AF 447 Search to resume
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Sallyann wrote:
But this is not the problem.
As has been stated before, the difficulty arises when several hundred aircraft are sending their individual data streams to a satellite receiver, and for this data to then be retrieved, combined and sent down to earth station/s."
Not entirely a problem Sallyann. If each aircraft transmitted in a unique address, similar to either an IP or MAC address, then much of that issue would vanish, no?
But this is not the problem.
As has been stated before, the difficulty arises when several hundred aircraft are sending their individual data streams to a satellite receiver, and for this data to then be retrieved, combined and sent down to earth station/s."
Not entirely a problem Sallyann. If each aircraft transmitted in a unique address, similar to either an IP or MAC address, then much of that issue would vanish, no?
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Jox,
Many thanks for your post!
I still remain with my two questions.
* Is there any real perceived requirement for transmission of these huge volumes of data in real time, when those same data can be downloaded from the QAR after the aircraft has landed?
(I'm not talking about some time-critical maintenance and performance data, mentioned earlier, which constitute only a small subset of the total data stream going into the FDR and QAR).
* How likely is it, that after a major event/upset the real-time data link to the satellite will remain fully intact until the final second?
FDR and CVR at least will stay with the aircraft until the bitter end.
CJ
Many thanks for your post!
I still remain with my two questions.
* Is there any real perceived requirement for transmission of these huge volumes of data in real time, when those same data can be downloaded from the QAR after the aircraft has landed?
(I'm not talking about some time-critical maintenance and performance data, mentioned earlier, which constitute only a small subset of the total data stream going into the FDR and QAR).
* How likely is it, that after a major event/upset the real-time data link to the satellite will remain fully intact until the final second?
FDR and CVR at least will stay with the aircraft until the bitter end.
CJ
@ rgbrock,
No, addressing is a simple matter.
The issue is that you cannot have a large number of transmitters each sending continuous streams of data at random because the receiver in the satellite would just receive a meaningless jumble of signals. There has to be a system of control that determines time or frequency slots for each packet of data so that it can be individually resolved and identified.
The cellular phone in your pocket is at all times controlled by the base stations telling it from one millisecond to another when to transmit and when to receive, which do not happen simultaneously. A similar thing already happens with satellite phone and data systems, but they were designed to communicate with limited amounts of data usually from static or slow-moving terminals.
The envisaged data from aircraft monitoring would be fast and continuous. With fast data the length of each data bit is very short, with time periods less than the time taken to travel from plane to satellite and return. The variable doppler-shift due to aircraft travel is also significant, placing system constraints. As stated before none of this is impossible given sufficient resources, but large volumes of data from many aircraft cannot just be bolted on to existing systems.
There are many online references to FDMA, TDMA and CDMA which will explain the concepts if you want to go into the details.
No, addressing is a simple matter.
The issue is that you cannot have a large number of transmitters each sending continuous streams of data at random because the receiver in the satellite would just receive a meaningless jumble of signals. There has to be a system of control that determines time or frequency slots for each packet of data so that it can be individually resolved and identified.
The cellular phone in your pocket is at all times controlled by the base stations telling it from one millisecond to another when to transmit and when to receive, which do not happen simultaneously. A similar thing already happens with satellite phone and data systems, but they were designed to communicate with limited amounts of data usually from static or slow-moving terminals.
The envisaged data from aircraft monitoring would be fast and continuous. With fast data the length of each data bit is very short, with time periods less than the time taken to travel from plane to satellite and return. The variable doppler-shift due to aircraft travel is also significant, placing system constraints. As stated before none of this is impossible given sufficient resources, but large volumes of data from many aircraft cannot just be bolted on to existing systems.
There are many online references to FDMA, TDMA and CDMA which will explain the concepts if you want to go into the details.
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SaturnV
I can only surmise that the BEA were not provided with QAR data from these flights. In the case of LH, there may be union/regulatory restrictions on the use of such data.
CONF iture
We have never been privy to the format in which the AOC position was transmitted, i.e. it's not in the printout of the ACARS messages routed to AF Maintenance, so one can only assume that it went to AF Flight Operations. One can surmise that there were parameters other than lat/long included, and that the BEA are avoiding at all cost further speculation on what may or may not have been happening to the a/c at 02:10:30z when the AOC data was transmitted.
