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AF447 wreckage found

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AF447 wreckage found

Old 29th May 2011, 12:28
  #841 (permalink)  
 
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Cricky do any of you fellas read previous posts?

Yes all the Attitude indicators where fully functioning.

The problem was with the Air Data Modules receiving crap info from the iced up Pitot tubes....

Some Aircraft have AOA displayed on the Primary Flight Display but in this case I don't think AF do. Certainly my Airline and many others do not on any of our Aircraft types.
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Old 29th May 2011, 12:36
  #842 (permalink)  
 
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I'm sorry, I'm losing the overview.
Can somebody please remind me, what the margins were in the given conditions?
Obviously, the air was relatively warm yet below dew point. How can we interpret that they couldn't climb higher because of the temperature gradient being shallower than expected? Was that just referring to the tops of the cb being above their ceiling at that time?
What's the speed margin between Vmmo and Vs?
What's the AoA in normal flight at that altitude and what's the Stall AoA? (did I see it's only 6°?)

What triggered the 13° nose up trim on the THS? What impact would that setting have, along with fuel trim aft, on their chances of recovering from a stall if they had positively identified it in the first place?

With so many indicators being unreliable or not available, what "direct", that is aerodynamic or "seat of the pants" feedback would you have in a machine of that size with FBW controls? Obviously, there's no feedback from the control surfaces, there's no stick force to overcome (or rather to soften when the control surfaces get into turbulent air from the stalled wings)
Can the turbulent flow be felt through the airframe?
I honestly have no idea if those guys would have had any primary means of identifying the stall, given that the secondary means (read: instruments) were unreliable.

Also, I've read a lot about "law changes" in this thread, how does an AB pilot stay aware of what law what control axis is in at any given point? I'm sure there's nice flow charts in the documentation, but I wonder how many distinct states of flight law degradations there are and how often the system is allowed to change between them.

If, and it might, this turns out to be a case of "loss of situational awareness" (or rather: they never gained awareness of the situation they were in), it begs the question how complex the situation was when it was presented to them. A simple AoA indicator might have made all the difference to them.

The interface between the automation systems and the pilots seem to be the most difficult part of any design these days. How does the system present all the relevant information while not overwhelm the pilots? And this in a situation where the system is forced to give up since it's parameters are outside what it knows to handle. We could interpret such situations as the design engineers saying "this is a situation we have not considered / thought possible, over to you, pilots". This almost necessarily also means that it's hard or even impossible to say what information is relevant and what can be withheld. As a system designer, you are faced with the decision to possibly withhold information that might be meaningful to interpret the situation or to present information overload which doesn't help either.

I don't envy you guys who poke around at the levels >300.

ps: the system "knows" the AoA. If getting AoA display is an optional item on the aircraft order and AoA is not automatically displayed when the stall warning goes off because the feature wasn't ordered, that would seem sickening to me.
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Old 29th May 2011, 12:44
  #843 (permalink)  
 
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Well this is a discussion forum after all, and just as Nitpicker has pointed out is anyone reading previous posts at all??!! I am no authority at all, but having just done a shiney new Airbus rating I just practised Unreliable Airpeed last week(!), all the alerts are going off left right and centre, with 3 different airspeed indications in the cockpit, so putting TOGA on and pitching up 15deg (sounding familiar yet anyone?!!) you have a manouver which gives you an airspeed that should be at least what you get on initial climbout, then its time to see which speed tape has what you think it should have and compare with the G/S for at least ball park ideal.
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Old 29th May 2011, 12:53
  #844 (permalink)  
 
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Opherben

With all due respect, we basicly agree on the fundamentals: more training, more situation awareness.
Systems redesign? Very unlikely.
I cannot envisage a better scenario for this ill fated plunge into the ocean than the described.
I have some good thousands of hours on both designs: Boeing and Airbus.
Both have their virtues and flaws.
It's very unlikely that systems control design have anything to do with the outcome.
The lack of 'aviate' certainlly have...
If they ever trained high altitude stall recognizing and recovering everybody would be probably at thome at this time.
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Old 29th May 2011, 12:55
  #845 (permalink)  
 
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Thanks bud and congrats on the conversion.

