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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 25th May 2011, 14:20
  #2361 (permalink)  
 
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I have little understanding of the complexities being discussed on this forum but have learned a lot from the lively discussion. But there comes a time to acknowledge excellence in an entirely other realm. As General George Patton said, "Sometimes I get carried away by my own elegance" and he was referring to his speech. Terms like "purple pissing Japs" come to mind. BTW General Patton "troubled" the German military stategists who feared his out of the box creativity, but I digress.

I am here to award the General George S. Patton speech elegance medal to deSitter who has risen to commendable heights is his literary elegance rare among the individuals in the digital age.

Following are excerpts of the text considered in this prestigious award.


"…people are starting to take models as reality, and to actually believe that the model is giving them direct information about the world….cause people to imagine that they've got reality licked down to the first nanoseconds of existence… and that up to 95 percent of the universe is unobservable… In this toxic and neurotic environment…the digital universe has acquired a life of its own, and a strange religious fervor has settled over… One fantastic whopper after another emerges from the dark vortex of neurosis that has ingested academic physics…There is no earthly reason to have an airplane whose crew are mere stewards to some cheap pile of circuits somewhere in its chin… irreal universe of modern physics. The same deadly neurosis is sweeping over aviation under the pretense of cost savings. There is something utterly disturbing about the idea of a perfectly good, flyable airplane falling from the sky because its crew are sitting there staring at screens and processing idiotically coded error reports generated by some pimply digeratus with a belly full of fast food and soda in some tacky office… it's ugly, and whether it's a pile of milspec engineers or a crowd of H1B slaves makes no difference…

For anyone violently opposed to this honor, we have just for you the Field Marshal, the Right Honourable Bernard Law Montgomery Operation Market Garden medal which is made of re-cycled aluminium in the shape of a wilted cabbage head. A monetary award of 25 expired stock options in Citibank are included with the prize. (Some have demeaned this award by calling it the ******** Medal in honour of Field Marshall Montgomery, and while it is discriptively accurate of the Field Marshall we at the Military Academy would have preferred the term "Cabbagehead").

The phrase "dark vortex of neurosis that has ingested academic physics" is just so Pattonesque.
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Old 25th May 2011, 14:23
  #2362 (permalink)  
 
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DozyWannabe said "Trust me, if you'd actually studied Software Engineering at even an undergraduate level, you'd quickly realise it's a discipline that shares the same reliance on repetition, models and a*se-achingly dry textbooks filled with complex graphs and barely-comprehensible formulae as engineering of any other stripe. Are you stating that as far as you're concerned the only "real" engineering exists in the physical realm?"

Yes, that's exactly what I'm stating. If it were real engineering it would be impossible for so many dolts to make money doing it. And the dress-up process for done for it, those ridiculous texts which are a mockery of knowledge compared to, say, the laboriously wheedled out facts of turbulent flow, make it look all the more like an aging strumpet.

Systems integration, which may or may not contain software components, is real engineering. That said, programming and networking are in their best forms elaborately detailed crafts that require extremely skilled craftsmen to execute - and how many of these have I met in my lifetime? Perhaps three.
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Old 25th May 2011, 14:46
  #2363 (permalink)  
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Originally Posted by bearfoil
BOAC wrote some scholarly papers on this. Can we see the links?
- heck - if it's money you want to borrow, just say......................

http://www.pprune.org/safety-crm-qa-...-aviation.html will take you where I think you want - it has dropped to a lower page on the forum, but I suspect will become quite relevant again over the next few weeks.
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Old 25th May 2011, 15:11
  #2364 (permalink)  
 
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Presumably there are a fair share of "dolts" in the physics world... however it's rather ironic isn't it? We're sitting here communicating over a massively connected, highly reliable IT network spanning the world, able to message pretty much anyone in realtime, and appear to want to paint the entire slice of the engineering world that make it work (and airplane software, etc - broad-brush "IT") as spotty, big-mac munching, money-grabbing "dolts". Shame on them.

The fact that there are many, many highly educated, professional, thoughtful software engineers, that understand the serious nature of safety critical software (for example - it's not just safety critical s/w) seems to be beyond deSitter - I presume you are bitter for some good reason - maybe Word crashed on you one too many times?

Anyway this thread seems to have seriously lost it's way. Right now we have no evidence that the intrinsic problem relates to the automation. Some here are assuming so and making 'it' (IT) the root of all evil.

