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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 23rd Jan 2012, 15:54
  #1121 (permalink)  
 
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@ Conf iture:

Quote:
Originally Posted by A33Zab
The yellow AOA indicator line [Current AOA] would have been at the bottom of the SLOW side of the scale

I was looking at the FCOM and things are described a bit differently :


Quote:
Actual Speed Reference Line (Yellow) :
This fixed reference line next to a yellow triangle, indicates the aircraft’s current speed.
Just a little bit different .....but you are absolutely right the Yellow line is fixed - like the normal speed reference - and the background is moving.
However the function remains the same......CAS vs AOA.


So that yellow line stays in the middle and probably and hopefully the GREEN area with the target speed (GREEN triangle) remains visible at the top of the scale whatever the current stall speed/AoA is.

For the Red SLOW area :

Quote:
This red area indicates the speeds that are lower than the stall speed.
For now, an image from A380 AMM but too fast for AOA....

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Old 23rd Jan 2012, 16:25
  #1122 (permalink)  
 
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For now, an image from A380 AMM but too fast for AOA....
Ok illustration however this is a too fast indication.
For too slow, you would be in the bottom red sector.
The arrow shapes seem a bit counter intuitive since they bear opposite relationship to the direction you might want to move the nose to recover.

Glad they didn't put that in my flying machine for landing aboard ship.
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Old 24th Jan 2012, 01:15
  #1123 (permalink)  
 
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MB, me too. Too much info to sort out when you are FUBARed. Keep it simple. Needle, ball and airspeed always worked in the past, now it is much more complex with computers flying most airplanes, especially the Airbus with pilots monitoring. Flying the 757 out of San Jose, Costa Rica one day with a check airman as my right seater on my initial captain check out our clearance got changed to an unlimited climb short cutting the level off and transition. He had the FMC so screwed up as I was making a right climbing turn and the FD was showing a left diving turn so ignored it until he caught up. Automation is fine if it is your helper, not your God. AF447 would not have happened with real aviators flying in my opinion.

Full back stick for over 3 minutes in a stall isn't what we are taught because it always kills you, guaranteed.
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Old 24th Jan 2012, 01:26
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Well, I'm sure there's many of us [me for sure] that agree with all that. Unfortunately, not enough apparently. It's just too bad it's come to this. Glad I got out when I did !!
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Old 24th Jan 2012, 01:43
  #1125 (permalink)  
 
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Me too. It was fun when we were flying. Now it looks like just a job with everything being monitored to verify you were stabilized below 1,000 etc. I liked it when you could do a roll over Mt Whitney inverted descending into Bishop in a charter jet. Guess the FAA can't violate me for something I did 35 years ago. It had no purpose, it was just fun.
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Old 24th Jan 2012, 02:02
  #1126 (permalink)  
 
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A33Zab,
Thanks for the illustration, it does clarify things on the BUSS.
As Machinbird I have to say I find this indication for an extreme case somehow counter intuitive ... Would be curious to experiment it in a simulator.
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Old 24th Jan 2012, 02:14
  #1127 (permalink)  
 
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Yes, I would gladly do the Mt Whitney maneuver again but am retired and do boats in the Keys now. I will always remember the event but it wasn't that big a deal. It sure was fun though. It is hard to screw up when once you clear the peak at 500 ft you have almost 10,000 ft below you in the valley.
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Old 24th Jan 2012, 03:45
  #1128 (permalink)  
 
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With respect but the BUSS is not intended for Nimitzclass landings nor for inverted maneuvres......

Its only goal is to supply a speed vs AOA indication in - remote situations - when normal speed indications are not available.

IMO - Fly The Green - seems not be too difficult unless your colorblind and don't understand the meaning of FAST and SLOW.......

'Stalled' indication (some copy paste work)

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Old 24th Jan 2012, 08:43
  #1129 (permalink)  
 
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A33Zab;

Thanks for the information on the BUSS.

Some time ago a post claimed that it displays AoA and nothing else. Would it be possible to retrieve information on how it works internally, i.e. what input data it uses and how these data are combined/processed to drive the display?

P.S.
See for example AF447 UAS by Joelle Barthe
The BUSS is optional on A320/A330/A340. It is basic on A380, being part of the ADR Monitoring functions.

This indication is based on angle of atack (AOA) sensor information, and is therefore not affected by erroneous pressure measumements.

The BUSS comes with a new ADIUR standar (among other new system standards), where the AOA information is provided through the IRs and nor through the ADRs. This enables selecting all ADRs off without loosing the STALL WARNING PROTECTION.
The AOA information provides a guidance area in place of the speed scale. When the crew selects all ADRs OFF, then:

- The Back-Up Speed Scale replaces the PFD speed scale on both PFDs,

- GPS Altitude replaces the Altitude Scale on both PFDs.

