour, even if it
may appear contrary to some provisions in the basic regulations, was judged to be
acceptable by the certification authorities by taking into account special conditions
and interpretation material. Indeed, the presence of flight envelope protections
makes neutral longitudinal static stability acceptable.

However, positive longitudinal static stability on an aeroplane can be useful since it
allows the pilot to have a sensory return (via the position of the stick) on the situation
of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at
constant thrust. Specifically, the approach to stall on a classic aeroplane is always
associated with a more or less pronounced nose-up input. This is not the case on
the A330 in alternate law. The specific consequence is that in this control law the
aeroplane, placed in a configuration where the thrust is not sufficient to maintain
speed on the flight path, would end up by stalling without any inputs on the sidestick.
It appears that this absence of positive static stability could have contributed to the
PF not identifying the approach to stall"

This sounds like in ALT 2 and Direct Law the 330 is almost like the new fighter planes that have negative stability and require the use of computers for control. This leads to my question...does the Boeing 777 have this same stability characteristic?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 20:47:30 and read 20629 times.

Quoting AirCalSNA (Reply 65):
Have the other heavily computerized systems caused the same type of spectacular catastrophe as happened with AF447?

There are several different things to remember about computerized aircraft systems.

When most folks talk about fly-by-wire - that is not what they mean.

They mean the Airbus version of "Flight Envelope Protection" - the systems which prevent the pilots from pushing the aircraft out of the Flight Envelope into unstable aerodynamic situations in normal flight.

That does not apply to this accident in that sense because the drop from Normal Law to Alternate Law turned off that protection. Very obviously, this aircraft exited the flight envelope quickly in direct response to the actions of the PF. It is clear to me from the CVR transcript that both the PNF and the PF knew FEP was no longer active.

Fly By Wire - has caused accidents in the past in military aircraft - often by pilots not understanding the way the systems worked. The Airbus and the Boeing and the Gulfstream and the Bombardier and the Embraer implementation is close enough to the same as to not be a issue in this accident.

Fly-By-Wire is electronic assisted movement of flight controls. There is no direct mechanical link between the control and the flight control surface. Unlike a GA plane where there is a direct cable between the stick and the control surface - where the pilot can feel the different pressure needed to move the control surface at different speeds - Fly-By-Wire does not provide that. Even electro-hydraulic systems like on larger props and early jets do provide some direct feedback to the controls.

The implementation of feedback is a point of difference between Airbus and Boeing. Airbus does not provide any control surface feed back. Boeing does provide a 'best guess' feed back to the controls. For example - if the elevator binds on a GA aircraft, I will feel it when I try to move the controls. That won't happen in an Airbus, and the modern Boeing will give me little to no such feel.

Note - a problem in past difficult to control crashes from the "Golden Age of Jets" has been fatigue with the level of physical strength necessary to maintain a flyable attitude. I've seen that in the cockpit of a USN C-121 when we had a dual engine failure on one wing.

Fly-By-Wire eliminates that fatigue. Some aircraft that have come back, like Sully's A320, have benefitted from having fly by wire allow finer control of the aircraft.

This is a separate issue different from linked controls. Boeing links the two primary flight controls - so that when one pilot pulls back on the yoke, the other yoke moves back.

Several Airbus pilots have said on these forums it is not a problem to identify what control inputs the other pilot is making. The BEA reports says it can be an issue. Whether or not it would have made any difference in this crash is unknown.

Note the BEA reports says that when the aircraft had fallen to 31,500 ft - very soon after the initial event - recovery of the aircraft was be very unlikely unless there was a crew on the aircraft - trained and expecting such an event.

The major problem with heavily computerized aircraft is, in my opinion, information overload. Just reading the full BEA report - you can see where the crew may have been distracted by some indicators which were not essential to survival.

But crew fixation on the wrong instruments, wrong indicators, wrong things - is a long bloody story in aviation history. Even long before computers.

Some folks think aircraft pilots were better when they had to do all the math, navigation, engine management manually - rather than monitoring the computer systems. Many folks, not necessarily the same ones, feel that pilots today are trained too much to keep their hands off the controls and use the automation.

The BEA appears to agree somewhat with that assessment. Their recommendations include more training on actually manually flying the aircraft at cruise altitudes.

People tend to believe the best pilots are those on the long haul flights. You judge - from the BEA report

Captain - in the previous 30 days: 57 hours, 3 landings, 2 take-offs
Co-Pilot (PNF) - in the previous thirty days: 39 hours, 2 landings, 2 take-offs
Second Co-Pilot (PF) - in the previous thirty days: 61 hours, 1 landing, 2 take-offs

Many regional turboprop and regional jet pilots, even LCC main-line pilots do more takeoffs and landings in a day than this entire crew did in a month.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 20:57:04 and read 20638 times.

Quoting rfields5421 (Reply 64):
However, I do expect that Airbus and other side stick controller companies will develop linked controls in a few years.

It might even be possible to develop such a system for aircraft types currently in production. However, retrofit of existing airframes will likely be impossible

I respect your opinion....and agree with the last part, but this would only require new joysticks capable of tracking and a controller to link the two. Plus it would eliminate the requirement for "my joystick" switches...if your hand is on the joystick, it is your airplane.

Quoting zeke (Reply 66):
t does not stall the aircraft, exceeding the critical angle of attack does. A stall can occur in any attitude and at any speed. What your theory does not explain is how aircraft with control columns have been crashed in similar scenarios with unreliable airspeed.

Absolutely correct....and holding the joystick full aft will increase the angle of attack and eventually stall the airplane....especially in the absence of "NORMAL LAW" protections.

Although I think control columns are better, joysticks work just as well. They just don't convey the same positional information unless linked.

Quoting zeke (Reply 66):
ECAM is for systems, the flight control law changes are displayed on the PFD, along with attitude, airspeed, height, and heading. the PFD is the primary method for determine the aircrafts attitude in any stage of flight, not the control column. Any IFR pilot will tell you that

Correct me if I'm wrong, but I don't believe that the Airbus PFD can display textural information when it is displaying flight data. It would seem more precise....less cryptic error information would be better displayed on the ECAM. I have flown planes with FD's and understand how they work. However if they didn't believe the PFD....which I seem to read the report saying.....would they perhaps have believed what the position of the joystick should have been telling them?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-05 21:02:23 and read 20576 times.

Quoting airtechy (Reply 67):
"The aeroplane was subject to roll oscillations to the
right that sometimes reached 40 degrees. The PF made an input on the side-stick to
the left stop and nose-up, which lasted about 30 seconds"

The PF appears to have been significantly focused on maintaining a wings level position. The aircraft continually wanted to roll to the right. The plane actually turned about 270 degrees to the right as it descended.

When the FDR data was released, many very experienced pilots were surprised the crew was able to maintain a basically stable attitude as it fell out of the sky for three minutes, 37,000 feet.

I'm thinking the initial nose up was likely more from a sudden imprecise input - the startle factor mentioned in the report. Beyond that I won't speculate.

Quoting airtechy (Reply 67):
This sounds like either a case of unstable/high gain control response or a lack of training in flying the plane in ALT 2 law at high altitudes.

The BEA says lack of training is an issue.

All aircraft will have some unstable control response when they get as far into a stall as this aircraft did. Many very experienced large aircraft pilots had expressed doubt that the aircraft would have had enough control response to bring the aircraft out of the stall after it fell below 30,000 ft.


Quoting airtechy (Reply 67):
I would be interesting to know if the response to control inputs changes between the flight modes on the 777 as it seems to do on the Airbus.

Obviously I've never flown either, or anything close. I've learned a tremendous amount trying to follow the technical aspects of this investigation. We will need an acutal pilot to give us that answer.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-05 21:04:49 and read 20649 times.

Quoting airtechy (Reply 69):
Correct me if I'm wrong

You are.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-05 21:14:16 and read 20509 times.

Quoting AirCalSNA (Reply 65):
Interesting, but undoubtedly they all work in different ways. Have the other heavily computerized systems caused the same type of spectacular catastrophe as happened with AF447?

You're again drawing a preconceived conclusion that the BEA investigation does not share.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-05 21:19:48 and read 20482 times.

Quoting AirCalSNA (Reply 63):
Interestingly the report, even as you characterize it, doesn't seem to refute that the "total confusion" of three experienced pilots in a structurally sound, flying plane was caused to a significant degree by the Airbus operating system on the A330.

It doesn't say that the Airbus systems caused the confusion either. We could point to minor differences all day and try and pin blame on one manufacturer or another, but at the end of the day the pilots need to know how to interpret their situation from the information the airplane is giving them. And this crew was not very effective at doing that. And we have no evidence to suggest that would have been either more or less effective in a different aircraft.

Quoting airtechy (Reply 67):
This sounds like in ALT 2 and Direct Law the 330 is almost like the new fighter planes that have negative stability and require the use of computers for control.

No. Negative stability and neutral stability are not the same at all. Negative stability is not controllable without computer assistance. Neutral stability is (though this is a function of the auto-trim that Airbus builds in to the flight control laws, not a function of the aerodynamics of the airplane - in direct law, the airplane should be positively stable again, as a result of aerodynamics).

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 21:22:03 and read 20482 times.

Quoting rfields5421 (Reply 68):
Fly-By-Wire is electronic assisted movement of flight controls.

I once thought that Fly-By-Wire was a direct replacement for the control cables. i.e a device such as a potentiometer determined the yoke or joystick position and with suitable processing transmitted it to the control actuators. This would be a direct replacement for the control cables. In the case of Airbus and probably Boeing, I now realize that is only true in "DIRECT LAW". In all other cases the designers, it seems, have now decided that because we have the control loop available in electronic form we should "improve it" with position limits, rate limits, and response shaping. I can see how the shaping especially would drastically change how the airplane responses to control inputs. Sorta like having the steering ratio change on a car suddenly.....easy to overcorrect. My job required designing flight control loops for "smaller" flying objects.   

As I said upstream, that response change might have been more than these two pilots could handle near the coffin corner. I didn't see anything in the report that called out the actual/simulator training required by Air France for ALT 2 flying at high altitudes.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 21:34:47 and read 20431 times.

Quoting Mir (Reply 73):
No. Negative stability and neutral stability are not the same at all. Negative stability is not controllable without computer assistance. Neutral stability is (though this is a function of the auto-trim that Airbus builds in to the flight control laws, not a function of the aerodynamics of the airplane - in direct law, the airplane should be positively stable again, as a result of aerodynamics).

I'm not sure I understand the affect auto-trim has on the stability of the plane. Doesn't it merely relieve the biasing of the force required by the control actuators? ie.out-of-trim? Or are you saying it trims/adjusts the response of the control equations?

Neutral stability would seem to be less desirable than positive stability, but I suspect it contributes to reducing the drag coefficient of the airframe and can be tolerated in "NORMAL LAW" when the computers are actually controlling the flight characteristics as opposed to "ALT 2/DIRECT LAW" where they are not.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: N14AZ
Posted 2012-07-05 23:21:13 and read 20117 times.

Quoting AirCalSNA (Reply 52):
I would hope that this accident prompts Airbus to rethink its over-reliance on computerized flight control, which, consistent with the use of joy sticks, relegates pilots to peripheral status except when the sh** hits the fan. This is a basic human-factors design flaw.

This is a very simplistic conclusion, to say it diplomaticallly. If your concerns were correct, the safety report would not have more than 200 pages (not considering the previous reports) and BEA would have come to the conclusion that the design philosphy is crap and has to be changed ASAP.

You will never know how many accidents have been avoided by Airbus' design philosophy.

There are thousands of Airbus flying around and thousands of other airplanes from B, McD, Fokker, Bae. So we have a huge database for statistical analyses. If your concern would be correct we would see a higher accident rate for the Airbus planes.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-05 23:34:15 and read 19969 times.

I wonder what drove this change re: Air France changes since the accident?

5.1.2

Documentation

ˆˆ- Changeover to manufacturer’s documentation in English. The B777 division will
be the first to be thus equipped in October 2012.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: amritpal
Posted 2012-07-05 23:35:34 and read 19955 times.

No matter what the report said, I think pilot did what they could to best of their abilities based on the what they had infront of them. They are professionals. RIP

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: aerobalance
Posted 2012-07-05 23:44:09 and read 19898 times.

I don't have time to read the report since the project I'm working on needs my attention, and reading through the posts hasn't offered what happened... What caused this accident to happen and does the report pinpoint blame? Thanks

[Edited 2012-07-05 23:45:14]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-06 00:01:32 and read 19892 times.

The report fairly specifically details what caused the accident and spreads the blame like butter on a piece of bread. Download and skip to section 4 for recommendations.

http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php

Jim

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ricknroll
Posted 2012-07-06 00:20:13 and read 19771 times.

Quoting AirCalSNA (Reply 57):
Given the amount of time and money that have gone into understanding what went wrong with AF447, it seems that even one accident like this is enough for most people to be deeply concerned.

I am guessing a large part of the effort is the standoff that must be occurring between Airbus and AirFrance. Airbus is very keen to clear itself, as is AirFrance.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-06 00:30:59 and read 19731 times.

Quoting ricknroll (Reply 81):

I am guessing a large part of the effort is the standoff that must be occurring between Airbus and AirFrance. Airbus is very keen to clear itself, as is AirFrance.

Which is probably why no changes will occur until all the lawsuits have been settled. Making changes at this point, even if the report recommended them, could be taken as an admission of guilt. With the publicity this accident has had.. and continues to have...you can bet some changes will be forthcoming. It will be interesting to see how the various parties "spin" these changes.

Jim

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: David L
Posted 2012-07-06 03:02:21 and read 19336 times.

Quoting airtechy (Reply 69):
Plus it would eliminate the requirement for "my joystick" switches...if your hand is on the joystick, it is your airplane.

I'm not sure I follow. The current set-up means that if your hand is on the side-stick it's your aircraft. The Priority buttons only disable the other stick, e.g. to override any inadvertent inputs by an incapacitated pilot. I'm pretty sure that in normal circumstances no button has to be pressed when control changes from one pilot to the other. If both pilots operate their sticks simultaneously then there are aural and visual warnings. If both pilots continue to use the Priority buttons to shut the other out then they've got bigger problems than how the priority works.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 03:13:40 and read 19394 times.

Quoting ltbewr (Reply 56):
he noted what he sees as critical differences and issues.

I'm very disappointed in Cpt Sullenberger, I should have thought he knows better than this. For all his piloting skills, I truly believe he never gave the aircraft the credit it deserved. I don't care what anybody says, AWE1549 would more than likely not have had the same result in an aircraft without envelope protection. Chances are it would have stalled at low altitude and pancaked into the river...hard.

Quoting airtechy (Reply 75):
I'm not sure I understand the affect auto-trim has on the stability of the plane. Doesn't it merely relieve the biasing of the force required by the control actuators? ie.out-of-trim? Or are you saying it trims/adjusts the response of the control equations?

Because ALT2 (the flight control mode in operation after ADR DISAGREE) is a load factor demand law the same as normal law, the autotrim works in conjunction with the sidestick to achieve a load proportional to sidestick deflection (within the confines of the load factor protection). The PF had the sidestick held back for long periods, so the autotrim would recognise an extended request for a positive g-demand exceeding 1g - basically an accelerating climb rate hence the THS moving virtually to the up-stop. Under normal law, the autotrim would have been limited by AoA protection to 4 degrees up but obvioulsy this protection was not available. Once the THS passed probably 6 or 7 degrees, to regain control would have required a full and sustained nose down input on the sidestick. The load factor protection would still have kept the aircraft within the -1g limit, and the THS would have travelled back towards zero. The position of the THS is shown on the Lower DU when the F/CTL button is pressed.

Thinking of it from this point of view, they might have actually been better off in their situation had the flight controls degraded to direct law instead of ALT2 - as the autotrim would not have been active and control might have been regained by a prompt nose down input.

It's easy to say this though from my office chair. At midnight, in light turbulence without the benefit of all this hindsight, identification of the problem and the solution is a different story.

One question as well - Does anybody know why the Stall warning is dependent on airspeed? I understand that you don't want nuisance alerts at low speeds, but why not link it to the air/ground mode switches? Might have really helped in this situation...

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: garpd
Posted 2012-07-06 03:40:45 and read 19294 times.

Quoting tom355uk (Reply 84):
I'm very disappointed in Cpt Sullenberger, I should have thought he knows better than this. For all his piloting skills, I truly believe he never gave the aircraft the credit it deserved. I don't care what anybody says, AWE1549 would more than likely not have had the same result in an aircraft without envelope protection. Chances are it would have stalled at low altitude and pancaked into the river...hard.

Sorry but: Bollocks, absolutely pure, unrefined, bollocks.

It is possible to stall an Airbus, AF447 tragically shows this. (Yes I know about the different laws of Airbus FBW. Still, the fact of the matter is, AF447 stalled)

A skilled pilot who knows the ref speeds for his aircraft and is switched on enough will not stall it. There have been several example. The three that come to mind are: Air Transat A330, Air Canada 767 (Gimli Glider), Ethiopian 767.

Notice that from those examples, two are aircraft with no envelope protection. The ET 767 may not have "landed" well due to the hijackers fighting in the cockpit, but it was glided from high altitude to ground level without stalling.

