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AF447

Old 11th Jun 2009, 19:18
  #1181 (permalink)  
 
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EPR

If one adjusted EPR's to Turbulence Penetration settings and maintained attitude manually using the standby ADI....how many reasons why that would not have worked. Can these things not be hand flown.....to that extent?
Not related to your question but, just for clarification:
EPR must be disregarded when flying unreliable speed indication procedures. One has to use N1, (and ATT) because EPR may well be also "influenced" by the severe weather conditions (if and when that is the case).
V.
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Old 11th Jun 2009, 19:26
  #1182 (permalink)  
 
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As layman I keep asking myself why the black boxes data ain't being sent to a central computer on Earth via satellite
Apart from how a Sat signal can be disrupted by a storm, if the antenna is at the wrong angle, You have to send from one place on the planet to another and it has to be bounced over several sats/ground stations........ Every down/uplink is a weak spot.

Sorry, but I think this is something else tht has been explained before. Sat signals can be disrupted easily by a storm (would have worked well IF AF447 flew into one, wouldn't it), as I am sure we have all seen live sport broadcasts "break up", we've seen Sat TV break up because of local weather and, if you have a GPS, you'll have seen that lose the signal too depending on local weather. All you need is a good storm in the way of one up/downlink station and you don't get a thing transferred from the Pacific to Paris (or, in this case, the Atlantic to Paris)
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Old 11th Jun 2009, 19:32
  #1183 (permalink)  
 
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Can I just confirm that the ONLY supporting evidence leading posters to discuss a VS mid air break up is the fact the French Navy found it in the water?
VS found intact with rudder attached. Speculation is that it was found that way because it contacted the water without the airplane. Inconclusive if VS being found alone is what caused the breakup, or is an artifact of the breakup.

Other evidence supporting in-flight break-up is the condition of the bodies, and the dispersion distance, which is similar to the China 911 flight and the Japan 707 breakup in 1966 at Mount Fuji.

These events can also be explained by a controlled, upright, low energy ditching, with crosscurrents and winds accounting for dispersion.

Consider the odds of a low energy ditching at night in a thunderstorm, with high seas, with compromised systems.
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Old 11th Jun 2009, 19:57
  #1184 (permalink)  
PJ2
 
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Safety Concerns;
Therefore the time of transmission is irrelevant as the faults are time stamped in real time and sent in real time. If there are any communications issues the time stamp remains time when fault occured.
Determining time stamps is the key as we know. I was going on the statement from the AMM concerning the FIDS:
Fault Detection at each AFS BITE

(1) Data descrtipion

a) Triggering event
A triggering event detected by the BITE function of a computer corresponds to a change in state of a functional variable of the application software of this computer.
This event triggers a fault isolation and memorization process. In order to avoid unwanted triggering of this process, the change in state of the examioned variables is only taken into account after a certain confirmation time dependant on the variable in question.
Thus, I think suspending judgement that the ACARS is the map of events as they unfolded. I think it is risky to assume otherwise until either case is examined and determined.

As can be seen, there is much more to this process in the AMM than can, or should be re-presented here. If the messages are time-stamped at the time the failure first occurs and the ACARS messages are indeed a sequential map of failure, that will obviously assist greatly in mapping downstream effects of the various failures, which of course is the attraction. My intent is to merely esablish this mapping, either affirming or refuting the view expressed, (as I'm sure you know). Many thanks for continuing the collegial discusssion in this vein.

