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AF447

Old 16th Jun 2009, 17:43
  #1701 (permalink)  
 
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Origin of the known ACARS messages

Being curious about the source of the two pages of ACARS messages, which are labelled 28/256 and 29/256, I looked around to see where they originated. Amazingly, this seems to be it:
AF447 accident - icing, pitot tubes and radar in the frame - Unusual Attitude
So the crucial text on which everyone is basing analysis, was hand copied from a screen visible during a TV interview! Furthermore I gather from other comments here, that this is just one ACARS stream (maintenance messages?) of several. Also that it isn't publicly known for certain that these two pages are even all the relevent messages from that stream.

I'm new to this forum, and have no aviation-related expertise whatsoever. (I'm an electronics and computer engineer.) I greatly respect the professional experience present on this forum and others. But... I'm astonished that there doesn't seem to be any indignation that Air France and the French aviation authorities have not seen fit to release *all* the ACARS messages from AF447. Are there legal reasons why they wouldn't? Liability? Insurance? Given that what appear to be at least a large proportion of the critical ACARS messages are now public, why not either officially release them all, or at least make some effective demonstration that there were no more?

If this topic has already been dealt with, my apology. 87 pages...

For reference, here are some other links to the ACARS messages and commentary:
http://www.pprune.org/4975386-post45.html single post - ACARS msgs
http://img197.imageshack.us/img197/3410/acarsaf447e.png ACARS msgs

Engineer decodes Air France Flight 447 emergency messages
20090608 Engineer decodes Air France Flight 447 emergency messages

http://www.iag-inc.com/premium/acars2.pdf
Line by line commenting on the ACARS msgs.

http://www.nytimes.com/2009/06/13/wo...lane.html?_r=1
Error Messages From Air France Jet Offer Details but Little Insight

The New York Times > World > Image > The Last Minutes of Flight 447
http://graphics8.nytimes.com/images/...ane-graf01.jpg

http://www.eurocockpit.com/images/acars447.png
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Old 16th Jun 2009, 17:46
  #1702 (permalink)  
PJ2
 
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JuggleDan;
When you increase "software intelligence", you exponentially increase incorrect specification risks, code complexity, testing costs... If you want a cheap, testable, reliable software, better make it as simple as feasible. You can go for more complex softwares only if you have the extra-money... and are willing to take the extra-risks that come with them...
Superb post - said far better than the point I was trying to make about expense in design. Unfortunately, your wisdom and experience as an engineer commenting on this thread will be ignored so ignorance can prevail. (I haven't had a good laugh in a while until I read some stupid comment about the software not letting the pilot fly the airplane until the ECAM is complete. Someone's stuck in childhood understandings of the world where mom says no desert until you finish your vegetables...

Quite unbelievable. ELAC's post a few pages ago is spot on. The discussion is agenda-driven and some other venue will have to be found for serious, knowledgeable enquiry.

Thanks again for your contribution.

PJ2
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Old 16th Jun 2009, 17:48
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EASA Safety Information Bulletin
SIB No.: 2009 - 17
Issued: 09 June 2009
Subject: Unreliable Airspeed indication
Background: During the recent accident of an A330 into the Atlantic Ocean
on 01 June 2009, and without prejudging the final outcome of
the investigation, a discrepancy between the different
measured airspeeds was reported. There have been a number
of occurrences of unreliable airspeed indications or misleading
air data information. The root cause of this may be due to, but
is not limited to, inappropriate maintenance, contamination by
small objects or materials on the ground or in the air, extreme
environmental conditions producing icing outside the
certification envelope of the probes or large amount of water
ingestion.
Description: The primary purpose of the pitot-static system is to provide the
flight crew with airspeed information, required to safely control
the aircraft. As noted above, the origins of potential pitot-static
system malfunctions are numerous and cannot be totally
excluded in the operational context. The Aircraft Flight
Manuals and/or Flight Crew Operating Manuals include
procedures for unreliable airspeed indication (Air data system
misleading information) and these should be well known by
flight crews. Correct application of these procedures by flight
crews may be crucial for assuring the safety of the aircraft
when such Pitot-static malfunctions occur.
Recommendations: Operators should ensure that flight crews have proper
knowledge and proficiency:
- To detect and to identify unreliable airspeed indication.
- To apply immediate and conservative actions for ensuring
short term safe flight control, in accordance with the
manufacturer procedures developed for the specific aircraft;
the use of memory items should be considered.
- To apply procedures for the safe continuation of a flight with
unreliable airspeed indication up to a safe landing.
EASA SIB No: 2009 - 17
This is information only. Recommendations are not mandatory.
EASA Form 117 Page 2/2
Familiarisation of flight crews with unreliable airspeed
indication procedures should be provided through adequate
training. Flight crew knowledge and proficiency should be
checked on a regular basis.
Applicability: All aeroplanes operating in commercial air transport.
Contact: For further information contact the Airworthiness Directives,
Safety Management & Research Section, Certification
Directorate, EASA. E-mail: [email protected].
I think EASA know what happened don't you?
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Old 16th Jun 2009, 18:16
  #1704 (permalink)  
 
