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AF 447 Search to resume

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AF 447 Search to resume

Old 3rd Jun 2010, 21:44
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auv-ee

The French are already familiar with Dr. Ballard, and Paul-Henri Nargeolet has an opinion:

http://www.titanicfiles.org/Essays_e...%20Ballard.pdf

Thank you for that insight and reference.

In return, may I recommend you have a look at the following site regarding the HMAS Sydney and in particular the Volumes 1-3 of the outcomes of the search and find.

The Search for the HMAS Sydney II Report Available for Download - Official Press Releases

They were also searching in deep water but no where near the depth of water AF447 is resting .

Thanks again for providing that reference - it enables one to get a better understanding of matters.

Mike McInerney
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Old 3rd Jun 2010, 22:36
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cc45

BBC AF447 documentary June 2010 available on the web

zSHARE video - Lost - The Mystery of Flight 447 _30 May 2010__PDTV_XviD__.avi.flv
Anyone aware of an alternate site hosting this program? The video streaming from that site...well, at least here, isn't.
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Old 3rd Jun 2010, 22:42
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"Without doubt, the BEA search effort has gathered the best minds and resources to recover the hull and black boxes. It's simply one of the most difficult researches so far undertaken in this 21st Century."

I'm sorry but I could not disagree more strongly. The stipulation within the last tender issued that AUV's would be used for this search raised eyebrows amonst many involved in the subsea search & salvage industry.

An AUV is designed to fly over ideally a flat sandy bottom flying a pre programmed route using waypoints, ideal for a lengthy cable / pipeline / route survey. The terrain involved in the AF447 is about as far from ideal as you could get for the use of AUV's. The second factor being the battery life of an AUV and the time taken to submerge to 4000m, basically by the time it gets down there there is very little time left to actually do any searching before it then needs to start the journey back to the surface.

Basically the use of AUV's are a great way to spend a lot of time messing about without actually getting much searching done, I'll leave it at that.
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Old 3rd Jun 2010, 23:23
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Currents and debris NE of LKP

Failure to so far locate F-GZCP to the N, NE, NW, W and SW of LKP prompted me to revisit information on the currents and surface debris locations.

I'm well aware of mm43's analysis suggesting a location SW of LKP, relatively close to the area resulting of Meteo France's reverse-drift analysis, and until recently reinforced by the French Navy supposed pinger data.

A SW of LKP location is of course still not to be excluded, but one should beware of tunnel-thinking. Although BEA's recent stance that F-GZCP "has never been south of LKP" may equally be qualified as such, please consider the following:

Unless there was an immediate catastrophic event @ 0210 (other than iced pitots) there is little reason to assume that F-GZCP would be instantly that much off course that it could within 4 minutes end up at a location that would require (significantly) more than a 90° turn. To maintain heading would normally be a priority for a crew dealing with a series of events as it was confronted with according to the ACARS messages.

And if weather ahead would have required a change of course under those circumstances, it would make sense to turn the least possible. Given the N/NE course of F-GZCP, that would imply a turn to E rather to W.

Not only have two US reverse drift analyses suggested an impact point to the NE and NE/E of LKP respectively, also data of the Mercator model (used by Meteo France) do not exclude that.

I'm not privy to all data available to Meteo France used for their reverse drift calcs, but the Mercator based graphs I got hold of show that although on 27 May (closest I could get to 1 June) the prevalent current NE of LKP was E/NE, on 2 June the current was W/NW, while turning N on 9 June. US model based data are even more clear on a prevalent W/NW current.

Taken together this would IMHO not rule out that F-GZCP after its LKP initially pursued along its heading followed by a (relatively shallow/controlled) turn right and possibly ended up fairly E/NE near the 40nm search perimeter. We know that this area wasn't covered that well initially and certainly has not been covered recently.

Such an E/NE point of impact could also better explain the three debris items found in that area (see map page 37 of BEA's 1st interim report). Strangely enough these three debris items do not figure in the 1st interim report's annex 4 where a day by day location of the finds is given. So, unfortunately it is impossible to say when they were found and, equally important, what they are (in terms of how high or low they would float).


Dutch
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Old 4th Jun 2010, 01:13
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Gwillie

I managed to download it and have it shared in Winmx..
Also, you could watch/download it using the BBC iPlayer from their site
If you are not in the UK you will have to use a proxy IP..
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Old 4th Jun 2010, 01:21
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Dutch, the area E and NE of the LKP was searched extensively between June 2 and June 5, and nothing was found. How do you reconcile your hypothesis with the first body and wreckage being found W and NW of the LNP on June 6?
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Old 4th Jun 2010, 04:49
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It's available on usenet, for those of you familiar with that concept. In alt.binaries.multimedia.
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Old 4th Jun 2010, 05:55
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Hi,

Just tested and the streaming fom Zshare still available ....
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Old 4th Jun 2010, 06:15
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Originally Posted by Unusual Attitude
The stipulation within the last tender issued that AUV's would be used for this search raised eyebrows amonst many involved in the subsea search & salvage industry.