To suggest that the aircraft type alone made the Cactus 1549 incident survivable is laughable.
Sully had a lot going for him, it was light, he was high enough to avoid buildings and spend a moment to weigh out his options. Above all, he had the skill and determination to choose the river and make it work. The fact he was flying an A320 had little bearing on the outcome.

[Edited 2012-07-06 03:43:06]

[Edited 2012-07-06 03:52:15]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 04:26:59 and read 19065 times.

Quoting garpd (Reply 85):
Sorry but: Bollocks, absolutely pure, unrefined, bollocks.

Bit harsh, but I will defend my opinion.

Quoting garpd (Reply 85):
It is possible to stall an Airbus, AF447 tragically shows this.

Which had no bearing on 1549, as the aircraft remained in normal law the whole time.

Quoting garpd (Reply 85):
skilled pilot who knows the ref speeds for his aircraft and is switched on enough will not stall it.

What reference speeds? Best glide? Not provided for instant access during such a situation. All engines out landing reference speed? Not provided. Best ditching speed? Cpt Sullenberger used a best guess for both these figures, and luckily both were pretty close to what was required.

Quoting garpd (Reply 85):
To suggest that the aircraft type alone made the Cactus 1549 incident survivable is laughable.

I'm not saying that it was the sole element. All I actually said was that it made life a lot easier for him - and something that he has been surprisingly quiet about. Not having to worry about where the critical AoA for stick shaker is during an unpowered glide and landing is one less problem to worry about.

The only reason I bought this up was due to him virtually blaming the design of the aircraft for 447's demise - a design that really did it's job for him when it mattered most.

Quoting garpd (Reply 85):
he had the skill and determination to choose the river

I'm not doubting his piloting ability or his coolness when it mattered. By the time the decision had to be made, he didn't really get the option of 'choosing' the river. There was no choice.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: scbriml
Posted 2012-07-06 04:38:20 and read 18974 times.

Quoting amritpal (Reply 78):
No matter what the report said, I think pilot did what they could to best of their abilities based on the what they had infront of them. They are professionals. RIP

Sadly, for all the passengers on board, their best appears to have been woefully inadequate.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: moose135
Posted 2012-07-06 04:39:16 and read 19017 times.

Quoting rfields5421 (Reply 68):
But crew fixation on the wrong instruments, wrong indicators, wrong things - is a long bloody story in aviation history. Even long before computers.

I remember an experienced 3-man crew that flew a perfectly good L-1011 into a swamp because a light bulb burned out...

Thanks for the thorough explanation of the report, rfields5421. I doubt I'll have the time to read it as closely as you have, so I appreciate the information and commentary you (and our resident pilots) are able to provide!

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: garpd
Posted 2012-07-06 04:39:27 and read 18974 times.

Quoting tom355uk (Reply 86):
All I actually said was that it made life a lot easier for him - and something that he has been surprisingly quiet about.

I have not seen any mention in any report that the envelope protection assisted in the incident. If there is such a citation, please share it.

I still do not understand why you think it did though.
Though, you are entitled to your opinion, just know that it is incorrect.

[Edited 2012-07-06 04:48:07]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 04:47:42 and read 18965 times.

Quoting garpd (Reply 89):
Not once is there any mention in any report that the envelope protection assisted in the incident.

NTSB Report, Page 88: http://www.ntsb.gov/doclib/reports/2010/AAR1003.pdf

The NTSB concludes that, despite being unable to complete the Engine Dual Failure checklist, the captain started the APU, which improved the outcome of the ditching by ensuring that a primary source of electrical power was available to the airplane and that the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall.

Reduced to key phrases:

the captain started the APU, which improved the outcome of the ditching by ensuring that...the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall.

So clearly, it does.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: jollo
Posted 2012-07-06 04:53:46 and read 18931 times.

Quoting aerobalance (Reply 79):
What caused this accident to happen and does the report pinpoint blame?

Not easy to wrap-up 200 pages in a nutshell, but I'll give it a try. Basically, BEA concludes that the accident was caused by:
* failure of the crew to apply proprer procedure
* failure of the training to cover high-altitude manual handling with unreliable airspeed indicators
* task fixation of the PF (on roll control, mainly)
* some aspects of instrument design did not help the crew

I think not enough emphasis is being put on the second item: pilots must be ready to take over when automation quits, and that typically happens when something went wrong. A peculiarly bad moment for training on the job: you don't want to do something for the first time ever right when the sh*t hits the fan.

[Edited 2012-07-06 05:41:01]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: garpd
Posted 2012-07-06 04:54:41 and read 18902 times.

Quoting tom355uk (Reply 90):

the captain started the APU, which improved the outcome of the ditching by ensuring that...the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall.

So clearly, it does.

No it doesn't.

It merely shows that the envelope protection was available. Which isn't a bad thing obviously.
There is, AFAIK, no data showing that the envelope protection was actually needed. Thus, it did not play a role.

Starting the APU is a no brainer. You need power to the instruments and the bleed air for the engines to try restarting them.

Sully doesn't mention the envelope protection because it did not play an active role in the event.
The flight would likely have ended the same way in any low winged aircraft, regardless of make or model, so long as the pilot knew what they were doing.

Show me data that shows Sully was stalling the plane and the protection kicked in and I'll shut up.
If there isn't any, your opinion is moot.

[Edited 2012-07-06 04:57:53]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 05:21:04 and read 18793 times.

Quoting garpd (Reply 92):
Sully doesn't mention the envelope protection because it did not play an active role in the event.

Page 89:

However, FDR data indicated that the airplane was below green dot speed and at VLS or slightly less for most of the descent, and about 15 to 19 knots below VLS during the last 200 feet.

Page 48:

Airbus performed a simulation of the last 300 feet of the accident flight, which indicated that the airplane was performing as designed and was in alpha-protection mode from 150 feet to touchdown.

The airplane’s airspeed in the last 150 feet of the descent was low enough to activate the alpha-protection mode of the airplane’s fly-by-wire envelope protection features. The captain progressively pulled aft on the sidestick as the airplane descended below 100 feet, and he pulled the sidestick to its aft stop in the last 50 feet, indicating that he was attempting to raise the airplane nose to flare and soften the touchdown on the water.

Alpha protection mode is the key here. In a conventional airplane, the stick shaker would probably have activated and made things much, much worse.

Enough for you?

[Edited 2012-07-06 05:25:25]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: s5daw
Posted 2012-07-06 05:23:23 and read 18769 times.

Quoting tom355uk (Reply 90):

As far as i understand the captain is criticizing the ergonomy of joysicks, not envelope protection?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: U2380
Posted 2012-07-06 05:39:53 and read 18677 times.

Quoting garpd (Reply 92):
Starting the APU is a no brainer.

It may well be a no brainer. However, I don't believe they reached the part of the checklist which specified starting the APU, it would have been very easy for him to forget to do so.

As for whether the flight envelope protections actually intervened, I don't know enough about the incident to comment on that. Surely though, they must have been reassuring to have whilst being in a high workload situation.

Personally, I also feel he didn't give the aircraft enough credit. However, that's not to say the outcome would have been any different in another aircraft.

I also believe that it is exceptionally unprofessional to have commented on AF447 before the final report was released, especially in the way he did.

[Edited 2012-07-06 05:40:38]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 05:40:38 and read 18762 times.

Quoting s5daw (Reply 94):
As far as i understand the captain is criticizing the ergonomy of joysicks, not envelope protection?

Quote from article:

Capt. Chesley "Sully" Sullenberger, CBS News' aviation and safety expert, said the same disaster would have been "much less likely to happen" in a Boeing plane

That isn't very helpful is it? Especially from somebody in his position - who's word on such subjects will be gospel to those who know nothing of aircraft design and operation. This is basically saying "This crash wouldn't have happened to a Boeing" - which we all know is not the case. Even if he is only referencing the sidestick philosophy, he hasn't really said that has he? That is why I am particularly disappointed with him.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-06 05:46:03 and read 18640 times.

Quoting airtechy (Reply 75):
I'm not sure I understand the affect auto-trim has on the stability of the plane.

The auto-trim will maintain the pitch attitude of the aircraft when the sidestick is released. So if you pitch up to five degrees and let go, the airplane will hold five degrees nose up on its own by use of trim, and thus it will, in effect, be neutrally stable. This is just a function of the FBW system though - the aircraft is still aerodynamically positively stable.

Why Airbus decided to do it that way I'm not sure, but I am sure there's a very good reason for it.

Quoting tom355uk (Reply 84):
One question as well - Does anybody know why the Stall warning is dependent on airspeed? I understand that you don't want nuisance alerts at low speeds, but why not link it to the air/ground mode switches? Might have really helped in this situation...

The only reason I can think of is to prevent nuisance alerts, like the ones that this flight had early on. But that is a big reason - it's probably a worse idea to let the crew cancel a nuisance stall warning, as they might cancel what is an actual warning without knowing it.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: s5daw
Posted 2012-07-06 05:47:53 and read 18631 times.

Quoting tom355uk (Reply 96):

In reply56 of thhis thread we can read he is referring to inability to see PFs commands in A, versus B where it is clear what PF is doing. It has been debated before and it will be in the future, but I seem to remember from the CVR transcripts that PNF (or was it the captain) was surprissed by the inputs of PF.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: flipdewaf
Posted 2012-07-06 05:51:00 and read 18651 times.

Quote:
Capt. Chesley "Sully" Sullenberger, CBS News' aviation and safety expert, said the same disaster would have been "much less likely to happen" in a Boeing plane

I now trust everything he says because those    CFM    56's    are    much    more    tough    on    737's.

Back on topic,

How long would any recomendations from accidents come in to force regarding design regulations for new aircraft, updates to older aircraft and updates to those still in production?

Fred

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: David L
Posted 2012-07-06 06:07:24 and read 18615 times.

Quoting s5daw (Reply 98):
It has been debated before and it will be in the future, but I seem to remember from the CVR transcripts that PNF (or was it the captain) was surprissed by the inputs of PF.

   The Captain and the PNF both kept telling the PF that he was "going up" and should "go down" instead. Why would they tell him to stop doing something they didn't know he was doing? If they knew they were stalled or stalling and didn't know what the PF was doing, why weren't they more assertive in telling him to get the nose down? I'm more convinced that they simply didn't have a much clearer idea of what the PF should be doing than he did himself.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 06:10:35 and read 18588 times.

Quoting amritpal (Reply 78):
No matter what the report said, I think pilot did what they could to best of their abilities based on the what they had infront of them. They are professionals. RIP

No, they were not behaving like professionals, and that is directly why they crashed their aircraft into the sea, as sad as it is.

Which doesn't justify a moral (or judicial) judgment, since it appears they succumbed to a thoroughly human, but unfortunately thoroughly unprofessional, state of panic and confusion.

Quoting garpd (Reply 85):
It is possible to stall an Airbus, AF447 tragically shows this. (Yes I know about the different laws of Airbus FBW. Still, the fact of the matter is, AF447 stalled)

You know too little, then, since AF447 was stalled by the PF only after it degraded to alternate law. In normal law it would have been quite difficult to be stalled.These distinctions do matter.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: jollo
Posted 2012-07-06 06:27:26 and read 18508 times.

Quoting tom355uk (Reply 84):
Does anybody know why the Stall warning is dependent on airspeed?

Stall warning is fed by AoA, and AoA vanes are unreliable under a certain airspeed (60 kts, IIRC). The design goal is to disable an alarm as soon as its inputs are flagged as invalid.

Quoting s5daw (Reply 94):
As far as i understand the captain is criticizing the ergonomy of joysicks, not envelope protection?

Yes, in the CBS article he clearly only referred to the lack of a cross-link between the joysticks. Still, selective quoting of his words, together with his (well deserved) "hero" status, will probably fuel disinformation (already happening).

One of the reasons why Airbus' sticks aren't mechanically linked is: in case of a control conflict, you'd put the most experienced pilot's left hand strength in competition with the least experienced pilot's right hand strength. Statistically, right-handed people are the vast majority and their right hand is stronger: you can see how this would likely be a bad setup. Incidentally, yoke controls have exactly the same problem when flying "hands on yoke and throttle" (e.g. on final).

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-06 06:43:35 and read 18442 times.

Quoting airtechy (Reply 69):
would they perhaps have believed what the position of the joystick should have been telling them?

I believe control input position indications would not have changed anything in this accident.

As the BEA noted in the other incidents they analyzed - the crews did not believe the stall warning to be an indication of a real stall.

There is nothing I can see in this report, and the previous reports where the AF447 crew every considered stall as a possibility.

Quoting tom355uk (Reply 84):
Does anybody know why the Stall warning is dependent on airspeed? I understand that you don't want nuisance alerts at low speeds, but why not link it to the air/ground mode switches? Might have really helped in this situation...

An electronic stall warning depends upon some instrument to measure the airflow. At certain points any mechanical measurement system is going to become unreliable. So rather than guess if the aircraft might be in a stall - the warning goes off.

As to linking the stall warning to things like the sensors which tell if weight is upon the landing gear - we might see such a design change in the future, and we might not.

However, the BEA report, in my reading between the lines, pretty much says that aural stall warnings are pretty useless in transport catagory aircraft at cruise. Crews ignore them and focus on other visual factors.

I do expect the manufactures to make a change to their PFD display to make the stall warning highly visible, which it is not currently.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: s5daw
Posted 2012-07-06 06:51:49 and read 18393 times.

How about changing ALT2? If I understand correctly, high AOA rpotections are retained UNLESS the two air data references disagree. This was the case in AF447, right?

So what if the pilots thought they had protections, but in fact did not? That would explain why they ignored stall warning and listened to FD.

Would this have ended any different if the plane simply went into Direct Law and the pilots would start to pay attention to the stall horn?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rcair1
Posted 2012-07-06 07:03:41 and read 18372 times.

Quoting s5daw (Reply 94):
As far as i understand the captain is criticizing the ergonomy of joysicks, not envelope protection?

Yes, that is correct. It is a position many have taken, including me. Others reject it, out of hand, with the argument that if it was that bad then Airbus aircraft would be falling out of the air. That, of course, is silly. Issues that bring modern airliners down are most often margin issues - in other words, they become important only in the margins - a somewhat unusual situation. Often changes to the aircraft/systems are driven by the failures that occurred in a single instance which was on the margin - most often coupled with secondary failures. It was not the lightbulb that brought the L1011 down in Florida - it was the lightbulb AND the crew.

The difficulty with the discussion regarding coupling of Airbus joysticks and addition of haptic feedback is that it is a soft issue - human factors/man-machine interface. It is nearly impossible to 'prove' that a factor of this nature caused, or contributed to, an incident. We can look at the physical device in some crashes - for instance, the fuel-oil heat ex-changer in a RR powered B777 and see that ice cause interruption of fuel and the BA crash. It is not debatable. We cannot say with the same certainty that lack of sidestick coupling contributed to the confusion in the cockpit of AF447. We can have that opinion, or not, but it is a soft conclusion.

When can almost never identify with surety that a user interface helped or hindered in an incident. We know that in 1549 the aircraft protections kicked in. We know there was a successful outcome. We do not know what would have been the outcome in an aircraft w/o protections. It is invalid to assume that Capt Sullenburger would have used the exact same inputs in an aircraft that was behaving differently. We can simulate and those simulations showed that it was impossible to achieve the Airbus recommended ditching attitude without consciously increasing the descent rate then pulling up at the end (this was demonstrated by an Airbus test pilot) - because of the way protections worked. But that does not prove anything about the protections or the success of the ditching if Sully had done so.

So arguments that the aircraft's protections "saved the day" or "helped the pilot" are not useful.

What we know, and all we know, is that the "system" (which includes the aircraft and crew) worked that day, and worked well. We change any part of that system in a subtle way - and other parts may or may not have compensated. The outcome may or may not have been the same, better or worse. It is an unsolvable problem. We can simulate, with 20-20 hindsight, other scenarios, but they are simulations only.

Ideally, this is a good argument to have. We want to understand and adapt already good systems to be better.

Practically, the politics and company philosophy makes it frustrating and useless.

I can not imagine a situation where Airbus would suddenly start coupling joysticks or adding haptic feedback because were they to do so, they would be admitting a philosophy which they have rabidly supported is not optimal. It would be more likely for Boeing to adopt sidesticks- but I suspect they would preserve coupling and haptic feedback. The argument is not about yokes versus sticks, it is about the tactile versus visual feedback.

In the case of Airbus versus Boeing, they have 2 very different philosophies regarding flight controls.

Airbus's approach is that tactical and haptic feedback is non-essential. They do not need to couple the joysticks because the other pilot can easily look over and see what the PF is doing. They use rate constant springs on the joystick because the pilot can see from the instruments what the aircraft is doing. They do not need to back drive the throttles because the visual cue of moving the throttles is unimportant.
Obviously it works because thousands of flights on Airbus's conclude safely every day.

Boeing's approach is that tactical and haptic feedback is important. You can feel what the other pilot is doing without looking. Throttles are back driven so you can see them move. Haptic feedback means the 'feel' of the controls changes with aircraft performance.
Obviously it works because thousands of flights on Boeing's conclude safely every day.

