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AF 447 Thread No. 7

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AF 447 Thread No. 7

Old 15th Dec 2011, 21:32
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Lyman,

No, N1 was reduced for turbulence penetration by one of the pilots in anticipation of turbulence ahead. I asked PJ2 the question about how this is actually done, moving the throttle levers or another way. It was a pilot initiated action to slightly slow down.

IMO, the A/P was doing what it does, making corrections for ups and downs. At the point of disconnect, it was correcting for an up and therefore the nose was down. From there on, what took place was pilot input. There was nothing wrong with the aircraft or its systems. The reason the A/P disconnected was UAS due to pitot icing, not turbulence. There is no evidence to support the "severe" turbulence theory, but plenty of evidence to support the pitot icing. In fact, I think that will be the #1 issue Airbus will address going forward. I think you will see some technological advances, perhaps on the A320Neo or even the A-350 if the program slips more.
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Old 15th Dec 2011, 22:01
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PF made a slight retard to .80 mach. AIR, that was it from the pilots.

How did the a/c get sideways enough to award a STALLSTALL to PF upon his first stick? His first input was nowhere near "full aft stick" which has become the Urban Myth collective bleat. ACARS, WINDSHEAR? TCAS? There is leeways aplenty for any analysis of the Turb value that the investigator wants. The noise heard by the pilots was not RAIN, nor was it ICE CRYSTALS, or Hail. I think it was a hellish updraft of perhaps 10000fpm, sufficient to start the entire a/c UP at 500fpm in 1.5 seconds. It's on the graph. The aerodynamic noise of an airmass turnaround/shift of 70-90 degrees is......noisy. I think the a/c was on the verge of a Stall, and dropped to ALTERNATE to sustain the NORMALLAWSTALLIMPOSSIBLE meme.

notquite, but you get my drift?
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Old 15th Dec 2011, 22:08
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Originally Posted by Organfreak
I too believe that BEA will make sure that the pilots are blamed. France cannot afford any other outcome. ("Billions and billions.")
Rubbish. The aircraft is already a success and the worst they'd face is a few million in repairs - it's not like the whole concept is unproven as the case was in 1988.
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Old 15th Dec 2011, 22:09
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Originally Posted by Lyman
...PITCH resting on 0, (Three degrees+ LOW)...
That is not correct, the 3°+ that is.

Interim Report #3 page 86 states :

Standard altitude (ft) 34.992
Computed airspeed (kt) / Mach 275 / 0.80
Pitch attitude (°) 2.8
Total weight (tonnes) / Centre of gravity (%MAC) 218 / 27.5

We can see that at the same altitude and speed but 13 tonnes heavier a pitch of 2.8° was required. At the actual weight of 205 tonnes the pitch would therefor have been less. Somewhere between 2 and 2.5°, probably closer to the 2.5 than 2.


...and power that was set correctly for an airmass that was markedly different in two seconds from what was indicated...


Interim Report #3 page 88 states:

2 h 09 min 58 Speed handling changes from managed to selected. The selected Mach is 0.8.
2 h 10 Pitch attitude decreases from 1.8° to 0° in 3 seconds. In 8 seconds, the N1 commanded and the N1 change from 100 % to 84 %.


A reduction in speed from .82 to .80 was selected and the ATS responded accordingly.


Originally Posted by Lyman
AoA was nine degrees delta PITCH

AOA did not reach 9° until approx. 02:10:55, some 50 seconds after AP disconnect and with the aircraft at 37500 ft. It did not exceed 6° untill 02:10:50, some 45 seconds after AP disconnect. See pages 42 and 106 of Interim Report #3.

I am also still looking for references to where those quotes you attributed to BEA comes from. I don't think a "keep looking" will do.

Last edited by Hamburt Spinkleman; 15th Dec 2011 at 22:36. Reason: Attempt to fix the quote function.
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Old 15th Dec 2011, 22:23
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I will take a break, try to find my reference, and return. The "a/c did not immediately climb.." was in reference to the PF's first aft stick, airecall. So it would be post box dump, first analysis, afaik.

It was as BEA first analysed the beginning of the fatal climb.
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Old 15th Dec 2011, 22:53
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BEA have actually done a fine job and having found the FDR and CVR have identified the causes of the accident. This happens to be the flight crew sad to say. Attempts to involved the machine are just grasping at straws and filleting our shoals of red herrings. I like some of the mechanical explanations of the processes but these are not causal factors. Causal factors are lack of CRM, poor training (especially at altitude - as Lonewolf50 and Machinbird have ably identified), company culture, failure to follow SOPs, poor cockpit discipline, no designated pilot in charge when the captain left the flight deck, need I go on. The Air France safety audit which was linked a couple of threads back should be essential reading for everyone wishing to comment. It provides all one needs to know about the causal factors in this accident. BEA are attributing responsibility to the flight crew because that is where the responsibility is. The causal factors are all human factors NOT machine factors. Even the UAS was curable by waiting and following proper procedures. These were not followed and disaster was the result.
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Old 16th Dec 2011, 00:15
  #667 (permalink)  
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I'm mostly wit Old Carthusian here

If it walks like a duck, talks like duck etc etc; then it probably is a duck.