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The A320 elevators and rudder hinges whose actuators had been
removed
shattered and the rudder and elevators came off.
That alone negates any other of his opinions as meaningless...
+ the rudder from F-GZCP seems still fixed to the fin itself.
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Old 16th Jun 2009, 18:30
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When you increase "software intelligence", you exponentially increase incorrect specification risks, code complexity, testing costs... If you want a cheap, testable, reliable software, better make it as simple as feasible. You can go for more complex softwares only if you have the extra-money... and are willing to take the extra-risks that come with them...
Naturally.

There'll have to be a demonstrated need, i.e., accident reports, pilot concerns, claiming there becomes too much for the crew to handle under a certain set of conditions. If true, then that'll become reflected in requirements to fix it. You can want a cheap airplane, but the requirements will tell you how cheap it can be.
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Old 16th Jun 2009, 18:37
  #1706 (permalink)  
I don't own this space under my name. I should have leased it while I still could
 
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First, I had a Pprune database error this message was posted at 1840 GMT+1hr.

Originally Posted by FE Hoppy
I think EASA know what happened don't you?
No.

Recommendations: Operators should ensure that flight crews have proper knowledge and proficiency:
- To detect and to identify unreliable airspeed indication.
- To apply immediate and conservative actions for ensuring
short term safe flight control, in accordance with the
manufacturer procedures developed for the specific aircraft;
the use of memory items should be considered.
- To apply procedures for the safe continuation of a flight with
unreliable airspeed indication up to a safe landing.
I think you might conclude that the air data system might have been a cause. They also say that flight crews (any flight crew) needs to have proper knowledge and proficiency in circumstances where there are air data errors.

You cannot infer that the crew on AF447 were not knowledgable or proficient nor that the air data system cause the crash. You might tentatively conclude that one or both were contributory but nothing else.
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Old 16th Jun 2009, 18:49
  #1707 (permalink)  
 
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EASA worth a read

EASA Safety Information Bulletin
SIB No.: 2009 - 17
Issued: 09 June 2009
Subject: Unreliable Airspeed indication
Background: During the recent accident of an A330 into the Atlantic Ocean
on 01 June 2009, and without prejudging the final outcome of
the investigation, a discrepancy between the different
measured airspeeds was reported. There have been a number
of occurrences of unreliable airspeed indications or misleading
air data information. The root cause of this may be due to, but
is not limited to, inappropriate maintenance, contamination by
small objects or materials on the ground or in the air, extreme
environmental conditions producing icing outside the
certification envelope of the probes or large amount of water
ingestion.
Description: The primary purpose of the pitot-static system is to provide the
flight crew with airspeed information, required to safely control
the aircraft. As noted above, the origins of potential pitot-static
system malfunctions are numerous and cannot be totally
excluded in the operational context. The Aircraft Flight
Manuals and/or Flight Crew Operating Manuals include
procedures for unreliable airspeed indication (Air data system
misleading information) and these should be well known by
flight crews. Correct application of these procedures by flight
crews may be crucial for assuring the safety of the aircraft
when such Pitot-static malfunctions occur.
Recommendations: Operators should ensure that flight crews have proper
knowledge and proficiency:
- To detect and to identify unreliable airspeed indication.
- To apply immediate and conservative actions for ensuring
short term safe flight control, in accordance with the
manufacturer procedures developed for the specific aircraft;
the use of memory items should be considered.
- To apply procedures for the safe continuation of a flight with
unreliable airspeed indication up to a safe landing.
EASA SIB No: 2009 - 17
This is information only. Recommendations are not mandatory.
EASA Form 117 Page 2/2
Familiarisation of flight crews with unreliable airspeed
indication procedures should be provided through adequate
training. Flight crew knowledge and proficiency should be
checked on a regular basis.
Applicability: All aeroplanes operating in commercial air transport.
Contact: For further information contact the Airworthiness Directives,
Safety Management & Research Section, Certification
Directorate, EASA. E-mail: .

I think EASA know what happened don't you?
Yes. This was known from the earliest by the investigation. What is puzzling is why did it happen?

Now we are at the stage what are we going to do about it.?

On the surface it seems like the pitot tube issue is only a "minor malfunction". However I have to ask is it a conditional malfunction in that it is lilely to be combined with other serious workloads on the crew?

