AF447
I don't own this space under my name. I should have leased it while I still could
The only possibility for F-GZCP to reach such a remote place, considering her flightplan, was to make a 180 turn East. [/QUOTE]
I agree.
I made a similar assumption some days ago, either in a PM or on the board. The only thing I would add is:
a second plot analysis for wind affected debris might give an additional coroborating position.
takata,
Very good investigative work! I think you also need to take into account that the human body does not float in seawater until about 72 hours after death. Then there should be some allowance for the time from establishing positive buoyancy to float from the wreckage at the bottom of the ocean up to the surface. Again some allowance should be made for the average sea current during the ascent time (unlikely to be the same as the surface current). So finally it could be possible that the surface drift time before discovery of the first body could have been less than 24 hours...this might put the wreckage very close to the flight plan track?
Very good investigative work! I think you also need to take into account that the human body does not float in seawater until about 72 hours after death. Then there should be some allowance for the time from establishing positive buoyancy to float from the wreckage at the bottom of the ocean up to the surface. Again some allowance should be made for the average sea current during the ascent time (unlikely to be the same as the surface current). So finally it could be possible that the surface drift time before discovery of the first body could have been less than 24 hours...this might put the wreckage very close to the flight plan track?
Per Ardua ad Astraeus
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takata - congratulations on some excellent and thorough work. I did ask 'the experts' a day or so ago which choice - continuing ahead or turning back through the weather - would be likely vis a vis ETOPS/fuel etc. and have had nothing back. Instinctively I think your 'turn-back' looks like a very likely scenario. Even your projected radius of turn is plausible.
I'd still like to focus on what was LEFT on the instrument panel for them following the known ACARS messages; whether there is some common electrical supply issue that could have caused these failures and whether there is a common 'software junction' in it all. What did the ?Air Caribe? have left in their incident? I cannot find any detailed report.
I'd still like to focus on what was LEFT on the instrument panel for them following the known ACARS messages; whether there is some common electrical supply issue that could have caused these failures and whether there is a common 'software junction' in it all. What did the ?Air Caribe? have left in their incident? I cannot find any detailed report.
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Very impressive Takata, but your plot assumes that bodies float on the surface. My understanding is that the buoyancy of bodies is highly variable, depending on the quantity of air in the lungs, and the ambient temperature. Often we sink, then, as our bacteria in the digestive tract and elsewhere continue their work, and generate gases, we float. So bodies aren't necessarily a faithful reflection of the surface current either.
--Edit: Flexible Response beat me to it!--
--Edit: Flexible Response beat me to it!--
ttcse
I think that ttcse is correct. Beyond a certain depth, a body is unlikely to ever return to the surface, due to the very high pressure exerted by the depth of water.
FlexibleResponse
Quote:
Then there should be some allowance for the time from establishing positive buoyancy to float from the wreckage at the bottom of the ocean up to the surface.
About 'the bottom of the ocean' part... given the extreme depths in that area and how much air cavities (& their gasses) compress and crush going down there, I would wonder whether those victims who actually went to the bottom could be refloated even after 72hours. For what it's worth.
Quote:
Then there should be some allowance for the time from establishing positive buoyancy to float from the wreckage at the bottom of the ocean up to the surface.
About 'the bottom of the ocean' part... given the extreme depths in that area and how much air cavities (& their gasses) compress and crush going down there, I would wonder whether those victims who actually went to the bottom could be refloated even after 72hours. For what it's worth.
Bodies don't always come back up
Here in Ontario, Lk. Superior is known to keep its bodies because cold water temperature prevents gas formation.
Bodies do tend to come up in Lk. Ontario when drowned near shore, but those lost well offshore may not. One sad Spring night several youths took a small overloaded boat out of a marina for a joyride. Not a single body ever came up -- even though the Ontario and New York shorelines were thoroughly searched and several items from the lost boat were washed to the NY shore.
As to the present case, people strapped in in fuselage sections that went to the bottom would be in water too cold for gases to form.
In the cases of bodies that have appeared on the surface, I suspect that they initially sank to an intermediate depth where the temperature was warm enough for gases to form.
Bodies do tend to come up in Lk. Ontario when drowned near shore, but those lost well offshore may not. One sad Spring night several youths took a small overloaded boat out of a marina for a joyride. Not a single body ever came up -- even though the Ontario and New York shorelines were thoroughly searched and several items from the lost boat were washed to the NY shore.