Someone who regularly reads the EuroCockpit postings may well have some useful input into resolving the matter.
mm43
I am curious why the simulation omits the tracks of IB 6024 and LH 507.
CONF iture
Also, why is it so hard for the BEA to state that the last automatic position point was 3 NM off track ???
Someone who regularly reads the EuroCockpit postings may well have some useful input into resolving the matter.
mm43
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CJ,
The customer required options or the system that I was involved in evaluating were many and comprehensive but to try and provide an answer to your question "is there any real perceived requirement for transmission of these huge volumes of data in real time” depends on what you seek to achieve from it.
How many commercial incidents and losses result in not being able to locate the two critical boxes or having done so, they contain no useable data? Answer – very few. How much money is required to be spent in an attempt to discover the whereabouts of the lost devices to provide analysis and information that may determine the cause of an accident or incident thus preventing its reoccurrence? Answer – a significant amount.
Now there are those who will tell you that no amount of money is prohibitive if it will save a single life, I tend to agree with the statement myself but then I am not running an aviation business. The commercial arm of aviation would certainly not agree, they aspire to agree but must make their financial decisions based on what they can afford to spend whilst remaining in business.
The system I have seen operates and records onto its own internal recorder just like a QAR which tends to record fewer parameters than the FDR. It can download the data by several means and not necessarily only whilst in the air via satellite. The data may be downloaded either live (nobody ever suggested that this would be the preferred constant option), at the demand of maintenance control for their purposes or at the initiation of the crew.
Historically aviation accidents are not caused by a single factor or generally a catastrophic failure of a single component. There are usually several factors all working together which culminate in a loss. One of the most common near misses with high workloads is that someone forgets to fly the airplane whilst they are working the problem. I defy any pilot to be able to say hand on heart he has not overlooked or missed something when the work rate to resolve an issue becomes intense.
This system provided an additional option that maintenance control could talk in real time to the pilots, get real time technical data from the aircraft and then engineering could work the problem, the pilots could fly the aircraft and then between them the issue can be resolved.
It is an interesting concept and has merit, if you need not download the data then you save the cost of not doing so. If you have an issue on board and the flight manual states “initiate download” then at least what is happening and being seen now is on its way back to maintrol. If the ship is lost at least they have something whilst they wait for the FDR and CVR to provide the whole picture.
Your second question “how likely is it that after an event/upset the real-time data link to the satellite will remain fully intact until the final second?” Answer I do not know, but if you still have power, your link is connected and you are downloading then your odds are improving all the time. I would rather have some chance than no chance.
Technology improves all the time, after a major event or upset how often does the radio link remain operable until the final second, one for Sallyanne 1234 I suspect.
Jox
The customer required options or the system that I was involved in evaluating were many and comprehensive but to try and provide an answer to your question "is there any real perceived requirement for transmission of these huge volumes of data in real time” depends on what you seek to achieve from it.
How many commercial incidents and losses result in not being able to locate the two critical boxes or having done so, they contain no useable data? Answer – very few. How much money is required to be spent in an attempt to discover the whereabouts of the lost devices to provide analysis and information that may determine the cause of an accident or incident thus preventing its reoccurrence? Answer – a significant amount.
Now there are those who will tell you that no amount of money is prohibitive if it will save a single life, I tend to agree with the statement myself but then I am not running an aviation business. The commercial arm of aviation would certainly not agree, they aspire to agree but must make their financial decisions based on what they can afford to spend whilst remaining in business.
The system I have seen operates and records onto its own internal recorder just like a QAR which tends to record fewer parameters than the FDR. It can download the data by several means and not necessarily only whilst in the air via satellite. The data may be downloaded either live (nobody ever suggested that this would be the preferred constant option), at the demand of maintenance control for their purposes or at the initiation of the crew.
Historically aviation accidents are not caused by a single factor or generally a catastrophic failure of a single component. There are usually several factors all working together which culminate in a loss. One of the most common near misses with high workloads is that someone forgets to fly the airplane whilst they are working the problem. I defy any pilot to be able to say hand on heart he has not overlooked or missed something when the work rate to resolve an issue becomes intense.
This system provided an additional option that maintenance control could talk in real time to the pilots, get real time technical data from the aircraft and then engineering could work the problem, the pilots could fly the aircraft and then between them the issue can be resolved.