Again - it is not about sidesticks versus yokes - both could work in either scenario.

It is also hard to prove - partly because we never hear about successes attributed to either. (if it works, we don't hear about it).

Let's consider backdriven throttles.
In the 737 crash at Schipol, the backdriven throttles should have indicated to the pilots the aircraft was in flare mode - they did not. So they did not help. Critics have used that to prove that backdriven throttles are not useful.
The problem with that is you do not have any data on how often the backdriven throttles may have alerted the pilots to something and they took corrective actions - so there was no incident and we never heard about it.

As a fireman involved in the recent Colorado High Park fire, I can tell you precisely how many homes we lost. I cannot tell you, with the same precision, how many we saved. Some survived on their own due to design/location/fuel/wind/etc. Some survived only because of direct intervention by fire crews. You never hear about those successes - only the failures.

This is a common problem in human factors based safety. You instigate a procedure and rule based on a low rate incident. Because it is low rate, you don't really know if you fixed it. Statistics does not work (low rate) - so you cannot measure it.

In my opinion, the truth is probably between the two philosophies (Airbus and Boeing). However, based on human factors work I have done, I believe the Boeing approach is better. People interact with machines using a variety of senses - and visual/cognitive is not always the most important. Why would you take away some of that ability to interact? When we first had cars with "power steering" people complained that they could no longer "feel" the car. When you buy a keyboard, you look for one with good 'feel' because a bad one causes you to type badly. In computer assisted surgery, haptic feedback is critical to the doctor's ability to feel the tissues. History is re-pleat with instances where we, inadvertently or on purpose, removed some 'sensory' from an interaction just to find it was wrong.

I cannot prove that visual cues/tactical inputs are important. I can have that opinion, and do, but I recognize it is only in the margins where this is the case. Does my belief mean that I won't fly on an Airbus? Of course not - that is stupid and silly. Nor do I feel "inherently" safer or less safe on one brand or the other.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 07:07:24 and read 18344 times.

Quoting Mir (Reply 97):
I can think of is to prevent nuisance alerts, like the ones that this flight had early on

I appreciate that - but to me it seems that in a situation such as this that an overspeed would have been less dangerous than a nose high low airspeed stall. I'm sure the aerofoil design on the A330 would have prevented the guys exceeding MD much in a dive anyway - and once in warmer air you lose the icing effects and hopefully regain all required indications.

Quoting jollo (Reply 102):
Stall warning is fed by AoA, and AoA vanes are unreliable under a certain airspeed (60 kts, IIRC).
Quoting rfields5421 (Reply 103):
So rather than guess if the aircraft might be in a stall

But if both WoW switches show 'Air' as the current mode and your airspeed is less than 100kts, you are stalled. Regardless of whether the vanes function correctly at low speed. Perhaps this should be part of the FCTL reference data.

Obviously, at the moment the stall warning references the AoA vanes if IAS is greater than a threshold value, maybe if the WoW switch showed 'Air' then in this case, the likelihood of both of these independent systems failing is virtually nil and the stall warning must be accepted as valid even if the AoA indication is rejected.

Quoting s5daw (Reply 104):
Would this have ended any different if the plane simply went into Direct Law and the pilots would start to pay attention to the stall horn?

Like I said before, Direct Law would probably of helped by disabling the autotrim that under the circumstances made recovery virtually impossible.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 07:26:43 and read 18266 times.

Quoting tom355uk (Reply 106):
Like I said before, Direct Law would probably of helped by disabling the autotrim that under the circumstances made recovery virtually impossible.

Upward autotrim was a result of the PF keeping the stick pulled aft most fo the time. It wasn't the autotrim that made it a problem.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-06 07:41:26 and read 18212 times.

Quoting Klaus (Reply 107):
Upward autotrim was a result of the PF keeping the stick pulled aft most fo the time. It wasn't the autotrim that made it a problem.

The autotrim moved the THS virtually to it's full up-stop as per its design. If the aircraft had degraded immediately to direct law, then the autotrim would have disconnected and frozen the THS value at it's previous setting. With the THS in the full up position, a sustained nose down input (for more than a few seconds - i'm not sure what the rate of movement in degrees per second is) would have been required to bring the aircraft back under control. If it had been frozen at the cruise value (probably near zero, or slightly up??) then the return to controlled flight would have been quicker, and probably achievable in exchange for much less altitude loss.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-06 07:58:19 and read 18144 times.

Quoting tom355uk (Reply 108):
at the cruise value (probably near zero, or slightly up??) then

The FDR annex says the THS was at -2.8 when the event occured. The aircraft pitch is 1.8 degrees nose up at that time/ setting.

The THS goes to -3.2 as the aircraft climbs and to -3.6 as it starts to fall. As aircraft falls the THS increases to -8.3 over the next 22 seconds. Then to -13.5 over the next minute.

Over the first two minutes of the incident - the THS is varying and finally stabilizes at -13.6. Well past the no-recovery point.

[Edited 2012-07-06 08:04:48]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: 135mech
Posted 2012-07-06 08:44:09 and read 17937 times.

Text edited out by 135mech

[Edited 2012-07-06 09:09:47]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 09:02:41 and read 17930 times.

Quoting tom355uk (Reply 108):
If it had been frozen at the cruise value (probably near zero, or slightly up??) then the return to controlled flight would have been quicker, and probably achievable in exchange for much less altitude loss.

They never attempted such a return. Quite the contrary, which is why the upwards trim resulted in the first place.

Losing autotrim would most probably exacerbate the situation in most cases when alternate law is being triggered, so would you really propose that Airbus should disengage it there already?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-06 09:13:31 and read 17902 times.

EDIT - Quote deleted


The crew did change course to avoid some weather - we don't know what they saw on the radars because that is not recorded in any place on the plane. The crew discussed the weather and avoidance several times.

From page 21 of the final report

Quote:
the co-pilot modified the scale on his Navigation Display (ND) from 320 NM to 160 NM and noted “…a thing straight ahead”. The Captain confirmed and the crew again discussed the fact that the high temperature meant that they could not climb to flight level 370.
Quote:
The co-pilot noted that they were “entering the cloud layer” and that it would have been good to be able to climb. A few minutes later, the turbulence increased slightly in strength.
Quote:
during which the PF (seated on the right) said specifically that “well the little bit of turbulence that you just saw we should find the same ahead we’re in the cloud layer unfortunately we can’t climb much for the moment because the temperature is falling more slowly than forecast”

On Page 22

Quote:
At 2 h 06, the PF called the cabin crew, telling them that “in two minutes we ought to be in an area where it will start moving about a bit more than now you’ll have to watch out there” and he added “I’ll call you when we’re out of it”.
Quote:
2 h 08, the PNF proposed “go to the left a bit […]”. The HDG mode was activated and the selected heading decreased by about 12 degrees in relation to the route. The PNF changed the gain adjustment on his weather radar to maximum, after noticing that it was in calibrated mode. The crew decided to reduce the speed to about Mach 0.8 and engine de-icing was turned on.

The CVR transcript shows even more discussion about the weather and where best to fly to avoid problems.

Also from page 46

Quote:
The infra-red imagery analysis does not make it possible to conclude that the stormy activity in the zone where flight AF 447 is presumed to have disappeared was exceptional in character, but it shows the existence of a cluster of powerful cumulonimbi along the planned flight path, identifiable from 0 h 30 onwards. This cluster is the result of the fusion of four smaller clusters and its east-west extension is approximately 400 km.

The band of weather facing them was 400 KM wide.

Yes, several flights that evening did alter their courses. But not ALL flights alertered their courses.

IB 6024 (12 min after AF447) altered their course about 30 nm east
AF 459 (37 min after AF447) altered their course about 20 nm west, then to the east 70 to 80 nm
LH 507 (20 min ahead of AF447) altered their course about 10 nm west

[Edited 2012-07-06 09:20:28]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-06 09:39:54 and read 17812 times.

Quoting canoecarrier (Reply 27):
I'll be interested to get Kaiarahi's input on part of the report that discusses the Human Factors Working Group (1.16.8)

I'm reading carefully - in the original French. As always, and particularly when analyzing "states of mind" (cognitive + emotional factors), there are nuances in the French version that are not caught in the English translation.

I suspect that there are some things that may be known or partially known to the investigators that do not appear in the public report. For example, the report questions why the PIC handed off command to the vastly less experienced FO, rather than the FO who had more experience on type and in the sector than the PIC himself, but does not attempt to provide any answer.

For me, one of the most revealing aspects at first reading is that most other crews that survived unreliable speeds incidents also did NOT run the UAS and survived - in previous threads, many pointed to not running the checklist as a primary cause. However, as Zeke has pointed out, the first caveat on the checklist is

Quoting zeke (Reply 45):
"if the safe conduct of the flight is impacted"

.

Another revealing aspect is the discussion of why the crew may have not reacted to the stall warning, including other crews' experience of "spurious" transient warnings.

Much more reading and re-reading to do ....

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirCalSNA
Posted 2012-07-06 11:14:22 and read 17505 times.

Quoting Mir (Reply 73):
It doesn't say that the Airbus systems caused the confusion either. We could point to minor differences all day and try and pin blame on one manufacturer or another, but at the end of the day the pilots need to know how to interpret their situation from the information the airplane is giving them. And this crew was not very effective at doing that. And we have no evidence to suggest that would have been either more or less effective in a different aircraft.

It's interesting how hard you try to avoid drawing any conclusion from the report. Unless the pilots were deranged or drunk, the only source of confusion was the environment they were in, which, other than the weather, was designed and built by ... wait for it .... Airbus. Saying that there is "no evidence to suggest that" the crew would have been "more or less effective in a different aircraft" adds nothing, since, by this statement, you also implicitly admit that there is no evidence disproving that a different outcome would have occurred in another aircraft.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: racko
Posted 2012-07-06 11:24:29 and read 17507 times.

Regarding US Airways 1549, the well-known American author (and former professional pilot) William Langewiesche has written an excellent book about the role the Airbus A320 played in avoiding a disaster.

http://www.nytimes.com/2009/11/29/books/review/Haberman-t.html

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: David L
Posted 2012-07-06 11:31:15 and read 17432 times.

Quoting rcair1 (Reply 105):
It is a position many have taken, including me. Others reject it, out of hand

I think you've neglected a more significant group than the few who "reject it, out of hand". There's also a group that has given specific reasons for their scepticism. For example, those who believe that the notion that AF447 is evidence that the rest of the crew can't tell what the PF is doing requires selective reading of the CVR transcript and trivialising the more fundamental CRM issues.

Quoting Kaiarahi (Reply 113):
in previous threads, many pointed to not running the checklist as a primary cause. However, as Zeke has pointed out, the first caveat on the checklist is

Quoting zeke (Reply 45):"if the safe conduct of the flight is impacted"

Guilty as charged. However, shouldn't one of them at least have mentioned it? I guess I need to know more about those other incidents.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-06 11:32:20 and read 17446 times.

I thought I read a report that tests showed the protection limits caused the Sully A320 to hit the water at a higher airspeed than if they had been disabled.

Jim

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-06 11:36:32 and read 17434 times.

Here are some additional interesting excerpts. Section 2.4 on page 191 goes to what we discussed with Zeke earlier on. The report says not only that it is difficult to identify the conditions when the procedure should be applied, but also that crews do not always consider their application necessary or even appropriate:

Quote:

The actions undertaken focused on reducing the risk of probe icing through the implementation of technical modifications. However, the concurrent existence of an operational procedure associated with the loss of airspeed information led the operator, the manufacturer and the authorities to consider that the risk was mitigated, as long as there was no significant excursion from the flight path during these known events. Thus, feedback from in-service events made it impossible to consider and analyse in advance the repeated failure to apply the unreliable airspeed / “Vol avec IAS douteuse” procedure.

As discussed in the section on crew training, the multitude of failure scenarios that can result in a loss of speed information complicates the analysis for the crew, and makes it difficult to provide both exhaustive training and an effective mechanised approach to the application of the procedure. The type of scenario produced and the formulation of the memory items made it difficult to associate the manoeuvre with the situations encountered in in-flight situations. Consequently, although technically adequate, the details of the procedure continue to be understood to differing degrees by crews, who do not always consider their application necessary, and even sometimes consider them to be inappropriate at high altitude.

Signs of stall were pretty clear (Section 3.1):

Quote:

The approach to stall was characterised by the triggering of the warning then the appearance of buffet.

In the absence of a display of the limit speeds on the speed tape on the PFD, the aural stall warning is not confirmed by any specific visual display.

The stall warning sounded continuously for 54 seconds.

Neither of the pilots made any reference to the stall warning or to buffet.

Recommendations relating to improvements in ergonomics (Section 4.1.7 on page 210). Note that these are the only recommendations on ergonomics:

Quote:

€€EASA require a review of the re-display and reconnection logic of the flight directors after their disappearance, in particular to review the conditions in which an action by the crew would be necessary to re-engage them; [Recommendation FRAN‑2012‑047]

EASA require a review of the functional or display logic of the flight director so that it disappears or presents appropriate orders when the stall warning is triggered. [Recommendation FRAN‑2012‑048]

EASA study the relevance of having a dedicated warning provided to the crew when specific monitoring is triggered, in order to facilitate comprehension of the situation. [Recommendation FRAN‑2012‑049]

EASA determine the conditions in which, on approach to stall, the presence of a dedicated visual indications, combined with an aural warning should be made mandatory. [Recommendation FRAN‑2012‑050]

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]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: 135mech
Posted 2012-07-06 12:06:23 and read 17301 times.

I've read through a lot of this thread and it has an amazing amount of information and input.

However, I have not read anything yet about why the pilots (other than the head pilot) seem to have missed so many basic flight lesson principles. If you are flying a widebody, you are NOT a "New" pilot...you have spent many hours and several years if not decades flying and training to get to the "heavy/jumbo" airframes, whether it be in Cessna planes and smaller puddle jumpers etc and worked your way up to the big ones. Why does this crew seem so "new" in the cockpit? CRM was initiated just for the prevention of incidents and accidents of this nature.

Quoting ltbewr (Reply 56):
This is a link to this article: http://www.cbsnews.com/8301-505263_1...odule

As the CVR shows the right seat pilot seems to completely have no idea what is going on...as if it's his first time in the cockpit.

I feel horrible for the friends and families of the deceased and hope they find some closure through this.

Regards,
135Mech

[Edited 2012-07-06 12:32:47]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: canoecarrier
Posted 2012-07-06 12:19:00 and read 17266 times.

Quoting AirCalSNA (Reply 114):
It's interesting how hard you try to avoid drawing any conclusion from the report. Unless the pilots were deranged or drunk, the only source of confusion was the environment they were in, which, other than the weather, was designed and built by ... wait for it .... Airbus. Saying that there is "no evidence to suggest that" the crew would have been "more or less effective in a different aircraft" adds nothing, since, by this statement, you also implicitly admit that there is no evidence disproving that a different outcome would have occurred in another aircraft.

This is completely oversimplifying the cause of the accident. There are several reasons (mentioned in the report) why the incident happened completely independent from the manufacturer of the aircraft. Including poor CRM, the absence of any training at high altitude in manual handling of an aircraft with unreliable airspeed, and the failure of the crew to identify the stall warning, to name a few.

Airbus certainly didn't tell the PF to pull back on the joystick and climb when the autopilot disengaged.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rcair1
Posted 2012-07-06 12:20:20 and read 17248 times.

Quoting David L (Reply 116):
I think you've neglected a more significant group than the few who "reject it, out of hand".

You are correct. In editing this rather long post, I deleted some words that would have separated the discussion of "out of hand" and "logical" beliefs. This made it seem I believed that all people who disagree with the position were being flippant.
My bad.

There are certainly people in 3 camps for each opinion.
- reject/accept for ideological reasons (both ways)
- reject/accept for reasons they believe are logical, supported and valid (both ways). I hope/believe I'm in this group.
- are open to discussion and revision. I hope the various safety boards, regulatory boards, manf, are in this group.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: s5daw
Posted 2012-07-06 12:23:56 and read 17260 times.

Quoting canoecarrier (Reply 120):

If I read all this correctly, in a way Airbus DID tell Pf to pull up!
the computer disengaged AP and went into ALT2 Law with no pitch protection, but FD stayed ON and it indicated PF should pull up, right?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-06 12:48:25 and read 17180 times.

Quoting 135mech (Reply 119):
However, I have not read anything yet about why the pilots (other than the head pilot) seem to have missed so many basic flight lesson principles.

We really don't know and will never know the full answer.

The PF - Pilot Flying - was 32 years old and had 2,936 total flight hours. His PPL was issued in 2000 and he had been with Air France for a little less than 5 years. He had been in the A330/A340 division less than a years. He received his A330 type rating about 6 months before and had 807 hours in type.

The PNF - Pilot Not Flying - was 37 years old and had 6,547 total flight hours. His basic flight license was issued in 1992. He had been with the Air France A330/A340 division since 2002 and had 4,479 hours in type.

The Captain was 58 years old and had 10,988 total flight hours - 6,258 hours as Captain. He had been with the A330/A340 division since 2007 and had 1,747 hours in type - all as Captain.