But please don't pitch up to 15 deg other than on TO below acceleration height!! Remember there a 3 different phases mentioned
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Old 29th May 2011, 12:56
  #846 (permalink)  
 
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Hi Delta!

No offense: are you sure you're Bus rated?
Were in the earth you're taught to TOGA and rotate to 15 degrees, upon a loss of speed indication and stall warning at 35.000'??
Please, go back to your FS.
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Old 29th May 2011, 13:01
  #847 (permalink)  
 
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You know what I think is that a lot of Pilots don't know the normal performance to expect on their Aircraft. ie normal CLB pitch and N1, Normal CRZ pitch and N1 and normal DES pitch and N1 ( yeah yeah idle !! )

If don't really know what's normal how could you know what to set when the shit hits the fan? Like in Iced Pitots or Volcanic ash flameouts etc...

I've asked FO's in the past what pitch attitude and N1 should we have in cruise now, don't look ( cheater ) Quite a few got it wrong by quite a bit.....
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Old 29th May 2011, 13:04
  #848 (permalink)  
 
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Anybody of YOU ...

anybody of you fellow pilots out there have been through this
(or something similar)?

  1. approaching CB killer cell without seeing it (why?, wx radar fault?, too-fast buildup?)
  2. entering the outer downdraft surprisingly (cpt woke up?), (ice)
  3. entering low-pressure inner updraft (water)
  4. back in the outer zone (N.E.) with new massive downdraft
aside from the overwhelming (and distracting) body of
technicalities, can (has it been shown somewhere else)
a large A/C survive this encounter? With what probability?

I remember a similar encounter: Pulkovo 612 which
came out of a large CB in a flat spin (is this still valid?),
where the PF tried to "fly over" the mess and failed.

Would AF447 PF try to "overfly" the "turbulence" that
he (obviously) didn't know what it really was (otherwise,
he wouldn't be heading straight into it).

This is a question of a layperson, so please pardon
any wrong assumptions.

Thanks & regards
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Old 29th May 2011, 13:05
  #849 (permalink)  
 
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Been following this and my amateur .02 is:
who has not fallen victim to the tyranny of the urgent at some time or other? - but tres dangerous in a cockpit..
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Old 29th May 2011, 13:08
  #850 (permalink)  
 
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Oh another one........

To save you from reading previous posts that have addressed your question I'll answer it for you again.

Yes, this has happened before in much the same circumstances as AF 447.
Other Airbus and Boeing types have entered CB's by mistake and lived to tell the tail. CB's large enough to injure Pax and freeze the pitot tubes with super cooled water......
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Old 29th May 2011, 13:20
  #851 (permalink)  
 
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Re: Oh another one.....

nitpicker330:

I read the posts, a lot of them, but not all 850+, so
sorry for missing some important parts.

I read many of your posts too and I'd like to ask
you as an AB driver: can you understand, why the
PF pulled
with N1 100%? Did he try to get out?
Sometimes, subjective assessments by the right
people are more instructive than loads of technical
detail.

But: maybe I'm completely on the wrong track.
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Old 29th May 2011, 13:57
  #852 (permalink)  
 
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Hi Graybeard

We can assure you: they didn't tried to pass over the CB.
One explanation why they pulled back an already stalled airplane is confusion, lack of proper training, panicking, etc.
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Old 29th May 2011, 13:59
  #853 (permalink)  
 
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@Flyerbob

As I noted earlier, the core difficulty faced by the crew was that the standard practice of using pitch + power to maintain safe flight without air data didn't seem to be working, and the problem is that it won't if the aircraft is already stalled. With the airbus' FBW [fly by wire] system and passive stick, the crew would have none of the force or buffet cues through the side-stick that might have told them this. Thus, once they stalled, with no instrumentation or VH, this was for all practical purposes unrecoverable in an Airbus. Under the circumstances, at night with no visible horizon, even an exceptionally well trained and experienced professional pilot would have lost situational awareness and would not have been able to discern the pitch attitude of the aircraft. I don't see how they can be blamed for their actions in the cockpit once the problems developed in an Airbus.
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Old 29th May 2011, 14:03
  #854 (permalink)  
 
