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AF 447 Search to resume

Old 30th Oct 2010, 19:30
  #2301 (permalink)  
bearfoil
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JD-EE

I would ask assistance relative to ACARS at this point. The data made public shows first the auto pilot disengage. Soon after, TCAS, ADIRU discrepants, a/s unreliable, etc. If the a/c upset, causing a/p loss and AirData problems, do we assume that the SAT antenna could remain serviceable throughout the ACARS stream? TCAS is Altitude reliant, where is its "antenna"? My question first off is could ACARS have been accurate through a stall, roll (>60 degrees), etc.? The possibility of ACARS loss, is it attitude sensitive? Could ACARS have been interrupted for the last time at cruise Altitude, to include Stall?

Next, re: your note of lack of comm, ID, PR, etc. Is that possibility consistent with unserviceable antennae? My recall has the HF antenna in the VStab, is that correct?

Boeing 747 has at least two airborne loss of VStab, one included the loss of the entire tail. One of these, a JAL I believe, remained airborne for some time before impacting a mountain (Fuji?). So the question is twofold, and probably would require some input from AB airframe specialists.

Can the 330 remain reasonably airworthy w/o VStab? If the VS separated, the radios are lost, yes?

Yaw is not consequential relative to the importance of Pitch, until Directional control is completely lost. Yaw is a trimming consideration, kept inside its limits. Pitch is critical to controlled flight, whether through loss of Pitch trim (or even its partial compromise), or compromise of elevators, flight without a VStab/Rudder is demonstrable, in the record.

ACARS (provenance). The release of ACARS data was without approval of the Airline, as I recall, although "Lightning" and "Fortes Turbulences" were offered immediately through PR sheets, I believe. Does this compromise the reliability of the data itself? Probably not, as the Airline later co-operated with BEA to help translate the data for its initial report.

In the interest of brevity (!), I would comment on the "Stain" briefly. The chevron shape wants an explanation, Anyone? Whether the mass (fuel?) deposited in one location and diverged, or was lost in two locations and converged, current considerations plus its rapid Satellite disclosure are compelling; it suggests strongly that the wreckage is beneath its "unwound" lat/long, no? Here, I believe mm43 has let loose the Tiger. What was the current heading? Does it suggest a particular a/c aspect at impact? A relook at all the recovered debris, as BEA is accomplishing, with a consideration of a data weighted impact point (?) will hopefully suggest a more focused area of exploration.

There are some interesting suppositions relative to location of victims, debris, and their condition that would follow.

bear


edit. Inertial reference data. The 330 is a large a/c. Relative to the location of the Inertial installs, is it not possible for each unit to sense differing a/c motion? In upset, would the IRU's send very different "interpretations" of the a/c's 'aspect'? Could unreliable airspeed have been joined with unreliable IRU's? My apologies if this is a sub intelligent query.

Last edited by bearfoil; 30th Oct 2010 at 19:43.
 
Old 30th Oct 2010, 21:23
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mm43, by the time they changed over their selcal to Africa they were effectively out of range of VHF communications, as I recall. Let's see, it was about 350 miles from the mainland and 200+ miles to Ilha Fernando de Noranha, the closest sizeable island. The mainland was completely out of range. The island was 140 miles away and VHF range from a 35,000' aircraft and a 200' tower is about 240 miles. So at their speed they had, at the crash site, about 15 to 20 minutes worth of increasingly poor VHF communications and HF communications that were extremely noisy with lightning static (QRN). Based on some short wave listening I've done on aircraft frequencies they do not SEEM to work out to the extreme VHF ranges. So the switch over makes sense EXCEPT that they did not assure their HF link was working. That was bad communications discipline on their part or a very poor set of standards they were following. Of course, I tend to assume "it's going to break when it will hurt me a lot." They followed a pattern supported by an assumption that it's going to work so no communications is no big deal. Usually that attitude is good. I prefer an "always" philosophy, myself.