Some have asked why the PNF had not moved up to Captain. One thing to remember is that moving to Captain could require him to move back to A320 or B737 aircraft, flying domestic or short haul routes with a substantial cut in pay. There are a lot of reasons senior Co-Pilots do not choose to become Captains - not necessarily that they are not Captain material.

The PF was obviously surprised at the aircraft disconnected and gave him control of the plane. Nothing unusual there. The plane started to roll, and he may have recognized the plane was starting to descend as he took the control.

His actions to the flight control system were obviously too quick and too much.

Soon after, the CVR and FDR data indicate he quit trusting his instruments. Which instruments he though were faulty, we do not know and we don't know what he saw because right side instrument information is not recorded in the FDR.

This incident in my mind calls for the PNF to provide firm guidance to the PF - which did not occur. There was what appears to many very little direct verbal communication between the pilots.

As I read through the entire group of recommendations - the BEA is saying - in my opinion - that a whole lot of how things are done in aviation today are potential disasters. From how simulator training is done, to how instruments and systems are designed ergonomically, to how aircraft are operated largely on autopilot.

Many pilots have expressed similar opinions on these threads, and many others in the past. Yes, they tend to be older pilots who haven't spent their entire careers in glass cockpits. But there are many critics of the current total system who have substantial time in those cockpits.

The comments and recommendations on the shortcomings of the SAR system are important. True - this crash was not survivable. But the crew taken some different actions and gone down with a survivable water landing - the SAR system was so delayed - that survival in the water until rescue was very unlikely.

The bottom line is that this was not a simple cause accident.

Yes, the PF made a mistake that should never happen. But why did the rest of the aviation system fail to give him better knowledge, and why did the rest of the flight crew fail to give him better guidance to deal with the problem.

This crash is a failure of the aviation safety system in my opinion, and I believe the BEA agrees.

I also can't prove this statement - but I'm very sure there is no one at Boeing, Embraer, Bombardier, etc - looking at this report today and saying "This could never happen in one of our airplanes."

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: 135mech
Posted 2012-07-06 12:51:37 and read 17108 times.

Quoting ltbewr (Reply 56):
Quoting ltbewr (Reply 56):
This is a link to this article: http://www.cbsnews.com/8301-505263_1...odule
Quoting rfields5421 (Reply 123):

Thank you for the information! Again, this is truly a sad event!

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: David L
Posted 2012-07-06 12:58:35 and read 17073 times.

Quoting rcair1 (Reply 121):

   OK, now we're on the same page.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-06 13:26:46 and read 16972 times.

Quoting AirlineCritic (Reply 118):
Signs of stall were pretty clear (Section 3.1):

The one thing that baffles me to no end is why they completely ignored the stall warning.

IIRC, you're not supposed to reduce airspeed, right? Didn't they do that or was that inadvertent?


I'm no pilot but the one thing I learned from my pilot friends is that if you're in a stall you level off and get to a good decent speed.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 13:33:42 and read 17032 times.

Quoting AirCalSNA (Reply 114):
It's interesting how hard you try to avoid drawing any conclusion from the report. Unless the pilots were deranged or drunk, the only source of confusion was the environment they were in, which, other than the weather, was designed and built by ... wait for it .... Airbus.

They were not "deranged" or "drunk", but they were unprepared, at least in part quite literally.

And that caused their confusion and catastrophically wrong decisions.

If you immediately lose your faculties as soon as something unexpected or distracting happens, you don't belong into the driver seat of a car, even less so into the cockpit of an airplane and least of all into the cockpit of a passenger airliner.

Pilots every now and then have to deal with suddenly occurring malfunctions and with weather. And they deal with it.

The investigation is perfectly right in going with a fine-toothed comb through every single instrument, display mode and aural warning that occurred, but the crux of the matter is that the near-total confusion and lack of situation-awareness exhibited by the crew of AF447 was not caused by warnings and alerts, it was just exposed by it.

And that is a crucial distinction.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 13:36:04 and read 16987 times.

Quoting PHX787 (Reply 126):
The one thing that baffles me to no end is why they completely ignored the stall warning.

Particularly since the combination of flat-to-upward horizon, maximum thrust and at the same time rapid descent told exactly the same story.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: XT6Wagon
Posted 2012-07-06 13:51:49 and read 16932 times.

Quoting PHX787 (Reply 126):
The one thing that baffles me to no end is why they completely ignored the stall warning.

IIRC, you're not supposed to reduce airspeed, right? Didn't they do that or was that inadverte

Airspeed measurement went unreliable. They started a climb and lost airspeed while having no reliable airspeed indication. This is part of the issue as the stall warning would start again when the PF let the nose drop and would stop when he pulled back as they were now down below 60 knots airspeed.

For myself, I really think Airbus should backdrive the throttles, This is a case where you can provide some rather critical information to the pilots in a easy and clear method thats not open to interpertation or confusion. I'm less certain of linking the joysticks, but they should look into providing SOME feedback to indicate what the other pilot is doing, as thats much quicker and instinctive than looking over and trying to see what he is doing with his sidestick while everything is starting to go sideways.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Pihero
Posted 2012-07-06 14:07:14 and read 16999 times.

Quoting Klaus (Reply 127):
the crux of the matter is that the near-total confusion and lack of situation-awareness exhibited by the crew of AF447 was not caused by warnings and alerts, it was just exposed by it.

I'm far from finished with the report but there are still quite a few aspects that deserve some looking into.
I've always been in the opinion that discussing airfcraft accidents with the benefit of one's favorite computer chair and tremenduous hindsight is in all occasions a very wrong assessment of the dynamics of the mishap.
Most come from people with little experience of IFR, and high altitude flight aerodynamics and all the traps of night flying and disorientation and overload... etc...

We start here with what psychologists call the"startling effect" of the initial occurrence, to which the PF response was overreaction and an extreme pitch command.
This report seems to be giving a few clues as to the whys of that manoeuvre , amongst which one could cite his constant harping about a higher level - on this subject, considering the flight conditions they were experiencing at the top of the cloud layer,they could have safely tried the REC MAX of 37,000 ft / FL 370...
There is also a new aspect I find quite fascinating : the return of the FD bars into view, prominently displaying very high pitch-up commands or at least not helping in the solving of their actual situation.

[Edited 2012-07-06 14:09:06]

[Edited 2012-07-06 14:11:14]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: canoecarrier
Posted 2012-07-06 14:45:17 and read 16785 times.

Quoting Pihero (Reply 130):
We start here with what psychologists call the"startling effect" of the initial occurrence, to which the PF response was overreaction and an extreme pitch command.

Correct me if I'm wrong but haven't you said the PNF was the most experienced pilot in type that night? He did have nearly 3,000 more hours than the Captain in the A330.

The report discusses that "(the) overall experience and on type of the PF, designated implicitly as relief Captain, was significantly less than that of the PNF, also OCC executive of the airline and as such enjoying recognition as an expert by his peers."

Although only a piece of the puzzle why this plane crashed, the Captain should have known this already.

We've talked about this before, in the report they mention that "He (the Captain) did however implicitly designate as relief pilot the co-pilot in the right seat and PF, but did so in the absence of the second co-pilot, just before waking him."

Its unfortunate that the BEA report didn't discuss further any interviews with crew that had flown with any of the pilots that night. We might gain some insight into the personalities or how (if they had flown together before) they interacted in previous trips.

I can see why our friend Kaihari prefers to work from the original French!

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-06 15:06:54 and read 16713 times.

Quoting Klaus (Reply 128):
maximum thrus

Oh I had no idea they were using max thrust

Quoting XT6Wagon (Reply 129):
For myself, I really think Airbus should backdrive the throttles, This is a case where you can provide some rather critical information to the pilots in a easy and clear method thats not open to interpertation or confusion. I'm less certain of linking the joysticks, but they should look into providing SOME feedback to indicate what the other pilot is doing, as thats much quicker and instinctive than looking over and trying to see what he is doing with his sidestick while everything is starting to go sideways.

It makes sense but could A be able to do that? Wouldn't the engine makers have to do something as well to support that?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-06 15:07:41 and read 16728 times.

Quoting PHX787 (Reply 132):

It makes sense but could A be able to do that? Wouldn't the engine makers have to do something as well to support that?

No. The pilots control the engines by manually moving the throttles. In auto-thrust, as a very simplistic example, a motor could do the same thing directly to the same throttles with a disengage clutch when off.

Jim

[Edited 2012-07-06 15:12:36]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-06 17:25:15 and read 16462 times.

Quoting Pihero (Reply 130):

     

Quoting canoecarrier (Reply 131):
Its unfortunate that the BEA report didn't discuss further any interviews with crew that had flown with any of the pilots that night.

My point earlier. Some things (psychological profiles, personal situations) may not be disclosed in a public report. I spend a chunk of my life doing management framework reviews, some of which is public (general observations), and some of which is communicated to the auditee without publication (e.g management letters). The PIC's "decision" to designate the vastly less experienced FO as relief PIC is a case in point.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ltbewr
Posted 2012-07-06 17:26:16 and read 16450 times.

The pitot tubes were iced, giving bad data. Like with any computer as the old saying goes GIGO - garbage in garbage out. Perhaps the closest comparison to AF 447 was the Berginair flight in the Caribbean where it is suspected bug nests clogged a pitot tube, giving bad speed info, confusing the pilots and believe led to a similar crash.

Is it possible to come up with some back up or other way to measure aircraft flight speed besides the pitot tubes? Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ricknroll
Posted 2012-07-06 18:15:14 and read 16327 times.

Quoting rfields5421 (Reply 53):

Quoting ricknroll (Reply 51):
if there was such incompetence and lack of adherence to procedures.

The information tells me that it is not incompetence.

Rather there is a training, and systems issue, in properly identifying unreliable airspeed in modern aircraft (a B777 is one of the aircraft identified in the BEA study where the crew did the same thing as the A330/A340 crews - so it is not an A vs B issue)

Has the BEA uncovered a systemic training failure, or adherence to the rules failure? I can understand that every so often, pilots will make a mistake, they are human. However, they have identified from several cases they have studied that pilots have not followed standard procedures. That is the message I am getting from this. This failure has happened across brands and models of plane, and airline companies.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-06 19:06:34 and read 16238 times.

Quoting ltbewr (Reply 135):
The pitot tubes were iced, giving bad data. Like with any computer as the old saying goes GIGO - garbage in garbage out.

And it's a misrepresentation in this case. When input data was detected to be unreliable, it was flagged as such and all automatic systems reliant on airspeed disengaged.

In flight systems it's closer to GIWO: Garbage in - warning out, as it should be.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-06 19:53:57 and read 16193 times.

Quoting airtechy (Reply 62):
it would have allowed the PNF to see that the PF was stalling the aircraft. Wouldn't any competent pilot realize that having the yoke or joystick all the way to the aft limits would stall the plane...especially if held there? I still don't believe that the PNF realized that the PF was holding the joystick aft as he was busy trying to interpret the conflicting instrument displays.

It would not stall an Airbus in normal law.

Quoting airtechy (Reply 117):
I thought I read a report that tests showed the protection limits caused the Sully A320 to hit the water at a higher airspeed than if they had been disabled.

Jim

Which is probably better than hitting it with lower airspeed but higher vertical speed due to a stall...

I've not read the report yet and don't really remember from the interim one, but reading through this thread I get the impression that the flight was doomed after only a few seconds, because the PF was too brutal on the joystick, what do you think ?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-06 19:58:13 and read 16199 times.

Would lives have been saved if the pilots had known beyond a doubt that they were stalled, even though their attitude was more or less stable? If I were a pilot (big IF), I might (big MIGHT) want to know by direct measurement whether the wings were generating enough lift to support the weight of the plane, something that an airspeed measurement doesn't do.

I watch videos of the 787 taking off, and the wings flex up before rotation: they're saying, "We can fly, now", it seems. At least they stay with much the same arc during rotation, climbout, and flight. Airspeed is only one way of inferring the magnitude of lift.

How would you measure lift directly, though? Pressure differential across the wing, I would have thought. Interpolate, integrate, display, and pilots could 'see' lift directly. Even at night, with iced pitots, in a nose-up, stable stall, a pilot might see the _lack_ of lift at once and know what should be done to save the plane.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-06 20:19:38 and read 16148 times.

Quoting XT6Wagon (Reply 129):
For myself, I really think Airbus should backdrive the throttles, This is a case where you can provide some rather critical information to the pilots in a easy and clear method thats not open to interpertation or confusion.

I don't see how that would have helped here ?

Quoting ltbewr (Reply 135):
Is it possible to come up with some back up or other way to measure aircraft flight speed besides the pitot tubes? Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

GPS gives ground speed, when what is needed is airspeed.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-06 20:28:42 and read 16122 times.

Quoting bellancacf (Reply 139):
Would lives have been saved if the pilots had known beyond a doubt that they were stalled, even though their attitude was more or less stable? If I were a pilot (big IF), I might (big MIGHT) want to know by direct measurement whether the wings were generating enough lift to support the weight of the plane, something that an airspeed measurement doesn't do.

I watch videos of the 787 taking off, and the wings flex up before rotation: they're saying, "We can fly, now", it seems. At least they stay with much the same arc during rotation, climbout, and flight. Airspeed is only one way of inferring the magnitude of lift.

How would you measure lift directly, though? Pressure differential across the wing, I would have thought. Interpolate, integrate, display, and pilots could 'see' lift directly. Even at night, with iced pitots, in a nose-up, stable stall, a pilot might see the _lack_ of lift at once and know what should be done to save the plane.

There is the angle of attack sensor already.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: PHX787
Posted 2012-07-06 20:42:07 and read 16114 times.

Quoting ltbewr (Reply 135):
Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

I have always had a problem with GPS systems when there is a lot of cloud cover in the area. If an airplane flies into a storm like AF447 I'm not sure if that would work.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-06 21:17:04 and read 16081 times.

Quoting AirCalSNA (Reply 114):
Saying that there is "no evidence to suggest that" the crew would have been "more or less effective in a different aircraft" adds nothing, since, by this statement, you also implicitly admit that there is no evidence disproving that a different outcome would have occurred in another aircraft.

Your mindset is one of "if there is no evidence disproving it, it must be true", which is a logical fallacy. In order to assert something, you need to be able to show evidence for it, not just a lack of evidence against it.

Quoting XT6Wagon (Reply 129):
For myself, I really think Airbus should backdrive the throttles, This is a case where you can provide some rather critical information to the pilots in a easy and clear method thats not open to interpertation or confusion.

I really don't think backdriving the throttles would do anything. Where the throttles are is irrelevant - what's important is what the engines are actually doing, and you get that from the engine instruments. And those aren't really open to interpretation or confusion.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: comorin
Posted 2012-07-06 21:44:21 and read 16012 times.

Quoting ltbewr (Reply 135):
Is it possible to come up with some back up or other way to measure aircraft flight speed besides the pitot tubes? Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

GPS would give you ground speed, not airspeed...might help if they could design pitot tubes that could 'sneeze' if blocked.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirlineCritic
Posted 2012-07-06 23:24:53 and read 15898 times.

Quoting ltbewr (Reply 135):
Is it possible to come up with some back up or other way to measure aircraft flight speed besides the pitot tubes? Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

There already is plenty of redundancy, also redundancy in terms of other instruments that they could have been following, such as the artificial horizon. The unreliable airspeed procedure, for instance, asks the pilots to display GPS altitude, too:

http://www.bea.aero/fr/enquetes/vol.af.447/imageshr/figure.74.jpg

I suppose speed could be displayed as well, even though it is ground speed. But I don't see this as the main problem. This crew had stopped relying on their instruments. One set of instruments goes bad. They are in the dark and cannot visually verify anything. Now they lose trust on all instruments. Which ones are good, which ones are bad? Adding more instruments and display might not have helped. Having a more cool head and process for figuring out what was wrong and what was still right might have, however.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rwessel
Posted 2012-07-07 09:31:55 and read 15285 times.

Quoting bellancacf (Reply 139):
Would lives have been saved if the pilots had known beyond a doubt that they were stalled, even though their attitude was more or less stable? If I were a pilot (big IF), I might (big MIGHT) want to know by direct measurement whether the wings were generating enough lift to support the weight of the plane, something that an airspeed measurement doesn't do.

I watch videos of the 787 taking off, and the wings flex up before rotation: they're saying, "We can fly, now", it seems. At least they stay with much the same arc during rotation, climbout, and flight. Airspeed is only one way of inferring the magnitude of lift.

How would you measure lift directly, though? Pressure differential across the wing, I would have thought. Interpolate, integrate, display, and pilots could 'see' lift directly. Even at night, with iced pitots, in a nose-up, stable stall, a pilot might see the _lack_ of lift at once and know what should be done to save the plane.

Even stalled wings produce lift - just very inefficiently. And they were in a steady descent (about 10,000ft/min), which implies that the wings (plus the drag from the fuselage, which would not be negligible in this situation) were generating about 1 G worth of lift.

