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

AF447 Thread No. 3

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

AF447 Thread No. 3

Old 28th May 2011, 14:05
  #361 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 63
Posts: 1,809
Cool

Hi,

Another graphic chronology events with ACARS included:

Click link
imgur: the simple image sharer
jcjeant is offline  
Old 28th May 2011, 14:18
  #362 (permalink)  
 
Join Date: Nov 2010
Location: Finland
Age: 53
Posts: 66
I suggested this on the initial AF447 thread, and didn't get much response, but I don't see why it would not work:

As long as you have a valid IAS, you systematically compare it to GS using GPS and compute wind speed and direction from that. You store this value. If the IAS fails, you use this stored value to correct the GPS-derived GS to get an estimated AS.

Except in the case of severe wind shear, why would this not work?

You could present the estimated AS as a range, with some degree of uncertainty, incorporating previous variations in wind speed, if any, or just an uncertainty factor (perhaps growing over time) to account for possible changes in wind speed.
I've suggested the same. Ok, flying into a weather front - as they did - could mean rapid changes in both direction and speed of winds. Yet having an advisory reading on your display, perhaps showing GS, IAS and their difference side by side in colored numbers could be, I'm imaging, a handy tool when things start to go wrong.
Caygill is offline  
Old 28th May 2011, 14:23
  #363 (permalink)  
 
Join Date: Sep 2001
Location: Toronto
Posts: 2,247
Why the backstick?

The consensus seems to be an incredulity as to why on Earth the PF held backstick? None of us would ever do that.

Speculation: PF felt the stall warning was triggered by a 10000'/min downdraft -- and just before, he felt he had hit a 7000'/min updraft that he had countered with forward stick. Perhaps PF hung his hat on his windshear/terrain avoidance training.

When in a rapid descent, a low airspeed indicates stall which requires stick forward while increasing airspeed indicates spiral dive which requires wings level and stick back (leaving out the finer details of spiral dive recoveries for sake of brevity).

But here the crew does not have an airspeed worth looking at as it is flopping back and forth.

Recovering from an upset at night in IMC is demanding enough. When you don't have a believable airspeed to distinguish between stall and spiral dive, you have a 50/50 chance of getting it wrong.

In normal weather in a spamcan or glider, you can hear increasing airspeed. Not so easy in a CB.
RatherBeFlying is offline  
Old 28th May 2011, 14:33
  #364 (permalink)  
 
Join Date: Aug 2008
Location: washington dc
Posts: 32
chron

jcjeant
do you have the spreadsheet, or just the image?
voyageur9 is offline  
Old 28th May 2011, 14:40
  #365 (permalink)  
 
Join Date: Mar 2010
Location: Sweden
Age: 83
Posts: 67
Devionics:

"listen to what ArnieG has to say..."
I got that talk in print. To a large part rubbish. Because it is in my own area of specaialist competence it was sad to read. Many statements made are wrong, e.g. that PWR:s dont't have containment venting systems, In Sweden I know of three PWR:s which have venting systems connected to venturi scrubbers.
The problems at Fukoshima seems to have been that their "hydrogen recombiners" needed electrical supply to operate. Electricity as assumed to be available from four sources - batteries, diesel generators, perhaps house turbine operation, and perhaps even the main grid. All had to fail during the same time.
I sincerely hope that most of you have better knowledge in the field of aircrafts and flying.

Regards
Diversification is offline  
Old 28th May 2011, 14:41
  #366 (permalink)  
 
Join Date: Sep 2007
Location: UK
Posts: 155
There's an aspect of the BEA report no-one has yet commented on on this thread.

It states: "The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds." [my emphasis]

My questions are:

1. What would be the effect of prolonged application of full roll deflection in a stalled A330, and
2. What might lead the PF to make such input?