The Back-Up Speed Scale then enables to fly at a safe speed, i. e. above stall speeds, by adjusting thrust and pitch.

Last edited by HazelNuts39; 24th Jan 2012 at 09:06. Reason: P.S.
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Old 24th Jan 2012, 09:09
  #1130 (permalink)  

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That is a a horribly counterintuitive display!

and "SLOW (down)" or "(too) SLOW"

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Old 24th Jan 2012, 09:40
  #1131 (permalink)  
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I quite agree, Mac - placing that in front of our 447 crew would, I think, have merely hastened their demise (if that was possible)

HN39 - if I read you correctly there, the BUSS is 'deducing' AoA from inertial GS/FPA and attitude?
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Old 24th Jan 2012, 09:55
  #1132 (permalink)  
 
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I have to admit, I didn't find the 'slow/fast' message one that leapt out and told me what to do without my first having to think about it - and when a pilot finds him/herself at 101% overload - (as virtually all of us would be in a situation like the one the AF FOs found themselves) - having to think about what the display is telling you is the very last thing you need.

I'll accept that the potential confusion might (should?) have been covered during conversion.
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Old 24th Jan 2012, 10:10
  #1133 (permalink)  
 
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As the name says it is a back-up speed scale replacing the standard speed tape. The red-yellow-green tape moves in the same sense as the standard speed tape. There is a target speed indicated by a green area and triangle.

Numbers have simply been replaced by colors. How is that confusing or counterintuitive?
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Old 24th Jan 2012, 10:25
  #1134 (permalink)  

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"Numbers have simply been replaced by colors. How is that confusing or counterintuitive"

Something like

GPS Speed 60kts

would be fairly attention getting....
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Old 24th Jan 2012, 10:32
  #1135 (permalink)  
 
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Perhaps, but that has absolutely nothing to do with the BUSS or whether its use is intuitive or not.
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Old 24th Jan 2012, 11:06
  #1136 (permalink)  
 
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Originally Posted by BOAC
HN39 - if I read you correctly there, the BUSS is 'deducing' AoA from inertial GS/FPA and attitude?
No, according to Joelle Barthe's description, the Back-up Speed Scale indication "is based on angle of attack (AOA) sensor information".
Originally Posted by Mac the Knife
Something like "GPS Speed 60kts" would be fairly attention getting....
Ground speed was 380 kts at the stall, 200 kts when stall warning was first lost, and never went below 100 kts.
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Old 24th Jan 2012, 11:55
  #1137 (permalink)  
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HN39 - that is not what I read
where the AOA information is provided through the IRs and nor through the ADRs.
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Old 24th Jan 2012, 12:24
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Originally Posted by BOAC View Post
I quite agree, Mac - placing that in front of our 447 crew would, I think, have merely hastened their demise (if that was possible)
they would probably never have seen the display since ( I believe) they would have had to select all ADRs off to get it, following a procedure - and they never even started any procedures.

However, by side-effect, BUSS might have saved them - if you believe off/on SW killed them, read on...

HN39 - if I read you correctly there, the BUSS is 'deducing' AoA from inertial GS/FPA and attitude?
No, what it says is that the BUSS options routes AoA sensor data (raw, I guess) through the IR side (as well). BUSS can then use that AoA data, maybe in conjunction with inertials, even when the airdata side is shot (or off).

Now, the interesting thing is the stall warning comment - which says to me that as well as feeding the BUSS, the re-routed AoA signal from the new ADIRU also feeds the SW logic. Which, I think, means that SW would be continuous even if airdata calculations invalidate AoA data on that side of the ADIRU, and that would apply whether the BUSS is engaged (ADRs off) or not.

Not saying BUSS would have helped, but if anyone's thinking that BUSS wouldn't have helped because it's useless above FL26 etc. and that the on/off SW was the killer... then they might want to reconsider.
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Old 24th Jan 2012, 13:25
  #1139 (permalink)  
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Originally Posted by iff
AoA sensor data (raw, I guess) through the IR side
- thanks for clearing that up - not the best wording before!
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Old 24th Jan 2012, 14:02
  #1140 (permalink)  
 
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Originally Posted by Hamburt Spinkleman
Numbers have simply been replaced by colors. How is that confusing or counterintuitive?


Disregarding the attitude and GPS altitude here that don't necessarily fit the situation, my gut reaction, without too much thinking, seeing that big up red arrow would be to pull, at least initially.
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