But as mentioned, there's already an alpha vane, the BEA report suggests making that information more available to the pilots. That's a bit of a personal hobby horse for me too, although more in the context of smaller aircraft, where I think they'd prevent a fair number of low altitude stall/spin accidents (which airliners don't generally have). But in this case, it's been pointed out that the pilots were ignoring so many different instruments giving them valid information, that there's little to suggest that they wouldn’t have ignored one more. And mind you, that only the pitot tubes malfunctioned, thus only airspeed was ever wrong, even that cleared up about a minute after the start of the incident.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-07 12:04:14 and read 15103 times.

rwessel @ 146: Thanks for your thoughts. I can't help but think that the pressure distribution (magnitudes, differentials) around the wing is different, vastly different, when falling at 10K fpm with about a 45 degree AoA (IIRC) compared to level flight. I also can't help but think that it would be impossible to ignore a display of the wing planform that conveyed this information. Also, IIRC, the pilots were being boxed in by the stall warning, which sounded when they approached the limit from the "back" side; that must have caused them to doubt their instruments and go back to trusting the seats of their pants, which, as you point out, were telling them 1 G. I would think that it would be much harder to doubt two dozen or so pressure transducers all telling you that something is seriously wrong, namely, the aircraft does not have normal lift over the wing. Maybe it's just me: I like to measure a quantity directly when I can, not infer it, and pressure distributions can certainly be measured around airfoils -- it's been done in tunnels and in the real world. RIP

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-07 17:34:40 and read 14818 times.

By that time it was too late to recover.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-07 21:16:59 and read 14694 times.

Quoting rfields5421 (Reply 68):

The implementation of feedback is a point of difference between Airbus and Boeing. Airbus does not provide any control surface feed back. Boeing does provide a 'best guess' feed back to the controls. For example - if the elevator binds on a GA aircraft, I will feel it when I try to move the controls. That won't happen in an Airbus, and the modern Boeing will give me little to no such feel.

The FBW A&B use digital control systems, the pilot inputs are nothing more than demands into this control system, the control system will work out what control surfaces to move to achieve the desired demand.

The "back driven" controls on B do not really give feedback on what the individual control surfaces are doing, it is the reverse of the input, it looks at all of the the control surfaces, and then displaces the control column for what it thinks is a best guess to what that is. For example when roll, when the control column is displaced in roll, it could be due to outer or inner aileron, roll spoiler, or rudder.

Quoting rfields5421 (Reply 68):

Note the BEA reports says that when the aircraft had fallen to 31,500 ft - very soon after the initial event - recovery of the aircraft was be very unlikely unless there was a crew on the aircraft - trained and expecting such an event.

It does not really say that.

Quoting rfields5421 (Reply 68):
Many regional turboprop and regional jet pilots, even LCC main-line pilots do more takeoffs and landings in a day than this entire crew did in a month.

The number of takeoffs and landings I think means little with the situation at hand.

Quoting airtechy (Reply 69):

Absolutely correct....and holding the joystick full aft will increase the angle of attack and eventually stall the airplane....especially in the absence of "NORMAL LAW" protections.

No, full aft movement will not always stall an aircraft.

Quoting airtechy (Reply 69):

Although I think control columns are better, joysticks work just as well. They just don't convey the same positional information unless linked.

And yet the report lists more accidents with aircraft that have such a control design, if anything history has shown that it is even more likely to result in a crash if you have it, than not have it.

Quoting airtechy (Reply 74):
In the case of Airbus and probably Boeing, I now realize that is only true in "DIRECT LAW".

That is a simplistic statement I would not agree with, direct law s still part of a digital flight control system.

Quoting tom355uk (Reply 84):
Does anybody know why the Stall warning is dependent on airspeed? I understand that you don't want nuisance alerts at low speeds, but why not link it to the air/ground mode switches?

Those with some rotary time would appreciate that airspeed measurements can be useless at low speed as the pitots are designed for an operating forward speed, likewise in large aircraft, the pitots are designed for a minimum airspeed to be within their operating range.

Quoting tom355uk (Reply 86):
What reference speeds? Best glide? Not provided for instant access during such a situation. All engines out landing reference speed? Not provided. Best ditching speed? Cpt Sullenberger used a best guess for both these figures, and luckily both were pretty close to what was required.

He had green dot showing, which is best L/D and flew below that increasing the ROD and reducing the glide distance.

Quoting tom355uk (Reply 96):
Capt. Chesley "Sully" Sullenberger, CBS News' aviation and safety expert, said the same disaster would have been "much less likely to happen" in a Boeing plane

That isn't very helpful is it? Especially from somebody in his position - who's word on such subjects will be gospel to those who know nothing of aircraft design and operation. This is basically saying "This crash wouldn't have happened to a Boeing" - which we all know is not the case. Even if he is only referencing the sidestick philosophy, he hasn't really said that has he? That is why I am particularly disappointed with him.

No it is not helpful, considering when the report which he could not have read at the time he gave that interview lists numerous accidents which shows that there have been actually been more accidents with Boeings/McDs.

Quoting Mir (Reply 97):

Why Airbus decided to do it that way I'm not sure, but I am sure there's a very good reason for it.

It provide better performance and less drag, i.e. better economics. The FBW Bs are similar, click the trim switch the THS will autotrim to the speed.

Quoting tom355uk (Reply 106):
I appreciate that - but to me it seems that in a situation such as this that an overspeed would have been less dangerous than a nose high low airspeed stall. I'm sure the aerofoil design on the A330 would have prevented the guys exceeding MD much in a dive anyway - and once in warmer air you lose the icing effects and hopefully regain all required indications

You can go a fair way past MMo and still not be near MD, I know of one that has gone up to 0.96.

Quoting tom355uk (Reply 108):
If it had been frozen at the cruise value (probably near zero, or slightly up??) then the return to controlled flight would have been quicker, and probably achievable in exchange for much less altitude loss.

The elevator should still be effective even at low speed with the THS where it was. The problem is being on the back side of the drag curve as they were, you need a lot to get it back on the correct side. Even if it sounds somewhat counter-intuitive, putting the gear down would assist in the recovery with a drag moment which is similar to the elevator effect, spoilers would normally also increase the stall AoA, and rolling the aircraft can change that pitch demand into a roll rate and a more rapid increase in speed.

Quoting rwessel (Reply 146):
Even stalled wings produce lift - just very inefficiently.

It is producing lift about the same as it was at the same position of the Cl/alpha curve on the other side of CLmax, however it is producing a lot more drag.

Quoting rwessel (Reply 146):
But in this case, it's been pointed out that the pilots were ignoring so many different instruments giving them valid information, that there's little to suggest that they wouldn’t have ignored one more.

The Boeing implementation of the AoA indicator has a red stall band which needs a valid mach number to work. With unreliable airspeed, this AoA indicator can show the aircraft is stalled, when it is not actually stalled, and this may even be reinforced with stick shaker at the same time.

I do not think anyone has shown that the pilots did not have enough information to tell them what was happening, if anything it is suggesting they had too much information and could not process it. I am therefore somewhat reluctant to give them even more information, when that information may add to the confusion.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-07 21:44:44 and read 14613 times.

Quoting zeke (Reply 149):

The elevator should still be effective even at low speed with the THS where it was. The problem is being on the back side of the drag curve as they were, you need a lot to get it back on the correct side. Even if it sounds somewhat counter-intuitive, putting the gear down would assist in the recovery with a drag moment which is similar to the elevator effect, spoilers would normally also increase the stall AoA, and rolling the aircraft can change that pitch demand into a roll rate and a more rapid increase in speed.

Some interesting points. I assume the stalled airspeed was low enough at that altitude to not rip the gear off. What would spoilers do at that high angle of attack....maybe help the nose drop?

I thought almost all commercial planes had auto-trim of some form or another. Our Cessna 310 automatically trimmed the plane in pitch by moving the trim tab with a motor to equalize the force on the elevator cables. The Airbus could do it by measuring the forces exerted by the elevator hydraulic actuators and equalize the push and pull sides.

Jim

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: justloveplanes
Posted 2012-07-07 22:16:05 and read 14573 times.

Quoting comorin (Reply 144):
Quoting ltbewr (Reply 135):
Is it possible to come up with some back up or other way to measure aircraft flight speed besides the pitot tubes? Most car GPS systems can also give you the speed you are going, perhaps using GPS technology could help as an alternative or back up to the pitot tubes if one is faulty.

GPS would give you ground speed, not airspeed...might help if they could design pitot tubes that could 'sneeze' if blocked.

What is the redundancy on pitot tubes for an A330 (I.E. how many do they have?). Some approaches to critical control in other industries include 3 instruments or computers, and 2 out 3 must agree on a quantity for a reading to be valid.

For something like AF447, as soon as 1 of the three pitots began to disagree, perhaps something like - "Airspeed fault imminent" alarm to trigger preparations for loss of airspeed before it actually happens. Does the A330 (or other aircraft) do something like this?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Mir
Posted 2012-07-07 23:24:07 and read 14644 times.

Quoting justloveplanes (Reply 151):
What is the redundancy on pitot tubes for an A330 (I.E. how many do they have?).

Three.

Quoting justloveplanes (Reply 151):
For something like AF447, as soon as 1 of the three pitots began to disagree, perhaps something like - "Airspeed fault imminent" alarm to trigger preparations for loss of airspeed before it actually happens. Does the A330 (or other aircraft) do something like this?

There is a caution message that will occur if there's a disagreement between sensor sources, yes. And there will be a checklist to run in association with that caution message.

-Mir

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-07 23:46:30 and read 14661 times.

Quoting airtechy (Reply 150):
I assume the stalled airspeed was low enough at that altitude to not rip the gear off.

I think any aircraft would have a lot greater issues landing if airloads could rip them off. Gear doors may be damaged, or depart the airframe, gear is held on with some very large hardware.

Quoting airtechy (Reply 150):
What would spoilers do at that high angle of attack....maybe help the nose drop?

I would only be guessing, and would depend on how much is deployed.

Quoting Mir (Reply 152):
There is a caution message that will occur if there's a disagreement between sensor sources, yes. And there will be a checklist to run in association with that caution message.

You can actually dispatch with one ADR inop, you still have autothrust and both autopilots, all you basically loose is CAT 3 autoland capability. Flying with two ADR sources is not dramatic.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-08 02:41:12 and read 14480 times.

Quoting airtechy (Reply 150):
What would spoilers do at that high angle of attack....maybe help the nose drop?

Given that the spoilers would be in the turbulent wake on top of the stalled wings at that point, I would not be very surprised if they had very little effect, if any (speaking as a layman).

Quoting justloveplanes (Reply 151):
What is the redundancy on pitot tubes for an A330 (I.E. how many do they have?). Some approaches to critical control in other industries include 3 instruments or computers, and 2 out 3 must agree on a quantity for a reading to be valid.

It has three, which were all subject to the same icing conditions and thus clogged up almost simultaneously, but came back online after about half a minute and after about a minute, respectively. The third is not recorded so we don't know about that one.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: par13del
Posted 2012-07-08 05:43:20 and read 14305 times.

Quoting Klaus (Reply 137):
And it's a misrepresentation in this case. When input data was detected to be unreliable, it was flagged as such and all automatic systems reliant on airspeed disengaged.

You are trained to operate a computerized a/c with redundancies that it is virtually impossible to have all computers fail at once, I can see operators of such a/c getting used to the technology, of course there is always the caveat of the paper list in case something hits the fan.
The design then is that if the computer detects faulty air speed data, it removes all the automation and reverts to the pilot, which is a bit more than Garbage In Warning Out - should be Warning and Control Out.
Now we have facts like the post below.

Quoting Aesma (Reply 141):
There is the angle of attack sensor already.
Quoting AirlineCritic (Reply 145):
There already is plenty of redundancy, also redundancy in terms of other instruments that they could have been following, such as the artificial horizon.

Now we now that even after the computer reverts automation because of faulty data, we have all these other redundant methods which pilots were supposed to use properly identify the situation and regain control.
A simple question would be if these redundancies exist and all experts are in agreement that they are / were reliable and are perfectly capable of providng accurate data to correct the situation, why does the computer not use them, after all, the computer is capable of operating the a/c more safely than the humans who in virtually all a/c accidents have proven to be the primary cause of accidents.

Simplistic yes, but I looking at the fundamentals of what's has been around for 3 years, in basic fashion, in relation to what was already theorized and data provided the fundamentals of what occured from the technical side have not changed, no new technical fault has been identified, according to my initial read, well do so again.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-08 05:56:43 and read 14271 times.

Quoting airtechy (Reply 150):
I thought almost all commercial planes had auto-trim of some form or another. Our Cessna 310 automatically trimmed the plane in pitch by moving the trim tab with a motor to equalize the force on the elevator cables.

That is what the THS does - but it moves the horizontal stabilizer rather than a trim tab to equalize force on the elevators.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-08 06:52:21 and read 14188 times.

Quoting par13del (Reply 155):
The design then is that if the computer detects faulty air speed data, it removes all the automation and reverts to the pilot, which is a bit more than Garbage In Warning Out - should be Warning and Control Out.

That would be confusing separate matters.

The claim was "garbage in, garbage out", and while that is a well known saying, it does not apply to the systems discussed here. When the systems see inconsistent redundant data, they flag them as unreliable.

That in turn – in a subsequent step – removes the basis for the autopilot's reliable function, which then disengages.

These are two distinct matters, the latter being a consequence of the former.

Quoting par13del (Reply 155):
A simple question would be if these redundancies exist and all experts are in agreement that they are / were reliable and are perfectly capable of providng accurate data to correct the situation, why does the computer not use them, after all, the computer is capable of operating the a/c more safely than the humans who in virtually all a/c accidents have proven to be the primary cause of accidents.

In the situation during the full stall the remaining instruments strongly suggested that they were in a stall, but at that point the cause might have been something else as well and was actually ambiguous.

They could also have been in a strong downdraft with the pitots still clogged up; That could have looked similar to them dropping due to the stall with forward speed so low that the pitot sensors stopped reporting, at least for a short while.

Whenever forward speed got high enough for the pitots to actually report it again, the stall warning did engage to alert the crew, so the systems did in fact report situation information when they could.

The PF just drew completely wrong conclusions in his confusion and instead of crossing through the stall warning by pushing down he pulled up again to silence the warning – just by making the warning invalid and not by removing its cause.

From a user interface point of view it might make sense to give different kinds of feedback at either end of the stall warning range to the effect of "stall ended" on one side (or simply ceasing the stall warning) and "sensors invalid - stall status unknown" on the other.

There are some issues related to that again, however:

One could argue that this would add even more acoustic "clutter" in an already stressful situation. Just the "sensors invalid" alert on the "bad" end of the stall warning might still be helpful, but in that case should it sound just once (with the possibility of being missed) or be repeated until canceled by the crew (possibly distracting them from resolving the situation)?

Also, with this being a very extreme situation which would not come up a lot in training, would that really help stressed and possibly confused pilots (as with AF447) to regain their situational awareness? That is not at all clear.

The stall warning was originally designed to warn at an approach to an actual stall; It is conceivable that not a lot of extra thought was given to the extreme outer end of the stall warning range, where the plane would be so far away from what the automatic systems could safely handle that the pilots' own basic flying skills would be called upon first and foremost anyway.

Maybe AF447 will prompt Airbus to reconsider that aspect of their design to include additional cues to the crew even in extreme situations, but I think the matter of possibly creating additional distractions should not be taken lightly.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: par13del
Posted 2012-07-08 07:07:48 and read 14140 times.

Klaus thanks for taking my post as intended, just a couple simple questions on the basic fundamentals from a layman, I did not want to attempt to get too technical as I am clearly out of my league on that score.

Quoting Klaus (Reply 157):

From a user interface point of view it might make sense to give different kinds of feedback at either end of the stall warning range to the effect of "stall ended" on one side (or simply ceasing the stall warning) and "sensors invalid - stall status unknown" on the other.

In one of the numerous other threads this issue was raised, during the convo it may I say may have been dismissed by some as attempting to justify or excuse actions or the a/c systems, but it is a valid question, should there be some way audio or visual to differentiate the entry or leaving of a stall situation, perhaps now it could be discussed without passion.
Pilots will always say that one could feel the difference but in the confused environment and what has been declared as poor management by the crew additional technical aids would become a part of the SOP's.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-08 07:33:00 and read 14125 times.

Quoting par13del (Reply 158):
Klaus thanks for taking my post as intended, just a couple simple questions on the basic fundamentals from a layman, I did not want to attempt to get too technical as I am clearly out of my league on that score.

I do work in computer systems and software design, but with no connection to aviation in that regard, so while I can speak to the principles of UI and systems design in general and I've looked into aviation systems to some extent out of personal interest, I would not call myself an actual expert either. So please read my statements on that background.

Quoting par13del (Reply 158):
In one of the numerous other threads this issue was raised, during the convo it may I say may have been dismissed by some as attempting to justify or excuse actions or the a/c systems, but it is a valid question, should there be some way audio or visual to differentiate the entry or leaving of a stall situation, perhaps now it could be discussed without passion.

The worst would be cues which may sometimes be helpful, but actually misleading in other cases, possibly even contributing to an accident. In such cases it will usually be the better choice not to present any recommendation at all, especially if it may be a distraction anyway.

Quoting par13del (Reply 158):
Pilots will always say that one could feel the difference but in the confused environment and what has been declared as poor management by the crew additional technical aids would become a part of the SOP's.

