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AF447

Old 14th Jun 2009, 13:17
  #1461 (permalink)  
 
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Originally Posted by A33Zab
IF ONE ADR IS CORRECT BUT THE OTHER TWO ADRs PROVIDE THE SAME ERRONEOUS OUTPUT OR IF ALL THREE ADRs PROVIDE CONSISTENT AND ERRONEOUS DATA:

The System will reject the 'good' ADR and will continue to operate using the two 'bad' ADRs. This situation can be met when. for example, two or three pitot tubes are obstructed at the same time, by the same amount, and in the same way. (Flight through cloud of volcanic ash, takeoff with two pitots obstructed by foreign matter (mud, insects)).
Human beings (the pilot) tend to use the same type of 'fault accommodation' principles to detect an erroneous IAS/altitude indication. Flight crews will tend to reject the outlier information, if the other two outputs are consistent. This choice is, in the majority of cases, correct; but, all flight crews should be aware of very extreme and unlikely situations where two (or even three) speed/altitude indications can be consistent and wrong.
A lightening strike at the right side of the cockpit could damage both FO and standby pitots as they are mounted close to each other.

Then we could easily have a situation as described above where the system is rejecting the 'good' ADR.
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Old 14th Jun 2009, 13:17
  #1462 (permalink)  
 
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ISIS is not just a [email protected] ring gyro. It also has pitot/static inputs from the systems being logged as faultly. Maybe thats why it logged a fault message
You are fast Safety Concerns. I'm going to have to stop editing on line! I was trying to rebut the "DG" misunderstanding by the professor, before I realized the ISIS is probably the entire suite of standby equipments. If we lost both Cpt's and F/O's pitot to ice, AND the standby pitot as well we might expect a 342200 FR (fault report).

For the 6,000,000,000,000 million billion time, there could be a weeks delay in sending the acars messages they will still show aircraft system time taken from the aircraft reference clock as indicated at the time of the event. I don't know how to make that any clearer.
Yes, you are right!!!!!! But when this all comes out, I trust you will be willing to accept that the average transmission time all the way to the user in france is only a few seconds. That's the average according to SITA data that I have already posted here. It's not going to take "weeks" for the data to get there. Right


Good work everybody. You guys have resolved a lot in my opinion. I just tried to summarize what ppruners have deduced collectively.

CC
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Old 14th Jun 2009, 13:21
  #1463 (permalink)  
 
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For the 6,000,000,000,000 million billion time, there could be a weeks delay in sending the acars messages they will still show aircraft system time taken from the aircraft reference clock as indicated at the time of the event. I don't know how to make that any clearer
Safety Concerns, you are correct in that there is no guarantee on the delivery time for an individual ACARS message, however I understand the Satellite Ground Earth Stations have an Service Level Agreement with SITA which requires the message delivery time is less than 60 seconds in 99.? % of the time (can't recall the number of 9's). I understand there was no significant delay in transmission in this case.
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Old 14th Jun 2009, 13:21
  #1464 (permalink)  
 
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Yes, you are right!!!!!! But when this all comes out, I trust you will be willing to accept that the average transmission time all the way to the user in france is only a few seconds. That's the average according to SITA data that I have already posted here. It's not going to take "weeks" for the data to get there. Right
WRONG. As with any messaging system there are issues. The servers and software involved in receiving and processing these messages do hang up.
Messages can be lost in the system for some considerable time but guess what?

They still come out of the tunnel days even weeks later and still show the actual time of the event and not the time they eventually re-appeared.
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Old 14th Jun 2009, 13:45
  #1465 (permalink)  
 
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GPS,IRS or INS GS

The GPS ,IRS or INS speed is difficult to use at high altitude. However it has been done by a B 747 400 crew who flew into a volcanic ash cloud over Alaska many years ago. Apart from multiple flame outs and opaque windows they managed to land safely at Anchorage using their IRS/GPS ground speed for reference during the remainder of the flight and approach.

Good Flying!

John
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Old 14th Jun 2009, 13:53
  #1466 (permalink)  
 
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Originally Posted by A33Zab
A330 FCOM Bulletin No. 810/1 (Jun 2004)
Actually that FCOM Bulletin was initially published as the No 09 from DEC 99 following the loss of two 757 for similar reasons.
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Old 14th Jun 2009, 14:02
  #1467 (permalink)  
 
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Safety Concerns,

I shouldn't have said "a few seconds all the way to france." I should have said a few seconds to the First Downlink Ground Station.

