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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 24th Jan 2012, 16:10
  #1141 (permalink)  
 
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I would like to know what the GPS speed is doing there in the 1st place. It does not tell you a darn thing about the aircraft as far a flying goes. The aircraft does not fly on GPS speed, nor does it fly on TAS (Unless you are talking MMO) BUT it does fly on IAS (or CAS if you are a purist) However a good AOA gauge should tell you everything you need to know, IF you knew a little about aerodynamics and knew how to read the gauge. (And pull yourself away from the FMS and actually fly the thing)
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Old 24th Jan 2012, 17:07
  #1142 (permalink)  
 
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I don't think it's reading GPS Speed but rather GPS Altitude.

Speed is on the left side of the ADI and is replaced by a coloured tape indication.

On the right side we usually find altitude information and my guess is the 000 is sea level and the 010 is a thounsand feet with the 520 being mid way on that scale so it's a 520 foot GPS Altitude read out.

Edited... Just noticed is actually says GPS ALT at the bottom of the scale so my assumption is correct!
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Old 24th Jan 2012, 18:10
  #1143 (permalink)  
 
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I agree with you however several people earlier mentioned GPS speed like it will tell you anything about aircraft performance.
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Old 24th Jan 2012, 18:42
  #1144 (permalink)  
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This BUSS speed tape is confusing me big time! What exactly does 'SLOW' mean? What is the required response? Since we are talking AB, why does it not just say 'push your side stick forward and increase power'?
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Old 24th Jan 2012, 18:56
  #1145 (permalink)  
 
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First you are confused and ask what it means only to show you know exactly what it means. A bit disingenous perhaps.

It is a speed tape, it operates as a speed tape. Are anybody here confused about how to read a speed tape or respond to it?
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Old 24th Jan 2012, 19:42
  #1146 (permalink)  
AR1
 
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No experience. Red is bad. Speed up.
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Old 24th Jan 2012, 19:48
  #1147 (permalink)  

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It's the arrow.

Up? What am I supposed to do?
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Old 24th Jan 2012, 21:17
  #1148 (permalink)  
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I am still not understanding

It is driving me towards a 'speed' marker (green)?
It cannot itself compute speed due to failures?
How does it compute the green marker?
How does it know when I have got there?

As far as I can see this is AoA driven. The AoA is too high. What is needed is reduction in AoA in fairly short order, not just an increase in 'speed' towards a dubious green mark.

Would not a 'DOWN' arrow, flashing perhaps, on the AI be far simpler and realistic? After all is is a matter of simplicity to compute an AoA at any altitude/Mach at which the wing will unstall.
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Old 24th Jan 2012, 21:19
  #1149 (permalink)  
 
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@BOAC:

What exactly does 'SLOW' mean?
NOT FAST

What is the required response?
Fly the GREEN !!

And to bring the green down, you lower the nose......

Since we are talking AB, why does it not just say 'push your side stick forward and increase power'?
If you see the 'SLOW' at the top of the scale (like the SLOW image), it is already saying "STALL STALL" for a while! (without interruptions)

Do anyone need more clues?
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Old 24th Jan 2012, 21:23
  #1150 (permalink)  
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Do anyone need more clues?
- I think that apparently we can all answer that, sadly.
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Old 24th Jan 2012, 22:25
  #1151 (permalink)  
 
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If you see SLOW written on the road while driving your car what do you do?

Last edited by cwatters; 24th Jan 2012 at 22:51.
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Old 24th Jan 2012, 23:10
  #1152 (permalink)  
 
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Originally Posted by BOAC View Post
I am still not understanding

It is driving me towards a 'speed' marker (green)?
It cannot itself compute speed due to failures?
How does it compute the green marker?
How does it know when I have got there?

As far as I can see this is AoA driven. The AoA is too high. What is needed is reduction in AoA in fairly short order, not just an increase in 'speed' towards a dubious green mark.

Would not a 'DOWN' arrow, flashing perhaps, on the AI be far simpler and realistic? After all is is a matter of simplicity to compute an AoA at any altitude/Mach at which the wing will unstall.
Before you've managed to stall, it's more of a green band than a mark, which might be clearer what to do with it.