It is an interesting concept and has merit, if you need not download the data then you save the cost of not doing so. If you have an issue on board and the flight manual states “initiate download” then at least what is happening and being seen now is on its way back to maintrol. If the ship is lost at least they have something whilst they wait for the FDR and CVR to provide the whole picture.
Your second question “how likely is it that after an event/upset the real-time data link to the satellite will remain fully intact until the final second?” Answer I do not know, but if you still have power, your link is connected and you are downloading then your odds are improving all the time. I would rather have some chance than no chance.
Technology improves all the time, after a major event or upset how often does the radio link remain operable until the final second, one for Sallyanne 1234 I suspect.
Jox
It appears that AF447 flew into an intense tropical storm.
The aircraft was subjected to extreme attitude changes, dense rain, and electrical interference. Any one of those effects could have interrupted a radio signal carrying the vital data to a satellite. In the presence of all three together it would have been very lucky to get through.
The aircraft was subjected to extreme attitude changes, dense rain, and electrical interference. Any one of those effects could have interrupted a radio signal carrying the vital data to a satellite. In the presence of all three together it would have been very lucky to get through.
Last edited by Sallyann1234; 23rd Feb 2010 at 11:11. Reason: changed 'turbulence' to 'attitude changes'
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SallyAnn:
If you're familiar with Internet Protocol (IP), data packets/streams from any source are uniquely encapsulated. The receiving "host" knows where the packets are coming from due to unique identifiers contained within encapsulated datagram. This receiving host can "receive" many, many streams of such uniquely identified data, and then passes them on if need be.
I'm just wondering if something similar can be done with aircraft communications, that's all.
If you're familiar with Internet Protocol (IP), data packets/streams from any source are uniquely encapsulated. The receiving "host" knows where the packets are coming from due to unique identifiers contained within encapsulated datagram. This receiving host can "receive" many, many streams of such uniquely identified data, and then passes them on if need be.
I'm just wondering if something similar can be done with aircraft communications, that's all.
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RGBROCK1 got it right
Further, there is a way to accomplish this massive data transfer with minimal reliance on satellites, that is to use IP forwarding, packets would be transmitted from aircraft to aircraft until they arrive at the final destination just like the land based internet. Ships or buoys could also assist. Extremely foul weather might impact those signals, however IP has the feature of continuously repeating a packet until it gets through, and in fact the packets could be transmitted after the incident if the transmitter survives.
Not if they are all on the same frequency and unsychronised.
Consider the same thing happening on an HF or VHF voice channel. If a hundred pilots press their buttons at the same time and transmit a long message, the result is just noise. The fact that they each precede their message with a callsign doesn't help at all. That is why there is a strict allocation of frequencies and a protocol to define when and how to transmit. Similarly data transmissions require their own protocol which may well be IP based but needs a complex hierarchy and infrastructure.
Regarding the store-and-forward idea, this has been proposed earlier in the thread. Like other suggestions it could be done, but requires a whole new generation of equipment that would be (a) very expensive and (b) difficult to retrofit in the existing fleet.
Consider the same thing happening on an HF or VHF voice channel. If a hundred pilots press their buttons at the same time and transmit a long message, the result is just noise. The fact that they each precede their message with a callsign doesn't help at all. That is why there is a strict allocation of frequencies and a protocol to define when and how to transmit. Similarly data transmissions require their own protocol which may well be IP based but needs a complex hierarchy and infrastructure.
Regarding the store-and-forward idea, this has been proposed earlier in the thread. Like other suggestions it could be done, but requires a whole new generation of equipment that would be (a) very expensive and (b) difficult to retrofit in the existing fleet.
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Lets pause and examine the reason why this discussion is taking place.
An aircraft has been lost over oceanic airspace and we have the privilege of knowing, due to the transmission of AOC/ACARS messages via Inmarsat, where it was at 2009-06-01 02:10:30z and that it was still flying for at least 4 minutes later.
We do know from forensic examination that the aircraft had a very high rate of descent with a small but positive attitude when it impacted the water. We do know that if the DFDR and CVR can be located that a more conclusive resolution as to the actual cause and handling of the mishap will be established. We do know that no ELT was activated, and that the ULB pingers were not detected and that the time for doing so expired 30 - 40 days after their activation.