Indulge me for a moment, will you? My point is not what happens after the ground station gets the message. I don't care. You're right. Anything could slow down then. My point is that from my readings, the satellite will not even send the message AT ALL, NOT ANYWHERE until it gets a C31A confirmation transmission from the aircraft. This means TWO transmissions have to come from the aircraft ON EVERY ACARS REPORT before the satellite will decide it's error-free, and then put that stamp of approval (C31A) on the SITA message and THEN (AND ONLY THEN) beam it down the first ground station and THEN is could get delayed. The fact that it exists testifies it passed the ACARs programing protocol.

Wouldn't you say?

7.3 Response Time [1973 - CC]

The average response time for Type A messages, i.e. the time lapse between the Instant an operator presses the transmit key of his terminal to send his query and the instant the first character of the reply appears on the screen (see Figure 6) ranges from 1.4 seconds to 3 seconds, depending on the number of links involved in route. A typical response time distribution is shown in figure 9.

7.4 Satellite Processors

The downtime of SPs is around 16 hours per month including scheduled and unscheduled stops (e.g. preventive maintenance, configuration changes, etc.)

Presently, certain SPs switch up to 6 message blocks per second during peak conditions of traffic.

Switching times are in the order of 5 ms per block for both systems.
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Old 14th Jun 2009, 14:14
  #1468 (permalink)  
 
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Unlike the VS, the spoiler panel is coated with oil/fuel/hydro fluid residue. Taken with the central disruption caused when the actuator was torn away, it's pretty safe to conclude that this panel detached when the wing was destroyed on impact with the water.
I'm not sure that this is conclusive.

Both the underside and visible edges appear damaged/scraped/worn. Some thoughts about possible inflight damage if it was shaking hard might still be open.

Not conclusive to me by itself so I tend to move on to the next piece of evidence.

as one poster suggested, you collect the positives and the negatives against the various speculations and then decide which ones are still viable (this is liable to take more than a few weeks for us)
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Old 14th Jun 2009, 14:16
  #1469 (permalink)  
 
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FDR missing

However 1500 replies long, this thread has the only available means for partial understanding of what happened until they find the box, if ever, thanks to You all.

Great brainstorm, despite the "sparks" jumping from time to time at somebody's reply.

I guess the Ps of PPRuNe meant professional pilots and some of us are not even pilots.

I would politely "bag" those of You not pilots to refrain from curiosities as our atempt here is trying to prevent this from happening again.

It may in the interest of other more powerfull force the FDR, if found,
not be disclosed to us ever and this thread eventualy saving real pax.

Thanks ALL for ALL the help.

from an A330 Capt 15000 hours, 7000 on this very same airway.
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Old 14th Jun 2009, 14:34
  #1470 (permalink)  
 
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sorry cc I was a bit hasty in replying and knew what you meant.

It just gets so frustrating that even after a 1000+ posts into a thread, there are still questions and comments over the time stamps.

PPRuNe can be a wonderful source of info if only posters would read before posting. I think closing down threads after x amount of posts may not be a bad idea after all. The jump from nonsense to a half decent read was very noticeable after the original thread was locked. It seems direction of this thread is now also slowly being lost.
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Old 14th Jun 2009, 15:04
  #1471 (permalink)  
 
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Aircraft ruptured in flight ?

From brazilian journos recovered bodies were found naked and with numerous skull and limbs fractures .
That scheme recalls exactly G-ALYP accident back in 1954. Flight BOAC 781, a de havilland comet broke up in mid air due to explosive decompression.

Here is a link to that accident. : http://en.wikipedia.org/wiki/BOAC_Fligh ... disaster-1
In order to find more evidence concerning the cause of the crash, the bodies were brought to the coroner for autopsy. During the examination, the pathologist Antoni Fornari discovered a distinct pattern of injuries, which were also identified as the cause of death, in most of the victims. Fornari found broken limbs and damaged limbs, which occurred after death. These injuries consisted of fractured skulls and ruptured and otherwise damaged lungs. Fornari found no evidence of an explosion, and he felt confused by the pattern of injuries.
The ruptured lungs were a sure indicator that the air cabin depressurised because the sudden decrease in pressure would cause the lungs to expand until they rupture. In order to support the theory and also to confirm the cause of the skull fractures, the crash was simulated at the Royal Aircraft Establishment in Farnborough, using the same conditions of the actual plane prior to crash. To do this experiment, a model fuselage was constructed similar to that of the Comet.
Dummies were also seated within the fuselage to simulate possible movements of passengers during the crash. To simulate the crash, the investigators deliberately ruptured the model by increasing the air pressure within it until it exploded. The movement of the dummies within the air cabin at the moment of explosion was conclusive of skull fracture as they were thrown out of their seats and slammed head-first into the ceiling.
Wreckage of the aircraft was eventually found on the sea floor and subsequently raised and transported to the Royal Aircraft Establishment for investigation. Upon examination of the wreckage it became obvious that the aircraft had broken up in mid-air, and initially it was thought that the aircraft might have been brought down by a bomb. Suspicion then shifted to the possibility of an engine turbine explosion and modifications were put in hand to encase the turbine ring in other Comets with armour plate, to contain a possible disintegrating turbine disk.
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Old 14th Jun 2009, 15:28
  #1472 (permalink)  
 
