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AF447

Old 30th Jun 2009, 18:30
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augustusjeremy:
If the AOA includes speed data, and if speed data includes inertial data - which I believe is correct - then an IR1 fault would indeed explain their problems with the AOA.
My understanding is that ADR is not in charge of AOA calculation, because when ADRs are off, you still have an AOA displayed. If ADR is not doing the math, only the IR is left to do it as all the air data stream is directed to ADIRUs.
Or I'm wrong somewhere.

The ADRs provide a number of outputs to many systems and a blockage of the pitot and/or static systems may also lead to the following:
SPD LIM flag on PFD
Alpha floor activation (because AOA outputs from the sensors are
corrected by speed inputs)

Wind shear warning (due to Mach input)
Flap load-relief activation
Flap auto-retraction from 1+F to 1
Alpha lock on slats retraction (due to the speed logic part of the alpha lock function)
ALTI DISCREPANCY on ECAM
RUD TRV LIM FAULT ON on ECAM
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Old 30th Jun 2009, 18:34
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Originally Posted by PK-KAR
Not the aircraft... but the circumstances surrounding the events of interest!

OK, now everyone is wondering about ADR, IR and AoA...
I wonder if the AoA estimator now links the ADR and IR together? Shouldn't, but then, perhaps someone can provide the details?
a few days ago DJ77 corrected me about the Qantas AoA spikes (ADR) by adding that these spikes were also present on the IRU channels. And indeed, if you look to the multiple graphs at the end of the Australian report (page 31), you can see a spike on the measured pitch, it came just before (a few tens of millisec ?) the first AoA spike (see page 30, AoA Captain), and it seems correlated (at least in time !) with the AP disengagement. This prompted the IRS failure (page 30), just before the ADR failure. Unless my interpretation of these graphs is as flawed as my understanding of your writings

Last edited by Hyperveloce; 30th Jun 2009 at 19:04.
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Old 30th Jun 2009, 18:37
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Thank you, takata.

augustusjeremy;
It is not logical to have inertial data validated by air data - hence the name, inertial.
No, it is not and that is a problem to come to terms with.

So - wonder why the message, "0211 ATA: 341200 FLAG ON F/O PFD FPV" and the same for the Captain's PFD?
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Old 30th Jun 2009, 19:05
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Question from SLF

Hi.

I am simply a SLF member and have been observing the discussions on this board since 1 June 2009. First, I want to offer my gratitude to all you
flight deck members. I applaud your professionalism and everything you do
"up there". As a very skittish member of the flying public I am often comforted by the fact that I am indeed in the hands of professionals.
Now, on to the question at hand. I have not only been reading here on PPRuNe, concerning AF447, but also on Eurocockpit. (I don't speak or read French but they do have translations into English.) On several of the Eurocockpit postings they have been referencing two other incidents involving the Airbus 300-series
and faulty airspeed registers and what-not. (Similar to AF447 and, yes, I'm writing in general terms). What comes to my mind, and this is the question I want to throw out to you professionals, is why in the other two incidents the crew was able to recover (assuming the pitot issue is indeed causal, why the crew of AF447 would not have been able to recover? In both accounts, one written by one of the flight deck members, a good description is given as to the steps taken to correct the issue at hand. Wouldn't the crew of AF447 have done the same? I just see a disparity between the other two accounts, and the outcome, and this one. Or, am i missing the point?
Thanks in advance.

Last edited by rgbrock1; 30th Jun 2009 at 19:06. Reason: corrected grammar: I'm anal.
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Old 30th Jun 2009, 19:07
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PJ2

they would be left to radio com and the aircraft had radio issues before departure).
Interesting - could you help out?...I don't recall reading this, (which just means, "I don't recall"); do we know what the nature of the issues was? Thanks!
I saw a post ages ago - quickly deleted, I think - which said that COM3 was inop when the plane departed. As a non pilot, I have no idea what COM3 is, but I was surprised the post elicited no interest at all.
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Old 30th Jun 2009, 19:33
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In answer to rgbrok1; recovering from upsets ....

If you can see the horizon, you can fly by 'the seat of your pants'.

