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Air France A330-200 missing

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Air France A330-200 missing

Old 3rd Jun 2009, 12:17
  #681 (permalink)  
 
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My apologies if this is drifting into the technical, but when looking at the debris field, bear in mind that wind and swell are both factors to consider, after the debris has entered the water, even independent of the direction of prevailing currents. Most of the studies on this subject are to do with oil spills, but I guess are relevant here too. The net effect of wind will be between 2.5% and 4.4% of prevailing wind speed, depending on wave interaction, with a mean average of 3.5%, so wind alone will cause floating objects, such as an oil spill or debris field to drift about 1knot per 30 knots of wind. Swell also has an effect, although less pronounced.
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Old 3rd Jun 2009, 12:20
  #682 (permalink)  
 
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Possible Jet Upset?
If bank angle exceeds 45 degrees then Autopilot will disengage.

If bank angle is greater than 125 degrees or
Pitch > 50 Up or 30 down or
AoA > 30 or < 10 or
Speed > 440 kts or < 60Kts or
Mach > 0.91 or < 0.1 ....
then Abnormal Attitude Law is activated which is Alternate Law in Pitch with no protection except load factor protection and no Auto trim and in roll it is full authority direct law with yaw mechanical...
With electrical problems as well....
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Old 3rd Jun 2009, 12:36
  #683 (permalink)  
 
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Hi

i would like to clarify some questions i have for my curiosity.

a. is it possible that the cockpit got struck by the lightning first. this would give me an explanation for the cabin decompression?

b. if ACARS reports ADIRU, PRIM1, SEC1, ISIS failure. Is this a reason for divert to alternate or something where the flight will follow the normal path?

c. AFAIK ISIS are the backup instruments. In the older type of A3xx, these instruments are analog. The newer A3xx have the digital. With this failure, do you still have altimeter, speed, attidude indicators?

Thanks

Cheers
Martin
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Old 3rd Jun 2009, 12:52
  #684 (permalink)  
RWA
 
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So, can an Air France pilot/engineer tell us which ADIRU manufacturer they use?
Thanks, RAD ALT ALIVE - so I got it wrong, Litton or Honeywell IS a customer option. So yes, it would be interesting (though not in any sense conclusive) to know which option Air France chose.

About the Qantas Learmonth incident, I discover that there were in fact three similar occurrences in quick succession (the first two being Qantas, the other unknown) and three cumulative Airworthiness Directives have issued, both covering most of the A330/340 range - significantly, those equipped with the Northrop Grumman (now Litton) ADIRUs.

Deciphering ADs is a bit like cracking the WW2 Enigma codes, so if I've got anything wrong someone please set me right.

In the first incident, the ADIRU started feeding erroneous data to the Airbus 'protection' system. So, although the aeroplane was flying level, the flight computers got the idea that it was climbing steeply - and therefore rammed the nose down.

"Investigations highlighted that at time of the event the Air Data Reference 1 (ADR) part of ADIRU1 was providing erroneous and temporary wrong parameters in a random manner. This abnormal behaviour of the ADR1 led to several consequences such as unjustified stall and over speed warnings, loss of attitude information on Captain Primary Flight Display (PFD) and several ECAM warnings. Among the abnormal parameters, the provided Angle of Attack (AoA) value was such that the flight control computers commanded a sudden nose down aircraft movement, which constitutes an unsafe condition. At this stage of the investigation, the analysis of available data indicates that ADIRU 1 abnormal behaviour is likely to be at the origin of the event. Due to similar design, Airbus A340 aircraft are also impacted by this issue."

The pilots eventually regained control, but only by turning off all the automatic stuff and reverting to 'alternate law' and doing an emergency landing at Learmonth. But 40-odd people were injured.

An AD was issued directing that that should be done any time there was a re-occurrence. But then another Qantas bird had the same problem, luckily without any injuries, approaching Perth. They followed the new procedure but it apparently didn't work! So a second AD was issued, and following yet another incident (don't know who or where that was) yet a third one went out:-

"Since that AD was issued, it has been reported that the “OFF” light did not illuminate in the cockpit after setting the IR and ADR pushbuttons to OFF. Investigation has determined that the ADIRU was indeed sometimes affected by another failure condition.

To prevent such a failure, the operational procedure has been updated to instruct the flight crew to de-energize the ADIRU if the “OFF” light is not illuminated after setting the IR and ADR pushbuttons to OFF.