As to the present case, people strapped in in fuselage sections that went to the bottom would be in water too cold for gases to form.
In the cases of bodies that have appeared on the surface, I suspect that they initially sank to an intermediate depth where the temperature was warm enough for gases to form.
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@takata
@takata
Nice work putting together the graphics. In your analysis you discounted the effects of wind condition on the drift of the bodies. I think this is a miscalculation. While wind conditions won't affect flat objects in the sea, like it would a floating galley for example, the wind does influence the wave action. Wave action, in addition to current, would determine direction and distance of floating objects. Thus, your conclusion of probable crash site can't really by determined from the floating bodies position at time of recovery. Theoretically, a computer program might be able to calculate float direction and speed from many samples of wind direction/force and current condition over 5 days. Often the wind direction is opposite of current, creating different wave forces then when wind and current are in the same direction. It's too complicated a model to figure out without the help of supercomputers.
Nice work putting together the graphics. In your analysis you discounted the effects of wind condition on the drift of the bodies. I think this is a miscalculation. While wind conditions won't affect flat objects in the sea, like it would a floating galley for example, the wind does influence the wave action. Wave action, in addition to current, would determine direction and distance of floating objects. Thus, your conclusion of probable crash site can't really by determined from the floating bodies position at time of recovery. Theoretically, a computer program might be able to calculate float direction and speed from many samples of wind direction/force and current condition over 5 days. Often the wind direction is opposite of current, creating different wave forces then when wind and current are in the same direction. It's too complicated a model to figure out without the help of supercomputers.
ELAC
Amen to that.
That's the fullfillment of being on scene. Most of the questions raised in two days of posts here (and stilll unanswered) could be answered in an hour on scene
Spot on, but it probably helps us to reject ignorant speculation from others that doesn't fit the little facts we can discern. Ask yourself how many times have we been asked by our friends if this or that they heard or read is true. Do we just brush them off even as friends or do we throw a fact or two at them to politely end their speculation.
ttcse
So far it only suggests that the pieces cited impacted the ocean in relatively free fall.
Most of the discussions in the last days have been about the tertiary events and understandably not about the missing links.
but it's a fair bet that those on the scene do know and that these particular bits will help forward the investigation.
ELAC
ELAC
That's the fullfillment of being on scene. Most of the questions raised in two days of posts here (and stilll unanswered) could be answered in an hour on scene
None of this discussion is going to solve this sad mystery in itself, but at least when we start talking about things that we can attempt to prove or disprove with available information we are using this forum more as it was intended as opposed to pushing out various personal theories that have no supporting facts.
Cheers,
ELAC
Cheers,
ELAC
ttcse
One aspect of this I can't get over, and others have also noted, is how the debris seems to come from a very-low speed impact. Perhaps if your analysis bears truth it can ultimately be tied to why the debris is in the condition its in.
Most of the discussions in the last days have been about the tertiary events and understandably not about the missing links.
I don't own this space under my name. I should have leased it while I still could
lhp, initially I agreed with you. Then I realised that takata was actually comparing like with like. He has a series of plots all similarly affected by current and modified by wind driven surface motion.
By taking one common type of object then he was able to deduce the combined drift rate. He parts of the wreckage been included then the plot would not have been as pure. It would be possible to do a similar exercise with debris alone and compare the two plots.
By taking one common type of object then he was able to deduce the combined drift rate. He parts of the wreckage been included then the plot would not have been as pure. It would be possible to do a similar exercise with debris alone and compare the two plots.
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drift
My previoous analysis was that the drift increased from day 6 to day 16 thus the trend was much less in the first few days leaving impact somewhere between last report point and 50 odd km north north east of it, (if there was no turn to reciprocal followed by ditching)
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Takata, in your analysis of the sequence and date of body recoveries, and the drift of the bodies over time (from ocean currents and/or prevailing surface winds) how do you account for the significant amount of wreckage found on June 7 that is well to the west and south of the bodies recovered that day?
The bodies (and wreckage) recovered on subsequent days suggest a northward drift, which then became NW or W last week.