An AUV is designed to fly over ideally a flat sandy bottom flying a pre programmed route using waypoints, ideal for a lengthy cable / pipeline / route survey. The terrain involved in the AF447 is about as far from ideal as you could get for the use of AUV's. The second factor being the battery life of an AUV and the time taken to submerge to 4000m, basically by the time it gets down there there is very little time left to actually do any searching before it then needs to start the journey back to the surface.
I'm curious to know what alternative you propose and what its search rate and percent coverage would be in mountainous terrain. All other systems I can think of are tethered and have issues of their own.

While any search system works better on a flat bottom, AUVs have characteristics that make them well suited to this work:

1. I covered the search rate parameters in post http://www.pprune.org/5692187-post1029.html
It works out to about 40 square kilometers/day for double coverage by one vehicle. [BEA: 100sq-km/day/AUV, maybe for single coverage.] A claim of much time lost in vertical transit is simply incorrect. REMUS-6000 descends and ascends at an average rate of about 60m/min, so it can make a one-way excursion to 3500m in 1 hour. With a 20-22 hour mission time, 2 hours lost in descent/ascent, and a 2-4 hour turn-around at the surface, that yields 18-20 bottom hours out of every 20-26 hours. Even with the worst of those values, the vehicle is on the bottom 70% of the time.

2. When surveying the bottom, the AUV transits at 4 knots. All the towed systems I know of are limited to 1-2 knots in deep water, to prevent the cable drag from lifting the vehicle off the bottom. [BEA: Orion system is listed at 2kts. BEA also lists 100sq-km/day/towed sonar, probably using lower frequency, lower resolution, but longer range to offset the slower tow speed.] Perhaps if the entire cable is faired, then the speed could increase, but that would significantly increase the size and complexity of the cable handling system.

3. AUVs spend no time in turns (other than the few minutes it takes to cover the offset distance between survey lines). [BEA: 15min for AUV.] Towed systems follow the ship track with 30-60min delay in deep water, and it can take 6-12 hours to align with the next track. There are perhaps operating skills that could shorten that time, but it won't be minutes. [BEA: Orion system turn time listed as 3hr.] Turn time is to the towed system, as vertical transit/servicing is to the AUV.

4. AUVs can follow the bottom more closely in rugged terrain than towed systems, at least more closely than I have seen towed operators willing to attempt. Contact of a towed system with the bottom in rough terrain carries the risk of fetching the vehicle under a ledge and breaking the cable if the winch operator and bridge watch don't react in time. For an AUV, collision with a cliff is a survivable event. While no one plans a mission to include a collision, it does happen and it is recoverable, usually with the mission continuing as planned. Aside from a collision, an AUV can follow terrain at about +/-30deg (depends on the AUV). Certainly there are steeper parts in the AF447 search area, but a lot of it is within +/-30deg, especially with "terrain aware" route planning.

5. Multiple AUVs can be operated from a single ship, further increasing search rate for a nominal increase in day rate (cost).

6. Navigation of track lines is generally more precise with an AUV, because there is no influence from ship motion. This improves coverage (fewer holidays) and becomes especially important if the debris field of AF447 is ever found, when the AUVs can be used to photo mosaic the field.

After the wide area search and initial photo work are complete, then tethered systems will be needed to finish any detailed survey or recovery.

Certainly, towed/tethered systems have advantages too. The most obvious being that the sensor data is available in real time, and similarly there is much higher bandwidth for control of the vehicle.

Enough said. I'm ready to be educated about the system(s) you have in mind.

Last edited by auv-ee; 4th Jun 2010 at 13:26. Reason: I re-discovered BEA's May 17 presentation, having a table of search asset characteristics. I have entered the relavant items in [], above.
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Old 4th Jun 2010, 09:52
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Pitots freeze

BBC Investigative Documentary
The theory the producers chose to go for was roughly as follows.

......the A/C encounters super-cooled rain at –40C. Pitots freeze,....
How about using secondary navigational inputs on GPS based data?
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Old 4th Jun 2010, 10:28
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Originally Posted by D Bru
Unless there was an immediate catastrophic event @ 0210 (other than iced pitots) ...

And if weather ahead would have required a change of course under those circumstances...
The weather models suggest AF447 was inside the storm system @0210. They had reduced speed from M0.82 to M0.80 at some point. The final ACARS position report which probably reports the position at 02:10:30, shortly after the incident started, shows deviation West from the planned route, but with a precision that the BEA report does not appear to believe significant

AF447 ACARS MESSAGES
Code:
2:10:34#0210/+2.98-30.59
The full set of ACARS position (and turbulence?) reports do not appear to be in the Public Domain. There are clearly false reports which appear to give a location for the 2:10:14z message.