If so we either have to minimize the heck out the pitot tube combinations or train the pilots for this malfunction in turbulence. (I won't use the word "severe" since we still don't know)
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Old 16th Jun 2009, 19:22
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HarryMann -
That alone negates any other of his opinions as meaningless...
+ the rudder from F-GZCP seems still fixed to the fin itself.
Ah.....if you'll read his report, he was NOT writing about the AF 447 tail assembly.
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Old 16th Jun 2009, 19:35
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RWA:

I've quite often 'advised' her to choose Boeings, rather than A330s/A340s, whenever possible. Without going into too much technical detail.

She just emailed me this arvo to say, "Thanks, Dad. Reading about the Air France thing, guess I'll try to follow your advice from now on........."

Anyone on here think that a basically-thick, but luckily 'cunning,' guy like me was over-reacting? Or that my (highly-intelligent, 'to a fault', honours-law-degree and Masters' ticket) daughter, who knows nothing at ALL about aviation, is over-reacting too?
I'm just PPL/SLF, with a similar professional background to your daughter, but I've no doubt you're both over-reacting, and that there are many, many aviation professionals on this site who could tell you the same.

But really you should get it from the horse's mouth: Boeing themselves. Have a look at their 2008 Statistical Summary of Commercial Jet Airplane Accidents. Pay particular attention to page 19, the summary of hull loss rates by aircraft type. I see nothing on that page to favour Boeing over Airbus. A casual inspection very much suggests the opposite in fact, although the period of time covered by the data undoubtedly muddies the waters.

But whether or not one type could be demonstrated to be superior to another is largely irrelevant. The rate of fatal hull losses per million departures is so fantastically low (~1) that any underlying systematic difference between manufacturers is likely to be a small change in an already tiny risk. Anyone seriously worried by such a marginal change should give up air travel for good. Not because air travel itself is dangerous, but because anyone so sensitive to such tiny risks must surely find getting in the car for the trip to the airport to be an activity so foolishly risky that they would never countenance it...
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Old 16th Jun 2009, 19:36
  #1710 (permalink)  
 
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Re pitot icing; the principles of pitot operation is that air does not flow through the tubing, the system captures a pressure. There are some types (probably used by Airbus) which allow a small calibrated leak, but downstream of the ‘leak’ the systems’ operation are essentially identical.
A change in pitot pressure (erratic IAS) could occur quite quickly if an ice/water accumulation reduces the effective diameter of the tube, particularly with the ‘leaky’ systems. Diagrams showing the types of pitot and a range of disruptive mechanisms are shown in www.sae.org/events/icing/presentations/2007s30duvivier.pdf
An indication of the atmospheric conditions, icing type, and rate of icing can be seen by comparing the events of unusual engine icing and TAT probe icing – http://airs-icing.org/AIRS_II/AIAAReno2006/AIAA-2006-206-739.pdf
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Old 16th Jun 2009, 19:42
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AF447

Having worked for a company manufacturing heated pitots that was bought by Goodrich, I accept that pitot heaters can fail, but what are the chances of three failing in a short period, all three would have been working at takeoff, it seem to me to be extremely unlikely that three would fail at once, they would likely be from different manufacturing batches.
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Old 16th Jun 2009, 19:51
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Having worked for a company manufacturing heated pitots that was bought by Goodrich, I accept that pitot heaters can fail, but what are the chances of three failing in a short period, all three would have been working at takeoff, it seem to me to be extremely unlikely that three would fail at once, they would likely be from different manufacturing batches.
What about extremely damaging hail or so much hail that the heater(s) couldn't keep up with the ice jamming up the orifices?
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Old 16th Jun 2009, 20:13
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I've written some software specifications. Computer reboot time, just in debugging exceeds response time available during an incident, before it becomes an accident. Also, the pilot can't be trained in what to expect during computer problems if there is a human, besides the flight crew, in the mix. The computer geek would be a wild card that the crew shouldn't have to deal with. Plus, you'd have to add weight back in for himself and his provisions, in addition to the computer weight.

Besides, if you introduce the third crew member back into the mix, one could make the case to get rid of the heavy and complex computers. All you'd really want in that case is FADEC to trim the engines for best fuel flow.

