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.

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.

- 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.

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.

Hi,
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:
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.

BOAC

:ok:

Garage Years

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.

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?

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? )

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.

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.

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.]

Graybeard

What exactly were the "environmental conditions outside those specified in the certification requirements for the pitot probes"?

Hi Bear,
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.

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."?

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.

Industry Activities
 

Arinc.com aviation has this:

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.

I was alluding to, among others, your own self.

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

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.

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).

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.

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.)

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 ????

Airspeed indicators & diversity
 

Pitot tubes have been around for a long time, but they are not the end-all solution for airspeed measurement. Other technology even predates that. Take this example from WWI:

http://thevintageaviator.co.nz/files...screensize.jpg


Diversification has posted links to two companies doing work with Laser measurement of windspeed. Previously we noted another set of patents related to use of lasers for airspeed measurement.

FBW aircraft have unique requirements for airspeed information that is not obvious to the casual observer. They need to know the airspeed in order to properly set system gains. This is critical for proper performance of the control servo loops.

The increasing prevalence of FBW technology is exacerbating the pre-existing problems with pitot icing.

Used to be, you iced up the pitot enroute, no big deal. Leave the trim and power set and pretty soon it will come back. And if it doesn't, it still flies like an aircraft and you can keep in a safe speed range by proper use of power, speed brakes, attitude, AOA, or whatever else works on that aircraft for that purpose.

On a FBW aircraft that trims itself, the situation is different. The aircraft suddenly has no idea if the power is set correctly, no idea if the control system gain is set correctly, and once it tries to change trim, has no idea if that is set correctly. The designers wisely pass control to a higher level computer that can figure this out.
Unfortunately, the higher level computer may have been processing other tasks, and has not been involved with actual control of the aircraft since 2 landings ago.

Add to this an array of messages sent by the computer relinquishing control trying to describe its problems and advising corrective actions, but initially delivered out of priority sequence. Further add to this what must be a cacophony of bells, clicks, alert tones, and short musical sequences in the audio spectrum.

If the FBW aircraft flew like an aircraft at this point, and I had flown it before in that configuration, probably no big deal, but the computer is still trying to help me out and I am lulled by its help. Four of five critical tasks are still being handled by the computer.

All I have to do is remember to handle the last critical task, wait for the display to settle, and push buttons, turn knobs in a carefully considered sequence.

When you consider the implications of loss of airspeed information on a FBW aircraft in full detail, it is an unacceptable risk.
It is time to provide more diversity in airspeed sources.

BOAC's thread about cockpits
 

Thanks for the link, BOAC. I had seen the thing two years ago when looking here for rumors and facts and opinions from "professional" pilots concerning the AF crash. I didn't post here then, but prolly should have joined the fray.

Despite one poster's complaint here, I have been compelled to add my 2 cents worth as I had experience with both FBW and "modern" cockpits/avionics. Granted, my background was military, but I assure you that several here prolly fly with the Guard or Reserve. point being, the AF crash will certainly raise questions as to FBW and the human interface with the plane. Anyone disagree?

Call me a dinosaur, but I adapted, maybe even prospered. From cables/pulleys/pushrods to hydraulic valves operated by the stick ( zero feel from the control surfaces) to a complete "electric jet" whose performance was only made possible by a FBW system.

On the cockpit side, I went from a fairly sophisticated interceptor with an awesome autopilot and avionics suite for its time to a completely manual, pushrod system and no autopilot or radar for four years, and then to a cosmic jet - the A-7D. Then to the F-16.

The human interface in the cockpit of the 'bus is sure to become an issue after this Friday, ya think? Trust me, I prolly flew with an inertial system and other things before many here. The jet, A-7D, had a HUD that displayed speed, altitude ( radar or baro), AoA and the magic flight path vector with associated pitch lines. It had a projected map display coupled to the nav system and a super ground radar we could use for bombing, navigating and avoiding storms. See the article about the map by Capt McAdoo ( gums in his earlier years with all his teeth, heh heh) here:

http://sluf.org/misc_pages/fwr_winter_1973.pdf

The Vought human factor folks did an awesome job, and we WERE NOT overwhelmed with a deluge of data or confusing failure messages/warnings/cautions when things turned to worms. The biggest thing was reduced pilot workload. Navigation capability was a quantum leap ahead of all other military jets at the time, as was bomb delivery capability. We still carried our circular slide rule and paper maps, but they were for emergencies.