"Bear in mind that ATLANTICO and DAKAR don't share the same HF suite of frequencies,..." Of course not. Otherwise they'd spend the day talking to each other or at least interfering with each other. {^_-}

I can understand switching to DAKAR, calling, getting no response, presuming they are busy, and waiting a few minutes to try again. After the second time "a few minutes" becomes one minute. After any third try I'd be asking nearby aircraft, on VHF, to relay for me. Maybe that attitude is why ham radio operators tend to get disaster communications through when everything else fails if there is a ham radio operator around.

"Remember the failed auto connect on ADS-C doesn't necessarily indicate cockpit activity or not." And that observation agrees with my comment that the event tree needs to step back at least that far when creating branches. I don't believe any of the ACARS messages really indicate an alive and aware cockpit crew, either. Although I'd suggest the communications break followed by recovery MIGHT indicate a severe attitude change and recovery indicative of somebody at the controls.

The CVR might have enough recording on it to probe backwards on this.

As a comment, it may be that the ADS-C carries automation a little too far, at least for my tastes. And usual (if not standard) cockpit practices don't put any form of premium on being in communications at all times possible. (That might even mean an Iridium phone in the cockpit over some parts of the Pacific Ocean and Antarctic routes. Color me paranoid. When things pickle I don't want to have to fumble around setting frequencies and hoping I have communications. It'd be nice to know as many of the remains of the PX would be recovered for repatriation as possible. Heck, in this case active communications might have allowed a wider detour around the bad weather spot leading to no crash at all.)

{^_^} (As a side observation note that the modern US military seems to operate on a "communicate first then act" basis now that they have very ubiquitous and nearly pain free communications at "amazing" data rates even on HF. As an engineer with over 50 years of experience in communications that in itself is a reward for my career.)
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Old 30th Oct 2010, 21:55
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Bearfoil, I remember calculating or at least generating a good estimate of the "beamwidth" for TCAS. With no satellite tracking a 45 degree or so banking turn to the left would break the beam. A heavy bank would mean TCAS could not maintain track, even though it has some beam steering capabilities. The fuselage would shadow it.

This question and mm43's observation about automation really starts me wondering if something happened to the crew way back shortly after the frequency/selcal switch. If they were out of action and the AP kicked out what would the plane do in severe turbulence?

(But, there are indications that between the pickle point and the ocean surface the plane's attitude did not switch such as to start dumping stuff on the floor such as a severe roll without a turn. This idea is out there to be shot down. {^_-} It helps build the event trees.)

I believe the VS does include the HF antennas. I believe VHF is on the fuselage and would still be present. (Experts know better than I. I've misplaced the antenna position plots that have been posted here.) And 121.5 is supposed to be continuously monitored by everybody in the air and on the ground concerned with aircraft in flight operations. Of course, even with the VS present they were effectively out of HF communications. No SWL, Short Wave Listener, has come forward with intercepts of their attempts to communicate, so far. And I don't know of DAKAR maintains days long recording logs BEFORE the selcal squelch of everything received on all their assigned frequencies. I doubt it. If there was such a log it might be illuminating. Otherwise HF is out of the picture here. (And if they called nobody would have heard - everybody else would have had their own selcal on for noise reduction.)

With active pilots present anecdotes indicate control is possible. Severe banking turns may become "an adventure", however. (correct me if I am wrong) If that is the case the plane should have been found since it would have flown at least far enough to end up in the areas already searched, I believe. That is probably why they were searched. It's not reasonable to presume the plane turned back either voluntarily or through some series of misfortunes.

The chevron shape? Well, wind sheer exists. Why not ocean current sheer? That is one hypothesis.