If you can't you had better hope that the instruments are giving you good info ... or else!
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Old 30th Jun 2009, 19:53
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Quote cpdlcads:

Yes but you have to turn off the 3 adrs to get this bu sdp scale/gps alt.
What I'd like is a permanent aoa readout
cpdlcads,

Actually, the instrument exists and has been an available option for FBW Airbus's for at least 16 years, and probably since the introduction of the A320 in 1989. If you look at a cockpit photo you can even see the "blank" in the upper left corner of the Capt.'s instrument panel where the AoA indicator is meant to be fitted. The problem is not the lack of the instrument, just an unwillingness of the airline's to pay for an instrument that they don't consider necessary.

ELAC
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Old 30th Jun 2009, 21:23
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No, it is not and that is a problem to come to terms with.
It dependes on what is meant by "validation".

The iru contains a 3 axis gyro triad, either mechanical platform or [email protected] ring, but also most importantly, accelerometers. The gyro triad can only provide attitude info but the accelerometer and gyro data via some fancy math gives absolute position on the earth's surface. Integrate acceleration once to get speed, twice to get distance travelled.

There may well be cross coupling between systems that measure similar parameters. Air data info may be mixed in to the IRU to provide cross referencing, fault detection etc. For example: detection of an unexpected transient between iru and adu calculated air speed that doesn't stabilise within defined time limits, points to ?...
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Old 30th Jun 2009, 23:51
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overthewing;
As a non pilot, I have no idea what COM3 is, but I was surprised the post elicited no interest at all.
VHF COM3 is not the main communications radio. It is used by ACARS and by the 3rd pilot when communicating with company. When out of VHF range, which AF447 was, ACARS automatically switches over to SATCOM. Just like the LAV ACARS message, there would be no real interest in the snag - it's a non-issue.
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Old 1st Jul 2009, 00:25
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PJ2 {
Just like the LAV ACARS message, there would be no real interest in the snag - it's a non-issue.
...especially when the MEled item was not COM 3 but RMP 3 !
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Old 1st Jul 2009, 01:04
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Oh, was it "RMP3" - thanks Lemurian, - I missed it completely.
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Old 1st Jul 2009, 04:19
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Airbus Fleet may be grounded

Article from: Times Online

AIRBUS is expected to face calls to ground its worldwide fleet of long-range airliners tomorrow when French accident investigators issue their first account of what caused Air France Flight 447 to crash off Brazil on June 1.

It is believed that the accident bureau will report that faulty speed data and electronics were the main problem in the disaster, which killed 228 people.

The European Aviation Safety Agency (EASA) is likely to be asked why it had never taken action to remedy trouble that was well known with the Airbus 330 and 340 series. Nearly 1,000 of the aircraft are flying and until last month, no passenger had been killed in one.

"EASA has a legal and moral obligation to get to the bottom of this problem now," said James Healy-Pratt of Stewarts Law in London. "If there is a defective system and the aircraft is unsafe then it should be grounded."

Stewarts Law, which specialises in aviation, is representing the families of 20 victims of the Air France disaster.

Only 11 bodies of the 50 recovered from the Atlantic have been identified. They include Captain Marc Dubois, 58, who is believed to have been resting when his two co-pilots lost control of the aircraft in a storm.

Suspicion over the air data systems on the Airbus 330 and 340 series has increased after the disclosure that the aircraft had experienced 36 episodes similar to the one that brought the aircraft down as it flew from Rio de Janeiro to Paris.

Airbus first reported problems with the speed sensors - known as pitot tubes - in 1994. The company advised remedies, but no mandatory action was taken.

Last weekend, the US National Transportation Safety Board began looking into two incidents in which Airbus A330s flying from the US suffered critical episodes apparently similar to that of the Air France flight.

The fate of the aircraft would probably have remained a mystery had it not automatically transmitted data back to the Air France base.

In the final four minutes, they told a story that was familiar to the airline. Ice particles or water had blocked the three pitot tubes. This upset the air data computers, which in turn caused the automatic pilot to disconnect. The pilots would have had to fly manually in near-impossible conditions.

Airbus fleet may be grounded | The Australian
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Old 1st Jul 2009, 05:48
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re: the earlier suggestion of engine flameout

The Ice Particle Threat to Engines in Flight

This paper discusses jet engine powerloss and damage due to ingestion of ice particles. In the mid-90s several commercial airplane jet engines experienced more frequent powerloss in ice particle conditions, resulting in a focused investigation, and a greater awareness that led to recognition of similar events on other aircraft.