KeyPilot is offline  
Old 28th May 2011, 14:49
  #367 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Hi,
Originally Posted by jcjeant
Another graphic chronology events with ACARS included:
This is a usefull job except for the time stamping of ACARS.
Those messages should not be based on such a precise reception time stamp as it is different from when it was triggered (and in what particular order), but rather by its time stamping from its emission time which is the nearest minute (0210, 0211, 0212...). If displayed like that, it may conduct to a very bad interpretation in relation with real time cockpit events.
takata is offline  
Old 28th May 2011, 15:00
  #368 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 63
Posts: 1,809
Cool

Hi,

This is a usefull job except for the time stamping of ACARS.
Those messages should not be based on such a precise reception time stamp as it is different from when it was triggered (and in what particular order), but rather by its time stamping from its emission time which is the nearest minute (0210, 0211, 0212...). If displayed like that, it may conduct to a very bad interpretation in relation with real time cockpit events.
S~
Olivier
Of course .. but who know the exact realtime stamp in situ of the ACARS ?

jcjeant
do you have the spreadsheet, or just the image?
Image only
jcjeant is offline  
Old 28th May 2011, 15:07
  #369 (permalink)  
 
Join Date: Nov 2003
Location: Over the Moon
Posts: 767
RBF

Surely in a spiral dive you would have increasing G if you pulled backstick which you could sense. Can't see the confusion myself, certainly not for 4 min's.

It may well be when all is said and done that we will have to accept that the crew got it wrong, in failing to avoid the weather (if that is what it was) and the Captain in his bunk and in how they dealt with the failure's when they occurred. Not a pleasent thought but there it is. What we need to ask ourselves, each individually, is if it could happen to them could it happen to me. I would like to think that I could have dealt with it, then again I would like to think that 3 trained pilots flying for a major carrier could have dealt with it They didn't. Time for me and all of us to review a few things.
Ashling is offline  
Old 28th May 2011, 15:09
  #370 (permalink)  
 
Join Date: Jun 2009
Location: Bangkok,Thailand
Posts: 106
This boys and girls is a poser and now you know... When you see the melodrama, they are using it to cover a lack of knowledge, read someone else.
Ok, got it. But you just pulled the same stunt...and you just joined....let's move on...
Razoray is offline  
Old 28th May 2011, 15:10
  #371 (permalink)  
 
Join Date: Jun 2001
Location: US
Posts: 245
Another leak (not verified): http://jacno.com/prov/images/extrait-fdr-cvr.png

See posts #83 and #84 on this page (in french): Forums Aviation Civile • Afficher le sujet - Airbus Rio-Paris : les dessous cachés des enquêtes
EVERY single post on that site seems to be by the same, vitriolically anti-Airbus poster. Caveat emptor, I'd say.
spagiola is offline  
Old 28th May 2011, 15:19
  #372 (permalink)  
 
Join Date: Mar 2010
Location: France
Age: 47
Posts: 22
Do the inboard weather radar can estimate air speed ?
peplum is offline  
Old 28th May 2011, 15:24
  #373 (permalink)  
 
Join Date: Nov 2001
Location: Los Angeles
Posts: 26
backup?

It seems odd that loss of the pitots should cause the whole system to become unworkable. Is there any sort of backup, eg inertial? I know there are three pitots, but if one can be overwhelmed by ice, then all can, and so three are no better than one. And if the FDR knows the pitch attitude, the angle of attack, and the rate of descent, why don't the pilots? The airplane seems to have had plenty of forward speed: 10,000 fpm vertical = 99 knots, with a flight path angle of -25 degrees (40 aoa - 15 pitch) suggests a TAS of 99/sin(25) or 234 kt (is this right? -- somebody help me out here) and it was responsive to roll inputs. I completely understand and sympathize with pilot confusion and mental paralysis, having experienced it myself, but it seems as if there are big issues here of information presentation and human/system interface, notably the counterintuitive behavior of the stall warning. We know, and the FDR seems to have known, that the airplane was stalled; why wasn't there a nice firm female voice telling the crew so the whole time?
Garrison is offline  
Old 28th May 2011, 15:26
  #374 (permalink)  
 
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,342
no, it cannot.

And i don't know if they had any GPS, but IAS and GS at that FL are so different that it would be useless.
Microburst2002 is offline  
Old 28th May 2011, 15:28
  #375 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Originally Posted by jcjeant
Of course .. but who know the exact realtime stamp in situ of the ACARS ?
You don't know the "exact" realtime, but the "nearest minute". Quite simply, when you don't know something (a precise factor), you don't make it up. In this case, you can only list those ACARS, in no particular order, by minute with what information the CMC provided (0210, 0211, 0212..) and assume the time range boundaries for each to be sent.