Of course, if one had the index to which parts of the plane (or passenger items) the white numbered dots represent, that would probably help. To date, neither BEA nor Brazil have released even the approximate coordinates for where significant parts of the wreckage were retrieved. What was retrieved at dots numbered 9 and 11 may be key. There are no items numbered 1-8, or 10, that I have seen on the BEA charts. There is a 12. It may be that the early numbers were assigned to flotsam mistakenly identified as being from AF447 in the earliest days of the search. Either that, or only the larger items are shown on the maps that were publicly released.
The bodies (and wreckage) recovered on subsequent days suggest a northward drift, which then became NW or W last week.
Of course, if one had the index to which parts of the plane (or passenger items) the white numbered dots represent, that would probably help. To date, neither BEA nor Brazil have released even the approximate coordinates for where significant parts of the wreckage were retrieved. What was retrieved at dots numbered 9 and 11 may be key. There are no items numbered 1-8, or 10, that I have seen on the BEA charts. There is a 12. It may be that the early numbers were assigned to flotsam mistakenly identified as being from AF447 in the earliest days of the search. Either that, or only the larger items are shown on the maps that were publicly released.
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PJ2 oxygen
According to my info fixed oxygen cylinders on the A330 are to be found in one other place than the one below the flightdeck reffered to: for cabin oxigen supply there are 5 + up to another 5 cylinders situated in the r/h sidewall lining in the fwrd cargo hold (source FCOM 1.35.20)
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PJ2,
Just to let you know gaseous oxygen is an option for the passenger system on the A340/340 aircraft. If it is fitted the oxygen bottles are fitted aft of the forward cargo door behind the cargo bay lining panels. I have worked on aircraft with generators and the gaseous systems fitted. I am not aware of what option Air France have on their longhaul airbus fleet.
Jimpy
Just to let you know gaseous oxygen is an option for the passenger system on the A340/340 aircraft. If it is fitted the oxygen bottles are fitted aft of the forward cargo door behind the cargo bay lining panels. I have worked on aircraft with generators and the gaseous systems fitted. I am not aware of what option Air France have on their longhaul airbus fleet.
Jimpy
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jimpy
AF uses gas cylinders for passenger oxigen. See also the accident report on AF's A340 F-GLZQ: http://www.tsb.gc.ca/eng/rapports-re...2/a05h0002.pdf
"The forward cargo door was found in place and closed. Next to the cargo
door, coincident with the location of the passenger oxygen cylinders, was a large hole in the fuselage wall that bore signs of explosive force."
"The forward cargo door was found in place and closed. Next to the cargo
door, coincident with the location of the passenger oxygen cylinders, was a large hole in the fuselage wall that bore signs of explosive force."
BOAC;
No, we do not.
The early, Class 3 maintenance message "LAV" would have nothing to do with any water/overflow issues. The "waste-water" theory is emerging in the absence of evidence. It is almost certainly a non-starter.
If that's the post, I do have a few comments:
Your post doesn't ask about a turn-back, it only suggests the possibility of a descent as may be indicated by other, associated messages (which, as you say, may or may not exist).
First, a bit of background on the ACARS ADVISORY message:
When a system requires the crews' attention but isn't serious enough to warrant formal master caution/master warning indications plus other associated ECAM actions, the affected system's page is brought up on the lower ECAM, displaying a pulsing green 'advisory' message of the relevant parameter, in this case, the "CAB PRESS" text display on the pressurization page.
An advisory message to the crew does not necessarily require immediate crew action but advises that system parameters have been exceeded, not by a lot but crew attention/advice is required.
The ACARS cabin "ADVISORY" message refers to a pulsing, advisory 'CAB PRESS' message displayed on the pressurization system page on the lower ECAM display.
From the QRH, the "CAB PRESS" pulsing green ADVISORY message is displayed when:
- the cabin vertical speed is greater than, or less than, 1800fpm, or
- the cabin altitude is equal to/greater than 8800ft, or
- the cabin differential pressure (delta 'p') is equal to/greater than 1.5psi in flight phase 7.
Flight phase 7 refers to the approach phase below 800ft AGL to touchdown.
In each case of an advisory message there are recommended crew actions listed in the QRH. These action items are, as described, not of an emergency nature.
That doesn't mean that there was no emergency - it just means we don't have further ACARS messages.