The BEA 40NM search radius would appear to assume less than 1 minute level flight plus 10,000 ft/min rapid descent - keeping airframe substantially intact, triggering pressure advisory below 8,000ft and end of flight less than minute later.

It seems to me most likely that loss of control occurred almost immediately, with one cascade of problems starting with the pitots - detected at 2:10, but possibly giving faulty data before?

Last edited by sensor_validation; 7th Jun 2010 at 12:21. Reason: Correction:- source attribution
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Old 4th Jun 2010, 11:50
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Hi,
Originally Posted by sensor_validation
The weather models suggest AF447 was nearly through the storm system @0210. They were already deviating some 10NM W of flightpath and had reduced speed from M0.82 to M0.80 at some point, so precise heading unknown.
a) sorry, but which weather model is suggesting that?
BEA (position) + Méteo France (0215 weather sat map) data -see reports- are showing that AF447 was close to the coldest part of this active CB system @ 0210 (and roughly half way - but previous meteo analysis from Tim Vasquez was showing the wrong position on the right map).
b) Where did you get this 10 nm W of flightpath?
0210 last know position was exactly recorded 2.94 nm W of flightpath with an error margin inferior to +/-0.3 nm (eurocockpit source):



Originally Posted by sensor_validation
The BEA 40NM search radius would appear to assume less than 1 minute level flight plus 10,000 ft/min rapid descent - keeping airframe substantially intact, triggering pressure advisory below 8,000ft and end of flight less than minute later.
... way too much reading into this estimation!
This 40 nm circle was drawn from day 1 barely without any data analysis and absolutely no wreckage to study: 5 mn of flight (ACARS transmitted) at speed inferior to 500 knots = 40 nm (= 5.000 square nm). Alpha zone (based on higher probability) was even extended near TASIL and the Southern part, passed 10 nm from LKP, was discarded.

Originally Posted by sensor_validation
It seems most likely that loss of control occurred almost immediately, with one cascade of problems starting with the pitots - detected at 2:10, but giving faulty data before?
It doesn't seem most likely at all -until someone will find where the wreckage is.

Probability that it was not discovered by sea scans inside already searched zones is currently very low (both pingers destroyed).
The most unreliable part of the search so far was the airborne SAR operation during the first six days due to the lack of adequate means (site distance, very few aircraft, no helicopters), inadequate weather (low clouds, poor visibility, rain, sea state), disturbance by floating garbage (high seas are full of floating debris), dispersion with time (floating stuffs -nearly fully submerged - finally covered a large area that made it very hard to be spotted from the air).

The probability that all three sensors were giving simultaneous faulty data before 0210 is many many times more unlikely (such an issue would more likely start from the ground). More precisely, it is almost ruled out by the fact that this pitot issue was detected in flight at 0210 and that relevant systems seems to have reacted as per design.

S~
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Old 4th Jun 2010, 14:10
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Certification

Hi Geoff,
You've got no answer as new post from new posters do not show up until a while and may be left unoticed. You did bring in a valid point:
Originally Posted by geoff sutherland
The second BEA interim report into AF447, (p62-67), identified 32 other incidents caused by or related to freezing of pitots on A330-A340 and also stated that the test/certification regime (JAR25) for those pitots was for a maximum altitude of 30,000ft.
Why is it that one of the most heavily regulated industries in the world allows almost all of its commercial operations to be conducted using a critical speed sensing technology that is neither tested nor certified for critical icing factors at the very altitude that almost all of their commercial flights are conducted.
Maybe they should limit all flights to within the certified envelope (30,000ft) and wait for the business out-cry to put funds into solving the problem
It is hard to make a very simple answer to this point as this is a very complex issue. I have read few papers on the subject and this may be summarized like that:

- Until not so long ago, about 10 years, most scientists thought that no ice/water particules of any dangerous size for aircraft sensors could be encountered at altitudes above 30,000 ft due to very low atmospheric temperature. There was several long haul airliner pilots testimony saying otherwise during specific flight conditions: oceanic flight over seasonal tropical thunderstorms or at proximity of them. The problem was that it could not be reproduced in laboratory. It has to be 1) to prove the phenomenon, 2) to develop some new probe certification process.

- In fact, almost all pitot events are taking place at lower altitudes on every model of pitots, causing a lot of accidents, mostly in general aviation. Airliners are supposed to be safe due to the constant care about this known issue as well as by multiplying their sensors and backup systems. But the risk still remain that those systems could be overwhelmed by conditions not reproductibles due to actual knowledge and experimental means. It is just not possible to take a sample of one particular atmosphere and to bring it into our labs without changing it. Conditions have to be re-engineered and this seems to be the core of the problem.