Last edited by ClippedCub; 16th Jun 2009 at 20:31.
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Old 16th Jun 2009, 20:15
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Me Myself

If the captain was on his break, then, the most experienced F/O would have been in the right hand seat. That's AF SOP for long haul crew relief so that the one in charge of let's say an emergency descent does it from the seat he is used to.
To tell you the truth, given the catastrophic system meltdowns, I can't see myself being able to fly the aircraft in a such a weather and no attitude indicator.
I am not sure about this. What if AF nominates IFR? In the worst case scenario the 600h on type F/O would have been in the RHS and the 2600h one in the LHS... What if AF stipulates that only the RH seated F/O can be in command...
The cheese holes could have been very much aligned even before the systems started to fail...
I would appreciate if an AF colleague can enlighten us about what actually are the SOPs and how stringently are they applied
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Old 16th Jun 2009, 20:35
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ClippedCub....

Understood.....thats why I asked.

Is it possible to have support from the ground when these ACARS messages come streaming in? That would make more sense.

The messages were not looked at till later, after the fact. And I assume this is the first time they have been so scrutanized.

I guess my faith in modern technology has taken a hit, and I assume that there has to be a way in this day and age to make these systems even safer than they already are.....
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Old 16th Jun 2009, 20:40
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Interflug, PJ2

Hey, Interflug (post 1701), there is a bit of difference between stick input in a gusty landing at approach stages and when cruising through CB at 35 kf. I'm confident that Airbus IT caters for the different circumstances.

PJ2, with respect for your posts in general, your questions about the mobile crew rest area on the 330 has already been dealt with elsewhere in this thread. Post nr 773 and subsequently (perhaps deleted inputs) from colleagues to confirm that A330 mobile rest area come in the form of a LD6 container is normally located below deck on the hight of the 3L/R doors, aft of the wings. I thought you said somewhere you were current on the 330 ?
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Old 16th Jun 2009, 20:46
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Airspeed sensor redundancy

it seem to me to be extremely unlikely that three would fail at once, they would likely be from different manufacturing batches.
Actually it seems that the ACARS messages are indicating the failure of just one of the sensors.

That's what is probably still missing in the "clogged pitot tube as a cause" hypothesis.

Correcting:

If the message 341115PROBEPITOT actually refers to all probes disagreeing 1+2/2+3/1+3 instead of only two of them in agreement then I stand corrected that all three probes failed.




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Old 16th Jun 2009, 20:52
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News - more wreckage sighted;

PRESS RELEASE 32

INFORMATION ON THE SEARCH FOR AIR FRANCE FLIGHT 447

The Brazilian Navy Command and Aeronautical Command inform that, in the search today, military personnel aboard aircraft sighted wreckage 950 kilometers from Fernando de Noronha, in an area close to where debris was found before. No bodies were sighted.

At this moment, more than a thousand Brazilian military are directly involved in the searches, 761 belong to the Navy and 250 to the Air Force.

The Frigate Bosísio is heading back to Fernando de Noronha with the six bodies found before by the French Navy and transferred to the Brazilian ship. The arrival estimate to the island is tomorrow, Tuesday, June 16th.

NAVAL SOCIAL COMMUNICATION CENTER
AERONAUTICAL SOCIAL COMMUNICATION CENTER
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Old 16th Jun 2009, 20:55
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chrefrp:

I don't think it would make sense to put a flight engineer in the cockpit. The systems in question have extremely limited inputs. In reality they should be simpler to troubleshoot than even the most simplistic systems one can think of. Additionally most of the real troubleshooting can only take place on the ground anyway.

Situation awareness is something that may need some additional work when looking at self-healing systems (this isn't really an FBW issue) but that is a separate issue.
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Old 16th Jun 2009, 20:56
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I am not sure about this. What if AF nominates IFR? In the worst case scenario the 600h on type F/O would have been in the RHS and the 2600h one in the LHS... What if AF stipulates that only the RH seated F/O can be in command...
The cheese holes could have been very much aligned even before the systems started to fail...
I would appreciate if an AF colleague can enlighten us about what actually are the SOPs and how stringently are they applied
Swish,

I can't state exactly what AF's procedure is, but there's no carrier that I'm aware of that would permit the scenario you describe. In a heavy crew, aside from the PIC one of the other pilots will be trained and designated as a "Relief" or "Cruise" captain. This pilot may be either another qualified captain or a senior F/O trained to hold a cruise captain qualification. In some carriers all pilots holding the F/O position are trained to this standard with the augmenting crew members coming from a lower seniority group specifically tasked to fly as relief pilots.

In the AF case it would appear that it was a senior F/O who held a cruise captain type of qualification. In any event, it would be this pilot, not the 600 hr. F/O who would be in charge during the PIC's absence. Decision making authority in the cockpit is not handed to the least qualified crewmember simply on the basis of the seat he is occupying.

ELAC

And I might mention further that I know a good number of relief pilots who are in fact very well qualified and capable pilots with significant command experience. The position a pilot holds on the flight is not in itself an indication of his experience or abilities.
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