This in and of itself wouldn't indicate either an aircraft descent or a turn-back. There would not likely be any ACARS messages associated with a descent per se, (and certainly none automatically associated with a turn-back), although a "top of descent" message may be automatically sent as a matter of individual airline ACARS design requirements - we don't know.
I understand the theory behind takata's fine sleuthing work and hope it bears fruit but as we can see, there are other considerations emerging which may place the aircraft differently. Very frustrating for all, as we know.
It is impossible to say whether the crew turned back and it is equally impossible to say whether such a decision would have been made or by who, (depending upon who was on the flight deck - we may surmise it would "definitely" be the captain, but we do not know this).
A turn-back at that point in the flight is a highly unusual response - it is essentially an emergency response made out of dire need. I can see a 90deg turn to the east to avoid Cu but that is not the maneuver contemplated by takata's work.
Clearly, there is a pattern, though "the data" is granular in nature, to where the wreckage and most bodies were found. I think takata's work is on the right track and (as I believe s/he him/herself would say), may require fine-tuning. I wouldn't be prepared to say there was a turn-back but such a notion teased as it is out of what little is known, is now a factor which must be proven/discounted.
RECAP!! Do we ACTUALLY have any 'ACARS message' about waste water other than a possible vaccuum flush fault?
The early, Class 3 maintenance message "LAV" would have nothing to do with any water/overflow issues. The "waste-water" theory is emerging in the absence of evidence. It is almost certainly a non-starter.
I did ask 'the experts' a day or so ago which choice - continuing ahead or turning back through the weather - would be likely vis a vis ETOPS/fuel etc. and have had nothing back.
Originally Posted by is this the post you're referring to, BOAC?
. . . if only we could be sure we have ALL the ACARS messages in sight, then there is a very good chance we can rule out a high-level break-up in view of the lack of an "EXCESS CABIN ALT" warning as you say. Without such a signalled disruption to the cabin pressure, the only subsequent ACARS message must surely refer to a descent? Dare we surmise? PJ? Bsieker?
Your post doesn't ask about a turn-back, it only suggests the possibility of a descent as may be indicated by other, associated messages (which, as you say, may or may not exist).
First, a bit of background on the ACARS ADVISORY message:
When a system requires the crews' attention but isn't serious enough to warrant formal master caution/master warning indications plus other associated ECAM actions, the affected system's page is brought up on the lower ECAM, displaying a pulsing green 'advisory' message of the relevant parameter, in this case, the "CAB PRESS" text display on the pressurization page.
An advisory message to the crew does not necessarily require immediate crew action but advises that system parameters have been exceeded, not by a lot but crew attention/advice is required.
The ACARS cabin "ADVISORY" message refers to a pulsing, advisory 'CAB PRESS' message displayed on the pressurization system page on the lower ECAM display.
From the QRH, the "CAB PRESS" pulsing green ADVISORY message is displayed when:
- the cabin vertical speed is greater than, or less than, 1800fpm, or
- the cabin altitude is equal to/greater than 8800ft, or
- the cabin differential pressure (delta 'p') is equal to/greater than 1.5psi in flight phase 7.
Flight phase 7 refers to the approach phase below 800ft AGL to touchdown.
In each case of an advisory message there are recommended crew actions listed in the QRH. These action items are, as described, not of an emergency nature.
That doesn't mean that there was no emergency - it just means we don't have further ACARS messages.
This in and of itself wouldn't indicate either an aircraft descent or a turn-back. There would not likely be any ACARS messages associated with a descent per se, (and certainly none automatically associated with a turn-back), although a "top of descent" message may be automatically sent as a matter of individual airline ACARS design requirements - we don't know.
I understand the theory behind takata's fine sleuthing work and hope it bears fruit but as we can see, there are other considerations emerging which may place the aircraft differently. Very frustrating for all, as we know.
It is impossible to say whether the crew turned back and it is equally impossible to say whether such a decision would have been made or by who, (depending upon who was on the flight deck - we may surmise it would "definitely" be the captain, but we do not know this).
A turn-back at that point in the flight is a highly unusual response - it is essentially an emergency response made out of dire need. I can see a 90deg turn to the east to avoid Cu but that is not the maneuver contemplated by takata's work.
Clearly, there is a pattern, though "the data" is granular in nature, to where the wreckage and most bodies were found. I think takata's work is on the right track and (as I believe s/he him/herself would say), may require fine-tuning. I wouldn't be prepared to say there was a turn-back but such a notion teased as it is out of what little is known, is now a factor which must be proven/discounted.
