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Old 24th Sep 2010, 14:09
  #1361 (permalink)  
 
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I don't say the crew is entirely not to blame, but they it seems as the automation failed first and foremost.
From a layman's perspective, it seems to me that a 'test' flight after major work has been done on the aircraft, must be carried out on the premise that any part of the plane and its systems might be inoperative. The crew was not supposed to believe that the automation would operate correctly - the purpose of the flight was to detect any maintenance-related glitches, including those that affected automation.

They managed to discover just such a glitch, but because they were not prepared for system failure as they should have been, the discovery struck them when they were poorly positioned to recover.

It seems to me that the airline should have deployed proper test pilots, or at least one pilot who could be trusted to follow the manufacturer's SOPs.
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Old 24th Sep 2010, 14:13
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As far as I understand this is the main cause, pilot errors came only after that
Think again.
The main cause was the crew attempting a stall manoever at low level and before that attempting a test flight without the proper precautions and briefings.

The sensor problem caught them with their trousers down, anything can be expected to fail on a test flight and you must assume that it will go wrong. That is what tests are about - to identify any problems.

Why do you think professional test pilots are a special breed.
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Old 24th Sep 2010, 14:50
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What kind of Test

There are not many things that you do to an Aircraft during maintenance that require an air test. In this particular case was there anything that was being tested during the accident event that was mandated in the maintenance manuals? Or was this a test 'created' to act as somekind of handover from one operator to another? When you buy a second hand car you will often take the car for a test ride. But what are you testing? Is there a parallel between this and handing back an Aircraft. There are no legal requirements (are there?) for transferring an a/c nor maintenance requirements (usually) so what tests will make the new operator 'happy'. Was this whole event avoidable if the transfer took place in the hangar with a good old kick of the tyres?
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Old 24th Sep 2010, 15:36
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Or was this a test 'created' to act as somekind of handover from one operator to another?
Brief summary:
The aircraft was about to be returned to ANZ after a lease. ANZ specified the same handover procedure as Airbus use when delivering a new aircraft.
Instead of asking Airbus to do the job properly the operator obtained a(partial?) unofficial copy of the test schedule and tried to DIY.

Read the official report for the sorry tale of misunderstanding, old information, inadequate briefing and general foolishness.
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Old 24th Sep 2010, 15:42
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Yes - but were they legally required to perform that particular test?
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Old 24th Sep 2010, 15:57
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Yes - but were they legally required to perform that particular test?
What do you mean by "legally".
There is probably no specific airworthiness requirement to conduct that specific test at the end of a lease (but ICBW).
If the lease contract specifies a handover procedure then that part of the contract is legally enforceable in the same way as any other contract.

If you borrow my aircraft you do so on my terms and I am NOT about to accept it back with just a walkaround and a kick of the tyres.
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Old 24th Sep 2010, 16:01
  #1367 (permalink)  
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Bizdev

"legally required...."
It may be splitting hairs, but nothing of this accident speaks of any crime, per se. All parties were attempting to perform duties agreed to in a contract.

No contract would require any action that is illegal, or it would not be a contract.

The mass of legal issues may be extensive, but almost certainly criminality was not an issue.
 
Old 24th Sep 2010, 17:03
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Main cause

The main cause was the crew attempting a stall manoever at low level
I don't think the low level had anything to do with the accident. If you read the report, they basically recovered from the first stall due to low speed but then stalled again due to trim against the end stops. Even if they had been at the correct altitude, I don't see a different outcome. A nose up stall with power on and trim at max is still going to fall out of the sky pretty quickly.

The example FDs in the report are very enlightening, whilst they initially had a warning of the need to use manual trim, the warning vanished due to the Airbus changing Flight Laws.