Consequently, AD 2008-0225-E, which superseded AD 2008-0203-E, required accomplishment of the updated AFM operational procedure. Since this second AD was issued, a new in service event has been reported highlighting that, in some failure cases, even though the “OFF” light illuminates in the cockpit after setting the IR and ADR pushbuttons to OFF, the IR could keep providing erroneous data to other systems.

In order to address all identified failure cases, de-energizing the affected ADIRU must be done by setting the IR mode rotary selector to OFF. Consequently, this AD, which supersedes AD 2008-0225-E, requires accomplishment of the updated AFM operational procedure."

You can read the whole latest AD here (click on 'Download' at the bottom):-

EASA Airworthiness Directives Publishing Tool

Can't claim to understand it all by a long chalk - in the things I used to fly, a radio (or even an engine!) was an expensive luxury! But I get the feeling that the pilots are being told, "If the inertia gimmicks start talking nonsense to the auto controls, and go ON doing it, turn them ALL off and go back to 'seat of the pants' flying......."

Thing is, I'm struck by the similarity of the earlier cases with what appears to have happened to Air France (on the basis of the 'Aviation Herald,' anyway):-

"New information provided by sources within Air France suggests, that the ACARS messages of system failures started to arrive at 02:10Z indicating, that the autopilot had disengaged and the fly by wire system had changed to alternate law. Between 02:11Z and 02:13Z a flurry of messages regarding ADIRU and ISIS faults arrived, at 02:13Z PRIM 1 and SEC 1 faults were indicated, at 02:14Z the last message received was an advisory regarding cabin vertical speed. That sequence of messages could not be independently verified."

So it reverted to 'alternate law' (whether automatically or by pilot action, we don't know) and then ISIS packed in (which I take to mean that the emergency panel lighting packed in and the instruments went black).........

No way you could fly through a storm at 35,000 feet, presumably in cloud, with no autopilot and no instruments?
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Old 3rd Jun 2009, 12:55
  #685 (permalink)  
 
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On the likelihood of DFDR and CVR salvage


The Indonesian Adam Air B734 that crashed in the Makassar Strait off Sulawesi on 1 January 2007 had its DFDR and CVR located after 3 weeks at depths of 2000m and 1900m respectively. According to the accident report underwater locator beacon (ULB) signals from the flight recorders were picked up on 21 January 2007 by a US oceanographic vessel Mary Sears and their positions logged.

Just to give an idea of some of the constraints concerning this type of operations, according to the accident report: "Mhe Mary Sears was required to pass within 500 meters of a beacon before it could detect a return. The US Navy Supervisor of Salvage shipped a towed pinger locator (TPL) from Washington, DC, to Makassar. This device is a sonic detector with umbilical cable capable of detecting the underwater locator beacons from the PK-KKW flight data recorder and cockpit voice recorder (if they are still operating), down to a depth of 20,000 feet." The speed with which the TPL was towed through the water was 2-4 kts in the case of the Adam Air B734.

Due to several circumstances (including an initial lack of specialised equipment and disputes about the costs of the salvage operations), the actual salvage started only on 24 August 2007, with the DFDR and CVR being retrieved from the ocean floor by Phoenix International on 27 and 28 August respectively. Functional data were retrieved from both recorders.

Also to give an idea of the specificities of this type of operation, the following text from the accident report: "The underwater survey and recovery used a small ROV, Remora 6000, which was capable of descending to a water depth of 3000 meters. The ROV had three visual cameras and two fixed lights fitted on the front of the vehicle, which were used for visual scanning. The visual range of the camera was about 10 meters. The ROV was also equipped with underwater sonar with good resolution horizontally up to 100 meters. The width of the sonar beam is about 50 meters at a distance 100 meters from an object. The position of the ROV relative to the ship was measured using an underwater positioning system and the ship used differential global positioning system equipment. The coordinates provided by the ship and the ROV were used to mark the location of the aircraft wreckage and these were mapped into a computer. The ROV had a pair of robot arms that were capable of lifting a 25 kg object of a maximum dimension of about 30 cm by 40 cm. The ROV was in the water for about 109 hours and completed five dives."

Although the AF A332 wreckage is arguably at greater depth (between half and double as deep) then that of the Adam Air B734, the above may give an idea of the challenges and constraints of the salvage operations with regard to the AF 332 DFDR and CVR. It would not be impossible though, since the salvage company at the time, Phoenix Intl, states on its website that 6000m is now the max depth of its remotely operated vehicle (ROV), provided of course that the ULB signals are picked up and pinpointed within 30 days.