Pontius Navigator;
The key is what takata and many other are attempting to do: pinpoint the actual position of the aircraft at 02:10. All the rest flows from that one piece of information.
A normal descent for a normal approach/landing will take, at the most, 160nm, with an average of 130nm. That would be the greatest "radius of action" in terms of the location of the larger sections.
The winds in the ITCZ are almost always light and variable, 20, 30kts or so, at cruise altitudes; the "polar jet" and "subtropical jet" are further north and south.
Somewhere, someone has these winds for the time of the accident.
Falling (not in a high speed dive) parts would be exposed to such winds for between roughly three and ten minutes depending upon weight and shape Even assuming the winds remain at, say, thirty knots all the way to the surface, (not likely), that translates to very little lateral distance covered in relation to the position of the aircraft at 02:10 - less than 20nm.
Ocean currents, as has been posited, will account for the rest of the displacement from original impact point. I don't think it takes a supercomputer to work out a reasonable radius of action - it takes the assumptions as demonstrated by takata's methods, which may then be fine-tuned by the availability of more accurate data, (as is stated).
Dutch Bru, jimpy1979uk;
Thanks, I wasn't aware there is an oxygen-tank option for the 340/330 - it isn't in the AMM - only the O2 generation system and the F/A portable O2 installations are.
To be completely accurate, we could reasonably assume from the quoted report, (thank you) that AF 340's have the cylinders installed. We need to confirm that the same installation has been made for the 330's.
In any case, the statement that the oxygen cylinder in the photograph IS from the cockpit, is in question.
ACLS65;
The key in this is the statement, "all this assumes"; this is precisely the situation where a little knowledge (and no experience on the airplane), is a dangerous thing. I think it is wise to suspend judgement on this risk and wait.
As I said a few pages ago, backups/flooding can and do occur on rare occasion but the F/As are very swift at ensuring any such overflow of water is mopped up. The concern is that the forward lavs or galleys may leak into the EE Bay under the cockpit. The concern is legitimate in the sense that it is good, cautious thinking on board an aircraft but is not legitimate in the sense that there is a problem with flooding the EE Bay.
The "LAV" ACARS message is not an indication of an abnormality; it is a Class 3 maintenance message which appears quite often, usually in climb.
The comments about "16,000ft altitude" and vacuum generators being driven by a system that "thought it was below 16,000ft", while possible, is highly improbable and would not result in flooding anyway. A galley tap which can't be shut off is more likely a source of local (I emphasize "local" to forestall further launching in new directions!), flooding.
As I suggested earlier, back plotting these with known surface wind correction would be interesting.
A normal descent for a normal approach/landing will take, at the most, 160nm, with an average of 130nm. That would be the greatest "radius of action" in terms of the location of the larger sections.
The winds in the ITCZ are almost always light and variable, 20, 30kts or so, at cruise altitudes; the "polar jet" and "subtropical jet" are further north and south.
Somewhere, someone has these winds for the time of the accident.
Falling (not in a high speed dive) parts would be exposed to such winds for between roughly three and ten minutes depending upon weight and shape Even assuming the winds remain at, say, thirty knots all the way to the surface, (not likely), that translates to very little lateral distance covered in relation to the position of the aircraft at 02:10 - less than 20nm.
Ocean currents, as has been posited, will account for the rest of the displacement from original impact point. I don't think it takes a supercomputer to work out a reasonable radius of action - it takes the assumptions as demonstrated by takata's methods, which may then be fine-tuned by the availability of more accurate data, (as is stated).
Dutch Bru, jimpy1979uk;
Thanks, I wasn't aware there is an oxygen-tank option for the 340/330 - it isn't in the AMM - only the O2 generation system and the F/A portable O2 installations are.
Originally Posted by Dutch Bru
AF uses gas cylinders for passenger oxigen.
In any case, the statement that the oxygen cylinder in the photograph IS from the cockpit, is in question.
ACLS65;
Can anyone confirm that there was a lav on AF447 port side directly aft of the cockpit? This could also refer to more than just a clogged lav, since it supposedly happened shortly after takeoff it might even be from before the lavs were in use.
. . . .