Apparently, some folks are concerned about the human interface in modern airliners, and I go with the folks that desire/demand a better interface. I fully understand the change from "flying" to "managing systems". But I don't understand a cockpit that can overwhelm the crew with a plethora of warnings and cautions and beeps/chirps/etc. And I also don't understand a cockpit that does not supply a straightforward means of reverting to basic flight control laws upon demand by the humans in the cockpit.

Somebody show 'bird how to change the size of his graphics! Doggone page is now a thousand characters in width, gasp.

Talking about pitots
 

Main problem this equipment (amongst others) is not its technology (simple and sturdy) but its certification specification dating back roughly to the early jet age in the last millenium.
Today's long-haul operations are led a a far more stringent environment than in those (golden, some of the posters will surely say :)) days.
We can be certain that the people who had established and validated the pitot's specification had never thought about flights at FL 350+, at -50° (and even below) and during several hours.
Time is up to revisit this type of "old" specs to ensure that they are still applicable in today operations.

Apologies if posted before but details of release on Friday now up on BEA site

Well. A Boeing with 8 turbojets and swept wings flew to 50k and higher.
The design is Sixty years old.

The technology is the problem, by process of elimination. Either the computer in the Airbus cannot fly without IAS, or it is incapable of retreating from the stage without insisting it be paid attention to first. Without BUSS, a pilot who has come to lean on a seemingly steady platform (with the encouragement and training and paychex of the operator) is sol. Wouldn't be the first time a lady seduced a gent to his doom.

bear
 

I dunno about that.
We can even talk about the Blackbird regarding altitude performance !

But, if we come back to airline ops, I guess my point remains valid.
We have a piece of equipment that is designed against specs that are not in line with today's requirements.

llagonne66

You may be right. Some one soon is going to ask if the flight was survivable.

By that I mean, some blend of autoflight (NOT AUTOPILOT), and Captain/FO could have punched through to Paris (Or Afrique, or...). In two years I have been unable to come up with a good story Air France (and Airbus) could use to deflect liability. If there is one, I'm stumped.

Because it looks like she made it to the water with both engines alight. If it is a couple ounces of frozen water, then that makes a poor wall behind which to hide.

You said.... "....But, if we come back to airline ops, I guess my point remains valid. We have a piece of equipment that is designed against specs that are not in line with today's requirements...."

By equipment did you mean PRIM? or PITOT.........

bear
 

I have strictly no trouble with the liability of anybody in this sad story (Airbus, AF, Thales, ..).

Equipment = pitot of course !!!

Good work, Professor - guess we can all pack up and go home now.

Yeesh... :rolleyes:

High altitude jets
 

Everything you wanted to know about the Blackbirds is here:

SR-71 Online - The Blackbird Archive

And it wasn't FBW.

The other plane was/is the Boeing B-52.

This is nothing new, and certainly not manufacturer-specific:

This is on a Hawker-Siddeley Trident 1C (useful part is from 0:00-2:20, especially the last 30 seconds)


This is on a Boeing 757 (as is the next) - useful part is 6:30-end


(useful part is 7:30-end)


Also, SR-71 wasn't perfect - the FSMs required to set the shock cone occasionally "went rogue"...

http://www.pprune.org/military-aircr...ml#post4005221

gums:

I recall from an A-7 jock the following comment (or something like this): the A-7 has one pilot and 1.3 pilots worth of workload. :cool:

He tried walking me through which finger on his left had he used to pickle what, and when, during a bombing mission, and I nearly followed him, but got lost ... some years gone. The A-7 guys at the time made a big deal about being single pilot, and leaving the bats to those that needed them. (bat ~ NFO/BN/RIO).

EDIT: from your SR-71 site.
Some interesting thoughts on how to improve a pitot tube. If the research into this high altitude ice phenomenon can provide sufficient data to create an improved spec, I don't doubt that the engineers at Thales, Goodrich, and others will be able to provide a more resistant probe.

That would address one of the holes in the cheese, but perhaps not all of the holes in the cheese for the AF447 crash.

System needs, the Pitot issue and Redundancy (I)
 

Hi,

Anticipating what we expect to hear about Pitot tubes from BEA there are many of us "looking" to the sensor. The invention of Henri Pitot is in the spot light.