To my mind the causes were:
1) Washing it in an unapproved method - missing covers and with a fire hose.
2) Failure to follow the SOP for the manoeuvre - crew didn't calculate speeds that the protection should activate at and aborted when it didn't activate.
3) Failure to manage the trim in the stall recovery - crew didn't check it during the stall recovery, and whilst the FD had warned earlier that manual trim was required it vanished from the FD at the time of greatest need.

Yes there was other naughtiness going on about flight testing without officially informing ATC and doing the test at the wrong level, but I don't think those actively contributed to the accident.
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Old 24th Sep 2010, 17:08
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The crew was not supposed to believe that the automation would operate correctly - the purpose of the flight was to detect any maintenance-related glitches, including those that affected automation.
Sorry but this doesn't make any sense concerning this particular crash. Firstly, AOA sensors were not serviced, so even if the crew was looking for a glitch caused by maintenance they wouldn't expect it with AOA sensors.

Furthermore, if what you are saying is true, the pilots could very well expect the elevators, flaps, rudder or any other part of the plane to fail - who in their right mind would fly such a plane!?

or at least one pilot who could be trusted to follow the manufacturer's SOPs.
AFAIK a specific Airbus procedure for such a flight does not exist.

Think again.
The main cause was the crew attempting a stall manoever at low level and before that attempting a test flight without the proper precautions and briefings.
I am thinking again - and the fact is the first point of failure were the AOA sensors due to inproper maintenance/handling/washing. If the AOA sensors didn't fail this accident wouldn't have happened.

A very important factor was also that there was no sufficiant warning for the crew about this failure. I therefore conclude that crew errors only contributed to the fact that the aircraft was not performing "as advertised", and that most importantly the automatic switching of flight laws prohibited the auto-trim system to move from the nose up position - and this caused the second, fatal stall.
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Old 24th Sep 2010, 17:54
  #1370 (permalink)  
 
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Their cavalier attitude towards ATC, ie. speed control; lack of informational communication with ATC .... and lack of prudent speed control, dependency (maybe) on automatic nose down trim during attempted recovery, which subconsciously perhaps the pilot at the controls was used to aircraft doing (I am unfamiliar with A320's, really all Airbi, and have no desire for that to change). Have no idea if they briefed expected flight control logic/action and what to expect prior to initiating the event.
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Old 24th Sep 2010, 18:47
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Mistake after mistake after mistake.

They were bent over the barrel with their underpants around their ankles long before the sensors sneaked up behind them.

The report describes a comedy of errors which should never have even started. Leave test flying to test pilots, they are trained and paid to expect and understand the unexpected. Starting a stall manoever at low altitude was only the last piece of idiocy in this tale of foolishness.

It does not matter how foolproof you make the machine, the world will breed a better idiot to outwit you.
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Old 24th Sep 2010, 19:21
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Firstly, AOA sensors were not serviced, so even if the crew was looking for a glitch caused by maintenance they wouldn't expect it with AOA sensors.
and
the fact is the first point of failure were the AOA sensors due to inproper maintenance/handling/washing.
It seems to me that these two statements contradict each other.

Further, I assume that if an aircraft is washed or painted, there is always a possibility of sensors being left inoperative or misreading? Presumably a main aim of a 'test' flight is to check for such glitches?
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Old 25th Sep 2010, 00:18
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It seems to me that these two statements contradict each other.
There is no contradiction. The AOA sensors were not serviced, meaning the crew had no knowledge that they were not protected during aircraft washing.
Why would they suspect any problems with AOA sensors if there was no maintenance done to them?

I assume that if an aircraft is washed or painted, there is always a possibility of sensors being left inoperative or misreading?
One could also assume that whatever washing or painting was done, that the sensors were proctected, as is standard procedure. You really cannot go fly "presuming" all kinds of glitches.

Starting a stall manoever at low altitude
They didn't start a stall manouver, they wanted to demonstrate speed/stall protection. Due to blockage of AOA sensors, such protection was inoperative. Furthermore, change to direct law prohibited the auto-trim system to move from its full nose-up position, causing another stall.
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Old 25th Sep 2010, 01:31
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They didn't start a stall manouver, they wanted to demonstrate speed/stall protection.
Which part of "test flight" do you not understand.