Regarding the IRUs I'm dragging out some old GPS knowledge here. Position is known relatively precisely depending on the GPS equipment involved. GPS alone can provide good estimates of long term velocity and crude to very crude estimates of attitude, velocity, and acceleration over short intervals. If the position error is say 5 meters and the sensors are 100 meters apart you can calculate for yourself the likely attitude errors from GPS alone. Also note that the position is not that if the receiver. It is the position of the antenna. A GPS receiver on a 100' cable to an active antenna can demonstrate this. Move the receiver around relative to the antenna. The position does not change by 200 feet or even 30 feet as you move around the extreme perimeter allowed by the cable.

This attitude issue is the part of the navigation solution the IRUs are designed to provide. And it is known that their sensor positions affect their data relative to the vehicle. So that is entered into the calculations (at least on military sets I know about.)

Where my knowledge leaves off is the dynamic range of the various IRU sensors when subjected to sudden high accelerations. If a sensor bumps its limits it's suddenly useless. Also note that in the dark at night with no radar to find a real horizon there is no way to distinguish gravitational acceleration from any other acceleration. So you probably lose all sense of precise attitude if a sensor hits its limits. So an intact aircraft and healthy aware crew can suddenly find themselves in the terrifying position of flying blind without even reliable seat of the pants observations if too many of the old crude instruments have been eliminated.

{^_^}
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Old 30th Oct 2010, 22:42
  #2304 (permalink)  
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TCAS is a passive alert/report re: traffic, I think it isn't connected via satellite. ACARS is, and so I would still ask if the a/c had accomplished a 180 and subsequently entered a dive of 30 nd, would that trip the 45 degree signal for a half minute perhaps?

I know the a/p has a limit in roll of 45 degrees each way, and a p/u of 9 and p/d of 13, for a total possible excursion in Pitch of 22 degrees. The Roll is 90 degrees of limit; I do not know if the point of disengagement (automatic, or "involuntary") has components of rate or g limit in either plane.

Lack of activity during (scheduled) radio reporting? Perhaps, but radio if intermittent or nonexistent quickly loses its attraction for a pilot in weather. The lack of 121.5 is alarming, if the ride was as exuberant as can be imagined by us. Incapacity of the crew is suggested only, it hasn't a whole lot to back it up. Distraction is perhaps a more believable event(s), for the element of surprise is there in ACARS, as is a trail of ever increasing criticality over the four minutes it reported. Direct Law at altitude and speed should get more than a little interest here, the possibilities are disturbing, RTLU notwithstanding, imo.

I think even the lav entry in ACARS should not be overlooked. As I recall, even the RTLU was Fail, its report didn't necessarily mean that it was working properly to limit Rudder travel, No? A loss of Hyd.? A loss of indexing in its sensor that mimiced serviceability? As found, there was no way to determine the sequence of fault/fail, but it was reported as found in 8 degree limit? That finding has no bearing on when the separation from the airframe occurred. One wonders what was found in the remaining lines, whether all fluid, fluid/water, or foam. Hydraulic lines can communicate whether they "drowned" or not, as can human lungs.

121.5 is extremely germane, as you have said!

edit to add: The working theory for BEA is most certainly logical, it is also to be taken with the bulk of the evidence. To land "forward" with slight Pitch up, and a robust vertical acceleration is quite possible. It also contravenes the body of evidence taken from ACARS, and the relative condition of recovered debris. The debris is a very long discussion, there is a great deal left unaddressed here (believe it or don't!!)

bear

Last edited by bearfoil; 30th Oct 2010 at 22:58.
 
Old 31st Oct 2010, 00:16
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JD-EE
... by the time they changed over their selcal to Africa they were effectively out of range of VHF communications, as I recall.
To refresh your memory - here is an abbreviated version of events:-
***************
01:31:44z, the RECIFE VHF controller gave AF447 the ATLANTICO HF frequencies: 6649kHz (primary), 5565kHz (secondary), then 6535 kHz after the TASIL. The crew read back the three frequencies.

Note: TASIL is the boundary between the ATLANTICO and DAKAR Oceanic FIRs.