Actually is a very simple and reliable invention. So good that is used in every a/c. And until now, a "killer product" (A trully K.I.S.S. invention)

The current a/c Systems (used by Airbus SAS, Boeing, etc.) need a reliable information of air speed. Certainly much more (than the logged 38, since 2003) cases occurred and created problems.

It seems to me there is an error when dealing with Redundancy in this issue:
(in the "extreme cases")

Why you put Redundancy in a design? When the fail rate of a single critical element is not compatible to your spec of (System) Availability. The need is obvious for "complex items" like computers (that can "fail" by Hardware, Software, etc.). EADS put 3X Redundancy ("acting as 5X")

In the case of a (vital) sensor extremely simple i don´t understand (and not agree) to use "on line" more than one! It seems an unjustifiable use of Redundancy. Perhaps "amplifying" existing limitations of current Pitot sensors (that could create a complex "soup" mixing SW, HW, Laws, etc.) :}with potential to result in stressful (even lethal) scenarios for pilots.

One may ask: And if the device breaks? (Bird impact, etc.). And if the device becomes the nest of the wasp? And if the heater fail? And if the Transducer fails? And if the wiring breaks? etc.

Any of those possibilities IMO not justify to have 3 on line (allowing a voting scheme) (being monitored/scanned) and "capable to degrade" the a/c when there is a AS "disagree". There are other possibilities or reasons to justify the redundancy? Please list! You can do "averaging, etc, by "software", for identical sensors, submitted to quite identical conditions? Why?

If you prefer to have redundant Pitot, no problem: You may put 2, 3..n with just one "on line". You could (should) "interrogate" the others to check if they are alive. Energy to them? Can be supplied. We can optimize this. Ideal number? May be 3.

If the "US made" is better (IF really is) let´s analyze and make ASAP a joint effort (US-EU) to improve the existing models. This is good for the entire Aviation industry.

We need (to deal with the rare "extreme cases") ASAP R&D for better Pitot´s. Redundancy (for identically unreliable sensors) is almost useless. Just tell you (immediately? not sure!) the important sensor(s) are failing.

The reading of n sensors could be used to "anticipate" the Main sensor is going to fail. Alerting the crew before the a/c starts to "degrade". (I´m using the term "degrade" just to simplify). As an alarm of "closeness of extreme conditions".

(to be continued)

Question:

If we make a bigger (size) one (scale 2X, 3X, nX) the "ice issue" could be improved? A bigger one, power modulated (up to 1KW) could solve the issue? No tiny holes easy to clog? (Up to 1KW? Or a non electrical, heater? Or dual heater?)

Why not to test (in real world) the "anti icing" characteristic of new designs (new size, geometry, max power, similarity to "US" model, etc) comparing (in actual flights) to the existing ones. (Checking in real time against the current US and Fr. existing models).


It seems there is a "deadlock" among the players (Cert., Mfrs.,Operators). Time now (and opportunity) to competent technicians to work and SOLVE* the issue. Keeping "bean counters" just waiting the results of the necessary R&D.

*I mean, a Pitot with better characteristics when facing the "extreme conditions"

pitot heat
 

Here's a simple idea. Apply different heat settings to the three pitot probes. In the event of all 3 probes icing up, at least this could ensure an asymmetrical failure. This seems to be a more graceful failure mode than automatics being fooled by wrong readings for some time before the UAS condition finally arises.

Just sayin'...

Sorry for the drift, if my post is impropriate pls disregard.
I was and still am very interested in this awfull accident.
I posted in june 2009 a reply at which I got "hit at" so i did not reply thereafter.
Apparently my suspision was right, the capt was not on the deck, and no, i do not and i don´t want to be right!!

I have read and learned a lot of all the aspects of this accidents, esp. the technical ones here on PPrune.

But, why was this A/C lost while others finished there flight, e.g. IB only 10 or so minutes behind them (but they diverted, 70 miles around or so?)

I am afraid it will turn out to be pilot-error; as mentioned earlier: pitch and power is performance, as far as i know that works in every airplane, A, B, C, E, F etc.

Maybe another simple idea: let pilots fresh from flightschool first do some (tough) turbo-prop flying, in stead of going straight for the big jets, with all the computers, software, defences, back-ups etc etc.