Also per the FCOM the vacuum generators for removing the wastewater are not used at altitudes greater than 16,000 feet. Could the lav ACARS msg we do have mean that this system "thought" it was at a lower altitude and tried to use the vacuum generators? Again maybe just another indicator that however this system receives altitude info was compromised.
Again all this assumes there is some validity to the original article and as of last night I had not found that same information anywhere else
. . . .
Also per the FCOM the vacuum generators for removing the wastewater are not used at altitudes greater than 16,000 feet. Could the lav ACARS msg we do have mean that this system "thought" it was at a lower altitude and tried to use the vacuum generators? Again maybe just another indicator that however this system receives altitude info was compromised.
Again all this assumes there is some validity to the original article and as of last night I had not found that same information anywhere else
As I said a few pages ago, backups/flooding can and do occur on rare occasion but the F/As are very swift at ensuring any such overflow of water is mopped up. The concern is that the forward lavs or galleys may leak into the EE Bay under the cockpit. The concern is legitimate in the sense that it is good, cautious thinking on board an aircraft but is not legitimate in the sense that there is a problem with flooding the EE Bay.
The "LAV" ACARS message is not an indication of an abnormality; it is a Class 3 maintenance message which appears quite often, usually in climb.
The comments about "16,000ft altitude" and vacuum generators being driven by a system that "thought it was below 16,000ft", while possible, is highly improbable and would not result in flooding anyway. A galley tap which can't be shut off is more likely a source of local (I emphasize "local" to forestall further launching in new directions!), flooding.
Last edited by PJ2; 21st Jun 2009 at 18:49.
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Very nice work, takata.
I was unaware of the SHOM PowerPoint and had not seen the last known position coordinates in print before - thanks. I have spent a bit of time re-plotting the BEA reconstructed flight path, and it is reassuring that the locations derived from reverse engineering the BEA flight path points in Google Earth are a good match for the GPS coordinates obtained from the ACARS 0210Z position report. My earlier analysis is in the Tim Vasquez forum:
Jet Crash forum • View topic - Crash location
The BEA flight path points are labeled to the second (e.g. 02:00:00, probably the GPS time stamp), so that by reproducing the coordinates of the points in Google Earth by moving them around until they are a good match for details in the sea floor bathymetry in BEA plot it is possible to calculate speed and distance covered. Here is the result:
0120Z - 2° 48.000'S, 33° 35.000'W
77.0 nm, 462 kt
0130Z - 1° 39.500'S, 32° 59.000'W
78.9 nm, 473 kt
0140Z - 0° 29.421'S, 32° 22.002'W
78.0 nm, 468 kt
0150Z - 0° 39.943'N, 31° 45.392'W
77.4 nm, 464 kt
0200Z - 1° 48.654'N, 31° 9.109'W
77.2 nm, 463 kt
0210Z - last known position - 2° 58.700'N, 30° 35.800'W
This last known position derived independently by reverse engineering the BEA plot is 2.978°N, 30.597°W in decimal degrees, a very close match to the location published by SHOM of 2.98°N, 30.59° W, which gives me some confidence in the others. Incidentally, this position is also a good match for the last reported position plotted on one of the actual FAB SAR maps (the red airplane symbol) used by the search teams, as I posted earlier:
http://www.pprune.org/rumours-news/3...ml#post4982877
Variation in the locations, and therefore the speeds and distances, could well be due to small errors in reproducing the BEA flight path positions in Google Earth. It will be interesting to see how close these are to the actual GPS coordinates that hopefully will be in the BEA accident report. The calculated speed between 0120Z and 0140Z is 468 kt, a match for the ground speed of 467 kt calculated by Barry Carlson from the flight plan speed of Mach 0.82:
Final Route of AF447 - an Analysis
One key result of my analysis is that there evidently was no change in speed prior to 0210Z.
Much of takata's analysis concerns the speed and direction of the drifting debris. There are actually some data on drift in this area that cover the period 1 June to 6 June from oceanographic drifting buoys, although they are not all that close to the last known position. Buoy 31919 NE of TASIL drifted 46 nm to the WSW during this period, and Buoy 31256 SE of TASIL drifted 64 nm to the NE. These are more or less in opposite directions, so I suspect the actual drift of the debris during this period was complex.