What we don't know is where its flight ended and though many pieces of debris along with 50 bodies have been recovered, they were not located for at least 5.5 days after the accident.
What we really want to know is where the aircraft was within say 30 seconds of its demise, as the problem relates to the last known GS which means that it could have moved in any direction at up to 8NM per minute. What we also know is that the area of the search will increase by the square of the time difference between the last known position and its impact position. Reducing the time between position reports also has the advantage of reducing the search area even further, as the probable direction and speed of flight will be known with a likewise diminishing percentage of error.
The answers to all the so-far unknown events have been carried with the aircraft to the depths of the equatorial North Atlantic, and we know once we can locate and recover the recorders those unknowns will become known. We also need to know where the wreckage is as it may be necessary to recover parts of it to complete the crash analysis.
So, having established the known and unknown issues, we need consider whether the duplication of flight data parameters, duly recorded in the DFDR/CVR, in a real-time radio data stream by any available means is ultimately cost effective. Not only that, but what will be the time scale and cost of effecting such a mammoth change to a whole industry, when only a small proportion of the worlds fleets are regularly flying outside of SSR coverage in Oceanic FIRs.
Perhaps it is time to be reminded again that the Final Report of the Flight Data Recovery Working Group -
Flight Data Recovery Working Group Report
established fairly sound guidelines to the practicality or otherwise of the means proposed. The "near to" or "short term" solutions are:-
(a)..Increased autonomy of ULBs (90 days instead of 30 days), and
(b)..Use of a lower frequency (~9kHz) for ULBs attached to the aircraft.
Any recommendations regarding real-time data streaming are essentially a long way off.
In respect of position reports, this post made a proposal that can and should be implemented "now" by SATCOM equipped aircraft.
mm43
An aircraft has been lost over oceanic airspace and we have the privilege of knowing, due to the transmission of AOC/ACARS messages via Inmarsat, where it was at 2009-06-01 02:10:30z and that it was still flying for at least 4 minutes later.
We do know from forensic examination that the aircraft had a very high rate of descent with a small but positive attitude when it impacted the water. We do know that if the DFDR and CVR can be located that a more conclusive resolution as to the actual cause and handling of the mishap will be established. We do know that no ELT was activated, and that the ULB pingers were not detected and that the time for doing so expired 30 - 40 days after their activation.
What we don't know is where its flight ended and though many pieces of debris along with 50 bodies have been recovered, they were not located for at least 5.5 days after the accident.
What we really want to know is where the aircraft was within say 30 seconds of its demise, as the problem relates to the last known GS which means that it could have moved in any direction at up to 8NM per minute. What we also know is that the area of the search will increase by the square of the time difference between the last known position and its impact position. Reducing the time between position reports also has the advantage of reducing the search area even further, as the probable direction and speed of flight will be known with a likewise diminishing percentage of error.
The answers to all the so-far unknown events have been carried with the aircraft to the depths of the equatorial North Atlantic, and we know once we can locate and recover the recorders those unknowns will become known. We also need to know where the wreckage is as it may be necessary to recover parts of it to complete the crash analysis.
So, having established the known and unknown issues, we need consider whether the duplication of flight data parameters, duly recorded in the DFDR/CVR, in a real-time radio data stream by any available means is ultimately cost effective. Not only that, but what will be the time scale and cost of effecting such a mammoth change to a whole industry, when only a small proportion of the worlds fleets are regularly flying outside of SSR coverage in Oceanic FIRs.
Perhaps it is time to be reminded again that the Final Report of the Flight Data Recovery Working Group -
Flight Data Recovery Working Group Report
established fairly sound guidelines to the practicality or otherwise of the means proposed. The "near to" or "short term" solutions are:-
(a)..Increased autonomy of ULBs (90 days instead of 30 days), and
(b)..Use of a lower frequency (~9kHz) for ULBs attached to the aircraft.
Any recommendations regarding real-time data streaming are essentially a long way off.
In respect of position reports, this post made a proposal that can and should be implemented "now" by SATCOM equipped aircraft.
mm43
Last edited by mm43; 21st Jul 2010 at 19:29.
Good post mm43
This thread should revert to its original purpose.
This thread should revert to its original purpose.
