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

AF 447 Thread No. 12

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

AF 447 Thread No. 12

Old 31st Oct 2014, 03:59
  #741 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,183
Originally Posted by Winnerhofer View Post
In my 42 year career as first a fighter pilot, than an airline pilot, and then a corporate pilot I encountered multiple airspeed indicator problems.
Er....

Winnerhofer/Join Date: Oct 2013/Location: Wengen/Age: 44/Posts: 281
I feel fairly certain that I'd probably have read about someone selected to fly fighters in the Schweizer Luftwaffe at the age of two. Either your profile age is dodgy, or there's something else fishy going on...

A computer did not cause this accident- the copilot did...
While I agree that this accident relates more to human factors than technology (despite conceding that there were contributory technological factors), the above point is simply not accurate. As with all aviation accidents there was a complex chain of events involved, and seeking to determine "blame" gets us nowhere.

Basic CRM doctrine says that the crew were supposed to act as a team - working together to solve problems, and they did not. AF - aware that their A330 fleet used Thales AA probes - were supposed to pass relevant info regarding UAS procedures to their crews and they did not. Airbus may have dropped a failsafe point on THS movement between the A320 and A330 design. The only important question is why.
DozyWannabe is offline  
Old 31st Oct 2014, 05:09
  #742 (permalink)  
 
Join Date: Aug 2014
Location: Montreal
Age: 50
Posts: 71
Originally Posted by DozyWannabe>

Either your profile age is dodgy, or there's something else fishy going on...
...either he retired two years ago, at age 42 of career, either there is a slight dysgraphia symptom

Airbus may have dropped a failsafe point on THS movement between the A320 and A330 design. The only important question is why.
Here you're talking, so why? Why the THS and AOA indicators are not mandatory?
_Phoenix_ is offline  
Old 31st Oct 2014, 07:45
  #743 (permalink)  
 
Join Date: Jun 2011
Location: france
Posts: 759
Usual Winnerhofer's quotation signs and ref mssing
Problem!
roulishollandais is offline  
Old 31st Oct 2014, 13:20
  #744 (permalink)  
 
Join Date: Jan 2005
Location: W of 30W
Posts: 1,939
Originally Posted by A33Zab
No we don't agree, pitot failures are clustered and result in NAV ADR DISAGREE (if value and time constraints are exceeded).
Apparently value and time constraints have been exceeded long enough to command the AP and A/THR to quit and the FCS to switch to a bizarre ALTN LAW but not to announce the reason why, be it NAV ADR DISAGREE ... !?

This crew at that time needed to do the comparison themselves and take the appropriate action (pitch and power) like it was done for many years.
That's far to easy to state as you were not on the hot seat.
This crew, as anyone who actually fly the thing, just needed the good honest briefing that Airbus missed the opportunity to publish ...
CONF iture is offline  
Old 1st Nov 2014, 01:41
  #745 (permalink)  
 
Join Date: Jul 2009
Location: DFW
Age: 58
Posts: 246
Winnerhofer, read the previous umpteen thousand posts before coming to the conclusion that the pilots were incompetent, please!

Now back to looking for Spaceship Two info.
TTex600 is offline  
Old 1st Nov 2014, 02:25
  #746 (permalink)  
 
Join Date: Jul 2003
Location: An Island Province
Posts: 1,156
jcjeant, considering the various regulations; a requirement for an indication of failure is not the same as an indication of system state. The pitot did not ‘fail’, the problem was that the data was not reliable.
Similarly before considering the ‘risk of error’, what is an error? A system should be designed to minimise risk, but it cannot ensure that there is no risk, nor any error.

Winnerhofer, irrespective of your experience with ASI problems, what was the experience in unusual ice crystals. And please do read a HF reference on the limits of human performance.

As per CONF iture’s link, Airbus had associated the pitot deficiency with ice crystals. Unfortunately, the manufacturer, regulator, operator, or all, continued to focus on the pitot system as the threat (flight with UAS) instead of the conditions which triggered the system problems.
Looking at this accident with hindsight, and with a ‘safety 2’ view (resilience – the human as a help not a hazard), a backward search can identify a situation where a crew’s normal behaviour could have avoided the pitot ‘failure’ situation – by avoiding ice crystals / cbs. The normal everyday behaviour, opposed to LoC recovery, would be using Wxr to deviate around cbs, with a greater distance margin due to an awareness of the ice crystal threat.
Comparing flight paths with other aircraft this operation might be questioned, as might the crew’s knowledge of the ice crystal threat as above.
Thus the safety weakness was with an incorrect choice of threat, possibly aided by considering the human as a hazard, requiring refresher training.
alf5071h is offline  
Old 4th Nov 2014, 02:58
  #747 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 78
Posts: 1,460
Would they have been to able to override AutoTrim with StabTrim in ALT 2B?
Yes they could. They just had to realize that they needed to.
Manual inputs override all other stab trim inputs on the A330, but if you let go of the trim wheel, the system will try to take it back to where it computes the trim needs to be.
Machinbird is online now  
Old 4th Nov 2014, 06:03
  #748 (permalink)  
 
Join Date: Jun 2009
Location: somewhere
Posts: 451
Hi CONF iture,

Apparently value and time constraints have been exceeded long enough to command the AP and A/THR to quit and the FCS to switch to a bizarre ALTN LAW but not to announce the reason why, be it NAV ADR DISAGREE ... !?