The problem is that the farther the aircraft has already departed from regular, controlled flight, the more ambiguous the sensor data can become on which automatic systems must base any of their conclusions, which makes any technical aids more and more unreliable.

One of the questions is whether there could be any aids which could have helped even the utterly confused cockpit crew of AF447 to regain proper situation awareness even under the same circumstances while simultaneously not deteriorating any of all the other flights with sometimes difficult conditions which actually made it safely to their destinations.

That is the primary crux of the matter: It is usually not very difficult to find some ways by which this specific disaster could have been averted. But the investigators and then the authorities, the airlines and the manufacturers need to weigh this particular disaster and its possible conclusions against all the other actual and potential situations at the same time.

Only measures which to a high degree of confidence could help in certain situations without creating unacceptable new dangers in others should be considered for actual changes to systems, procedures and/or training.

The language and the recommendations in the investigation reports very much reflect this kind of dilemma; And especially the manufacturers have to anticipate vast numbers of different scenarios in their designs beforehand.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: frmrCapCadet
Posted 2012-07-08 12:50:55 and read 13872 times.

As I read comments it quoted the study as saying that 30,000 feet altitude may have been too low to recover. If I read that right would any of the pilots discuss this. It seems to imply that they only had 7000 feet or so to make the right decision.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ltbewr
Posted 2012-07-08 14:32:13 and read 13746 times.

Quoting Klaus (Reply 159):
That is the primary crux of the matter: It is usually not very difficult to find some ways by which this specific disaster could have been averted. But the investigators and then the authorities, the airlines and the manufacturers need to weigh this particular disaster and its possible conclusions against all the other actual and potential situations at the same time.

That is what bugs many here and elsewhere. 1000's of flights a week and indeed at least 6 flights within 100 NM of AF 447 make it through the area and others like it around the world, without crashing or having an incident. To me this leads to 3 questions that from the excerpts of the final report and past reports seem not to be discussed:

1) Was there something very specific to the time and place as to the weather when AF 447 flew that was a more extreme than usual weather situation? Past commentary here and elsewhere have suggested this as a factor, that other flights might have changed or did change their flight paths to avoid a 'known unknown' risk situation.

2) Was there pressure on this AF 447 flight crew to stick to a particular route despite potential risks to limit the the need to refuel if they re-routed ? This question has been discussed here and elsewhere too.

3) Did the investigation include looking at tapes and recorders or other flights near the area flight AF 447 went through that night or since then to see if they had some similar issues and how they handled them?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-08 15:05:08 and read 13726 times.

Quoting ltbewr (Reply 161):
1) Was there something very specific to the time and place as to the weather when AF 447 flew that was a more extreme than usual weather situation? Past commentary here and elsewhere have suggested this as a factor, that other flights might have changed or did change their flight paths to avoid a 'known unknown' risk situation.

The problem with AF447 seems to have been that the cockpit crew immediately lost awareness and control of the situation when the situation was not very unlike situations which are more or less routinely mastered by crews all around the world.

So the severity of the weather doesn't seem to have been the crucial factor there, just a non-forcing contributing one.

Quoting ltbewr (Reply 161):
3) Did the investigation include looking at tapes and recorders or other flights near the area flight AF 447 went through that night or since then to see if they had some similar issues and how they handled them?

I don't think they could, since the recorders overwrite themselves before reaching their destination because their capacity is too limited for holding an entire long-range flight.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: InsideMan
Posted 2012-07-08 15:28:46 and read 13634 times.

The wheather did contribute to the accident, since the freezing of the pitot tubes was the catalyzing effect that launched the sequence of disorientation, errors etc.

If other a/c would have had pitot tubes frozen during their flights we would have known.

So yes, flying through the bad wheather front did contribute, but not in the sense that the conditions where so bad they were doomed from the beginning. Up until the point they fully stalled the a/c was easily recoverable but even after that they have had a chance if they would have realized what was going on....

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Klaus
Posted 2012-07-08 15:45:25 and read 13612 times.

Quoting InsideMan (Reply 163):
If other a/c would have had pitot tubes frozen during their flights we would have known.

That does happen every now and then and it is almost always survived by crews who are reacting properly. Even those who are not doing it by the book generally make it through.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-08 15:49:20 and read 13670 times.

Quoting InsideMan (Reply 163):

If other a/c would have had pitot tubes frozen during their flights we would have known.

Just aboubt every airliner flying today ( prob apart from the newest) have had incidents with pitot tubes being unreliable. This was not something new to the industry, or confined to Airbus or the A330.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: airtechy
Posted 2012-07-08 16:44:37 and read 13530 times.

Quoting Klaus (Reply 162):

I don't think they could, since the recorders overwrite themselves before reaching their destination because their capacity is too limited for holding an entire long-range flight

I think that's correct as regards the cockpit voice recorder as the required data rate is pretty high. On this flight I recall it was two hours normally and one hour in hi-def mode.

On the other hand the modern DFDR has the capability to record several flights worth of data. Now whether they retrieved it from the other flights before it was overridden on subsequent flights is another story.

I read other accident reports that covered takeoff and landing accidents where they go back to many prior landings to compare the data. I'm sure on some of the prior incidents involving frozen pitot tubes the data was preserved and formed part of their analysis of this event.

Jim

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-09 03:17:49 and read 13178 times.

Quoting zeke (Reply 149):
Those with some rotary time would appreciate that airspeed measurements can be useless at low speed as the pitots are designed for an operating forward speed, likewise in large aircraft, the pitots are designed for a minimum airspeed to be within their operating range.

I understand the lack of forward motion affects the pitots' ability to provide accurate speed measurements, but I think you misunderstood the way I've phrased the question.

Firstly, the stall warning references the AoA calculated by the Alpha vanes when above a certain airspeed - correct? Now, I also know that under that reference airspeed, the Alpha vanes are also pretty useless, and can't be relied on (as small aerofoils themselves) to provide an accurate AoA measurement. The point I was trying to get across was if, as an additional layer of safety, the stall warning referenced the WoW switches if the airspeed was to fall below the reference value for activiation.

Surely this would alleviate the issue of pulling back on the sidestick to stop the stall warning? Before anyone flames me either, I know that there were a multitude of other issues here, and that they ignored the stall warning anyway etc etc but it just seems to be a simple additional safety feature that might stop somebody else flying a perfectly safe and functional aircraft into the hard stuff.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: InsideMan
Posted 2012-07-09 05:44:03 and read 13028 times.

Quoting Klaus (Reply 164):
That does happen every now and then and it is almost always survived by crews who are reacting properly. Even those who are not doing it by the book generally make it through.
Quoting zeke (Reply 165):
Just aboubt every airliner flying today ( prob apart from the newest) have had incidents with pitot tubes being unreliable. This was not something new to the industry, or confined to Airbus or the A330.

Please re-read my post. I know it did happen on many occasions before and only this crew managed to put the a/c into a full stall and crash into the sea. I did not say anything to the contrary. All I did was to point out, that the wheather and the blocked pitot tubes was the catalyst for it all. A better trained or less panic prone crew probably would have done a better job and noone would have ever known that AF447 flew through these wheather conditions....

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-09 08:06:18 and read 12959 times.

Quoting tom355uk (Reply 167):
The point I was trying to get across was if, as an additional layer of safety, the stall warning referenced the WoW switches if the airspeed was to fall below the reference value for activiation.

Probably the reason why that is not done is the air data computers are part of the few vital systems that continue to run when the aircraft is in an emergency electrical mode running just on batteries or by the RAT. The gear position and other gear related sensors go through a different computers which are not powered until just before landing to preserve battery life.

The aim of the emergency electrical configuration is to minimize the number of items that are being powered. Crews may elect to put an aircraft into the emergency electrical configuration in response to an unknown smoke source.

Quoting InsideMan (Reply 168):
I know it did happen on many occasions before and only this crew managed to put the a/c into a full stall and crash

No, they are not the first crew to do that, I would suggest reading page 159 onwards of the report for some very similar accidents.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tom355uk
Posted 2012-07-09 10:59:36 and read 12739 times.

Quoting zeke (Reply 169):

Just the sort of answer I was after. Thanks Zeke - concise and to the point as always.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-09 18:21:43 and read 12525 times.

Quoting tom355uk (Reply 167):
The point I was trying to get across was if, as an additional layer of safety, the stall warning referenced the WoW switches if the airspeed was to fall below the reference value for activiation.

Surely this would alleviate the issue of pulling back on the sidestick to stop the stall warning?

It would fix that issue, absent electrical reconfigurations as zeke noted. However, zeke touches on another crucial point...it introduces a whole host of new failure modes into the stall warning system. Proximity sensors (responsible for gear indication and WoW signals) are notoriously flaky. Hooking a new and low reliability component into what should be a high reliability system completely screws up the fault tree analysis. The certification burden is not insignificant and, given the nature of the issue, there's almost zero chance that it passes cost/benefit analysis.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: flyingturtle
Posted 2012-07-14 11:53:18 and read 11704 times.

Today, I read nearly the whole report, skipping the more technical parts (certification of the pitot probes, organization of the maritime control and SAR authorities...) and, like the previous reports, it is a sobering read.

If both FO simply had done nothing, 228 people would be alive today.

I don't remember where (and my mind may be flaky after travelling the whole day), but the report mentions that it would have taken a dedicated aircrew to save the A/C after it descended through 31500 ft after its excursion to 37000 ft. Does this mean that AF447 was doomed at that moment?

In annex 2, it says that at 2 h 11 min 55/58, the altitude was about 33000 ft, the vertical speed was 15300 ft/min and the AoA was close to 40 degrees. Is there any ballpark figure about the "minimum safe altitude" for stalls in a A330-sized aircraft?

Can anybody describe how deep airliners are stalled during flight testing, and compare it to the AF447 situation?



David

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: XT6Wagon
Posted 2012-07-14 12:09:09 and read 11680 times.

Quoting tdscanuck (Reply 171):
It would fix that issue, absent electrical reconfigurations as zeke noted. However, zeke touches on another crucial point...it introduces a whole host of new failure modes into the stall warning system. Proximity sensors (responsible for gear indication and WoW signals) are notoriously flaky. Hooking a new and low reliability component into what should be a high reliability system completely screws up the fault tree analysis. The certification burden is not insignificant and, given the nature of the issue, there's almost zero chance that it passes cost/benefit analysis.

Much better to have extra training hours regarding stalls and stall warnings, as this will cover more potential problems for the same or less cost.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-14 14:17:47 and read 11603 times.

Quoting flyingturtle (Reply 172):
Can anybody describe how deep airliners are stalled during flight testing, and compare it to the AF447 situation?

I didn't think they were stalled at all. Or maybe I'm confusing with spins.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: spacecadet
Posted 2012-07-14 14:49:06 and read 11589 times.

Quoting flyingturtle (Reply 172):
Is there any ballpark figure about the "minimum safe altitude" for stalls in a A330-sized aircraft?

Much lower than 33,000 feet. Many tests are done at between 10,000 and 15,000 feet and the expectation is that you will lose little altitude during the stall test - a couple hundred feet.

The problem is there's an expectation that a pilot will recognize the stall before it's fully developed, and that actually never happened in the case of AF447. I did read the full report but I can't recall if it said there was really a "point of no return" beyond which they couldn't have saved the plane even if they recognized the stall, but I can't imagine it was 33,000 or 31,500 feet. It sure seems that if they had simply let go of the controls even at that point, they would have lost another couple thousand feet of altitude but the airplane would have pitched down and regained AoA on its own - I don't remember the report mentioning them being in a deep stall at that point. The problem is the PF continuously thought they were either at the onset of buffet or in an overspeed condition, so he made inputs either consistent with one of those or he just followed the flight director. At the onset of buffet, the procedure for at least some aircraft is that you power out of it before the stall fully develops.

Quoting flyingturtle (Reply 172):
Can anybody describe how deep airliners are stalled during flight testing, and compare it to the AF447 situation?

Definitely not that deeply - I mean not to the point of a "deep stall". Some airplanes actually have full stall characteristics that are predicted but not fully known in practice because it would be dangerous to test them - the whole idea is you never let it get to that point. The DC-8, for example, has had a couple of crashes during stall testing long after the type was first put into service partly because the simulators flat-out had the stall characteristics modeled wrong. They had predicted a benign, level stall, when in reality the DC-8 is prone to asymmetrical stalling with severe pitching. Expecting something more controllable, two separate crews that I know of were surprised when they stalled the plane in testing and it pitched violently and rolled. They did not have the proper training to recover from it. But the stall was never meant to get to that point; plenty of DC-8's had been stall tested prior to that, and the pilots had either just powered out of it (the earlier procedure) or let the nose fall through to regain AoA.

AF447 actually seems somewhat similar in that it's obvious that the plane did not stall in a way that the flight crew expected (in that they didn't even recognize it as a stall), and they were not properly trained to handle a high altitude stall. Obviously the A330 has been stall tested, but the assumption is always that pilots will recognize the stall quickly and recover from it before it becomes difficult to control. Nobody tests airplanes in stalls from which it would be difficult to recover, so there are limits as to how far the testing goes. Airplanes these days are designed in such a way to minimize the chance of a deep stall, while being easy to recover at the onset of a stall. And that's what's tested.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: mandala499
Posted 2012-07-15 06:56:11 and read 11374 times.

Quoting zeke (Reply 42):
Over reaction to many events in aviation can cause more problem than the original event.

That's the sad reality...

Quoting huxrules (Reply 49):
The report says that for low altitude stall recovery the suggested method is 12.5 deg and TOGA throttle. It goes on to say that the PF might have remembered this procedure and used it (the plane was near 12 deg pitch up for most of the time and TOGA for some of it). My question is - how is low level stall recovery 12 deg nose up? I thought stall recovery is always descend or be level.

Cognitive limitations.

Quoting ltbewr (Reply 56):
Using an A-320 simulator (similar to the A330 and the A320, a plane Cpt. Sullenberger was very experienced with) and a B-747 simulator, he noted what he sees as critical differences and issues. As the linked article notes, he thinks the 'joystick' design of A's does not give you enough status or feel of your flight position, while B's 'wheel' design shows more obviously your flight position. He also notes that the A's joysticks of the pilots are not interconnected so a mistake by one will not be understood immediately by the other flight officer.

I'll throw this argument of the window.

Quoting canoecarrier (Reply 60):
I'll have to go back and check our timeline from the previous threads, but didn't the Captain enter the cockpit just as the last stall warning was sounding and it ceased shortly afterword?

I'll have to combine the new transcript into the spreadsheet first before making anything more than an initial comment *see below*

Quoting zeke (Reply 66):
What you also do not mention, is that large aircraft with control columns normally have artificial feel built into them, if the airspeed is off, so is the artificial feel as it has an airspeed input.

Adding to Zeke's... and when feel is lost, it goes back to.. spring loaded everyone... (it's in the Boeing FCOMs).

Quoting tom355uk (Reply 84):
Thinking of it from this point of view, they might have actually been better off in their situation had the flight controls degraded to direct law instead of ALT2 - as the autotrim would not have been active and control might have been regained by a prompt nose down input.
Quoting garpd (Reply 85):
Sorry but: Bollocks, absolutely pure, unrefined, bollocks.

And I do wish that Capt. Sully would stop talking bollocks or the guys quoting him would stop turning what he says to bollocks. Well, tom355uk may be talking bollocks, but Capt. Sully is also talking unrefined bollocks too! Just because he's a hero of the Hudson ditching, doesn't prevent him from talking bollocks on AF447... to which he is by forgetting or not realizing that yoke equipped aircraft have crashed due to aft yoke inputs to the extent where the critical AoA was exceeded and the aircraft stalled to its doom. If the crew doesn't realize they're in a stall, yoke, sidestick, or mind control aircraft controls, isn't going to give a miraculous escape.

Quoting canoecarrier (Reply 27):
and if Mandala can glean any more information from the more complete transcript included in the Appendix to this report for his spreadsheet.

I just read the report and the transcript. New findings? A shocker.
Previously, I thought that the PF didn't know what was going on and that the PNF tried to correct but was not assertive enough and was rather "half-hearted" in his takeovers. However, after reading the new transcripts, my initial conclusion is that the PNF knew less of what was going on than the PF. What's new is the CPT's input. Previously I thought that the Captain was largely a spectator late in the game. From the new transcripts it seems apparent to me that he had difficulty in comprehending the PF and PNF, and tried to get them to focus on controlling the plane. Previous speculations that he knew the aircraft was stalling and that the PF was being a hard head is thrown out with this new transcript. Even the Captain was puzzled on why the aircraft couldn't be "controlled".

Quoting rcair1 (Reply 105):
Ideally, this is a good argument to have. We want to understand and adapt already good systems to be better.

Practically, the politics and company philosophy makes it frustrating and useless.

Again, sad truth. Politics and "habits" and "comfort zone" and egos... the combination of which is a major hurdle for a lot of airlines when it comes to training programmes, and this is before it's put in front of the beancounters!