Basically I say "bollocks" to that - the days of the open shirted, cigar smoking, "hero"wresting the bucking bronco radial engined monster from the dark skies is GONE.

That is not to say there are not improvements possible - but the Luddites are not going to win.

Last edited by Jetdriver; 25th May 2011 at 23:10.
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Old 25th May 2011, 15:30
  #2365 (permalink)  
 
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Hi,
Originally Posted by Graybeard
Agreed, Jig Peter. There are thousands of planes relying on pitot at this instant. Icing seems to be a rare event, and even more rare in non-Airbus.
Excepted very few experimental aircraft, all others, civil or military, be there small or big, are still relying on pitot tubes today because it is the most robust piece (of very simple hardware) available for doing quite well the job required in most circumstances. Nonetheless, it is also known as one of the major cause for aircraft accidents (mostly in light aviation).
Icing/obstructions by rain, foreign objects, poor maintenance, is not rare. What is a very rare is the fact that long hauls airliners could be affected at cruise levels and lose more than one probe, or all of them, in a very short window of time (as generaly, it doesn't last more than few dozens of seconds, it is erratic for a short while, then return to normal).

I'm not sure that Airbus airframes are more affected than competitors as no statistics about it is available anywhere (and most of the time, plenty of frequent events, like single failures, are not even reported at all). Only companies operating both Boeing and Airbus on the same lines (and for a long time) could really make an informed comparison about those failure rates related to manufacturers/models. Sadly, they really don't like to publish those informations about their fleet "failure rates": classified matter.

Beside, those probe makers are working for any manufacturer and their specs are based on the same regulation. Hence, such consideration about Airbus probe failure rate could be only based on the fact that AF447 is attracting a wide attention on probes issues related to certain flight conditions. This caused some data to be collected around by digging in A340/330 fleet archives (many such cases were unknown by operator/regulators and Airbus before June 1st 2009).

For example, an internal Delta Air Lines memo is quoted here Incident: Northwest A333 over East China Sea on Jun 23rd 2009, unreliable airspeed and is showing that there was an internal survey of such kind of issues dating from 2006, which is giving some intersting figures about this failure/rate and issue analysis on Northwest A330s fleet:
A memo dated June 17th 2009 circulating within Delta Airlines (parent company of Northwest Airlines) states, that the airline's data support the theory of blockages rather than icing of pitot tubes stating, that constantly heated items don't just instantly freeze up and thaw again. The manufacturer has indicated, that the drain size of the pitot tubes is insufficient in the original probe. 0.0012 percent of the flights (approx. 1 in 83.300) are affected according to data collected by Delta Airlines since 2006, incidents have only occured on flight levels 330 to 400 in moderate and stronger turbulence during months of May to December between latitudes North 3 and North 37 degrees.

The memo also describes, that usually the airspeed drops to between 80 and 60 KIAS, the airspeed returning to normal within 4 to 32 seconds. The encounter may be single or repeat over a couple of minutes, followed by normal airspeed operation during the remainder of the flight. Master Caution and Master Warning will activate, the autopilot and autothrust systems disengage, the autopilot not accepting to be reengaged until airspeed is back to normal. Autothrottle will enter thrust lock until throttle levers are moved or autothrust is reengaged. If two systems are involved, an ADR DISAGREE message occurs, the fly by wire will drop to alternate law if the disagree lasts more than 10 seconds and will remain in alternate law for the remainder of the flight. Normal autopilot and autothrust operation can be expected once the event is over.

Delta/Northwest Airlines are replacing the pitot tubes on all their A330 aircraft as quickly as possible.
One should note also the fact that Northwest A330s were equiped with the same Thales/Sextant "C16195AA" probes as Air France A330s and that they did not change them, neither before nor right after AF447 (despite being aware of some issues as it was monitored from 2006): in fact, there is another incident on their fleet on the 23 June 2009, involving their A330-323, #552, registered N805NW using the same probes (see BEA 2nd report), following the one of the 11 June 2009 involving their A330-223 #620, reg. N854NW, following another one on 10 August 2008 to N809NW (A330-323 #663) after the same thing happening again on 6 August 2007 to N854NW. This frequence of "0.0012 percent of the flights (approx. 1 in 83.300)" should have been considered quite low for an event lasting only "4 to 32 seconds" for such flights cruising at FL330 to 400.
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Old 25th May 2011, 15:30
  #2366 (permalink)  
bearfoil
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Whether the leaks are accurate or not, most folks anticipate a political struggle over BEA's work. Shame. And totally unnecessary. On a basic level, alot of folks here see a flaw in the automatic cockpit, and it has little to do with IT.

