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Airbus trepidation... convince me otherwise!

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Airbus trepidation... convince me otherwise!

Old 12th Jan 2012, 16:36
  #101 (permalink)  
 
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Talking Time for a re-post!

In case some of you didn't see this article when it was first posted:

Technique: The 'Panic Pull'

AOPA Online: Technique: The 'Panic Pull'
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Old 12th Jan 2012, 17:34
  #102 (permalink)  
 
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Cosmo Kramer

Perfect explanation of the problem with the Airbus philosophy and its limitations. WRT to "goes against laws of nature", I offer this:

[QUOTE][For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.

Richard Feynman
US educator & physicist (1918 - 1988)
/QUOTE]

GF
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Old 12th Jan 2012, 18:13
  #103 (permalink)  
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Perfect explanation? I don't think so, when a pilot can't relate attitude / ROD / ground speed, multiple warnings, the airplane will crash.

With no tactile feedback from the stick
Has nothing to do with it as demonstrated by several accidents in Boeing aircraft with bad pitot indications.
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Old 12th Jan 2012, 18:45
  #104 (permalink)  
 
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I'm not an expert on the Boeing or the Airbus (but fly Airbus) but the thing that strikes me as odd in this thread is the fact that various causal factors in accidents involving Airbus are being attributed to the philosophy or Airbus, for various reasons.

However, as far as I can see, nobody seems to be attributing any Boeing accident to their philosophy. This is more than just Airbus vs Boeing, and I mention it because it seems to be a flaw in the argument of those who argue against the Airbus philosophy, when it's not beyond unreasonable thought to suggest that it was perhaps pilot error and not knowing the aircraft that was a causal factor, rather than purely down to the manufacturer.

For example, Turkish 1951. In some ways, it has its similarities with AF447. Lack of situational awareness, lack of monitoring and possible task saturation, for instance. After all, would that accident have occurred in an Airbus? I'd suggest not, since the sensing of the low energy state (SPEED, SPEED) or alpha floor would have saved the day. Is that an issue or problem with Boeing aircraft? Well apart from identifying the issues surrounding a faulty RA, I'd say not.

I do wonder whether some are blaming the aircraft when in reality, those in control should know their aircraft and the signs the aircraft they are type rated on will present in certain conditions.

I think it's probably "pilot nature" to compare the two (primarily if you've flown both!) but should we not know the basic characteristics of the aircraft and assuming the manufacturer has provided us with something sensible, be able to handle it in all conditions?

If the Swiss Cheese Gods align without appropriate intervention from the crew, then an accident will occur. You could go through most accidents and say "well....if they had this function / feature / attribute / characteristic then it might not have happened" but that's the nature of safety in an industry that has so many variables. The Airbus vs Boeing debate with regards to safety, is surely just another one of those statements...
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Old 12th Jan 2012, 19:23
  #105 (permalink)  
 
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DreamLand

First, I'll admit I haven't flown an Airbus, I do, however look forward to a FBW plane. But, WRT "multiple warnings", with each warning, th pulled on the side stick and what happened? The warning stopped, in a sense, they were rewarded by the cancellation of the warning and thought they solved the stall. Game Over! They hadn't been trained to assume there were TWO methods of stopping the stall warning--the usual way we all assume it works and the Airbus alternative by reducing airspeed below 60 knots.

I completely agree they should have been trained to see the whole picture and recover by recognizing the ROD and speeds.

Would the TU AMS plane, if it had been an Airbus with the same RA failure leading it to believe it was at zero feet, not have crashed, too?

GF
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Old 12th Jan 2012, 19:27
  #106 (permalink)  
 
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FWIW, over 3000hrs cmd time on Airbus. It does some things very well, and some things very poorly.

Non moving thrust levers are a pain, sidestick is not a problem as long as you are ok with being "disconnected" with the aircraft.

Screens, especially early ones, are crap. LCD screens an improvement.

Cockpit lighting, again better on newer models, garbage on older models.

No trim, good for some, not others.

Controls law, complicated but understandable. Not as clever as airbus like to think since electrical failures can drop you into the biggest pile of s**t imaginable.

Autothrust can be glacial in response to demands, even when they are computer generated demands.

Main issue is the relationship between systems and how one, seemingly innocuous, failure can swiftly develop into a whole miserable world of hurt....hence the phrase "What's it doing now?"

Overall, Boeing!
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Old 12th Jan 2012, 19:57
  #107 (permalink)  
 
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Hi galaxy flyer,
Would the TU AMS plane, if it had been an Airbus with the same RA failure leading it to believe it was at zero feet, not have crashed, too?
Yes it would.
From OEBProc-38

"During ILS (or MLS, GLS) approach with AP engaged, in the event of an
unexpected early THR IDLE and FLARE modes engagement, the flight crew must immediately react as follows:
‐ Immediately perform an automatic Go-Around (Thrust Levers set to TOGA),
OR
‐ Immediately disconnect the AP,
‐ Then continue the landing using raw data or visual references (FDs set to OFF),
OR
‐ Perform a manual Go-Around (Thrust Levers set to TOGA). Significant longitudinal sidestick input may be required.
Note: 1.If the flight crew does not immediately react, the angle-of-attack will increase and may reach the stall value."
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Old 12th Jan 2012, 21:10
  #108 (permalink)  
 
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RRR and OK465

I'll let you two fight it out, but it seems to me with an RA below some value (50'?) the Airbus must go into a landing "law", else it never would land. Or is there an algorithm that looks at RA and pressure altitude for just this case and negates the erroneous RADALT? The TU B737 had an essentially 0' RA for sometime during the approach, sending the autothrottles in RETARD mode. I suspect the TU plane, if an Airbus, would have looked similar to Habesheim, no?