Last edited by PJ2; 11th Jun 2009 at 20:35.
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Old 11th Jun 2009, 20:54
  #1185 (permalink)  
 
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Eroneous airspeed indications in a climb with blocked pitot tube

Just for interest I put the Nimrod simulator into a climb between F350 and F370 and then blocked the starboard pitot tube. The airspeed and the mach number rose rapidly and the pilot raised the nose to bring the speed back which made the (apparent) overspeed worse. The correct IAS was shown on the port instrument panel but the mach number (which is driven by the same source as the stbd instrument) continued to show the very high mach number. The pilot closed the throttles and deployed the airbrake. There was then some stall buffet which the pilots misinterpreted as mach buffet, and so on (the artificial stall warning does not work well at this flight level). The mach protection then operated, giving a pitch up which made matters even worse. It is a very different aircraft, but it shows how little reliable information you have got in these circumstances. When teaching pitot static diagnosis I usually advocate levelling off, as it at least stops things getting worse. But if the problem is on the static side, this too is difficult.
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Old 11th Jun 2009, 20:56
  #1186 (permalink)  
 
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with respect pj. my main aim in hammering home the acars point is to stop this nonsense about a vs departing the aircraft first.

One can determine that the vs was fixed in place due to a complete lack of real time messages relating to a whole range of other systems that would shout fault immediately.

The problem with reading the manual without the specific aircraft experience is that you can read more into a technical statement than is actually there.

I can assure you that a departing vs would excite the fids to such an extent it would shout fault in real time

As to the rest of the sequence of events I may even agree with you
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Old 11th Jun 2009, 21:28
  #1187 (permalink)  
 
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Sims

Nimsim tks for your post....it brings to mind has anyone seen any results of any a330 sim rides trying to recreate the incident based on what is out there so far from the weather and the acars mtc messages?
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Old 11th Jun 2009, 21:40
  #1188 (permalink)  
 
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Nimsim tks for your post....it brings to mind has anyone seen any results of any a330 sim rides trying to recreate the incident based on what is out there so far from the weather and the acars mtc messages?
All very true, but....
How many times did we do a sim-ride/check/re-current and the sim (read computer!) was not programmed to behave the same as the A/C would in real life. Again; the outcome of a computer depends on a) how you program it you want to behave (software written) and b) what you insert as an input to it.

I´ve done many sim-sessions and sometimes "the sim" comes with a outcome thats is/could/should-not be realistic to the real A/C..

My few cents......
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Old 11th Jun 2009, 21:55
  #1189 (permalink)  
 
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HiFlyer 1757,

Did you not read this?
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Old 11th Jun 2009, 22:23
  #1190 (permalink)  
 
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Explosive Decompression

I saw this information in a Brazilian blog, hosted in a very well appraised newspaper's website (Jornal do Brasil).

It says that people involved in the retrieval of the bodies, said the remains are being found mutilated and without any piece of clothes.

According to them, the absence of clothes indicates an explosive decompression due to fuselage rupture, in which the huge air blow into the cabin would be able to triturate the clothes even if the person got his seatbelts fastened.

I would appreciate comments on whether or not the recovery of bodies without any closes is indeed an indication of explosive decompression

If so, it's an important piece of information.
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Old 11th Jun 2009, 22:27
  #1191 (permalink)  
 
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1sloth

HiFlyer 1757,

Did you not read this?
Possible misunderstanding here.

My read of the various posts is that the Simulator scenario only showed that the Sim would place the aircraft in a very difficult situation probably leading to breakup.

It is not programed to reproduce all the system and structural degradations that might happen in real life.
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Old 11th Jun 2009, 22:29
  #1192 (permalink)  
 
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It says that people involved in the retrieval of the bodies, said the remains are being found mutilated and without any piece of clothes.
Bodies were found this way in the Comet disasters...

At first assumed the decompression or fall from 30,000 + feet was the reason. Subsequently it was established that the lack of clothes was caused by lapping waves that effectively (and surprisingly), stripped them...

It was also established that in an explosive decompression the majority suffered skull fractures (within 0.2 seconds), but that severe injuries to limbs was a result of impact with the sea.

Nothing was ignored in Sir Arnold Hall's comprehensive RAE Farnborough investigation into those (first jet airliner) disasters and it was ALL published for the world to see.