01:33:25z, the crew contacted the ATLANTICO controller on 6649kHz.

01:35:15z, they informed the controller that they had passed the INTOL point at 0133, at FL350. They announced the following estimates: SALPU at 0148 then ORARO at 0200. They also advised their SELCAL code: CPHQ.

01:35:26z, the ATLANTICO controller coordinated flight AF447 with the DAKAR controller.

01:35:32z, the ATLANTICO controller transmitted the following items to the DAKAR controller: TASIL estimated at 0220, FL350, Mach 0.82.

01:35:38z, the ATLANTICO controller sent a SELCAL call: CPHQ.

01:35:43z, the crew thanked the controller [assume that means, "SELCAL checks"].

01:35:46z, the controller asked them to maintain FL350 and to give a TASIL estimate.

01:35:53 ~ 01:36:14z, the ATLANTICO controller asked the crew three times for their estimated time passing the TASIL point. The crew did not answer.
***************
"Bear in mind that ATLANTICO and DAKAR don't share the same HF suite of frequencies,..." Of course not. Otherwise they'd spend the day talking to each other or at least interfering with each other.
There are limited Aeronautical HF frequencies available, and most oceanic FIRs share some if not all of the adjacent FIR's frequencies. RECIFE CONTROL operates remote VHF tx/rx from Fernando de Noronha (SBFN), and the SSR at SBFN is available to the RECIFE/ATLANTICO controlers (both in the ATC Recife Control Center). The ATLANTICO HF equipment is located near Natal (from memory). SSR was lost at around 0145 - 250NM from SBFN and VHF would have been marginal a few minutes later.

The talk of heavy QRN on the night in question is rather doubtful, as there has been no mention made of it by the BEA in their Reports, and no one to my knowledge has offered up any tapes to confirm it one way or the other. The only paths that matter are the a/c to ATLANTICO or DAKAR HF facilities.

AF459 reported -
On leaving the ATLANTICO FIR, through the TASIL waypoint, the crew attempted in vain to contact Dakar control in HF on the 5565 KHz and 6535 KHz frequencies, and on the other HF frequencies given in the on-board documentation. Likewise, the attempted ADS-C connection was unfruitful.
Strangely, they haven't made mention of static, and propgation or distractions at DAKAR could be the reason for the difficulty in making contact. In fact, it appears that 5565 is common to both FIRs and ATLANTICO gave AF447 the 6535 frequency, to get them "out of earshot" beyond TASIL.

Satellite observations reported no sign of lightning in the area during the critical period, i.e. 0200 ~ 0220z.

So in summary, the comms procedure with RECIFE/ATLANTICO was correct, and AF447 wouldn't normally be expected to call DAKAR until approaching TASIL, and if ADS-C had been established, DAKAR would give them a SELCAL check on HF along with further calling instructions. None of the final bit happened as the a/c became involved in some unscheduled events.

mm43

Last edited by mm43; 31st Oct 2010 at 00:34.
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Old 31st Oct 2010, 00:57
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So then comms were as expected. This leaves 121.5. There was Lufty, and AF459?

If this offends, please forgive me. I do business with many French, and we have many French family members. A Frenchman, even in struggle, is loathe to ask for help. 121.5 is exactly that. MayDay! is anglicized French, M'aider, M'aider!! Help Me!!

I'm sure it does not pertain here, given the surprise of auto pilot loss, and the (assumed) attendant weather related challenges, things were most likely very pressing. However, we are left with inop Tx or dreadful workload. Is there another? Distance?

bear
 
Old 31st Oct 2010, 05:09
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Pattern Matching

Here is my best guess on the cusp shaped POL spill mapped by the satellite at T+30 hours.
First, it would be incredible that AF447 would not leave behind a POL mark on the surface. The image is close enough to the track, and the scan encompasses enough area to almost rule out any other spills as being derived from AF447. Note: This post continues below the first picture.