Quoting tom355uk (Reply 108):
The autotrim moved the THS virtually to it's full up-stop as per its design. If the aircraft had degraded immediately to direct law, then the autotrim would have disconnected and frozen the THS value at it's previous setting. With the THS in the full up position, a sustained nose down input (for more than a few seconds - i'm not sure what the rate of movement in degrees per second is) would have been required to bring the aircraft back under control. If it had been frozen at the cruise value (probably near zero, or slightly up??) then the return to controlled flight would have been quicker, and probably achievable in exchange for much less altitude loss.

The Autotrim being disabled in this case would result in the crew still chasing whatever pitch attitude they wanted... albeit they had to struggle more, but that risks tunnelling their task orientation as the flip side of the coin.

Quoting PHX787 (Reply 142):
I have always had a problem with GPS systems when there is a lot of cloud cover in the area. If an airplane flies into a storm like AF447 I'm not sure if that would work.

What is your GPS system that you have problems with when under a lot of cloud cover?
GPS works in L-band which relatively (if not very) rain-fade resistant in that it is used for essential services. However, to use it without rain-fade issues, you need aviation and/or military and/or maritime grade (certified) equipment with the approved installation/use methods.

Quoting spacecadet (Reply 175):
AF447 actually seems somewhat similar in that it's obvious that the plane did not stall in a way that the flight crew expected (in that they didn't even recognize it as a stall), and they were not properly trained to handle a high altitude stall. Obviously the A330 has been stall tested, but the assumption is always that pilots will recognize the stall quickly and recover from it before it becomes difficult to control. Nobody tests airplanes in stalls from which it would be difficult to recover, so there are limits as to how far the testing goes. Airplanes these days are designed in such a way to minimize the chance of a deep stall, while being easy to recover at the onset of a stall. And that's what's tested.

The problem is when the crew doesn't recognize the stall (unarrestable nose down movement and a one wing drop)...
This goes back to a human problem, the better the design, the more "cushion" they have from a stall, which leads to more time until the stall compared with "worse designs", which, unfortunately, opens the risk to tunnel visioning or task saturation... so when the stall happened, they failed to recognize it.

Mandala499

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-15 22:20:19 and read 11127 times.

re mandada499 @ 176: The problem is when the crew doesn't recognize the stall (unarrestable nose down movement and a one wing drop)...

We have discussed pitot tubes, too. And AoA. And human factors. And training. And on and on.

I would like permission to present, once again, the idea that I have mentioned several times before. I do not like to persist -- show me why it is a ridiculous idea and I'll drop it -- but it does seem to me to have some merit and I have not yet seen it shot down on its merits.

So, again, it is this: measure the lift distribution on the wing directly and display it to the pilot. Presumably, doing so would require some number of pressure transducers mounted in the wing's surface -- two dozen, perhaps?

Pros: There will be some family of lift distributions which say that all is well; outside of this family, all is _not_ well. Both humans and computers should find it fairly easy to recognize the difference. Specifically, the lift distribution over the wings of AF447 for about 3 minutes was toxic, and there is nothing like a direct measurement of the quantity in question, namely, lift, to concentrate the attention. The pilot would have seen two dozen transducers saying the aircraft's wing was generating no lift to speak of. He would have had to believe that. First of all, pressure transducers are pretty sturdy lumps of metal -- they are not going to get clogged or go out of range. Second of all, for their answer to be nonsense, you would have to have multiple failures in that system. You look at your altimeter and find it is unwinding very, very quickly. Situation clear: you are in a beguilingly stable, one-G stall and falling, so do whatever will get your lift back.

Cons: Cost, perhaps? Compared to what? Transducers should not be expensive. Processing power required should be modest. Display real estate does not have to be used all the time: the lift distribution need only be displayed when requested by the pilot or when the computer detects an anomaly.

AF447 shows that even at 30k feet altitude, the pilot does not have the luxury of waiting to see whether things will sort themselves out; sangfroid is not an option. Lift is life: measure it and display it.

P.S.: And if my car, after I had driven counterclockwise around a city block, cranked, say, 20 degrees of left turn into the steering geometry all on its own and didn't even bother to tell me, I would have it back into the dealer's hands that same day. Maybe that hidden automatic trimming of the horizontal stab based on recent control inputs is a great idea, but I do. not. see. it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: ricknroll
Posted 2012-07-15 22:46:43 and read 11089 times.

Quoting bellancacf (Reply 177):
So, again, it is this: measure the lift distribution on the wing directly and display it to the pilot. Presumably, doing so would require some number of pressure transducers mounted in the wing's surface -- two dozen, perhaps?

I think the argument against that in this instance was that they already had plenty of information that they were in serious trouble, and ignored it. For example, they were being told they were dropping like a stone, and complained about all the failed instruments.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: AirbusA370
Posted 2012-07-16 01:37:22 and read 10996 times.

An exact copy of this accident won't happen ever again, due to the extremely low accident rate in aviation. Statistically, the next dozen of accidents will be CFITs. So why take drastical design changes to the current cockpit and sensor design that will possibly lead to other problems? Airlines should improve training especially CRM, that's the main lesson from this...

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-16 09:52:34 and read 10808 times.

Quoting bellancacf (Reply 177):

Specifically, the lift distribution over the wings of AF447 for about 3 minutes was toxic, and there is nothing like a direct measurement of the quantity in question, namely, lift, to concentrate the attention. The pilot would have seen two dozen transducers saying the aircraft's wing was generating no lift to speak of. He would have had to believe that. First of all, pressure transducers are pretty sturdy lumps of metal -- they are not going to get clogged or go out of range.

Contrary to what you may have told before, post stall, a wing still produces lift, and lots of it. I have not seen post stall flight test data for the A330, however other aircraft data have seen exhibit a simlator rate of change of the Cl vs angle of attack pre stall, as they do post stall, just in the opposite direction.

Wings get their surfaces clogged up all the time with rain, snow, and de-ice fluid. The industry is also not very keen on running electric wires inside wings either these days, their other function is to hold fuel. What you are suggesting in a way is similar to the way the B2 air data system operates. Being a flying wing, they derive their air speed data a number of flush mounted static ports to reduce the radar signature. The loss of a B2 on takeoff in relatively good conditions in Guam along with the other concerns i mentioned I think would dampen support for such a proposal.

I have even seen post stall data done on some rotating wings (props), where post stall the Cl decreases and then increases to a second peak lower than the original Clmax. It is a very interesting area of aerodynamics, which is still is not fully understood.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-16 12:46:07 and read 10685 times.

For what it's worth (there's not much in the report from the specialized Human Factors Working Group commissioned by BEA):

1. The vastly less experienced right-seat FO was anxious/fixated on climbing above the wx, even suggesting a non-standard altitude (His wife was a pax - mindset?).

2. The captain never responded to his concerns.

3. The captain did not display much in the way of leadership (e.g. he left the cockpit as the flight was entering the ITCV; the right seat FO carried out the briefing when the left-seat FO returned to the cockpit; the captain did not indicate in what circumstances he should be called back to the cockpit).

4. The captain delegated command to the vastly less experienced right-seat FO (antagonism, professional conflict, professional distrust/jealousy between the captain and the right-seat FO, who was substantially more experienced than the captain - i.e. put him in his place?). The captain didn't even know if the right-seat FO held an ATPL.

5. The left seat FO was a by-the-rules guy.

6. The left-seat FO had no training in flying from the left seat.

7. The left-seat FO was anxious to get the captain back because the captain had explicitly handed off command to the right-seat FO, and the right-seat FO was not responding to the left-seat FO's suggestions.

8. After the captain came back to the cockpit, the right-seat FO was focused on maintaining wings level (reinforced by the captain's comments - and no mean feat in a slushy full-stall environment) and still fixated on climbing (reinforced by the uncycled PFD).

9. After the captain re-entered the cockpit, the left-seat FO abdicated responsibility (e.g. it was the right seat FO/PF who called out, eventually, the unwinding alti - why wasn't the right-seat FO monitoring basic flight parameters?).

10. The right-seat FO continued to try to climb; the captain remained unanalytic and unassertive; the right-seat FO was a pax.

11. Impact.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: BA84
Posted 2012-07-16 13:12:10 and read 10644 times.

Kaiarahi,

You need to edit the references to the pilots.

Better to call them PF and PNF.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: N14AZ
Posted 2012-07-17 00:27:16 and read 10476 times.

Quoting Kaiarahi (Reply 181):
there's not much in the report from the specialized Human Factors Working Group commissioned by BEA

I have to be careful here and I would like to start with saying that this report is not made for our entertainment. However, I also would have been interested in reading more information about the results of that working group. Chapter 1.16.8 of the final report is just a summary of what they did.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-17 05:16:16 and read 10301 times.

Quoting N14AZ (Reply 183):
I have to be careful here and I would like to start with saying that this report is not made for our entertainment.

Understood and agreed. If the working group's activities uncovered personal information, I would not expect it to be included in a public report.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bikerthai
Posted 2012-07-17 06:19:06 and read 10220 times.

Quoting BA84 (Reply 182):

Better to call them PF and PNF.

Actually for us "non-pilots", left seat and right seat was easier to visualize and understand. I know there is more information embedded with PF and PNF, but I have not yet able to keep the two straight.   

bt

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-17 09:15:37 and read 10136 times.

Quoting bikerthai (Reply 185):
Quoting BA84 (Reply 182):

Left seat / right seat is important here, because the FO sitting in the left seat was not trained to fly from the left seat.

Having said that, I made a typo in para 4    - the reference to antagonism, conflict, etc should have been between the captain and the left-seat FO.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Aesma
Posted 2012-07-17 16:39:16 and read 9965 times.

Also, when talking about PF and PNF, you assume those don't change or aren't expected to, when here there was a discussion as to who should fly the plane.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: cmf
Posted 2012-07-17 18:10:37 and read 9904 times.

Quoting Kaiarahi (Reply 181):
The captain did not display much in the way of leadership (e.g. he left the cockpit as the flight was entering the ITCV

Is leaving as they entered ITCV a big deal? Why is it a display of lack of leadership? Correct me if I'm wrong but it isn't every pilot qualified to fly that route capable (expected to) handle those conditions?

Also, isn't it normal for the captain to take his break in that part of the flight?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-17 20:45:10 and read 9840 times.

Thanks to ricknroll, AirbusA370, and zeke for their thoughtful replies.

re ricknroll@178: "they already had plenty of information that they were in
serious trouble, and ignored it. For example, they were being told they were
dropping like a stone, and complained about all the failed instruments."

The altimeter was working, and, yes, they ought to have given that information
its full weight, but they had no obvious unifying explanation for all they saw
and felt. Slight nose up attitude, one-G, gentle rocking (and full nose-up
stab trim) -- a stall configuration apparently unknown to them. Nothing
really said, "You are presently stalled." The stall warning says, "Don't do
that! You will stall if you do." I am trying to suggest a direct measurement
and a clear display that would have provided that needed unifying explanation.

re AirbusA370@179: ". . . this accident won't happen ever again, due to the
extremely low accident rate in aviation. Statistically, the next dozen of
accidents will be CFITs. So why take drastical design changes to the current
cockpit and sensor design that will possibly lead to other problems? Airlines
should improve training . . ."

1. Earlier in this thread there was mention of the surprizing number of
similar accidents and events. 2. Would this be a drastic design change?
Finding out the proximity to stalling is one purpose of having airspeed and
AoA measurements; I am suggesting measuring the stalled/unstalled condition
directly. Sure: it's a step outside of the familiar. 3. In a macabre way,
AF447's fall itself was a CFIT, but that trivializes the tragedy.

re zeke@180:

A: "Contrary to what you may have told before, post stall, a wing
still produces lift, and lots of it. I have not seen post stall flight test
data for the A330, however other aircraft data have seen exhibit a simlator
rate of change of the Cl vs angle of attack pre stall, as they do post stall,
just in the opposite direction."

Are you arguing that AF447's stalled wings were producing lots of lift as it
descended? If one had measured the pressure distribution around the wings as
they fell, one should have found pressures >> Patm on the lower surface and
pressures close to Patm on the upper, as the wing had become a nearly
horizontal flat plate in an oblique descent; its drag was sufficient to cause
the aircraft to reach terminal velocity and for the occupants thus to
experience one-G or so. Is this what you are calling "lift"?

There was a much-sold R/C sailplane design that I twice saw soaring level,
when it was given a twitch of up-elevator: the nose pitched up severely, and
then the wings folded up, wingtip-to-wingtip. Such a drastic increase in lift
with a slight AoA increase that even strengthened wing-half joiners bent and
broke. That was a pathological degree of C-lift increase with AoA! What lift
that design would have generated post-stall we never got an opportunity to
find out . . . I never bothered to build another one of those.

B. "Wings get their surfaces clogged up all the time with rain, snow, and
de-ice fluid."

I am not talking about orifices in the wing skin; I mean transducers that
feature a continuous, smooth surface. Nothing to clog. What _does_ bother me
is coping with temperature swings from, say, +40 degrees C to -40 and back
during the course of a flight? Oh well, that's why God invented engineers.
Piezoelectrics? Strain gauges?

C. "The industry is also not very keen on running electric wires inside wings
either these days, their other function is to hold fuel."

Any transducers I've encountered have involved weights, currents, and voltages
trivial compared to even a navigational light, never mind a flap motor. I
would not think that this would be an issue. Again -- engineers.

D. ". . . derive their air speed data a number of flush mounted static ports
. . ."

Again, I'm not suggesting an alternative to pitot tubes, nor ports. I am
concentrating solely on giving pilots a picture of the pressure distribution
around the wing, an aspect of which is lift.

Thanks for the critiques, but it seems to me that this ball is still in play.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-18 04:56:25 and read 9725 times.

Quoting bellancacf (Reply 189):
I am trying to suggest a direct measurement
and a clear display that would have provided that needed unifying explanation.

They have a direct measurement and a clear display. The crew chose to ignore it.

Quoting bellancacf (Reply 189):
Are you arguing that AF447's stalled wings were producing lots of lift as it
descended?

Yes, that's what he's arguing. And he's correct. They were in a 1g descent; that's only possible if the upward force on the airplane (vertical components of lift and drag for the given flight path vector) equals the weight. That means they still had lots of lift. They also had lots of drag (the major feature of a stall is a huge drag increase, not a lift decrease).

Quoting bellancacf (Reply 189):
C. "The industry is also not very keen on running electric wires inside wings
either these days, their other function is to hold fuel."

Any transducers I've encountered have involved weights, currents, and voltages
trivial compared to even a navigational light, never mind a flap motor. I
would not think that this would be an issue. Again -- engineers.

The safety engineering around in-tank wiring is *enormous*, far worse post TWA800. You would need an incredibly compelling reason to do it and I don't think this meets the threshold. It's absolutely technically possible, it would absolutely be a huge issue.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-18 06:15:51 and read 9663 times.

Quoting bellancacf (Reply 189):

Are you arguing that AF447's stalled wings were producing lots of lift as it descended?

It is not an argument, is it just aerodynamics. Past the stall angle of attack the wing still produces lift, lift is primarily a function of the angle of attack and airspeed for a given configuration. Past the stall angle of attack, the lift curve slope decreases, however it does not go to zero straight away. If somehow you could either convert energy either by trading height or with thrust to overcome the additional drag, you can fly in the post stall regime (e.g. the SU-27 Cobra). We see this in nature when birds come into perch, a bird deliberately stalls its wings to uses the post stall drag to reduce speed. They can maintain height or slowly descend while decelerating rather quickly.

The downside in flying in the post stall regime is the that drag increases significantly, which normally means speed reduces. As the speed reduces, the lift generated reduces as both the Cl is reduced, so is the speed.

As AF447 got slower and the angle of attack increased even further post stall, the amount of lift generated reduced even more.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bikerthai
Posted 2012-07-18 06:58:01 and read 9612 times.

Quoting zeke (Reply 191):
Quoting bellancacf (Reply 189):

Are you arguing that AF447's stalled wings were producing lots of lift as it descended?

It is not an argument, is it just aerodynamics.

For those out there who is not following the logic being discussed.
An everyday example would be to take a thin sheet of ply wood and try to fly it.
The plywood will produce lift at angle greater than 0 degrees. But at angle greater than 0 degrees, the ply wood will stall (because of the sharp leading edge) and generate lots of drag (along with the lift).

Thus the reason why a sheet of plywood don't fly too well.

bt

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Kaiarahi
Posted 2012-07-18 09:28:05 and read 9542 times.

Quoting cmf (Reply 188):
Is leaving as they entered ITCV a big deal? Why is it a display of lack of leadership? Correct me if I'm wrong but it isn't every pilot qualified to fly that route capable (expected to) handle those conditions?

Qualified and experienced are not the same thing. On previous threads, many experienced captains indicated they would have remained in the cockpit for the relatively short time it took to cross the ITCV.

In this case, what the captain left behind him was a right-seat PF with very limited experience who was already expressing anxiety, and a left-seat FO not trained to fly from the left seat.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-18 20:54:05 and read 9355 times.

Thanks to tdscanuck@190, zeke@191, and bikerthai@192 for thoughtful,
informative, and -- for me -- enlightening responses.