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I seem to remember an excellent suggestion in an earlier post that rather than just pinging for 30 (or 90) days they should be programmed after 30 days to hibernate until something pings them to wake up, at which point they would, like anyone lost at sea, wave like mad and fire off a few flares with all their remaining strength;-)
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Originally Posted by SaturnV
I am curious why the simulation omits the tracks of IB 6024 and LH 507
If they can sell the idea that AF447 was glued to the airway and fell victim of a Monster CB, then everything is back on the the shoulders of the dead pilots.
And Al Gore will use it for his next conference ... if he dares to show up again ... !?
mm43, the attitude was small and positive.
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There is a problem. A small but positive attitude, yes, but don't forget that there was said to be a yawing moment, sufficient to fail the VS at impact, and in a leftward direction. The BEA make a great deal of there being no aerodynamic loading to cause the separation of the Vertical in flight, and I think their term was "Struck the water En Ligne de Vol", (direction of flight). This means to me no yaw whatsoever at impact. So it seems to me someone is letting the authority have it both ways.
The Stabilizer stayed with the a/c, "what a stout airframe". It rotated off at impact even though the tail was following the nose "En Ligne"? Did it rotate forward around the #1 Clevis?
Two things are missing, as I see it. Metallurgy/Composite autopsy. Passenger autopsies as to injuries. One cannot learn from less than forthcoming analysis.
bear
The Stabilizer stayed with the a/c, "what a stout airframe". It rotated off at impact even though the tail was following the nose "En Ligne"? Did it rotate forward around the #1 Clevis?
Two things are missing, as I see it. Metallurgy/Composite autopsy. Passenger autopsies as to injuries. One cannot learn from less than forthcoming analysis.
bear
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Bearfoil
Without referring back to the 2 interim reports, I believe your comments relate to the 1st report, and if my memory is correct, the BEA changed their "En Ligne de Vol" statement in the 2nd report and omitted any reference to the tail rotating to port.
The reason for doing so is not clear.
mm43
Without referring back to the 2 interim reports, I believe your comments relate to the 1st report, and if my memory is correct, the BEA changed their "En Ligne de Vol" statement in the 2nd report and omitted any reference to the tail rotating to port.
The reason for doing so is not clear.
mm43
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mm43
Thanks for your kind response.
It is unfortunate that BEA included the statements at all. It struck me as precipitous and committed them to a course of analysis that ended up causing doubt about their motives. Honestly, I'd have been tempted to say something similar had the a/c been proprietary, as well. It seemed that it was too important to establish at the outset that the a/c had not involved itself in inflight breakup. This, to me, prompted the "En Ligne de Vol".
An a/c absent a Vertical Stabilizer sees "En ligne de Vol" only occasionally, and that by "accident". There is NO lateral control. Ask Al Haynes, or the Japanese Captain post aft bulkhead failure and loss of VS in the JAL 747.
Their second statement that there had been "Yaw" at impact might conflict with an intact empennage. Their initial report was somewhat biased, and prematurely so. As any investigation progresses, decisions are made that are unfortunately political, and economical in nature. As CONFiture has pointed out, dead pilots cause no trouble. I for one am far less interested in streaming positions and airframe performance moment to moment than I am in finding out why well trained crew in Legacy service ended up in the Sea, with all the others on that "ill-fated" flight.
Pingers and side scan? Awesome. What of the CAUSE?
bear
Thanks for your kind response.
It is unfortunate that BEA included the statements at all. It struck me as precipitous and committed them to a course of analysis that ended up causing doubt about their motives. Honestly, I'd have been tempted to say something similar had the a/c been proprietary, as well. It seemed that it was too important to establish at the outset that the a/c had not involved itself in inflight breakup. This, to me, prompted the "En Ligne de Vol".
An a/c absent a Vertical Stabilizer sees "En ligne de Vol" only occasionally, and that by "accident". There is NO lateral control. Ask Al Haynes, or the Japanese Captain post aft bulkhead failure and loss of VS in the JAL 747.
Their second statement that there had been "Yaw" at impact might conflict with an intact empennage. Their initial report was somewhat biased, and prematurely so. As any investigation progresses, decisions are made that are unfortunately political, and economical in nature. As CONFiture has pointed out, dead pilots cause no trouble. I for one am far less interested in streaming positions and airframe performance moment to moment than I am in finding out why well trained crew in Legacy service ended up in the Sea, with all the others on that "ill-fated" flight.