On both sides, and very much as you say, neither admits to stark reality. GIGO and FAIL happen. "Confusion", distraction, and boredom happen. It is too apparent that at least in one application, no, philosophy, the way out of the weed patch is forestalled by Corporate and Financial reliance on something that is presented a leetle bit as something it is not.

I think for what it's worth, a good example is the lack of readily available fall back flight data, when the event horizon looms near.

takata

"Excepted very few experimental aircraft, all others, civil or military, be there small or big, are still relying on pitot tubes today because it is the most robust piece (of very simple hardware) available for doing quite well the job required in most circumstances. Nonetheless, it is also known as one of the major cause for aircraft accidents".

NO. NO. NO. If I ever thought that a pitot could kill me, I would never fly.

The one-item ultimate MEL has to be the Operator of the aircraft. Now that can be a hard drive or a hardass, but one cannot be unprepared to aviate. Laying a crash off on equipment needs to be demonstrable. ICE is not unknown, nor unprepared for.
 
Old 25th May 2011, 15:31
  #2367 (permalink)  
 
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from Aero Caraibe report:
At 22:22:59, a very rapid decrease of CAS, of mach, and of altitude (correction of mach). The parameters changed respectively from 273KT to 85KT, MO.80 to MO.26 and altitude from 35,000FT to 34,700FT. At the same time, the FD1&2 and I'AP2 disconnected...

Shortly appeared six ECAM messages: F/CTL ADR DISAGREE; F/CTL ALTN LAW; F/CTL RUD TRV LIM FAULT; AUTO FLT REAC W/S DET FAULT; ENG1 EPR MODE FAULT; ENG2 EPR MODE FAULT. Each message was accompanied with MASTER CAUTION and a SINGLE CHIME. Also, the SPD LIM RED FLAG appeared on both PFD.

At 23:23:36 (their typo) and at 22:23:45, STALL was broadcast over the loudspeaker. It was accompanied by the CRICKET and illumination of MASTER WARNING.

From 22:23:00 to 22:23:54, the value of TAT diminished(?) to -14C.

AT 22:24:25, the CAS increased from 111KT to 275KT, the mach returned to initial value of MO.80 and the altutude increased quickly from 34,200FT to 34,500FT.
-----------
Note: You are welcome to correct my translation, as Spanish is the closest to French I can do.
http://www.eurocockpit.com/docs/ACA.pdf

It's obvious from the above that it was the ram tube that clogged, and the drain remained open, causing the quick decrease of airspeed. The clogging was less than 90 seconds duration. Would a longer clog time have mattered?

If the clogging had been more gradual, would the drop in sensed altitude cause the A/P to command Fly Up, rather than disconnect, and would further clogging cause lower sensed altitude increasing pitch up to the point of a real stall?
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Old 25th May 2011, 15:43
  #2368 (permalink)  
 
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takata: thanks for the excerpt from the NW analysis of the malfunction.

This observation of yours is one that the industry may or may not be able to remedy. (Aren't there tools/forums/industry standing working groups that concern themselves with such issues across all corporate boundaries? )

Only companies operating both Boeing and Airbus on the same lines (and for a long time) could really make an informed comparison about those failure rates related to manufacturers/models. Sadly, they really don't like to publish those informations about their fleet "failure rates": classified matter.
Is there not a means to issue "cleansed" or "raw" analysis discovered? Would not the Aircraft manufacturers and any company who operates their aircraft be in dialogue over such malfunctions?

Don't understand the industry well enough to understand if I am even asking the right question.
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Old 25th May 2011, 15:44
  #2369 (permalink)  
 
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Originally Posted by GarageYears View Post
I presume [deSitter is] bitter for some good reason - maybe Word crashed on you one too many times?
He laid it out on the line earlier. It would appear that he got involved with a (software) company or companies that failed, and ever since has had a very dim view of the profession. There were a lot of companies (not just dot-coms) that folded around the turn of the century because far too many wannabe entrepeneurs thought that computer technology was a fail-safe way to make insane amounts of money*, it's true. It's also true that a lot of people decided to take computer science/software engineering courses in the '90s for the same reason. What I've discovered is that the ones who did it for the love of the craft tended to stick with it through the tech crash and beyond whereas those that were in it for the money have switched to management as a career path.