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I shouldn't have said "a few seconds all the way to france." I should have said a few seconds to the First Downlink Ground Station.
I receive ACARS messages on my SITA printer at work. One message is sent when the aircraft is airbourne. It is sent by VHF to the local receiving station, then transmitted 800 miles to our home base. The Ops computor then sends out the auto departure message that comes back 800 miles and clacks out on my printer. As I hear this message four times a day, I know what it sounds like. Yes the clackety clack of the printer tells me it is a dep message. I look out of my window and see the aircraft retracting irs gear as it flies past. These are very small data packets, and they move fast.
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Old 14th Jun 2009, 15:30
  #1473 (permalink)  
 
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Without the FDR to bring in a surprise, the majority of a civil jury (US law) would conclude that Thales, Airbus and Air France share in the negligence that allowed this fleet to contine after five serious incidents caused by icing of obsolescent pitot tubes. I don't see why anyone would try to thwart recovery of the FDR. The evidence from it could hardly be more damning.

GB
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Old 14th Jun 2009, 15:52
  #1474 (permalink)  
 
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4krew

I would politely "bag" those of You not pilots to refrain from curiosities as our atempt here is trying to prevent this from happening again.
If it is in your opinion that air safety - and preventing re-occurrence of this disaster - is solely a professional pilots issue then this 'opinion' might be a part of the problem.

However if it is just because this is the 'Flight Deck' section I will refrain from 'curiosities'

"Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots."

A330 Tech.
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Old 14th Jun 2009, 16:01
  #1475 (permalink)  
 
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Quoting BROSA

A lightening strike at the right side of the cockpit could damage both FO and standby pitots as they are mounted close to each other.

You mean Ledft side for Capt. + Stby positions and right side for F/O...
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Old 14th Jun 2009, 16:04
  #1476 (permalink)  
 
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insurance companies might have to foot a bill of up to 750 million USD. And they have to recuperate the money themselves from somewhere
Insurance companies are not stupid. They have mathematicians who calculate accident probabilities from data from, say, the last 30 years and adjust the premiums accordingly. Im sure the premiums collected from insuring the thousands of aircraft which have not crashed cover this expected payout and then some.
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Old 14th Jun 2009, 16:29
  #1477 (permalink)  
 
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Probable cause

Let's just list the "Probably Cause" now and save all this bandwidth of speculation.

The Probable Cause of the loss of AF447 was due to the aircraft having problems with the pitot static systems in an area of storms that caused the pilots to lose control of the aircraft because of erroneous airspeed and altitude indications, resulting in an upset from which they were unable to recover.
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Old 14th Jun 2009, 16:33
  #1478 (permalink)  
 
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You mean Ledft side for Capt. + Stby positions and right side for F/O
Yes, of course.
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Old 14th Jun 2009, 16:37
  #1479 (permalink)  
 
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Finn

While insurance companies do seem a bit vulture-like and you would think look on a catastrophe as a chance to zing the policy-holders, they have what in the States is called "re-insurance", which is a policy the insurance company takes out against a major catastrophe. For example, after 9-11, our re-insurance industry was hit hard, far more than the insurance industry, as no one expected to actually collect on replacing the WTC.

Also, don't forget the insurance companies dont have the luxury of gaining additional fees beyond their contracts as the catastrophe value increases - its the lawyers that get the percentage cut that incentivies the increase in the total settlement.

Keep up the good work, y'all, I really miss working in comm av. My ACARS experience is now twenty years out of date, but if anyone has questions about the ACARS I protocol I can help.
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Old 14th Jun 2009, 16:38
  #1480 (permalink)  
RWA
 
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"Without the FDR to bring in a surprise, the majority of a civil jury (US law) would conclude that Thales, Airbus and Air France share in the negligence that allowed this fleet to continue after five serious incidents caused by icing of obsolescent pitot tubes."

On present evidence, Graybeard -couldn't agree more.........'open and shut''

Buy you a drink in five or six years, when all the hearings and appeals and 'reviews' are done with.............
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