This image has a heavy deposit which appears to have moved SSW from the apex and which curves a bit. My interpretation of this is that the wind has carried some of the spill from its initial position and the curvature represents the effects of wind direction changes. The thinner branch of the spill which points SE is more interesting though. This branch probably represents fuel released from the wreckage after its arrival on the bottom. The ocean currents appear to be from the SE and are pushing the initial spill to the NW.Looking at the SE branch, the North side is relatively straight, the South side also shows the effect of wind pushing some of the POL to the SSW and so is a bit "blobby."


In an effort to establish what a spill from deep underwater might look like, I found some information on the DeepSpill sea trial carried out in the Norwegian Sea at the Helland Hansen location in June 2000. During this trial, various types of Petroleum products were released from a test platform on the bottom. The SLAR image below is from that sea trial. Can you see the similarity with the SE leg of the cusp in the first image? The Sea Trial report is somewhat lengthy. The current directiion and wind direction so derived from this spill's motion may conflict with official data but the official data is highly suspect in my mind.
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Old 31st Oct 2010, 06:03
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bearfoil, my mind skipped a beat on the TCAS. I meant ACARS. It's antenna has a wide beamwidth and can steer. How well it tracks on turns with steep banks I don't know. I figure it would take nearly a full aircraft roll well past 60 degrees bank for a turn to the right to cut off communications until near the end of a 180 degree turn. A left hand turn would be shadowed sooner for a satellite to their East along the Equator. That might go out with a 45 degree bank at a rude guess. That's if the antenna steering gets aiding from the navigation systems' turn and bank sensors as well as the position data. Otherwise a rapid bank could bring the beam too far off the satellite at about 30 degrees bank for a turn to the left.

Once the situation had pickled silence on 121.5 indicates a very busy pair of pilots. And I am so communications oriented I tend to scratch my head excessively (no, no dandruff {^_-}) over the lack of affirmative attempts to get into communications with Dakar. That just "feels wrong." I probably dwell on it too much. About the only explanation IF being in communications was seen as an imperative, is two incapacitated pilots at the controls. And that's too much of a stretch.

If they DID have communications they could have cried emergency and given their "exact" position as the altimeter unwound. MAYBE somebody could have been fished out of the drink. (Indications are that would not have happened. But, a priori the pilots would not know they could not plant it without breaking it.)

mm43, there is a good argument that things started to go sour right around the time of that confirmed SELCAL test at 01:35:43z. As soon as the end of that transmission something bad may have happened OR they changed to DAKAR and never bothered to reestablish communications.

Regarding frequencies, limited is quite true. At least enough are available that what is audible from here near ONT indicates frequencies are not "shared" within rather large radii. And they do pick frequencies that suit the required communications distance. 5MHz is a band that can perform on extremely long hauls as well as close in. At night it would open up for "thousands" of miles, even in the solar minimum. Although during the recent solar minimum that might have been very near the maximum usable frequency for F2 bounces and that only to very great distances. That's a period I heard 3.5 MHz go numb some nights - usually well after 2400 local time. I am presuming the frequency choice was made intelligent. That's well understood by the people involved.

Finally someone mention something about nominal comms procedures. I am surprised it's appropriate to have a plane on a modestly busy traffic route out of communications for any significant period of time. (I'm only half surprised that there are not two HF receivers with appropriate TR switching so that both ATLANTICO and DAKAR could be monitored at the same time. That might be deemed "expensive". But for receive only not much is needed except the T/R switching to protect the second receiver. And mumbling off topic from my experience the military Automatic Link Establishment protocol could easily be bent into automatic link establishment for aircraft. It's a digital mode that sounds like polite turkey gobbles. It's designed to find optimum frequencies for communications dynamically in real time..)