The "lots of lift as AF447 fell" statement still surprizes me, I have to say.
Lift, so I read, is a force directed at right angles to the free stream.
AF447 fell at an angle of descent of 45 degrees, and it was in a nose-up
attide ranging up to about 15 degrees. Thus, the wings, we can say, were at
an alpha of 60 degrees. Lift would be directed only 30 degrees above the axis of
the aircraft. It is hard for me to see the wings acting much differently from
flat plates, but that doesn't help me analyze the situation much further, I'm
afraid; nevertheless, it does seem that L/D must have been less than unity.
It also seems to me that the engines' thrust must have been providing lift
directly (again, at 90 degrees to the direction of descent) to the tune of
sin(15 degrees) * thrust, and sin(15.) is 0.25. But that is really neither
here nor there. The main thing is that -- and I guess that we do agree that
this is true, don't we? -- flow separation was essentially complete.

So putting wires in wings is a major effort. Well, that probably kills the
idea of instrumenting the wings to measure pressure distribution directly.

Unless -- cue Flash Gordon   -- the time comes when we can apply solar-powered,
nanotech pressure sensors thinner than a coat of paint that will wirelessly
transmit their readings to a flight computer. The wings will be conformal,
and the computer will tweak the shapes of the wings to maintain optimal lift
and drag, even during maneuvers, much as software twiddles the ailerons on the
new 747 to damp out flutter. And as a side effect, the computer will be able
to inform the pilots of just exactly what is happening out on that
all-important wing -- no more wondering and guessing and waiting those three
minutes too long.

Thanks to all. I have enjoyed the exchange immensely.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: N14AZ
Posted 2012-07-18 23:33:39 and read 9288 times.

Quoting Kaiarahi (Reply 184):
If the working group's activities uncovered personal information, I would not expect it to be included in a public report.

This is an aspect I even didn't think about. Surely they made a characterization of the three persons similar to what you did above. However, and as you wrote above, they did not opt to publish this.

Seems as if we have to accept that there will be no more additional information.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-19 02:28:43 and read 9222 times.

Quoting bellancacf (Reply 194):
AF447 fell at an angle of descent of 45 degrees, and it was in a nose-up attide ranging up to about 15 degrees. Thus, the wings, we can say, were at an alpha of 60 degrees. Lift would be directed only 30 degrees above the axis of the aircraft.

The aircraft actually climbed after it stalled, this is a plot of the vertical trajectory, airspeed, angle of attack

http://oi51.tinypic.com/dbr05u.jpg

As it became fully developed the value in black shown would be at high level, and in red just before impact

http://oi56.tinypic.com/52lv5t.jpg

A swept wing aircraft will normally stall at the wing tip first, the whole wing does not stall at the same time, so even if an aircraft has stalled, normally in the first part of the post stall area parts of the wing are still unstalled.



If one is to look at the relationship between CL and the angle of attack, it maybe similar to this

http://home.comcast.net/~shademaker/Ostowari&Naik_PostStall4412.jpg

As you can see, past the maximum Cl, the Cl does not drop to zero immediately, on that plot the maximum Cl is around 18 degrees, if you look at the Cl at 20 degrees, it is similar to the Cl at 16 degrees. A plot of teh Cl vs alpha for a wing would be different to this.

Quoting bellancacf (Reply 194):
Lift would be directed only 30 degrees above the axis of the aircraft. It is hard for me to see the wings acting much differently from flat plates, but that doesn't help me analyze the situation much further, I'm afraid; nevertheless, it does seem that L/D must have been less than unity.

I would agree that drag would have increased significantly after maximum Cl.

Quoting bellancacf (Reply 194):
It also seems to me that the engines' thrust must have been providing lift

Yes a component of thrust was vertical.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: flyingturtle
Posted 2012-07-19 02:32:02 and read 9206 times.

Quoting N14AZ (Reply 195):

One could hope that this report will be leaked...

Has happened before with the full CVR transcript that was published in a book.


IMHO, this part of the report should be transmitted to every airline at least, as they have to select the aircrew for each flight. Psychologists could develop tests or at least strategies to improve CRM in such cases.


David

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-19 13:56:08 and read 9032 times.

Quoting bellancacf (Reply 194):
The main thing is that -- and I guess that we do agree that
this is true, don't we? -- flow separation was essentially complete.

No argument from me on that one.

Quoting bellancacf (Reply 194):
So putting wires in wings is a major effort. Well, that probably kills the
idea of instrumenting the wings to measure pressure distribution directly.

It's not impossible; if you could do it with fiber optics you could avoid running any electrical power in the tank. The technology probably isn't commercial yet but it exists in R&D. The real question is whether it can buy its way onto the airplane.

Quoting bellancacf (Reply 194):
Unless -- cue Flash Gordon   -- the time comes when we can apply solar-powered,
nanotech pressure sensors thinner than a coat of paint that will wirelessly
transmit their readings to a flight computer.

That's basically how you do pressure distribution during flight test now (the sensors are called "pressure belts" and they're not solar powered, but they are extremely thin MEMS sensors that you stick directly on the wing surface). The problem is that they're fragile as heck; their half life is measured in hours or days.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-19 16:32:15 and read 8949 times.

re tdscanuck@198: That's basically how you do pressure distribution during flight test now (the sensors are called "pressure belts"

Well, I'll be darned. So someone _has_ taken a crack at getting real-time pressure distribution info. (Since NASA's outfitting of the X-15, too.) I was wondering about fiber optics, too. Then I wondered about powering the converters (or whatever you call the thing that makes the light ... ). Then I thought, well, there are lights flashing and surfaces moving out there, so _something's_ getting powered. The search for efficiency may well be what in time buys sensors their place on the wing, with the side effect of a real-time pressure distribution display.

Thanks very much for taking your time to comment so helpfully. (This AF447 incident _does_ get into your head, doesn't it? It's the only crash that's ever gripped my attention anything like this.)

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-19 17:06:02 and read 8935 times.

re zeke@196:

Interesting graphics. I would like to respond intelligently, but I have to confess that I have lost track of the point you are making.

Thank you, though. Lots of good info to tuck away. Where does that NACA 4412 blade pop up in the real world?

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-19 18:14:39 and read 8910 times.

Quoting bellancacf (Reply 199):
Then I wondered about powering the converters (or whatever you call the thing that makes the light ... ). Then I thought, well, there are lights flashing and surfaces moving out there, so _something's_ getting powered.

The OEM's work really really hard to make sure all the stuff that's powered is ahead or or behind the spars (i.e. in the leading and trailing edge) or out past the last solid rib (i.e. the wing tip) just so that they don't have to run wires inside the fuel tanks. Unfortunately, you can't pull this trick with pressure sensors because all the good stuff happens on the wing surface where the only thing to mount on is the outside of the fuel tank. Unless you want to run the wires on the outside (and the aero guys will try to kill you) you have to run them inside the skin, which means inside the fuel tank on all current designs.

Quoting bellancacf (Reply 200):
Where does that NACA 4412 blade pop up in the real world?

Linnet 2 used it for it’s elevator, and MiLan ‘81 and ‘82 as well as Mowe 4, 5 and 6 used it for the wing. (taken from http://library.propdesigner.co.uk/html/naca_4412.html)

Quoting bellancacf (Reply 200):
Interesting graphics. I would like to respond intelligently, but I have to confess that I have lost track of the point you are making.

He's showing that even past the stall point, the wing is making considerable lift. It's the drag, not the lift, that gets you in a stall.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-19 18:34:18 and read 8954 times.

re tdscanuck@201: "He's showing that even past the stall point, the wing is making considerable lift. It's the drag, not the lift, that gets you in a stall."

Which is why the L/D goes south, then. OK; can I restate it like this? "The resultant vector (L + D) may/does in fact lengthen, but it aligns more closely with the free stream as alpha increases into the stall regime."

Thanks for all the insights and information, Tom. I really appreciate it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-19 19:05:36 and read 8926 times.

re tdscanuck@201: Mowe

Awww, that's a sweet plane. I want to build it and see how it goes. [edit: Ooops. I looked at the Focke-Wulf passenger plane from the '20s. Was that the one you meant?]

True story: I built an electric-powered R/C Bellanca Airbus from old Cleveland plans, and a friend gave me a copy of the Smithsonian's book about the Bellance C.F. and their restoration of the only one ever made. The very accurate illustrations and the good photos showed a reflexed airfoil, which I'd never seen. One thing led to another, and after a while I was measuring the airfoil of the C.F. with one of the restorers at the Museum. I built a model using this airfoil, and since I figured that G. Bellanca had figured out the best structure for the plane better than I ever could; even the fuselage bracing followed the original's layout. (I did do the wire bracing in the vertical stab with stick balsa, but mostly because it's a pretty design that I wanted to show through the covering.) The time came to fly it, and the teen-aged son of my friend did the honors, while my friend filmed. When it had done everything we could have hoped and more, and before the batteries sagged, the pilot lined it up and brought it down, but we heard him yell, "It doesn't want to come down!" This cracked me up, because that's exactly what was written by one of the pilots who evaluated the original C.F.: it seemed not to want to come down. The model's pilot actually climbed out and lapped the field again before gliding it in.

Yeah, I had a good time recreating the flight characteristics of that Golden Age plane. The first cabin monoplane, you know. The great-granddaddy of modern passenger aviation. What would that Mowe airfoil do? Insane STOL performance?

[Edited 2012-07-19 19:53:21]

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-19 19:34:35 and read 8915 times.

Quoting bellancacf (Reply 202):
can I restate it like this? "The resultant vector (L + D) may/does in fact lengthen, but it aligns more closely with the free stream as alpha increases into the stall regime."

Yes, that's a very accurate statement.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: billreid
Posted 2012-07-19 20:16:24 and read 8890 times.

Quoting N14AZ (Reply 76):
You will never know how many accidents have been avoided by Airbus' design philosophy.

This is irrelevant to the crash because the Airbus systems failed to save the flight, passengers and crew.
Read the comments on reply 105. This guy is right.

Quoting rcair1 (Reply 105):
Again - it is not about sidesticks versus yokes - both could work in either scenario.

It is also hard to prove - partly because we never hear about successes attributed to either. (if it works, we don't hear about it).

What I do know and believe is that pilots mostly prefer and feel more comfortable using the Boeing philosophy. It gives them a subconscious feeling of being more in control. And if the pilot who is driving the plane feels more comfortable in a B than an A, then that is really important to me when I go through the cabin doorway on the way somewhere.
This is about human interaction with machinery not about the machinery because we all know the crash was avoidable.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-19 20:56:38 and read 8836 times.

re tdscanuck@204:

And I guess you'd like the rotation of the resultant to lag behind the rotation of (the normal to) the wing chord (maybe the resultant even rotates forward to a position "in front of" the wing's normal), but at some point the resultant is going to say, the heck with it, and snap to the free stream. Love to see an animation of that for various airfoils and conditions.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: Unflug
Posted 2012-07-20 00:21:40 and read 8782 times.

Quoting billreid (Reply 205):
What I do know and believe is that pilots mostly prefer and feel more comfortable using the Boeing philosophy.

I think you know that you believe it, but I don't believe that you know it  

There have been many discussions on that matter. I was always left with the impression that Boeing pilots mostly prefer the Boeing "philosophy" and Airbus pilots mostly prefer the Airbus "philosophy". And that doesn't prove anything.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: David L
Posted 2012-07-20 02:18:32 and read 8706 times.

Quoting Unflug (Reply 208):

   Mistrust of the Airbus method comes almost entirely from people without experience of it. There was even scepticism in France in the beginning, when hardly anyone had any experience of it.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: zeke
Posted 2012-07-20 03:22:15 and read 8679 times.

Quoting bellancacf (Reply 200):
Interesting graphics. I would like to respond intelligently, but I have to confess that I have lost track of the point you are making.

When an aircraft stalls, it is normally not the whole wing, only a portion of it initially. Even the parts of teh wing that are stalled still produce lift.

When an aircraft goes beyond the stall angle, drag rises significantly, while lift reduces by a smaller amount, this tends to reduce speed, and thus reduces the amount of lift generated for a given Cl.

Quoting billreid (Reply 205):

This is irrelevant to the crash because the Airbus systems failed to save the flight, passengers and crew.

I would disagree with that, if anything the FBW system in my view actually prolonged their flight at high flight levels. A non FBW aircraft I believe would have departed in spin in similar circumstances.

Quoting billreid (Reply 205):
What I do know and believe is that pilots mostly prefer and feel more comfortable using the Boeing philosophy.

I do not agree with that, that is like saying PC users like using PCs, and mac users like using macs. Neither operating system is directly in control of what is going on in the CPU.

Quoting billreid (Reply 205):
It gives them a subconscious feeling of being more in control.

I do not see how this is possible, if true, it is a dangerous mindset.

Quoting billreid (Reply 205):
. And if the pilot who is driving the plane feels more comfortable in a B than an A, then that is really important to me when I go through the cabin doorway on the way somewhere.

I prefer to fly an Airbus, to me they are more ergonomic and have lower noise levels, that is just my personal preference. Ergonomics and noise directly impact on my fatigue levels. Sticks are found in all levels of aviation, from light aircraft, narrow bodies, wide bodies, military fighters, military transports, and helicopters.

Quoting Unflug (Reply 208):
I was always left with the impression that Boeing pilots mostly prefer the Boeing "philosophy" and Airbus pilots mostly prefer the Airbus "philosophy". And that doesn't prove anything.

True, and the report actually shows that more of these sort of accidents have occurred in Boeings/McD aircraft.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: InsideMan
Posted 2012-07-20 04:20:16 and read 8624 times.

Quoting billreid (Reply 205):
What I do know and believe is that pilots mostly prefer and feel more comfortable using the Boeing philosophy.

*sigh*  

I've spoken to many pilots professionally and none of them prefered the Boeing system, quite contrary it was refered to as antique and outdated. In fact many claimed the only reason the 787 has yokes is, because Boeing didn't wanted to give Airbus the satisfaction of "being their first" and Boeing following....

Quoting Unflug (Reply 208):
I think you know that you believe it, but I don't believe that you know it

Indeed.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-20 06:31:13 and read 8522 times.

Quoting zeke (Reply 210):
A non FBW aircraft I believe would have departed in spin in similar circumstances.

Before the recovery of the FDR, and the report of the data - I doubt you could have found anyone on this forum, or other aviation forums who would believe it possible to stall an aircraft at FL370 and hold it basically stable in a stall throughout a four minute descent to the ocean surface.

In all the threads before the FDR data was released, the only times I saw the word stall was in speculation why the aircraft crashed. The concept of a stall was dismissed because it was felt the aircraft would have spun, and there would have been a breakup of parts of the aircraft due to the spin before it hit the water. The initial report which showed conclusively that the vertical stabilizer was attached to the fuselage at the moment of impact proved there was not breakup of the airframe before impact.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bikerthai
Posted 2012-07-20 06:34:18 and read 8514 times.

Quoting tdscanuck (Reply 201):
Unless you want to run the wires on the outside (and the aero guys will try to kill you) you have to run them inside the skin, which means inside the fuel tank on all current designs.

Yes, but with a composite wing (787, A350). . . there might be a possibility to embed the wires (&sensor) in the lay-up itself.

Maybe not now . . . but perhaps in the not so distance future.   

bt

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: rfields5421
Posted 2012-07-20 06:55:56 and read 8494 times.

Quoting bikerthai (Reply 214):
might be a possibility to embed the wires (&sensor) in the lay-up itself.

The maintenance part of me finds that frightening. Having to take apart a wing to fix a broken wire. Yes, I know - extremely remote possibility. But.....

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: tdscanuck
Posted 2012-07-20 09:48:12 and read 8411 times.

Quoting InsideMan (Reply 212):
In fact many claimed the only reason the 787 has yokes is, because Boeing didn't wanted to give Airbus the satisfaction of "being their first" and Boeing following....

Anyone who claimed that is either ignorant or trying to start something. The 787 has a yoke because the 777 has a yoke and they share a common type rating.

Quoting bikerthai (Reply 214):
Yes, but with a composite wing (787, A350). . . there might be a possibility to embed the wires (&sensor) in the lay-up itself.

Oooooh...good point.

Quoting rfields5421 (Reply 215):
The maintenance part of me finds that frightening. Having to take apart a wing to fix a broken wire.

I think you'd go for redundancy...have enough sensors and embedded wires that you expect enough working ones over the life of the aircraft.

Tom.

Topic: RE: BEA Final Report AF447: July 5, 2012
Username: bellancacf
Posted 2012-07-20 10:44:02 and read 8364 times.

re rfields5421@211: Before the recovery of the FDR, and the report of the data - I doubt you could have found anyone on this forum, or other aviation forums who would believe it possible to stall an aircraft at FL370 and hold it basically stable in a stall throughout a four minute descent to the ocean surface.

I remember that as soon as I read about the nose-up attitude with full nose-up horizontal stab deflection, I thought of Space Ship One (and now S.S.2), and Rutan's "shuttlecock" re-entry configuration. Stable stall from the limit of the atmosphere; greater angles involved there, but the same principle, I imagine. OK, the AF fuselage obviously didn't bend, but the flight surfaces took up analogous positions. Do you think this is a valid comparison?


The messages in this discussion express the views of the author of the message, not necessarily the views of Airliners.net or any entity associated with Airliners.net.

Copyright © Lundgren Aerospace. All rights reserved.
http://www.airliners.net/