Some are basically ignoring the posting I made earlier where my professor went to visit Airbus - in which he explicitly states that the processes were way in advance in terms of testing and redundancy than he had previously thought and also that pilots were very much in the loop for the requirements-gathering process of the systems that went into the A320 and her descendants. In short, this is not and never was a case of eggheads trying to tell pilots what to do or stop them from doing things the way they wanted. If management and corporate finance departments in airlines are misusing automation in this way then it is a problem within the aviation industry and not the fault of the product, in the same way that blaming the manufacturers of Ginsu kitchen implements for knife crime is also nonsensical.

Anyway this thread seems to have seriously lost it's way.
You're right, and I'm going to leave this part of the discussion there.

[* - EDIT : There's a reason that the successful technology companies were either backed at an early stage by big investors (e.g. Oracle, Apple, Yahoo! and Google were all backed by Sequoia Capital), or piggybacked on the success of long-established companies (as Microsoft did with IBM, a deal partially brokered by Bill Gates's parents both being senior product lawyers for the latter) before they became successes in their own right. Any smaller-level entrepeneurs would have done well to factor that in before they put their money down.]

Last edited by DozyWannabe; 25th May 2011 at 18:15.
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Old 25th May 2011, 15:45
  #2370 (permalink)  
 
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Graybeard

However, both of the events involving EBA occurred in environmental conditions outside those specified in the certification requirements for the pitot probes.
What exactly were the "environmental conditions outside those specified in the certification requirements for the pitot probes"?
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Old 25th May 2011, 15:53
  #2371 (permalink)  
 
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Hi Bear,
Originally Posted by Bearfoil
NO. NO. NO. If I ever thought that a pitot could kill me, I would never fly.
If you ever quote me, please, do not trunk my sentence by removing "(mostly in light aviation)" as in fact it is one of the main accident cause. And here, I really meant "general aviation". But I surely won't dig in my documentation in order to extract some quote for you. I'm just feeling that it is completely useless to argue with you, considering your constant use of this "selective memory" trick.
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Old 25th May 2011, 16:06
  #2372 (permalink)  
 
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Icing Tests

Maybe one reason for not testing the pitot for icing at high altitude is the lack of an objective test. Airframe, and presumably pitot, icing testing is performed at lower altitudes by following a plane that sprays droplets.

Maybe now with the availability of DC-10 and 747 aerial firefighting tankers, realistic, objective icing tests at cruise altitudes could be performed.

Takata, what is the source of your info that pitot icing in light General Aviation "is one of the main accident cause."?
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Old 25th May 2011, 16:07
  #2373 (permalink)  
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bonjour Olivier

Had it not been in parents, I would have included it. "Mostly", then, I take your meaning.

takata

"What is a very rare is the fact that long hauls airliners could be affected at cruise levels and lose more than one probe, or all of them, in a very short window of time (as generaly, it doesn't last more than few dozens of seconds, it is erratic for a short while, then return to normal)."

You may be missing my point. It matters not whether it is B or A. If, (When), pitots crap out, it should be no more notable than other transient failures that must not be allowed to endanger a flight. It may be the way it is presented here, but UAS drill seems a bit more of an event than it needs to be. If FMS can quench the 'fire', fine, if it gets wippy and cannot, also fine; there is a critical point, seemingly accentuated by indecision, at which the safety of the a/c and its people seem in doubt.

FIX IT.
 
Old 25th May 2011, 16:15
  #2374 (permalink)  
 
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Industry Activities

Arinc.com aviation has this:

The AMC is an air transport industry activity organized ARINC. The objectives of AMC are to promote reliability and reduced operating cost in air transport avionics by improving maintenance and support techniques through the exchange of technical information. AMC's premier event is the annual Avionics Maintenance Conference, attended by more than 750 avionics maintenance experts from around the world. The AMC meeting report contains technical solutions to maintenance issues that save the airline industry over $50 million annually.
For $250, you can buy your own copy of each year's report. You can bet that pitot have been discussed the last two years, especially.
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Old 25th May 2011, 16:23
  #2375 (permalink)  
 