[images credit to google search and a site I know nothing about - but it's not mine, just to be clear]

I think this is more or less an AoA indicator dressed up as a speed tape, but I think it does do the "compute an AoA at any altitude/Mach at which the wing will unstall" without the pilot having to remember or read tables (I guess).

By the time you've been pulling up through the stall warning for best part of a minute, it's going to look like the previously posted image and probably isn't helpful (green ? what green, where ?). But if you kept it in the green in the first place, you wouldn't have that problem.

Also, look at the conventional AoA gauge (which option AF didn't give them either):



At the same point in the timeline, that needle would have been firmly pegged at 25, and the size of the nose-down inputs they made would not have shifted it. Pull or push, the needle doesn't move - must be broken gauge... no ?
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Old 25th Jan 2012, 00:17
  #1153 (permalink)  
 
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I've read the whole thread...

It seems that the crew simply had no understanding of the anatomy of a stall and therefore an AoA gauge may not have helped....was there pre-stall buffeting noted? for it seems that the A330 has very docile stall characteristics perhaps further misleading the crew

were AF's A330s actually equipped with 'BUSS'? I seemed to have missed where it was first mentioned in the thread
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Old 25th Jan 2012, 02:01
  #1154 (permalink)  
 
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I don't think a competent pilot needs green arrows or any computer generated warnings to recover from a stall. It is so basic, you push down. Stall warning goes off, push down, works every time. Not with these clowns.
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Old 25th Jan 2012, 02:41
  #1155 (permalink)  
 
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But you apparently don't have to be a pilot to "operate" an Airbus. A systems monitor will do. (Where did the German shepherd go? Oh, he's aft taking a whizz.)
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Old 25th Jan 2012, 02:51
  #1156 (permalink)  
 
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Originally Posted by fantom
It's the arrow.

Up? What am I supposed to do?
The arrows appear to be an unfortunate choice of shape. The angled part of the arrow head is there to indicate whether you are just beginning to get into trouble (The tip of the arrow) or are fully in trouble tail over tea cup. They do not point to anything. It is not at all like an AOA indexer display (for those who know what that is).

The whole display is intended to look as much like the airspeed tape as possible. What I see as an issue with this approach is that this requires mental interpretation before you respond and it leans on the visual mode of information input like everything else on the 'Bus does. You will have to go through a thought process something like this:
  • I'm getting near the 'Slow' arrow tip.
  • Shall I add power or shall I push the nose down?
This is not the instinctive response those of us used to controlling AOA on approach have developed. Perhaps with enough training you could reverse the arrow indication mentally to move the nose the correct way, but then again, the 'Bus does not trim for speed so it is probably irrelevant in most cases.
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Old 25th Jan 2012, 03:49
  #1157 (permalink)  

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If it said "TOO FAST" and "TOO SLOW" it would be a lot clearer.

(The system knows what power the engines are putting out so maybe a "GET THE NOSE DOWN!" or "AOA TOO HIGH" would help too.....)
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Old 25th Jan 2012, 04:06
  #1158 (permalink)  
 
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"I don't think a competent pilot needs green arrows or any computer generated warnings to recover from a stall. It is so basic, you push down. Stall warning goes off, push down, works every time. Not with these clowns."

Ptretty strong language considering you obviously haven't read the transcripts carefully enough to avoid putting your foot in your mouth.

If you take the trouble to read back you will see that the stall warning was off, UNTIL the nose was pushed forward to get out of the stall and at that point the stall warning came on.

In a pitch dark environment with everything seeming to be in conflict with everything you thought you understood about your aircraft's behaviour, perhaps it was all too easy to become a clown as you so eloquently and kindly put it.
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Old 25th Jan 2012, 09:34
  #1159 (permalink)  
 
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Nojwod

Suggest YOU take your foot out of your mouth and re-read the transcript correctly!
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Old 25th Jan 2012, 09:50
  #1160 (permalink)  
 
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Does this thread really need to continue?
All the pro's know what happened.
All the amateurs want to drag it on.
Let's just drop it, shall we?
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