Machinbird, released from the bottom and bubbling up to the surface in a sharp edged pattern as shown seems improbable to me. I'd expect more dispersion from the random direction changes bubbles experience on their way up. So I'd want to see some information about kerosene releases at that depth to be certain. The length of that "tail" is about right to my intuition. The width seems too narrow. I don't see a scale, for comparison, on the lower picture. Nor does it indicate the depth of release or the hydrocarbon fraction leaked. Heavy bunker oil will certainly remain more coherent on the way up than a lighter fraction like kerosene.

{^_^}
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Old 31st Oct 2010, 16:02
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My question relative to rate of Roll, Rate of Pitch, and the autoflight wants a look. Within these limits is allowance for a large amount of "Upset". Not in the sense of Stall, more along the lines of rock and roll cockpit (Cabin).

Two things come to mind. One, is the air mass producing accelerations in the cockpit that would challenge normal ergonomics? Well belted (Tightly, as these two pilots must have adjusted to the turbulence), was the action preventive of normal arm, leg movements? If it was, perhaps there was another concern (bear with me). What is the FP's choice given such local "g" challenges. Obviously aware of the a/p's "drop zones", was he sufficiently confident in the automatics continuing the flying such that he made a decision not to deselect? This is important, and goes to a/p in turbulence or in a cell. Involuntary drop means Alternate Law, retained protections, etc.? Does he weigh this against the possibility of Direct Law? I think once in Direct Law, Normal Law is not available until ground re-indexing. Is the choice as simple as continued autoflight in turbulence v. the possibility of having to hand fly in crap?

Re: 121.5. A pilot would be less inclined to announce a current position perhaps, if he thought continued flight was possible, especially if he was loaded up to the gills with alerts, a busy screen, and maintaining control. Control is Black and White under the conditions, you keep it, or you Ditch, maybe, but someone (many) will be hurt or perish with loss of control. Did he choose continued a/p? Or was the upset sudden, and decided for him? Perhaps I can help ease your concern re: comms. Given the result, and the likely need for heroic measures, a pilot simply isn't thinking about talking, except to his mate. (Meaning F/O).
 
Old 31st Oct 2010, 16:58
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POL

Machinbird: I don't trust my own arithmetic to scale, could you give an estimate for the length of the 'legs'? Also, presume the starting point on the test spill was the 'SW' extreme (spill streaming from SW to NE as it were). Is that correct in your view ? If so, doesn't this make it hard to interpret the mysterious slick ? Thanks for your work BTW.
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Old 31st Oct 2010, 19:01
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Mr. O...

Taking the inherent problems of pixelation into account, the slick (at the time of the image) is:

Length of longest "arm" (SSW / NNE orientation): +/- 1390 metres
Length of other arm (SE / NW orientation): +/- 1280 metres
Width at widest point (W / E): +/- 1300 metres

grizz
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Old 31st Oct 2010, 22:20
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G, thanks

If it is T+30 hrs that's an awfully slow dispersion speed isn't it and the sea state must have been quite rough given the weather. Hmm.
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Old 31st Oct 2010, 23:30
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Mr. O

Exactly my thoughts re the dispersion rates. Seems v e r y slow. Having said that, there are possibilities that could account for that.

Machinbird: Can you confirm the "T + 30 hours" time of the sat photo. I tried going back to find original references but wasn't successful.

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Old 1st Nov 2010, 00:27
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The dispersion rate is not ipso facto slow. At the point of origin, there are several factors to consider. The first is that the fuel wants to get thinner, and increase in area. After days, the film would be a good deal larger in area, and perhaps be mostly at its most stable depth: 2-3 mm. Immediately upon entering the sea, it is thick, never to be "deeper", However, it is also a stable mass, with integrity and a stasis point that will see it behave as if it were a floating ship. Only the top portions are affected by wind, the mass gives up its most shallow parts first. The body will have to deplete somewhat to reach its "largest/thinnest" state. Keep in mind that the part of the slick that is the oldest, is furthest from the origin, the mass left at the impact point would move with the current, slower rates than the prevailing wind. The smallest, sharpest point of the slick is the original impact point, that point at which the entire mass fell in to the sea, its weight overcoming its buoyancy almost completely. Consider the origin as a "smokestack", a source for the slick that immediately starts to widen as it disperses into a thinner and thinner layer.