Since the mid-90s, events have been more numerous, and costly, and have generated greater industry interest. These events have been predominately associated with flight at high altitude near deep convective systems, often in tropical regions...
from:

American Institute of Aeronautics and Astronautics (2006), 1801 Alexander Bell Drive, Suite 500, Reston, VA, 20191-4344, USA, American Institute of Aeronautics and Astronautics - Home Page
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Old 1st Jul 2009, 06:09
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Originally Posted by BeerBaron
"EASA has a legal and moral obligation to get to the bottom of this problem now," said James Healy-Pratt of Stewarts Law in London. "If there is a defective system and the aircraft is unsafe then it should be grounded."

Stewarts Law, which specialises in aviation, is representing the families of 20 victims of the Air France disaster.
If that gross misunderstanding of how continuing airworthiness actually works is indicative of their specialism, then I'm not very impressed. Of course, that last sentence casts a fair degree of doubt on their status as a disinterested commentator on the topic.
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Old 1st Jul 2009, 06:15
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In the final four minutes, they told a story that was familiar to the airline. Ice particles or water had blocked the three pitot tubes. This upset the air data computers, which in turn caused the automatic pilot to disconnect. The pilots would have had to fly manually in near-impossible conditions.
Reading between the lines, I have to wonder if Airbus had seen the same sequence of ACARS messages in other non-fatal upsets.
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Old 1st Jul 2009, 06:35
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JAA FAA

Sorry if this info was posted before but it is not possible to me to keep up with this thread size.

Before this AF447 crash Airbus had issued an OPTIONAL pitot change, it was not a recall. Since long Airbus had warned operators of this ADR PITOT
thing and as I hear my friends on A330 are flooded with stories of speed loss in cruise and I wonder if FAA and JAA were also aware of this, its consequences allied with the fact that under total ADR failure the angle of attack sensor is also inhibited putting the pilots clueless
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Old 1st Jul 2009, 06:41
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Hi,

What can you expect from James Healy, pratt of Stewarts Law in London?
We can expect he will use all the legal ways for satisfy the requests of the famillies he defend.
That's what anyone expect from his laywer.

Bye.
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Old 1st Jul 2009, 07:01
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The call for grounding is no surprise, nor is it a surprise to learn who seems to be leading the call.

Though we know differently, the grounding of an aircraft is a flight safety matter, not a legal, economic or political matter.

Such a serious undertaking is for those who do this work including flight safety specialists and those who certify airliners, not "specialists" in the prosecution of aviation accidents whose goal is winning large quantities of money for clients not the enhanced safety of passengers, and who use as their primary weapon the media in which whipped emotion, not knowledge, advances their goal.

We have seen here and elsewhere, claims that "vertical stabilizers come off Airbus airplanes too easily".....-sweeping generalizations that pitot systems are unreliable and that one "solution" is to mount pitot heads nearer the middle of the fuselage away from where the ice hits first or to mount them behind protective covers. Such lack of understanding and knowledge is precisely what such lawyers value most - it is most easily manipulated.

The goal of this meeting should be to enlighten and to state what new information has been found, if any. The pressure to state preliminary causes may be the 30-day requirement but that should not provide a platform for such calls turning what is a serious responsibility into a media circus.

Whether the case for grounding will be proven cannot be presently determined. Any decision would have to be substantiated by a very high standard of evidence. That is the point that should be made in response to any call to ground the aircraft.
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Old 1st Jul 2009, 07:31
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Hi,

Though we know differently, the grounding of an aircraft is a flight safety matter, not a legal, economic or political matter.
Are you sure you can discard the factor "economic" (and BTW .. economic can be linked with "politic")so surely from a decision or not to ground a type of aircraft ?
It was not easy to ground the Concorde .. and in fact this plane was a economic disaster in exploitation .. so it was not a great lost for AF and BA .. just a lost of "prestige"..
For the Airbus type .. it's completely different.
Imagine all the A330 and 340 grounded ...
Who will have the "balls" for take such decision if necessary ?

Bye.
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Old 1st Jul 2009, 07:48
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Nobody was prepared to do it with the DC-10 ... I think the worst that ever got for DC was some limited time ADs
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