My most importand CRM/MCC is: FLY THE AIRCRAFT.

Hope i am wrong.......

leave the pitots alone... arright? ;)
 

With all due respect to the brilliant minds on this forum who have been discussing alternate solutions for the pitot issue and without sounding insensitive to the families and friends of those lost to this tragic event:

The issue of pitot ice, IMVHO, is not something that warrants a complete rethink/redesign of a major sub-system like the pitot-static system. Even if this was possible, it would take years if not decades to get this done. Inferring from Airbus and other airlines' response to this problem, its reasonable to assume that they think this issue can be fixed with minor tweaks/fine-tuning of the existing well-proven system. If this is in fact their assessment, I have to say, I agree with it, notwithstanding the scale of this tragedy. Are there any reported cases of pitot ice triggered UAS events on a/c with Airbus recommended fix (of replacing the pitots) applied?

Having that said, we may learn on Friday that pitots played a more important role in the chain of events than we imagined. Even so, it is hard to conceive of a chain of events that would warrant an extreme reaction like redesigning the entire pitot-static system. Does anybody else think this is the wrong approach? We may end up creating more problems than we solve.

Then again what do I know, I'm only a pilot...

redundant airspeed indication
 

Just a wayward thought from an engineer. We know GPS is not accurate enough to be used as a backup airspeed indicator because it tracks ground speed rather that airspeed. the two are often vastly different. Might it be possible to derive a backup airspeed indication by looking at the doppler shift of weather radar returns? After all, the cloud droplets are suspended in the same air mass that the aircraft is flying through. This would only work when there were echo returns present, but then again those are the times when pitot tubes are likely to be fouled by ice.

Perhaps the pitot redesign brigade's thrust is analogous to the engineer with a solution looking for a problem (and most of us have been guilty of that at times ..)

As at least one poster suggested a few posts back, if the underlying problem is found to be pitot icing, then the appropriate first tack is to

(a) look at icing requirements in the design standards,

(b) identify and redress the Standards deficiencies and

(c) move via AD (as appropriate) to fix the presumed heating deficiency.

Such, at least, chains up the initiating problem.

That is not to suggest that the Standards ought not to be revisited in respect of automation paradigms and the philosophy of degraded modes and flight deck presentation.

If, and that's still a big if, the fallout is along the lines of the crew's being overwhelmed by mode degradation and associated alerts, then one foresees a period of Regulatory navel gazing (both certification and operational standards) in the coming months.

I read the whole thread, and in my personal and unqualified opinion as a mere SLF, it's quite clear that on friday, all the doubters of modern aircraft design philosophy and the conspiracy theorists will have a field day - regardless of what will be revealed, it will be either the fault of Airbus, the BEA or a big coverup...:( So many people here already know what happened and don't need any facts to change their opinion...

I think it's interesting to see how many people either propose new gadgets designed to fix the "AF447-problem" or just see the modern reliance on computers and automation as the cause of the crash, but fail to prove that those "fixes" are more reliable than current "modern" technology. Because that's the design case, to reduce the number of "avoidable" crashes. Not just to fix the cause of this crash, but to improve the whole safety record. None of the doubters of "computerised planes" proved that older planes are safer, and it could very well be that these technological advances (?) improve safety for 99,999% of the flights, and that "fixing" these methods might decrease the safety of 99,999% of all flights, just to fix the freak occurance on 0,001% of all flights. (All figures are made up :ok:)

I'm not judging because I just don't know enough, but in my opinion it's up to those people to prove that on the whole balance, the safety of all flights would be improved by their proposed changes - not just the safety of those flights that encounter the same conditions as those on AF flight 447. So in my opinion it's quite obvious that the changes coming from this crash will be evolutionary (as in "bugfixes") instead of revolutionary.

But we will all know more on friday, for sure...

Eliminate the Suprise factor
 

Maybe not, provided that in the CRZ pitch and power along with static pressure and altitude is automatically monitored independently and if UAS starts to become an issue for the A/P it switches to flying the "pitch and power" equivalent to the last valid pitot data. Signal the UAS condition and at the same time show the FPV value. The crew are now aware of the condition, and the "suprise" factor has been mitigated.

As an after-thought, GPS Altitude and GS could be incorporated into the monitored triangle as a backup, should one of the other two components become suspect.

I know its not the total answer, but who/what judges the Judges?