Last edited by HarryMann; 11th Jun 2009 at 23:41.
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Old 11th Jun 2009, 22:36
  #1193 (permalink)  
 
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Pitot tubes fault tolerance

Working with fail safe systems in another business there is one thing I do not understand that maybe someone can answer;

The pitot tubes are obviously important enough to put 3 of them on the a/c to make sure that you have backups. But, why would you use 3 of the same brand/type/design? When the a/c is built, I even bet they come off the same production batch. If there is a design flaw or malfunction, you have a much higher risk to face problems with more than one if they all are the same. It is a bit like putting two new halogen lamps in your car, with today's automated production they will probably fail at about the same time. If there is a problem with icing in the pitot tubes, they will probably experience the problem at about the same time if they are built equal.

So, why not use at least two designs/brands ?
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Old 11th Jun 2009, 22:37
  #1194 (permalink)  
 
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Got that in an email from senior cockpit crew at a major US carrier yesterday...did not see it posted here .....and the email was as 'washed' as the post of detail such as what type of sim and when was it run which could give an idea of what data they were working with.

The results they got in those 'rides' is chilling but I would think there has been more than that run around the world....would like to see the variables and the subsequent results for comparison. Absent recovery and download of data from the boxes these sim runs could provide a 'next best' look into possible causes.

This incident, down the road, could have a long term impact on future aircraft automation for manufacturers and suppliers in regards to flight into severe weather as well as a possible 'relook' of systems already certified IMHO....for all manufacturers and suppliers.
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Old 11th Jun 2009, 22:50
  #1195 (permalink)  
 
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thomasfo

There's a thread specifically on the issue of air data sensing here in the Tech Log forum with some info on this issue.

One issue with a dissimilar design is that it becomes quite hard to ensure similar performance from dissimilar designs, which makes it more difficult to monitor for errors between different types of sensor, as the "error" may not be due to a failure but simply the expected issue. Since errors between different air data systems can be quite important for things like RVSM performance, this isn't a trivial issue.

You also have to remember that all probes,even if differently sourced, would have to be to a common specification. If the aircraft then encounters conditions outside those covered by the spec, even dissimilar probes could fail together.
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Old 11th Jun 2009, 22:52
  #1196 (permalink)  
 
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So, why not use at least two designs/brands ?
Sometimes they do, at least different releases of the same product...

And having proved the performance (of said item) in extensive tests, you wouldn't want misreading when cross-comparing or calibration issues.
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Old 11th Jun 2009, 22:55
  #1197 (permalink)  
 
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Bodies were found this way in the Comet disasters...

At first assumed the decompression or fall from 30,000 + feet was the reason. Subsequently it was established that the lack of clothes at least, was casued by lapping waves that effectively (and surprisingly), stripped them...
Well, then it's not conclusive by itself. They will have to couple with the state of the debris recovered...

Understandably officials and the media are not broadcasting "nude mutilated corpses" and also they are not giving details about the debris to avoid a thunderstorm of misinterpretations.
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Old 11th Jun 2009, 23:23
  #1198 (permalink)  
 
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So, why not use at least two designs/brands ?
So all three strand steel cables should be replaced with cables made from three strands of three different metals
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Old 11th Jun 2009, 23:32
  #1199 (permalink)  
 
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Tied sneakers leave the feet at three G. Consider not the decompression, but the freefall at 400 knots through the atmosphere. Not all our people stayed inside a disintegrating fuselage. At 200 knots stick your paw out the little vent window of the 402. Actually, don't, just put your finger tip into the airstream, and hopefully you'll pull it back with its fingernail. A Tornado at 250knots will disintegrate a Cadillac, at 400 knots?
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Old 11th Jun 2009, 23:47
  #1200 (permalink)  
 
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Iced Pitot in climb

Yes - NWA 727 on ferry out of NYC had exactly this problem (1 Dec 74) and the outcome was as PTH and NimSim described. If anyone has access to full NTSB reports, the # is NYC75AN070.
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