Hence, you can't have a direct relation with any particular "second" of the real time scale :
- if an ACARS was CMC stamped at 0210 and stamp recieved at 0210:26, all you know is that it could have been triggered between 0209:31 (the nearest minute) and 0210:20 (as you will allow about 6 seconds for processing). If the same was recieved at 0211:31, it would be meaningless to look outside the 0209:31-0210:30 window in order to understand what caused it (in this case, there is certainly no relation with events past 0210:31 even if it was recieved one minute later).

Last edited by takata; 28th May 2011 at 15:48.
takata is offline  
Old 28th May 2011, 15:29
  #376 (permalink)  
 
Join Date: May 2011
Location: In a house
Posts: 13
EVERY single post on that site seems to be by the same, vitriolically anti-Airbus poster. Caveat emptor, I'd say.
And isn't it interesting that these "vitriolically anti-Airbus posters" always manage to have 'sources' in the investigation that get 'leaks' that -just happen- damn Airbus... but later when the real facts come out, the 'leak' was poppycock.

It's almost as if they are sitting in their mom's basement making stuff up.... not that we'd ever see anyone do THAT on the internet.
Bienville is offline  
Old 28th May 2011, 15:30
  #377 (permalink)  
 
Join Date: Jul 2009
Location: IAH
Posts: 58
'At 1 h 55, the Captain woke the second co-pilot and said "… he’s going to take my place" Who was he referring to? The DailyTelegraph reports ....'according to flight recorder data, the younger of the two men, Pierre-Cédric Bonin, 32, angled the jet's nose higher'. David Robert, 37 was the other FO, and he was licensed to replace the captain. So if M. Bonin was nominated by captain Dubois to take over, then why as it appears he was not licensed to replace the captain, as per the BEA Interim report.
promani is offline  
Old 28th May 2011, 15:59
  #378 (permalink)  
 
Join Date: Oct 2007
Location: netherlands
Age: 52
Posts: 730
I did not read the previous hundreds of post, but it seems the crew had an entirely different perception of what was happening during the last minutes.

It seems if they had a better awareness they could "easily" have regained control, right? (pushing the stick)

I'm admit to be lazy here , but isn't there any speed measurement backup procedure if e.g. the pitots block/freeze? (e.g. GPS, Iphone ? ) It seems they had little time but some minutes..

The 330 in better days..
JetPhotos.Net Photo » F-GZCP (CN: 660) Air France Airbus A330-203 by Aurélien TRANCHET
keesje is offline  
Old 28th May 2011, 16:03
  #379 (permalink)  
 
Join Date: May 2011
Location: Moscow
Age: 50
Posts: 38
peplum

We're not on a river but a jet in the atmosphere.

The wind could be evaluated at max +-75kts in this cas. Even if you add or remove 75kts you're always in the flight domain of the plane using my values !

Anyway think one moment. To fly a plane to must evalute the air speed. Because they were high altitude, and the 3 pitot was off, the only indicator effective at this moment was ground speed.
unless you prefer to open the window and reach out to assess !
I'm not Einstein but I hardly imagine none of the 3 pilots try to use this evident method to adjust thurst and sustain a correct FL
This was exactly my post in 2nd thread. Although for actual flying you do need True Air Speed which is the speed of aircraft relative to given part of the atmosphere, but inertial navigation system should give a very good clue to onboard computer by telling it:

- Hey HAL your air speed dropped from 275knots to 60 knots WITHOUT any decceleration!

-So disregard your speed change and keep the current flying parameters - thrust and pitch. Until deceleration/acceleration tells it that speed changed.

And then give pilots info about unrelaible airspeed.
mitrosft is offline  
Old 28th May 2011, 16:03
  #380 (permalink)  
 
Join Date: Jan 2007
Location: East of Edenbridge
Age: 59
Posts: 94
Apologies to anyone with a pilot’s licence or knowledge of aerodynamics.

To everybody else on this thread please listen;

Ground speed is only relevant to an aircraft when you come into contact with the ground (or want to know at what time you will arrive at your destination)

Air is a fluid medium. Whilst airborne air speed is the key to staying there.

When assessing student pilots grasp of this concept I used to ask them a simple question; The wind is 270 degrees at 20 kts and I release a helium filled toy balloon, where will it be in one hour?

During instrument training the mantra is “believe your instruments but keep the scan going” in other words; don’t fixate on one, the primary instruments will tell you everything you need to know. Do not believe your senses, spatial disorientation will kill you.

One other thing I used to teach was APT (Attitude Power Trim)
OPENDOOR 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.