Each item on the test schedule must be tested to see if it works CORRECTLY OR NOT. Nothing can be assumed. This is a TEST not a demonstration or a routine ticking of boxes.

A competant test pilot assumes that each and every test could fail and has prepared for all eventualities including the worst case. Starting the stall test at low altitude was a stupid error made by a crew who were not competant test pilots and should never have attemped to fly a test flight.

Scrounging an unofficial copy of the manufacturer's test schedule does not make you competant to conduct a test flight.
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Old 25th Sep 2010, 13:50
  #1375 (permalink)  
 
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You really cannot go fly "presuming" all kinds of glitches.
I'm not sure that's true even for routine flights. I certainly don't think it's true for a flight which is being conducted to test the aircraft after heavy maintenance. Presuming glitches was exactly what they were supposed to be doing, surely?
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Old 25th Sep 2010, 14:37
  #1376 (permalink)  
 
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If the point of the "demonstration" was to ensure that a crash as a result of a failure would occur before passengers were embarked, I guess the flight was successful. Unless that was the goal, though, the crew should not have started with the assumption that the system being demonstrated would work.
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Old 25th Sep 2010, 19:51
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Hi,

They were bent over the barrel with their underpants around their ankles long before the sensors sneaked up behind them.

The report describes a comedy of errors which should never have even started. Leave test flying to test pilots, they are trained and paid to expect and understand the unexpected. Starting a stall manoever at low altitude was only the last piece of idiocy in this tale of foolishness.

It does not matter how foolproof you make the machine, the world will breed a better idiot to outwit you.
Knowing the experience of these pilots does they can still make so many errors .. This is sobering


Experience of the CBD:
- 12 709 flying hours, including 7,038 on type. 128 hours in the last three months, all on type. 14 hours within thirty days, all on type. Any flight time in the past 24 hours.?
- Service time: End of the last service before the accident flight: 2 November 2008 21 h 24. • Start of service on the day of the accident: 4 h 30. • Resting time: 13:30 min.

Experience of co-pilot:
- 11 660 flying hours, including 5,529 on type. / 192 hours in the last three months, all on type. / 18 hours within thirty days, all on type. / No hours flying time in the past 24 hours.
- Service time: End of the last service before the accident flight: November 4, 2008 at 20 h 52. / Start the service on the day of the accident: 4 h 30. / Rest time: 120 h.
Or maybe .. it's also other factors at play

From a french page:

While the low speed tests were carried out in haste, it is also true that the crew was not alerted that two probes were blocked effect. This is a serious anomaly. Indeed, if the pilots had been warned that two probes were blocked effect, they never sought to test the proper operation of protection systems in which these probes are the main element.

The certification document SC 25 requires in its Subsection 1309 (c) that pilots are informed of any failure so they can take appropriate action.

CS 25.1309 (c) Information concerning unsafe conditions Operating System Must Be Provided To The Theme to enable crew to take corrective action appropriée. A warning indication Must Be Provided if immediate corrective action IS required. Systems and Control, Including indications and Annunciation Must Be Designed to minimize crew errors, Which Could create Additional hazards

The pilots did not have a visual alarm and / or sound informing them of the unavailability of two probes impact which is contrary to the standards required for certification. The BEA does not say in his report.

Page 16 of its report, the BEA dares say: "Between 15 and 15 h 04 h 06, the probes of incidence 1 and 2 are blocked and remain frozen until the end of the flight to values affect local quasi- identical and consistent with values of incidence of cruising without the crew perceive it. " It should of course read "without the crew being informed." It is intellectually dishonest.