Correct, AFS = Δ 20kts 425ms, apparently they don't want the 'logical but with lack of intelligence' AP to make inappropriate actions.
EFCS ALTN = Δ 30kts 1s compared to median @ T-1, latched > Δ 50kts after 10s compared to median @ T-11

No bizarre ALTN LAW, THE only ALTN LAW (PROT LOST) as it is announced.
PROT LOST = NO protections.

The 'reason why’ AP dropped off and EFCS reverted to ALTN LAW was direct in view,
on the PFDs, different speed displays / flagged SPD and SPD LIM in capitals, bold and red.

Last edited by A33Zab; 4th Nov 2014 at 12:33.
A33Zab is offline  
Old 5th Nov 2014, 01:18
  #749 (permalink)  
 
Join Date: Aug 2014
Location: Montreal
Age: 50
Posts: 71
Scheiße kapitalistischen Technik

Winnerhofer

WOW, this video is surreal, it represents the quintessence of upsets due of THS function programmed in wrong way
_Phoenix_ is offline  
Old 5th Nov 2014, 02:47
  #750 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,183
Originally Posted by OK465 View Post
why does the report indicate that ALT2B latched relatively quickly during the initial airspeed excursions, not one period of which, from the FDR plot timeline, exceeded 9 seconds until much later?
I can't see anything in the final report's main body specifically relating to the *latching* of Alt2B, just the flight law change itself, which would obviously occur in a much shorter period of time.
DozyWannabe is offline  
Old 5th Nov 2014, 04:53
  #751 (permalink)  
 
Join Date: Jun 2009
Location: somewhere
Posts: 451
OK465,
For the EFCS LAW:
The MEDIAN value is polled every second (T0) and compared to the MEDIAN at T0-1s, if the MEDIAN at T0 falls below 30kts of MEDIAN at T0-1s then at T0:

A// The EFCS goes to ALT LAW (ALT2B) and this is announced on ECAM: F/CTL ALTN LAW (PROT LOST)
B// A monitoring timeframe of 10sec is opened and if the MEDIAN value at T0+10s returns within 50kts of the MEDIAN at T0-1s then the EFCS returns to NORMAL LAW.

However if, like in AF447, the difference is more than 50kts then ALT LAW is latched for the remainder of the flight.

Resume: ALT LAW at T0 and LATCHED after T0+10sec.





(Source BEA report #1)

Last edited by A33Zab; 5th Nov 2014 at 05:06.
A33Zab is offline  
Old 5th Nov 2014, 23:43
  #752 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,183
@Winnerhofer - I don't mean to be a pain, but it'd really make interpreting your posts a lot easier if you could state where your quotes come from.
DozyWannabe is offline  
Old 6th Nov 2014, 01:53
  #753 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 64
Posts: 1,809
Dozy
@Winnerhofer - I don't mean to be a pain, but it'd really make interpreting your posts a lot easier if you could state where your quotes come from.
I understand your curiosity
But what is going to help (interpreting) you to know from where come this text or who is the author (it's plain english)
What is important and that can be analyzed or criticized .. in first place is what is in the text and not the author or the place ...
This can also avoids bias
Apart a netiquette problem of course ...
jcjeant is offline  
Old 6th Nov 2014, 03:30
  #754 (permalink)  
 
Join Date: Jun 2009
Location: NNW of Antipodes
Age: 77
Posts: 1,330
@Dozy,

Its from an Airbus v Boeing blog at:-

dailykos.com
mm43 is offline  
Old 6th Nov 2014, 15:54
  #755 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,183
@mm43 - Cheers, I did Google it last night. It's actually a comment on the blog IIRC, but I looked up the guys profile and he seems to know what he's on about. I don't know where the first one came from though.

@jcj - One of the fundamental things that my history teacher taught me about critical thinking is that most information is useless unless you have at least some idea of its provenance. By copy/pasting verbatim, Winnerhofer is making it very hard to ascertain the value of the info being posted.

Also, for people reading the forums who aren't regulars (remember that journalists do tend to prowl here from time to time), it won't be at all clear that WH is in fact copy/pasting. This is why we have a [QUOTE] function.
DozyWannabe is offline  
Old 7th Nov 2014, 16:06
  #756 (permalink)  
 
Join Date: Jul 2008
Location: USA
Age: 73
Posts: 1
Question about AirFrance 447

A fellow A-320 Captain and I were discussing the findings in the crash of AF 447 . Was there ever any evidence of in flight break up of the aircraft? Specifically the separation of the vertical stabilizer and rudder? The image of that part of the aircraft floating on the surface seems similar to the same image of the American Airlines A-300 accident at JFK some years ago.