Let me add at this point that I do not think the slimmer arm is fuel that surfaced after deep submergence. Instead, I believe it is simply a surface deposition that comes from a smaller (in volume) source. The most southerly points are the arrival at the surface of two separate volumes of fuel that originated with this aircraft, but from different areas of the airframe. The larger volume is perhaps most likely the area where both wings impacted, the smaller volume the area where the Horizontal Stabilizer hit. The HS contains roughly eleven thousand pounds of kero when full, the trim tank is assumed to have been loaded fully at this portion of the flight.
If the fuel simply sank a bit to ascend perhaps a thousand metres away, there would not be such a focal deposit of fuel. It most certainly could not have sunk far further, kero rises in sea water far slower than air bubbles, and air bubbles could take several hours to surface from 8- 10 thousand feet. I also believe that if sunk, the kero mass would not have remained small, it would branch into several rivulets, to appear at the surface in a far larger deposit, and much thinner in depth.

This of course is in conflict with BEA's initial conclusion of "En Ligne de Vol" and intact at impact. So be it.

If I was unclear, consider: the mass of fuel beneath the surface is drifting with the current, unaffected by winds, the increasing surface area is drifting and being blown by the winds. This is an additive that must be resolved to further pinpoint the impact point. In other words the distance from impact is not the length of the arms, it is the length of the arms Plus the 'current'.

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Old 1st Nov 2010, 00:27
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HF-sets

Excuse a comment from a non-aviator/ but one who directed safety related research in the nuclear field for may years before retiring:

I have been following this string for a long time now, and much of the reasoning is very interesting also in a broader context.

According the first interim report the aircraft had two HF-sets (Tx/Rx). One way both could be down is if their connection to the HF-antenna in the VS failed in some way. This could possibly hint at some emerging problem with the VS-connection to the main airframe (however this is a very long shot). I have been thinking about the accident with PartnAir long ago where some strange symptoms were seen earlier - but ignored.

Regards
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Old 1st Nov 2010, 00:44
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Diversification

That is a powerful and important point. The HF antenna is in the leading edge of the V/Stab, I believe about two metres up. Without calling it a "Long Shot", I would suggest the damage could have been caused by a loss of the Radome. The leading edge of the V/S is perennially pock marked with debris, ice, hail, birds, etc. The photo of the a/c taken just before the fatal flight shows evidence of this. Radomes are notorious for damage, after all, they lead the pack of the entire airframe. I think lightning is a long shot, but there are numerous occasions where the radome is shattered or even lost after a strike. The fact that they are constructed of composites (Non-Conducting), makes them even more prone to damage from an electric charge. Electrons get pissed when they have to "walk" instead of following a suitable metallic path.

rgds'
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Old 1st Nov 2010, 01:10
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The time factor is interesting to contemplate. I'd also recommend bearfoil go looking for satellite images of the BP oil spill and the area around the rig shortly after the disaster. The oil coming up from 5000' was spread around an area of as much as 5000' in radius judging from the size of the ships trying to control the spill as it got to the surface. With AF447 we're talking about 15000' give or take. And we're talking about a lighter fraction which would rise quicker. So I'd expect pretty much the same roughly oval or fan shaped dispersion from fuel released from AF447 from the bottom, if any was. Of course, the fan shape would be filled in between its legs.

One other thing to consider is "why was the plane THERE rather than somewhere 'more logical?'"

A look underneath that spill may be in order. But, I suspect we're making more of it than exists and stretching too far for explanations. You're making some good points. I made a point worth checking but probably not entirely germaine to a solution for AF447 so you could see someone else what I perceive you doing. I certainly did not cross all the Ts and dot all the Is in the discussion of 121.5 and I stretched a little a times by way of demonstration. (Please forgive me guys.)