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Originally Posted by Bearfoil
Precisely.
I was alluding to, among others, your own self.
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Old 25th May 2011, 16:29
  #2376 (permalink)  
 
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Available alteratives to pitots

The intereting discussion about airspeed measurements seems fixed on pitot systems. However, several commercially available alternatives exist. Maybe they are too expensive or too new to be used by the civil aircraft industry. Some links to illustrate my statements.
Michigan Aerospace Corporation
Ophir Corporation Overview
Finally as far as I have found pitot tubes are normally tested in wind-tunnels and some water sprayed on them. However, the possible conditions seem not to cover the altitudes and velocities where many aircraft fly today.
Regards
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Old 25th May 2011, 16:57
  #2377 (permalink)  
 
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Originally Posted by Graybeard
Maybe one reason for not testing the pitot for icing at high altitude is the lack of an objective test. Airframe, and presumably pitot, icing testing is performed at lower altitudes by following a plane that sprays droplets.
They use also wind-tunnels, but their capacity for simulating "cruise conditions" (speed, temp, particles etc.) are actually too limited. Nonetheless, such tests are showing that probes don't freeze at the same rate as it is a very chaotical process.
The other factor, in fact the primary factor, is to identify (then modeling) the threat in order to address any probe/sensor design flaw: it is probably an ice crystal which size is about a flour grain but may be encountered in very high density ratio in particular conditions. Nobody is able to recreate it in lab and there is no means for taking a sample back into the lab (as no atmosphere sample can survive out of its environment!). This issue need to be studied in situ (into those specific tropical clouds)... and if such phenomenom exist, it is far from being a frequent one.

Originally Posted by Graybeard
Takata, what is the source of your info that pitot icing in light General Aviation "is one of the main accident cause."?
You should be able to retrieve it by googling for "pitot+ice": I don't have it here but I think it is taken from a symposium (around 2007) which was addressing those pitots issues, and more generaly those icing problems. There was a dedicated site with several dozens of very interesting papers made by scientists working on such problems for years (this is far from being new, this issue affects everybody in the industry).
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Old 25th May 2011, 17:00
  #2378 (permalink)  
 
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Originally Posted by Graybeard View Post
Maybe one reason for not testing the pitot for icing at high altitude is the lack of an objective test.
I was on the point of posting something similar....

I'm baffled by those who want to replace the pitot by something else.
Nothing wrong with the principle, except the possibility of clogging up by icing (or wasp nests, but that's another story).
Re icing, the solution exists... it's called "pitot heat".

As already mentioned pages back, the certification standards for pitot sensors and pitot heating are ancient and totally obsolete, and I'm amazed that subject was not pursued further..
What's needed is not another gadget, but enough research and hard work to bring those standards up to a satisfactory conformity with the present-day operating environments.
In a way, UAS procedures are a joke... a band-aid on a big open sore. They shouldn't be needed... air data are basic and simple, and should be reliable, not need guessing by the crew "what is it doing now...?"

With Thales and Goodrich both mentioned repeatedly... I'm sure both companies would be delighted having unequivocal and reliable certification standards, rather than being hauled over the hot coals time and again.

Graybeard, you're right about testing.... "proper" icing conditions are not always easy to find, as we found out with Concorde.
And spraying from an aircraft in front doesn't really create the right conditions either.... there are comments in the flight test reports of great chunks of ice and "bloody great snowballs" only barely missing the windshield.
I think the knowledge about the various forms of ice and supercooled water at current operating altitudes (such as in the ITCZ) is still very sketchy, if not anecdotical. Reproducing the same conditions reliably at ground level (wind tunnel or otherwise) isn't evident, either.
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Old 25th May 2011, 17:04
  #2379 (permalink)  
 
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GB, thank you. Are operators/pilots a part of that collegial working group, or not?

(I have been to a few "users group" symposiums at the airfcraft level, which is what I had in mind when I asked the question.)
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Old 25th May 2011, 18:23
  #2380 (permalink)  
 
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Cool

Hi,

Pitot tube......
Pitot tube was designed time ago ....
It was not firstly designed for aviation.
And when used in aviation .. his first usage was to give at the pilot and indication of speed
Today pitot tube is also used to give information to flight computers and this at altitudes not corresponding at the capabilities of the design
So it's not a surprise for everyone that some problems can arise.
Mixing of new and old technology (design) is the safe way to go ????
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