Pingers and side scan? Awesome. What of the CAUSE?
bear
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djp
On 9th November you suggested active life of recorders on seabed could be extended by not transmitting active accoustic signals until active searching was observed. The degreeof extension depends on ratio of "listening" power drain to "speaking" power drain.I have no idea of this.
An alternative could be to eject recorders(with flotation device) when outside pressure corresponded to few feet of water. Problem would be demonstrating lack of "nuisance" events. You might like to consult with manufacturers of recorder packages.
Keith
On 9th November you suggested active life of recorders on seabed could be extended by not transmitting active accoustic signals until active searching was observed. The degreeof extension depends on ratio of "listening" power drain to "speaking" power drain.I have no idea of this.
An alternative could be to eject recorders(with flotation device) when outside pressure corresponded to few feet of water. Problem would be demonstrating lack of "nuisance" events. You might like to consult with manufacturers of recorder packages.
Keith
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Bearfoil
Der Speigel Online published a couple of days ago a rather strange and perplexing article on the demise of AF447. The tone of the article was that younger crews were breaking the regs regularly by falsifying MTOWs and when range became an issue, filed for Bordeux in the case of AF447 with the alternate Paris Charles de Gaulle. It was then claimed that getting to the optimum CRZ ALT as soon as possible and avoiding all enroute deviations was the next objective.
Luftfahrt: Gehirnschlag im Cockpit - SPIEGEL ONLINE - Nachrichten - Wissenschaft
With regard to the V/S, the following translated comment was made:-
Many parts of the wreckage recovered were no bigger than one square meter. The shear lines run at the impact angle. Consequently, the aircraft has not broken up longitudinally, but has been compressed and broken by the acceleration force of a belly impact with the water, though with a positive 5 degree attitude. The large vertical tail fin, recovered by the Brazilian Navy from the water was particularly revealing. It was torn away from its anchorage and flew away to the front. The measured acceleration force on impact of the A330 was more than 36 times the force of gravity.
The "flew away to the front" is something the BEA have never mentioned.
I suspect the article was really aimed at the French, as reference was made to findings (yet to be published) by the BFU on a LH A320 wing scrape landing incident - with the finger pointing at Airbus/BEA.
mm43
Der Speigel Online published a couple of days ago a rather strange and perplexing article on the demise of AF447. The tone of the article was that younger crews were breaking the regs regularly by falsifying MTOWs and when range became an issue, filed for Bordeux in the case of AF447 with the alternate Paris Charles de Gaulle. It was then claimed that getting to the optimum CRZ ALT as soon as possible and avoiding all enroute deviations was the next objective.
Luftfahrt: Gehirnschlag im Cockpit - SPIEGEL ONLINE - Nachrichten - Wissenschaft
With regard to the V/S, the following translated comment was made:-
Many parts of the wreckage recovered were no bigger than one square meter. The shear lines run at the impact angle. Consequently, the aircraft has not broken up longitudinally, but has been compressed and broken by the acceleration force of a belly impact with the water, though with a positive 5 degree attitude. The large vertical tail fin, recovered by the Brazilian Navy from the water was particularly revealing. It was torn away from its anchorage and flew away to the front. The measured acceleration force on impact of the A330 was more than 36 times the force of gravity.
The "flew away to the front" is something the BEA have never mentioned.
I suspect the article was really aimed at the French, as reference was made to findings (yet to be published) by the BFU on a LH A320 wing scrape landing incident - with the finger pointing at Airbus/BEA.
mm43
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"a positive attitude, a low bank and a high rate of descent."
Which looks a lot like "en ligne de vol" explained in more words for the english speakers.
All the impact damage evidence in the report (including to the VS) points away from in-flight breakup, as does oxygen system state (no depressurisation) and the autopsy results (not available at time of first report).
An a/c absent a Vertical Stabilizer sees "En ligne de Vol" only occasionally,
Pingers and side scan? Awesome. What of the CAUSE?
I'm not sure I like "these pitots are a bit rubbish, use some other ones instead" as a conclusion (also almost seems too convenient - shift the blame to a minor component mfr.) - but again, that may be all we end up with. Unless the side scan and pingers do turn out to be awesome...