And regarding roll rate, as long as the roll itself stays under maybe 30 degrees to 45 degrees either way the antenna won't care. It's beam width is rather wide at the 3 dB (half power) points. It MIGHT matter if something else already made the path loss close to allowed margins. My INMARSAT experience is with the M equipment, not aircraft equipment. Among the INMARSAT specifications there are words about transmitter power management and minimum user equipment maximum power capabilities. M had pretty significant margins. From the West Coast of the US I was able to use the Atlantic satellite for testing quite nicely. It was about 15 degrees above the horizon so I was in a self interference zone from multipath signals bouncing off the ground. Margins were sufficient to make the link work even in pretty dreadful weather. (Yes, it does rain in Torrance California sometimes. My poor Beetle nearly floated away from one storm.)

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Old 1st Nov 2010, 01:23
  #2318 (permalink)  
 
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Good point, and it supports some of bearfoil's observations. And two radios suggests either poor discipline, some official use for the second transceiver (emergency channel monitoring near 2 MHz?), or bad procedures. One should have been left on the old selcal and frequency while the other was tuned to DAKAR, the anticipated next configuration. "Why in heck didn't they hear the last few calls from ATLANTICO?" If something had already weakened the vs attachment bearfoil's scenario becomes a little more realistic. (The shape of the tears still seems a little "off" for the VS departing the plane at altitude, to me.)

The electronics should have reported a fault. I wonder if the fault would be reported in such a manner that the pilots would associate it with a problem in the tail structures. Somehow I doubt it. But as soon as the TX button was pressed on one of the transceivers the fault would be instantly reported - SOMEWHERE - if the antenna connection was becoming "ratty". Even modest power transmitters (25 watts and more) REALLY hate operating without a proper load. They have protection circuits to cut off the transmit power and save the output transistors from losing their magic blue smoke.

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Old 1st Nov 2010, 01:44
  #2319 (permalink)  
bearfoil
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Ah, Torrance. Lived with my cousins for a spell in PV. About the time the Dominator went aground. Marineworld, skateboarding, ah well.

A place more "logical".Hmmm......... If the crew were merely hanging on and allowing Otto to fly, the upset and Otto dropping may have been concurrent. The a/c did upset.
The a/c was in a "vicinity". The last RP was, etc. etc. My point is that logic is not at this point the priority. It is in entertaining the Possible, that when combined with the evidence available, produces the logic we seek. When new evidence appears, do we regret the leaving behind of a pet "Theory"? Absolutely not, We propose, we think, we destroy, and move along. If the boxes remain unfound, the existing evidence will be the foundation of an "educated" guess.

The crew rest module suffered a total destruction, the Galley tower and kitchenette barely look damaged. It is as if they came from two separate a/c. The spoiler is beaten to a pulp, the elevator looks like it snapped off and landed lightly on the surface. The VS has been done to death. Looking for results (logic?) prior to eliminating all the possibilities is simply not done, or is it? A path of 30k feet (down to the Bottom and back up) is six miles. The HS (both) was intact? because if not, fuel doesn't sink then rise again in a compact column, it simply doesn't. The only difference between the focal fuel deposits to me is their size (volume). I simply suggest that it would appear that the two origins were created by two different impacts.

The provision of a working theory in haste is not unknown, it is at all times an obstacle to further discovery. "Conclusion bias" it is called. It is amateurish. A great deal of what I have been on about has to do with pointing out the bad practice of "establishing a lead". Walking down a road without a map or compass gains nothing.

It discourages further research, and blocks the Truth. Who would do such a thing?

fellow coastie,

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Old 1st Nov 2010, 01:48
  #2320 (permalink)  
bearfoil
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AF447 launched without a complete suite of radios, remember. They were compliant, but a review of MEL might ignite a new spark, as it were.

bear
 

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