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Old 3rd Jun 2009, 13:12
  #686 (permalink)  
 
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SLFinAZ

I think the French investigator/spokeman was simply being realistic - no doubt the Press want to know when recorders will be recovered, he's quite rightly emphasising it's an if.

I'm watching some of this in the States at the moment and some of the conjecture is not being helped by the standard of live translating being used by the networks and others...e.g. translating "recorders" as "registers".... and yes, I do know translating is difficult
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Old 3rd Jun 2009, 13:16
  #687 (permalink)  
 
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...said the flight data and voice recorders may never be found.
I'm not a commercial salvage operator, but I do dive and read up on deep/technical diving and commercial salvage operations.
According to Reuters, the wreckage lies bewteen 1500 and 2700 metres under the sea: that is incredibly deep for any salvage operation. It is far too deep for divers (the current record is 330m) and while remote operated vehicles or small submarines can reach these depths it is uncharted territory for salvage.

To get two small items from a broken wreckage at that depth will be difficult and expensive. That's not to say it can't be done, but it will be unprecedented, except for the Titanic (in 3900m) which took considerable planning.
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Old 3rd Jun 2009, 13:17
  #688 (permalink)  
 
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Flying Mech - post #638.

You asked if it's a possibility to get a lightning strike and lose the radar. The answer is yes. Did it happend? No one knows.

We'll have to hope that the CVR and FDR are recovered. Hopefully their recovery will solve this accident.
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Old 3rd Jun 2009, 13:28
  #689 (permalink)  
 
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Arslanian also reportedly said that they would do their best to find the causes without the aid of the recorders.

After catching up reading several new pages here I resisted the urge to hit the reply button to several posts until I read everything. So now only a single reply.

When we talk about large transport aircraft there is no sense in asking or intimating that one design is stronger than the other in turbulence. They are essentially the same. The critical structures are designed to limit loads and less critical stuff is expected to fail first.

So the finding and identification of bits of debris along a path would give a hint of the relative breakup and shedding of parts which in turn may indicated the differences between fire, explosions, upset etc.

Not necessarily a postive conclusion but at least a pointer along with the already commented ACARS.

And perhaps already covered, the pingers on the recorders are distance related from the sonar. So when you consider the possibilities as a three dimensional box including the depth along the debris field in miles, it truly is a needle in a haystack.
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Old 3rd Jun 2009, 13:35
  #690 (permalink)  
 
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I suspect that if the recorders are not found by the french investigators, a privately funded search for them may ocurr.

the potential financial impact of substantial unanswered questions about this crash on the comercial aircraft industry is suffeciently great to justify spending years searching if necessary.

so I suspect the recorders will be found, but possibly not anytime soon.
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Old 3rd Jun 2009, 13:35
  #691 (permalink)  
 
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Worrals in the wilds Quote:
...said the flight data and voice recorders may never be found.
I'm not a commercial salvage operator, but I do dive and read up on deep/technical diving and commercial salvage operations.
According to Reuters, the wreckage lies bewteen 1500 and 2700 metres under the sea: that is incredibly deep for any salvage operation. It is far too deep for divers (the current record is 330m) and while remote operated vehicles or small submarines can reach these depths it is uncharted territory for salvage.

To get two small items from a broken wreckage at that depth will be difficult and expensive. That's not to say it can't be done, but it will be unprecedented, except for the Titanic (in 3900m) which took considerable planning.
Not true .... as has already been said - SAA Helderberg - they recovered the one of the boxes (I think the CVR) from 3500m deep after 2 months of searching, also brought up about 1% of wreckage for analysis.
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Old 3rd Jun 2009, 13:36
  #692 (permalink)  
 
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US navy P3 to assist in search

http://www.armytimes.com/news/2009/06/navy_p3_airfrance_060208w/"The Navy has sent a P-3 Orion to Brazil to help search for survivors and debris from Air France Flight 447, which went missing Sunday, the Navy said.
The U.S. Southern Command on Tuesday sent the maritime patrol aircraft and 21 crew members from its forward operating base in El Salvador, where it was doing counter-drug missions, according to a statement from the command."
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Old 3rd Jun 2009, 13:36
  #693 (permalink)  
 
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Does anybody know how far can the signal of the ULB (Underwater locator beacon) of the CVR/FDR be detected?
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Old 3rd Jun 2009, 13:48
  #694 (permalink)  
 
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Zulu01, fair enough, and thanks for that. I was unfamiliar with that operation. I wanted to assay the conspiracy theorists amongst us that seem to think retrievals at that depth are easy and guaranteed.