Having said all that - I flew the A320 in the LH seat for just 2 years. Whilst a brilliant aircraft in many ways I can see how the inexperienced, and perhaps badly trained pilot, could be suckered into this type of event.

It's still a duck though however you wrap it up.
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Old 16th Dec 2011, 08:28
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Lyman,

From BEA Interim Report #e3, p.89:
2 h 10 min 10: The stall warning is triggered. The angles of attack 1, 2, and 3 values are respectively 2.1°, 4.9° and 5.3°.
02 h 10 min 10,4 : SV : “Stall, stall” (without cricket)
From the graph on page 42 at 2 h 10 min 10,4: Pitch attitude = 4.2°, V/S = 495 fpm, Updraft velocity = 1124 fpm. That same graph also shows that in the simulation of the sidestick inputs without turbulence the AoA would have reached 4°.

The stall warning threshold at Mach=0.8 has been documented prior to FDR recovery in BEA Interim Report no.2 and in the Air Caraibes memo to be slightly above 4°.

Why is it so difficult to understand that the stall warning was triggered when the AoA exceeded the warning threshold due to the combination of sidestick input and a minor gust?
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Old 16th Dec 2011, 13:01
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Originally Posted by Lyman
I will take a break, try to find my reference, and return. The "a/c did not immediately climb.." was in reference to the PF's first aft stick, airecall. So it would be post box dump, first analysis, afaik.

It was as BEA first analysed the beginning of the fatal climb.
A few posts ago you were theorising a BEA cover up of "uncommanded climb" and now it's "did not climb when commanded". Which is it ? Can't have it both ways.

BEA went to great lengths to release (unprecedented, I think) public video of the search and recovery, including shots of serial numbers on the sea floor, recovery and storage with police/judicial oversight and multiple observers etc.

I think it is extremely unlikely the flight recorder data is faked, and certianly can't be subject to the same allegations as Asseline made. The data clearly shows commanded climb, and the simulation with the same commands results in the same crash (without turbulence input).

Aside from the loss of airspeed, that particular plane didn't fail on the night, and the crash was down to the pilot input. Whether or not there are design flaws that contributed to that pilot input is a different and more complex question.
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Old 17th Dec 2011, 10:43
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In the Rumours-News forum GerardC refers to NTSB Report DCA09IA064 which describes A330 UAS incidents to NWA and TAM. Interesting reading, in particular the TAM incident where the crew reengaged the AP when two airspeeds agreed but were still low.
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Old 17th Dec 2011, 13:44
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Remember that, in ALT2, the A/P physically cannot be re-engaged.

(ALT1 it can)
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Old 17th Dec 2011, 16:11
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HN39,
Thanks for posting the link to the NTSB report, just downloaded it into the 'archive' and read it.
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Old 17th Dec 2011, 18:15
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Danger

"Les cow-boy d'Airbus" is the title of Bernard Ziegler's book... HIMSELF !
preface from Jean Pierson, Edition : Privat (TOULOUSE-France).

This book has been written before the RIO-PAR crash...

"The aircraft cannot stall", aso.

Last edited by roulishollandais; 18th Dec 2011 at 23:24. Reason: small coorections
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Old 18th Dec 2011, 10:42
  #674 (permalink)  
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It is not just the Airbus.................

It is interesting to read this, especially the last block 'Who is to blame'

The moment a computer crash nearly caused my car crash ? The Register
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Old 18th Dec 2011, 21:10
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Big Red Button

Another reason to have a "BIG RED BUTTON".
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Old 18th Dec 2011, 21:29
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Another reason to have a "BIG RED BUTTON".
"Oh no....OOPS! I thought it was the autoland!"
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Old 18th Dec 2011, 21:38
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There is no stopping people being stupid, except by selection and training to the extent possible.

The referenced report is a confession by a car driver that he almost got killed on a level crossing when his car was “acting up” – periodically slowing or stopping when supposed to be driving at a normal speed. So what did he do, when it was doing this and he approached a level crossing? “ . . .I decided to plough on forward and try to make it the last 20 blocks to the dealership”. Car drivers are not specially selected, and their (OK, our – including my) training did not and does not include much on fault analysis, nor on decision making.

In aviation, there is selection, and training. But others, professionals, are pointing out that modern training is not covering enough of the old essentials that used to be acquired.

Years ago, I was giving evidence to a UK House of Commons Select Committee about some aviation issues, and I pointed out that, too often, airlines only adopted safety measures if forced to by legislation, or if somebody else paid for it. I quoted as examples rear facing seats and the fatal accident at Manchester (?) where passengers survived the initial crash only to be killed by smoke inhalation – the airlines would not adopt measures to provide safe exit in the event of fire.

Have they now? You know the answer. Do you care? Have you tried to influence any such decisions?

Now, re AF447, many professionals are complaining about economising on training, late replacement of Thales pitots, and some mention not going for optional extra instruments or systems (AI, BUSS IIRC), etc..