The blocking of 2 probes incident resulted in the miscalculation of the characteristic speeds (and Vαprot Vαmax), rejection of ADR 3, the direct passage into law and made inoperative automatic compensation. This succession of automation in a very complex system has not been seen by the crew. The pilots did not understand what was happening. (Remember Habsheim, Bangalore, Ste Odile, Congonhas ..., the pilots did not understand what was happening.)

If the BEA agrees that "the real situation of the global aircraft was not known to the crew," he does not question the technology as the Airbus CENIP Brazil has in its report on the accident an A 320 of the company TAM July 17, 2007: "The Automation Of The aircraft, however complex, capable of Providing Was Not The Pilot With sufficiently clear and Accurate stimuli, To The Point of favoring Their Understanding of What Was Happening In The moments just the after the landing in Congonhas "

The BEA also forgot to mention that feedback has still failed because two similar events took place in a French company before the crash of Perpignan. If all players in the accident on 27 November 2008 had benefited from these lessons learned, good awareness and good safety, it would have saved seven people dead and a plane.
Les dossiers noirs du transport aérien
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Old 25th Sep 2010, 21:14
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Forgive me for jumping in, but there's been so much BS on this thread.

First, in doing test flights whether they are experimental test flights, maintenance check flights or research flights the mantra is "Plan the flight and fly the plan." I've been engaged in flight test for thirty-plus years and may have been tempted to deviate from the flight card (or told to), I've always resisted, which many explain why I'm still around. I'm not any better than the others, just more methodical (and more wary of what can go wrong).

I can not imagine doing this test essentially in the traffic pattern. If you missed the point at a safe altitude, you need to go back to the safe altitude and conduct the test. And don't do things on the fly (no pun intended.)

If you're doing a test such as this, where the alpha-protection logic should engage at XXX knots, and it doesn't by XXX-2 knots, I'd take the airplane back and figure out what happened on the ground.

I've seen some negative comments about voting out one alpha probe, but then allowing it to trigger stall warning. Isn't this the conservative thing to do? I don't have any problem with this at all.

As far as decluttering the mode annunciations during the recovery, I feel partly guilty. In some of my studies, I recommended doing just this to clean up the PFD when a unusual attitude recovery was to be made. After the A-330 accident during flight test in Toulouse, I realized the error and no longer recommend decluttering essential information. This means, however, we need to move this off the PFD and have the annunciations adjacent to but not on the PFD.

Sorry about the rant.

Goldfish
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Old 25th Sep 2010, 22:51
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Goldfish,
Your post is justified.
Just one thing : To out vote one alpha probe or one ADR is not an issue, but to not tell IS.
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Old 25th Sep 2010, 23:54
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Hi,

This is interesting ....

Crash Perpignan yet the failure of feedback!

(Page 84 of the BEA report). "An event on the A320 has been reported by an airline after the publication of the interim report."

In fact, there were 2.

The BEA does not give the dates of these events (or the name of company), but does not specify that they occurred after the accident on November 27, 2008. We have reason to think that these precursors two serious incidents occurred before the crash of a French company in Perpignan.

If all players in the accident on 27 November 2008 had benefited from these lessons learned, good awareness and good safety, it would have saved seven people dead and a plane.

Excerpts from the BEA report:

"The circumstances of this event were determined from maintenance records, the minutes of the aircraft equipment and the testimony of the copilot. The test probe 1 indicated a blocked probe to 5 degrees. Blockage of the probe 3 was found in the manual verification of freedom of movement. The record review indicates that icing residues and muddy water has probably led to the blocking probes on the flight.

During this flight, the alpha floor function did not activate. The PF found that the speed was less than ten knots in the V max expected alpha. The crew felt the aircraft sink and the captain decided to discontinue the investigation. The PF made a maneuver similar to a recovery stall. There was no stall warning.

On another A320 from the same operator, abnormal values of incidence were also found during a check flight. The three probes have been examined in the workshop, which revealed the presence of fluid in the bodies of two of them. "

These two incidents are precursors of the crash events in Perpignan.
Source:
Les dossiers noirs du transport aérien
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