"...however the flight data recorder was never found."
from the dreaded Wiki about the SAA, because an operation at that depth is always touch and go. As doubledolphins said, the data may also be degraded.
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Old 3rd Jun 2009, 13:51
  #695 (permalink)  
 
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It is quite obvious the airplane was destroyed inflight by extreme turbulence.
Bollocks.

It is quite obvious that nobody has any idea what appened to that aircraft until a complete investigation iaw ICAO annexe 13 has taken place, a viable accident cause theroy has been created and then tested to prove it's validity.
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Old 3rd Jun 2009, 13:59
  #696 (permalink)  
 
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The US Navy recovered the UAL 811 cargo door about 20 years ago from a depth of over 4300 metres, and seeing that did not have a pinger, recovering the black boxes is not so unlikely.
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Old 3rd Jun 2009, 14:02
  #697 (permalink)  
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"Isn't a computer on an aeroplane supposed to be an aid to good airmanship rather than a substitute for it?

The flying community is rapidly becoming totally dependent upon computers for all aspects of flight based upon the assurance of the manufactureres that "nothing can go wrong - it's all 100% reliable."
Zeque, there's a clear difference between the approaches of the two major manufacturers.

Generally speaking, Boeing leave the final decision to the pilot - they provide him with warnings, like stick shakers and klaxons -but if he 'decides' to try to stand the aeroplane on its head or its ass or its elbow, the 'systems' will let him do it.......

Airbus, on the other hand, build in 'protections' in normal flying trim. Essentially, they won't LET the pilot turn or climb or descend too fast or too hard - they just 'take over' and keep the parameters within set maximums.

"Pilots should be able to isolate computers when the programming has obviously gone wrong."
I believe that you can do that in either aeroplane, in theory. In a Boeing, you always have that privilege. In an Airbus, you can go to 'Direct Law' (I think!). But, also as far as I know, that means that you won't have elevators or ailerons to fly with, just the rudder and the trim controls.......

Others will correct me if I'm wrong - but as far as I know, that's the situation.

Both sides of the argument have their ardent supporters. All depends, I suppose, on whether you reckon 'situations' cause most accidents - or pilots do........
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Old 3rd Jun 2009, 14:04
  #698 (permalink)  
 
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DFDR and CVR bis: lomopaseo, md100 and others

See post # 685


Max detection range would theoretically be in the order of 4000 meters, but in case of the Adam Air B734 actual TPL detection of the ULB's was only within a 500 meter range.

Mapping the ocean floor first with other (faster) detection means (currently ongoing) may locate bigger pieces of the A332 wreckage, assuming that the A332 didn't fully disintegrate in flight as the Adam Air B734 did. Which in the case of the A332 may considerably narrow down the search area for TPL trawls in order to successfully detect the ULBs of the DFDR and CVR and locate them for ROV salvage.

Last edited by Dutch Bru; 3rd Jun 2009 at 15:21. Reason: post number referred to changed due to deletions of other posts
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Old 3rd Jun 2009, 14:04
  #699 (permalink)  
 
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LEM,

The 747 in question survived, and so did 3 other 747's that encountered turbulence sever enough to kill one or more passengers. The Russian Tu-154 that entered a flat spin was also intact all the way down. My question here is pretty simple...

Assuming we had an initial upset, does the follow up stream indicate failures during decent (not sure what limits are required for a vertical cabin speed warning) or was the AP fail sensor driven and in effect the plane was unexpectedly handed back to the pilots unexpectedly but in a condition where altitude was maintained for a period of time and a combination of weather and internal issues caused a later loss of control due to system degradation?

Can a FBW avionics system degrade to the point where the plane is still physically flyable but the avionics don't allow it? More and more I get the feeling that the KISS principle is at work here...
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Old 3rd Jun 2009, 14:17
  #700 (permalink)  
 
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In an Airbus, you can go to 'Direct Law' (I think!). But, also as far as I know, that means that you won't have elevators or ailerons to fly with, just the rudder and the trim controls.......
  1. There is no specific cockpit control to select Direct Law, as Airbus and the civil aviation authorities are convinced that the system would automatically switch to Direct Law in any situation that warranted it. But, I suspect that any Airbus crew would know that you can get to Direct Law, if desired, by switching off enough of the fly by wire computers.
  2. Once in Direct Law, you have conventional control, using elevators, ailerons, roll spoilers, rudder etc. There is a direct relationship between the position of the cockpit controls (i.e. stick and rudder) and the position of the flight control surfaces. In other words it is very much like a "conventional" aircraft.
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