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at night with no visible horizon, even an exceptionally well trained and experienced professional pilot would have lost situational awareness and would not have been able to discern the pitch attitude of the aircraft.
maynardGkeynes, so what about the pitch displayed on the attitude indicators?
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Old 29th May 2011, 14:15
  #855 (permalink)  
 
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well this pax is adding AirFrantic to its no fly list
BrutishAir has been on there for a while...
and I am thankfully never going to India
j
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Old 29th May 2011, 14:52
  #856 (permalink)  
 
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As far as can be determined, all three ADIs (Attitude Direction Indicators, or artificial horizons in layman's terms) was FULLY FUNCTIONAL.

As for pitching to +16 degrees of pitch at TOGA at FL380 (above optimum cruise alt for the weight and conditions)...

To quote the report:

The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and angle of attack being 16 degrees.
I'm not very good at English but this is telling me that the PITCH ATTITUDE WAS +16 DEGREES.

Anyone care to explain why this could possibly be considered a safe pitch attitude at FL380?

I can understand lots of alerts confusing the crew, but seriously, does anyone actually think that +16 degrees of pitch at high altitude is going to enable the aircraft to maintain a healthy airspeed?
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Old 29th May 2011, 14:57
  #857 (permalink)  
 
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As a simple-minded Twotter driver there is one factor here which seems critical to me. If the stall warning sounds I know to get the nose down in a hurry then grab for the apehangers to add power.

In this case the stall warning only sounded (twice?) briefly which was probably the critical misleading clue which convinced the crew that they were not stalled.

If the stall warning had behaved as expected by any sane pilot and sounded continually during the stall then any sane pilot would have realised that the aircraft was indeed stalled and applied the correct recovery.

Why the hell did the stupid automation silence the stall horn ?
THIS SHOULD NOT HAPPEN .
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Old 29th May 2011, 15:03
  #858 (permalink)  
 
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Why the hell did the stupid automation silence the stall horn ?
A great question. The systems silenced it because the IAS fell below 60 kts for a time. This caused the FWC (Flight Warning Computer) to silence the STALL warning.

It should be that any time stall AoA is sensed with the aircraft in the air mode that the stall warning sounds. Airbus must have assumed that if the IAS is < 60 kts then the aircraft is on the ground even if the weight on wheels switches say it is in the air. There is no logical explanation for it silencing the stall warning based apparently on IAS alone.

I'd love to know why display of AoA on the PFD is a very expensive paid-for option. IMHO knowing the AoA is at least as important as knowing IAS, if not more so, and should be a mandatory instrument/display.

Last edited by ECAM_Actions; 29th May 2011 at 15:15.
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Old 29th May 2011, 15:04
  #859 (permalink)  
 
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If you think about what could have been done to prevent this accident, rather than about whether the crew were competent/incompetent or whatever, it seems as though if they had had available the information that we have from the FDR, ie alpha, airspeed and descent angle, they would have recognized the problem immediately and recovered. But that info was not provided evidently because the system designers considered this scenario impossible. But three identical pitots known to be able to be overwhelmed by ice are not triply redundant; they are a single point of failure. The airplane -- any airplane whose systems rely so heavily on airspeed -- needs a truly alternate airspeed source, a full-time angle of attack indicator, and a stall warning that does not go to sleep and then wake up at inopportune moments.

Last edited by Garrison; 29th May 2011 at 15:45.
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Old 29th May 2011, 15:10
  #860 (permalink)  
 
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well this pax is adding AirFrantic to its no fly list
BrutishAir has been on there for a while...
and I am thankfully never going to India
So you've decided to spend the rest of your life hiding under your bed, since the riskiest part of a flight is the drive to and from the airport, rather than fly on some the safest international airlines? British Airways hasn't seen a fatal accident that could be attributed to the airline since it was formed. It's been something like 45 years since its predecessor companies had a fatal accident. They've seen millions of safe takeoffs and landings in the meantime.

In short, you're thinking irrationally.

Last edited by ST27; 29th May 2011 at 17:41.
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