Just curious...
Pappy320 is offline  
Old 7th Nov 2014, 19:37
  #757 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,183
@Pappy320:

None whatsoever - the vertical stab was still partially attached to the fuselage frames and the break pattern was consistent with detachment upon impact with the ground. See Final report section 1.12.2.6 - "Visual examination of the vertical stabiliser".
DozyWannabe is offline  
Old 9th Nov 2014, 01:32
  #758 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 73
Posts: 2,452
Winner, all these pointers and references to other incidents have made me curious; are you involved in any aspect of the flight safety programs at your carrier and if so in what capacity? SMS? FDM? Investigations?
PJ2 is offline  
Old 9th Nov 2014, 15:38
  #759 (permalink)  
 
Join Date: Dec 2010
Location: Middle America
Age: 80
Posts: 1,159
Original Quote by Winnerhofer: An ounce of prevention is worth a pound of cure!
This pitot tube icing issue was gone over in detail several times in the early AF 447 Threads. Information was available to airbus pilots explaining UAS as resulting from pitot tube icing starting with the A-300-600:




Now, specifically as applying to the A-330 and A-340:


It seems to me, emphasis has been placed on pitot tube icing by both Airbus and Boeing, specifically at high altitudes and high speed. Additionally, training of this situation by airlines together with safety organizations certainly has made flight crews more aware of procedures to be followed when UAS happens, lesson learned from AF-447.
You should keep in mind that UAS resulting from pitot tube icing is a temporary situation that self corrects given the opportunity, 30+ Airbus flight crews proved that point, 1 did not.
Back to the peanut gallery…
Turbine D is offline  
Old 9th Nov 2014, 15:51
  #760 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 73
Posts: 2,452
Re, "and try to figure why one airline does this and one airline does that."

Now that's a question.

In a word, the manufacturer has no actual authority over what airlines do with their airplanes or how they fly them. The manufacturer writes what it considers the operating procedures for their product. Airlines are free, within a country's regulations, to change the procedures as they wish. They are of course accountable for such changes but the notion of "accountable" is often freely interpreted.

Most stick to "the book" and make small modifications. Some increase "guidance", and some simplifiy it. Line flying proves the procedures and it's why at an airline these things never stay the same...change is the only constant at most carriers, as learning from incidents and even accidents takes place.

Practically speaking however, an airline isn't free to radically alter the manufacturer's operating instructions, not, at least, without placing itself at risk should something occur. But some crazy things do emerge from airline folks who believe they know best...

Individual incidents and seeing how such incidents enable change is interesting enough and well understood within the industry but it's well worth finding some of the authors known for producing good work on flight safety to understand how the process works; for example, Charles Perrow, Sidney Dekker, Tony Kern, Robert Helmreich, Earl Weiner, the publications of the Flight Safety Foundation, the NTSB, (look up NTSB Docket). Such work has been used in the healthcare industry and also in medicine in recognizing that "human factors" aren't limited to only one industry which has risk associated with it.

At times, some modifications by one carrier might not make clear sense to another, or to many others. But the requirement to conform closely either to others or to the OEM SOPs doesn't exist even as the results may themselves be similar.

Such modifications are often positive, as many airlines have more experience operating a manufacturer's aircraft than the manufacturer does - the manufacturer must get the product certified according to standards already discussed here and elsewhere. The airlines must teach its pilots to operate the airplane safely and within the regulatory environment.

TurbineD;

Re, "Information was available to airbus pilots explaining UAS as resulting from pitot tube icing starting with the A-300-600:"

Absolutely correct.

I see now that even the QRH UAS memory item in the above drill to increase pitch to 5° when above FL100 is being questioned and instead indicating that no change in pitch and power should occur during the drill.

However, the "do nothing, maintain pitch and power" response by the crew was already in place in some flight crew training manuals and presentations which provided instructions on how to handle the procedure when the "safe conduct of the flight is not impacted", which it is not in stable, level flight at cruise altitude.

As you know I've maintained from the time we knew what transpired that the UAS drill was confusing and misleading if followed "precisely" - but thirty other crews knew what would happen to the airplane and it made no sense whatsoever to pitch the airplane up at all...just keep doing what it was doing prior to the failure of the pitot, and, as you point out, the airspeed information returns to normal, (as AF447's did, within about 50"). I subsequently found the Airbus presentation cited below which makes this clear.

First, from a number of FCTMs:

->>>>>> enlarged printing ->>>




From an Airbus presentation in 2006 on the UAS issue:

->>>>>>>>>from the same document->>>>>>>

Last edited by PJ2; 10th Nov 2014 at 01:15.
PJ2 is offline  

Thread Tools
Search this Thread

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

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.