GF

PS: Just a dumbbell cable 'n fluids pilot, not too sure why we need to computer whizs to fly.
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Old 12th Jan 2012, 21:27
  #109 (permalink)  
 
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aa73, I had the pleasure to fly MD 80s for ten years before hopping on the bus and I must say that the good old MD felt like "my wings", we where one once I strapped in and the JT8s where running. Then came the A 320 course and after 10 minutes in the Sim I loved the fly by wire, the comfy office and all the electric gismos. Today, after 11 years of "busdriving" I still don't miss moving throttles or flightcontrols at all. Airbus has "golden rules" and No. 1 says: " This aircraft can be flown like any other aircraft" and they are right. You can treat it like a proper aircraft and it will do anything a conventional aircraft does, plus a lot more.
I hope you will enjoy it as much as I do!
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Old 12th Jan 2012, 21:35
  #110 (permalink)  
 
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Hi OK465,
No. Alpha Floor would have kicked in.
I don't think so:
FCOM DSC Aircraft systems, 27, 20, 10, Pitch Control Protections.
"The αfloor function is available from lift-off to ​100 ft RA before landing."

Same as Habesheim.
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Old 12th Jan 2012, 23:43
  #111 (permalink)  
 
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AZR,
For AF447 the trim did not reach the stop when actually the sidestick request was still there. In the meantime the BEA has not communicated about any USE MAN PITCH TRIM PFD MSG and dixit BEA, Abnormal Attitude Laws have not been triggered ... so what's going on here ?
  • Why the THS did not go to the full UP position ?
  • Is it possible for any reason the autotrim stopped working ?
  • If so has the crew been advised through a PFD message ?
I think some questions deserve to be asked.
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Old 13th Jan 2012, 01:23
  #112 (permalink)  
 
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Conf sorry I'm muddled, are you saying auto trim should continue to work in alternate law below vs1g - i.e. while the aircraft is stalling? FCTM doesn't agree.

The aircraft was in alternate law, it's stated in the report date 1/6/2009 at 1.16.4.2 (P40)

Last edited by babotika; 13th Jan 2012 at 01:25. Reason: add reference
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Old 13th Jan 2012, 01:39
  #113 (permalink)  
 
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Stall warning logic.

With the first problem being unreliable airspeed, it may have caused them to subconsciously dismiss the warning.
Further another Airbus "feature" may have enforced their belief that they in fact where not in a stall.
As they pulled back and the speed dropped below 60 kts the stall warning seized.
Question: How can you design a stall warning that stops when the airspeed get extremely critical?
How can the "logic" dismiss a speed of less that 60 kts as being "invalid" when the air/ground sensor is in flight?
this was not the - Airbus Stall Warning Logic - it was the ADIRUs which invalidated the AOAs.....

Boeing drivers, be prepared,

B777:

The AOA will be invalidated if the CAS <30 kts = NIL stick shaker......
Don't rely on your SAARU because it already did quit at CAS <50kts
and Yes this is true when the air/ground sensor is in flight!
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Old 13th Jan 2012, 03:23
  #114 (permalink)  
 
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Originally Posted by 99jolegg
I'd suggest not, since the sensing of the low energy state (SPEED, SPEED) or alpha floor would have saved the day.
...
I do wonder whether some are blaming the aircraft when in reality, those in control should know their aircraft and the signs the aircraft they are type rated on will present in certain conditions.
How is it possible then you are not aware your Airbus will not trigger Alpha Floor below 100 feet RA erroneous indication or not ?

SPEED SPEED SPEED would remain available for a 320 but not for a 330 … Go and figure ?

Are things really that simple in the Airbus world … ?
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Old 13th Jan 2012, 03:50
  #115 (permalink)  
 
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Originally Posted by babotika
Conf sorry I'm muddled, are you saying auto trim should continue to work in alternate law below vs1g - i.e. while the aircraft is stalling?
Not I would expect but still what AF447 did ... up to 13 degrees up.
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Old 13th Jan 2012, 18:07
  #116 (permalink)  
 
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Hi OK465,

Sorry the only information I have is from my current FCOM. (My bolding)
What's your latest source?

FCOM OEB 201/2 says:
!Erroneous Radio Altimeter (RA) height indication
APPLICABLE TO:
All A318/A319/A320/A321 operators
... other pages of faults and explanations ....