- Until AF447, known pitot issues encountered in A330-340 fleet (only) lasted from 5 to 20 seconds. After AF447, other incidents occured, including the other probe models considered less sensitive than Thales AA (Thales BA & Goodrich/Rosemount probes). Actually, it seems that the probe makers are working empirically on this issue, without exactly knowing what to change in order to fix the problem, and it is the same for the regulator. Nowaday, a lot of ressources seems to be affected in order to study very seriously this phenomenon. Some scientists are pointing that it may be caused by climate changes and that it is much more frequent, others that it always existed and was dismissed, but as traffic increased, its frequency increased.

S~
Olivier
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Old 4th Jun 2010, 15:06
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Slightly off the current topic, is it possible that they have found some of the wreckage with their current search, but because of logistical restraints they are unable to explore those sights?

BS
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Old 4th Jun 2010, 15:14
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Ignore me I'm sure Takata is correct re facts re location/storm - there was much discussion in previous thread and elsewhere about how quickly you can get down in one piece from 35,000ft, clearly not a gentle 20:1 glideslope?

As stated in the BEA report, pitots on this type of aircraft have a history of problems. The AA probe itself was introduced to replace inferior earlier models, and then early examples had manufacture QC issue with drain hole

http://ftp.resource.org/gpo.gov/regi.../2004_5788.pdf

This earlier incident on an Airbus quantifies the effect of pitot drain hole blockage for the probe in use at that time - is much higher/ faster much different in dynamic pressure?

http://www.aaib.gov.uk/cms_resources...pdf_501829.pdf

So drain hole blockage alone is sufficient to disengage autopilot/ thrust.

Having identical probes makes it easier to detect one outlier - they should all read the same - but why would they then not fail in same way when subject to same ice cloud?

Last edited by sensor_validation; 4th Jun 2010 at 15:41.
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Old 4th Jun 2010, 15:48
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Hi Bluestar51,
Slightly off the current topic, is it possible that they have found some of the wreckage with their current search, but because of logistical restraints they are unable to explore those sights?
Quite on topic!
They might have found something without actually knowing it (further data analysis may later reveal some possible traces of wreckage) but I don't think that logistical restraints would have been an issue. Those vessels were fully equiped for recovering any wreckage, or simply to verify any doubtfull spot at will.

For those interested, there is also some good videos about the search means used during this last campaign posted on BEA's site (three parts):
1.
http://www.bea.aero/fr/enquetes/vol....es.navires.mp4
English subtittles:
http://www.bea.aero/en/enquetes/flig...es.navires.srt
2.
http://www.bea.aero/fr/enquetes/vol.af.447/videos /premieres.plongees.operationnelles.mp4
English subtittles:
http://www.bea.aero/en/enquetes/flig...tionnelles.srt
3.
http://www.bea.aero/en/enquetes/flig...donnees.en.mp4
English subtittles:
http://www.bea.aero/en/enquetes/flig...donnees.en.srt
[in order to read the subtittles file with the video, save it in same folder with video, use vlc, mediaplayer classic, or any player with vobsub filter.]
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Old 4th Jun 2010, 16:10
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sensor_validation,
Having identical probes makes it easier to detect one outlier - they should all read the same - but why would they then not fail in same way when subject to same ice cloud?
Airflow related to probe has to be perfectly symetrical, which is barely never the case in flight, because they are on both side of the fuselage. The value displayed is a mean value of two or three pitot readings.
If one probe is failling to drain one kind of particule, it doesn't mean that it will fail to drain another kind. You'll have to know what kind of particule you are dealing with.
S~
Olivier
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Old 4th Jun 2010, 17:31
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Median or mean?

Originally Posted by takata
The value displayed is a mean value of two or three pitot readings.
Hi takata,

My understanding is that the PRIMs use the median value of the three ADIRU's, not the mean, except for the AOA where it uses the mean of #1 and #2, as explained in the ATSB report on QF72.

Regards,
HN39

EDIT:: As to displays: no averaging, see tubby linton post #1399 below

Last edited by HazelNuts39; 4th Jun 2010 at 20:36. Reason: system changed to PRIM; EFIS switching
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Old 4th Jun 2010, 17:53
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median of 3 (or bigger odd number) values is generally interpretted as you take the middle one when sorted in order of magnitude, without any averaging. This is sensible as it automatically ignores extremes and spikes values on any one channel. For even number you do average the middle pair. No difference between mean and median if you only have 2 values! A median filter also be applied to multiple samples over a time period, linear/ averaging filters tend to turn spikes into bumps.
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Old 4th Jun 2010, 19:11
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Hazelnut -efis switching for capt is -normal(sys1),then sys3 then sys2.
FO switching is -normal(sys2) then sys3 then sys1.
Reference fcom 1.31.50 p3
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