I hope those who see deficiencies are raising these issues in their companies, and rousing BALPA etc., and writing to their governments. I should not have been alone, and from GA rather than professional aviation, in my representations to that select committee.

IMHO.

Last edited by chrisN; 18th Dec 2011 at 23:17.
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Old 18th Dec 2011, 22:33
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Sadly for those who would like to believe so we have no evidence that the accident was caused by anything other than pilot actions. Furthermore, this evidence is not likely to be faked or incomplete. What we do have is serious deficiencies in airline procedures and piloting skills which may or may not extend to other carriers besides Air France. There is some anecdotal evidence that training and piloting skills have been neglected outside Air France as well. However, this is an cultural issue not a complexity issue. It is possible to encourage a culture of excellence and professionalism and to reward this. Certain airlines fail to do this and Air France are just the latest example.
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Old 18th Dec 2011, 23:27
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AirBus should be Russian, Here the plane flys you.
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Old 19th Dec 2011, 05:26
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New Background Information on PIO

Recently I theorized that AF447 suffered a roll PIO condition that completely overload PF's ability to control other axes of the aircraft.
While looking for a definition of PIO to compare against the BEA data, I came across a relatively recent paper showing how thinking is moving on the subject of PIO. You can read the paper here. Aircraft and Rotorcraft Pilot Couplings – Tools and Techniques for Alleviation and Detection (ARISTOTEL)
Among the key points in the paper are:
An aircraft- or rotorcraft-pilot coupling (A/RPC) is an unintentional (inadvertent) sustained or uncontrollable vehicle oscillations characterized by a mismatch between the pilot’s mental model of the vehicle dynamics and the actual vehicle dynamics. The result is that the pilot's control input is out-of-phase with the response of the vehicle, possibly causing a diverging motion.
and
It can also be said that in normal situation, the pilot drives the vehicle, whereas during an A/RPC event the situation is reversed. In that case, the pilot is driven by the vehicle due to this mental mismatch and actively tries to control it

Based on the many comments from the industry, [ref. 6] suggested the following ten features (definitions) characterizing virtually every APC documented in the open literature:
1.
PIO is a sustained or uncontrollable unintentional oscillation resulting from the efforts of the pilot to control the aircraft. This is the MIL-STD-1797A definition, with the word “unintentional” added.
2.
PIO occurs when a response state of the airplane is approximately 180 degrees out of phase with the pilot. It could be any response state of the airplane, the most common for fixed wing aircraft are pitch attitude, roll attitude, and load factor [ref. 6]
3.
PIO is an event that results from faulty aircraft design, extension of the airplane’s operational usage into an area for which it was not intended, or following a failure, and is not the fault of the pilot.
4.
PIO is commonly found to be related to deficiencies in basic flying qualities characteristics, though it should be treated independently from flying qualities. Most PIOs outside of the research world are related to rate limiting of a control effector or software element upstream of a control effector, but rate limiting can be both the cause of PIO and the result of it.
5.
PIO may be either constant-amplitude, convergent, or divergent with time.
6.
PIO may be any number of cycles of oscillation; there is no minimum number to declare it a PIO.
7.
PIO may occur at very low frequencies – near the phugoid mode in pitch – up to frequencies of around 3 Hz (“roll ratchet”). The most common frequency is in the range for pilot closed-loop control, typically 1/6 Hz to slightly above 1 Hz (1 rad/sec to 8 rad/sec), but frequency alone does not determine whether an oscillation is a PIO.
8.
High-frequency, small-amplitude oscillations in pitch (sometimes referred to as “pitch bobble”), and in roll (“roll ratchet”), may be considered a “mild” form of PIO, and may not even be judged as PIO in all cases. If the amplitudes of the oscillations become intrusive on the piloting task, they are PIOs.
9.
PIO that interferes with, but does not prevent, performance of a primary mission task is a “moderate” PIO; if a Cooper-Harper Handling Qualities Rating 7 is obtained, it is usually in the range of 4-6 (Level 2 by handling qualities specifications). In general, “moderate” PIO is associated with peak-to-peak angular rates of less than ±10 degrees/sec and control forces less than ±5 lb.8 “Moderate” PIO requires corrective action for normal operation of the airplane, but if it occurs in developmental testing the flight test program can continue.
10.
PIO that prevents performance of the task, or that requires the pilot to abandon the task in an attempt to stop the oscillation, is a “severe” PIO; if a Cooper-Harper Handling Qualities Rating is obtained, it is usually 7 or worse (Level 3 or unflyable by handling qualities specifications). Peak-to-peak angular rates are usually greater than ±10 degrees/sec, and control forces greater than ±10 lb, though rate limiting can attenuate the former and result in large increases in the latter.8 “Severe” PIO requires immediate changes to the airplane, and if it occurs in developmental testing the flight test program should be postponed or redirected until the corrections are made.

Last edited by Machinbird; 31st Dec 2011 at 15:38. Reason: Specifically Naming the reference.
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