Attachments do not seem to be enabled, or I would post a map of the flight path and drifter buoy paths. You can view it in the Sun Jun 21, 2009 6:53 pm post at:
Jet Crash forum • View topic - Crash location
-rer47
I was unaware of the SHOM PowerPoint and had not seen the last known position coordinates in print before - thanks. I have spent a bit of time re-plotting the BEA reconstructed flight path, and it is reassuring that the locations derived from reverse engineering the BEA flight path points in Google Earth are a good match for the GPS coordinates obtained from the ACARS 0210Z position report. My earlier analysis is in the Tim Vasquez forum:
Jet Crash forum • View topic - Crash location
The BEA flight path points are labeled to the second (e.g. 02:00:00, probably the GPS time stamp), so that by reproducing the coordinates of the points in Google Earth by moving them around until they are a good match for details in the sea floor bathymetry in BEA plot it is possible to calculate speed and distance covered. Here is the result:
0120Z - 2° 48.000'S, 33° 35.000'W
77.0 nm, 462 kt
0130Z - 1° 39.500'S, 32° 59.000'W
78.9 nm, 473 kt
0140Z - 0° 29.421'S, 32° 22.002'W
78.0 nm, 468 kt
0150Z - 0° 39.943'N, 31° 45.392'W
77.4 nm, 464 kt
0200Z - 1° 48.654'N, 31° 9.109'W
77.2 nm, 463 kt
0210Z - last known position - 2° 58.700'N, 30° 35.800'W
This last known position derived independently by reverse engineering the BEA plot is 2.978°N, 30.597°W in decimal degrees, a very close match to the location published by SHOM of 2.98°N, 30.59° W, which gives me some confidence in the others. Incidentally, this position is also a good match for the last reported position plotted on one of the actual FAB SAR maps (the red airplane symbol) used by the search teams, as I posted earlier:
http://www.pprune.org/rumours-news/3...ml#post4982877
Variation in the locations, and therefore the speeds and distances, could well be due to small errors in reproducing the BEA flight path positions in Google Earth. It will be interesting to see how close these are to the actual GPS coordinates that hopefully will be in the BEA accident report. The calculated speed between 0120Z and 0140Z is 468 kt, a match for the ground speed of 467 kt calculated by Barry Carlson from the flight plan speed of Mach 0.82:
Final Route of AF447 - an Analysis
One key result of my analysis is that there evidently was no change in speed prior to 0210Z.
Much of takata's analysis concerns the speed and direction of the drifting debris. There are actually some data on drift in this area that cover the period 1 June to 6 June from oceanographic drifting buoys, although they are not all that close to the last known position. Buoy 31919 NE of TASIL drifted 46 nm to the WSW during this period, and Buoy 31256 SE of TASIL drifted 64 nm to the NE. These are more or less in opposite directions, so I suspect the actual drift of the debris during this period was complex.
Attachments do not seem to be enabled, or I would post a map of the flight path and drifter buoy paths. You can view it in the Sun Jun 21, 2009 6:53 pm post at:
Jet Crash forum • View topic - Crash location
-rer47
Last edited by rer47; 21st Jun 2009 at 23:22.
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qantas report - normal to alternate law - PRIM 1 reset
From the plots in the qantas preliminary report
http://www.atsb.gov.au/publications/...070_prelim.pdf
a) IR1 fault is detected but the A/C continues in normal law even after master PRIM becomes PRIM2;
b) When master PRIM is switched back to PRIM1 then the a/c gets into Alternate Law and the crew regains control.
http://www.atsb.gov.au/publications/...070_prelim.pdf
a) IR1 fault is detected but the A/C continues in normal law even after master PRIM becomes PRIM2;
b) When master PRIM is switched back to PRIM1 then the a/c gets into Alternate Law and the crew regains control.
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From the plots in the qantas preliminary report
http://www.atsb.gov.au/publications/...070_prelim.pdf
a) IR1 fault is detected but the A/C continues in normal law even after master PRIM becomes PRIM2;
b) When master PRIM is switched back to PRIM1 then the a/c gets into Alternate Law and the crew regains control.
http://www.atsb.gov.au/publications/...070_prelim.pdf
a) IR1 fault is detected but the A/C continues in normal law even after master PRIM becomes PRIM2;
b) When master PRIM is switched back to PRIM1 then the a/c gets into Alternate Law and the crew regains control.
Jeff