Warnings / Callouts
-
Untimely Terrain Awareness and Warning System (TAWS) alerts
-
Untimely or absence of “RETARD” callout
-
Untimely L/G GEAR NOT DOWN ECAM warning
-
Absence or interruption of RA automatic callout (height announcement)
-
Activation of AUTOLAND warning light in ILS (or MLS, GLS) approach (Refer to FCOM 1.22.30) with AP engaged in LAND or FLARE mode when:
o
One RA height goes below 200 feet and
o
The difference between both RA height indications is greater than 15 feet
Note: There is no ECAM message or audio warning in association to the AUTOLAND warning light. The AUTOLAND warning can be triggered even if AUTOLAND is not planned
Auto Flight System mode changes (indicated on FMA)
-
NAV mode engagement not possible after take off
-
During an ILS (or MLS, GLS) approach, and depending on the engaged Flight Guidance (FG) modes, the consequences may be:
o
Untimely/early engagement of the LAND / FLARE / THR IDLE modes if the RA height used by the FG is erroneous and lower than the real height.

Note: During ILS (or MLS, GLS) approach with AP and A/THR engaged, THR IDLE (RETARD) mode untimely engagement will be associated with an initial pitch attitude increase due to FLARE mode engagement.
o
In AUTOLAND, the LAND / FLARE / THR IDLE modes will not engage, if the RA height used by the FG is erroneous and higher than the real height.
o
In case of Go-Around and if the RA is still frozen at a very low height indication:

SRS and GA TRK modes engage

NAV, HDG or TRK lateral modes cannot be selected

LVR CLB will not be displayed on the FMA at THR RED ALT

ALT* and ALT will not engage at FCU altitude
Disconnecting AP and resetting both FDs enable to recover basic modes (HDG and V/S).
During an ILS (or MLS, GLS) approach with AP engaged, if an erroneous and very low RA height indication occurs, THR IDLE and FLARE modes may engage early with the following consequences:
-
In CONF FULL, the High Angle of Attack protection is not available. As a consequence the autopilot will not automatically disconnect at α prot +1°. If the flight crew does not immediately react, the angle-of-attack will increase and may reach the stall value.
-
In configurations other than CONF FULL, the High Angle of Attack autopilot disconnection is available. The autopilot will automatically disconnect at α prot +1°.
-
Loss of ALPHA FLOOR.
-
The LOW ENERGY AUDIO WARNING – “SPEED SPEED SPEED” - remains available. In case of activation of LOW ENERGY AUDIO WARNING, the flight crew must react as per procedure (QRH 2.03).
-
In CONF FULL, the auto-trim function is inhibited.
-
In manual flight or after AP disconnection, significant longitudinal sidestick input may be required."

If only No1 AP is engaged with No 1 RAD ALT giving erroneous readings of below 30 feet, then the above may occur.
With no Alpha Floor - that sounds like Habesheim to me.

How the heck could anybody just sit there and watch it?
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Old 13th Jan 2012, 20:07
  #117 (permalink)  
 
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Originally Posted by OK465
If only No 1 RadAlt is below 30 feet with only No 1 A/P engaged, is the other RadAlt ignored totally?
Not totally as the difference between RA readings will trigger the AUTOLAND warning light for an ILS approach.

With only one RA below 100 feet, what other conditions must be in place to cause FLARE mode activation?
Except from being on an ILS approach, none.

As per the OEB as quoted by rudderrudderrat the consequences of an erroneous RA indication for the Airbus are numerous and surprising ...
Anyway, it is a long stretch to affirm that the AMS event would have ended differently if the aircraft was an Airbus ...
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Old 13th Jan 2012, 20:14
  #118 (permalink)  
 
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CONF iture:
As per the OEB as quoted by rudderrudderrat the consequences of an erroneous RA indication for the Airbus are numerous and surprising ...
SLF checking in again:
I've said it before and I'll say it again--

I will NOT get on an AB, ever. I want a plane that can be flown (and landed) by a well-trained human being without undue confusion or SURPRISES. The above is frightening, given the cut-rate training on some airlines.
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Old 13th Jan 2012, 20:33
  #119 (permalink)  
 
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Hi Organfreak,

I hope you don't really mean "I will NOT get on an AB, ever." because of something you've read here.

The advantage of sharing mental models on PPRuNe of how we think some remote failure might affect the aircraft, is that we learn from others. It would be a shame if we stopped because it was having an adverse effect on the travelling public.

Please rest assured, the vast majority of us learn something useful here and are better prepared to "take control" when needed.
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Old 13th Jan 2012, 20:46
  #120 (permalink)  
 
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Rudderrudderrat and OK465,
Thanks so much for your thoughtful replies. Sure, I expect that most pilots posting here are the cream of the crop, given their obvious interest in learning and even self-examination, IOW, intellectual curiosity. I would fly with most any of you if you could show me your official PPRuNe Membership Cards first!

I doubt that I've done much damage to AB's reputation by saying I'm scared to fly on one. I think they're already quite familiar with this attitude (pun intended). But, I'm a firm believer in Murphy's Law, which is, of course, what caused AF447 to get all broken.

I know one pro 767 driver who doesn't come here for the reason that "it gets too technical." YIKES! How many pilots are like that?
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