Malaysian Airlines MH370 contact lost
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Economist article:
"The disappearance of a Malaysia Airlines passenger jet shows how air-traffic communications need to be updated"
The enigma of flight 370: The sound of silence | The Economist
"The disappearance of a Malaysia Airlines passenger jet shows how air-traffic communications need to be updated"
The enigma of flight 370: The sound of silence | The Economist
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More thoughts on ping accuracy
- Inmarsat-C uses TDM (time division multiplexing).
- Symbol duration within the time slots is 8.64s/10368 symbols = 833 microseconds per symbol
Transmissions in adjacent time slots have to arrive at the receiver (satellite) within the accuracy of one symbol. => Propagation delay has to be known with min. accuracy of 833 microseconds which is corresponds to 250km.
That is imho the upper error margin for the ping accuracy. For reasons given earlier I'm still optimistic accuracy is far better.
The arcs with greater radius have more favorable geometry thus accuracy is better further out. Think cutting a tomato (earth) into slices. Put the tomato to the far left of the cutting board and imagine the satellite to the far right. Each cut through the tomato marks points that are equidistant to the satellite. The skin of the slices is the set of points on the surface that lie within the error margin. The outer slices (those closer to the satellite) have more skin, i.e bigger error.
Stand to be corrected.
- Symbol duration within the time slots is 8.64s/10368 symbols = 833 microseconds per symbol
Transmissions in adjacent time slots have to arrive at the receiver (satellite) within the accuracy of one symbol. => Propagation delay has to be known with min. accuracy of 833 microseconds which is corresponds to 250km.
That is imho the upper error margin for the ping accuracy. For reasons given earlier I'm still optimistic accuracy is far better.
The arcs with greater radius have more favorable geometry thus accuracy is better further out. Think cutting a tomato (earth) into slices. Put the tomato to the far left of the cutting board and imagine the satellite to the far right. Each cut through the tomato marks points that are equidistant to the satellite. The skin of the slices is the set of points on the surface that lie within the error margin. The outer slices (those closer to the satellite) have more skin, i.e bigger error.
Stand to be corrected.
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What facts do we know for certain?
Can I ask a fairly basic question.
Is there anywhere an unimpeachable peer reviewed and generally acknowledged statement of the known facts as opposed to theories?
For instance do we know with any degree of certainty whether the various statements about:
changes in altitude,
following pre-programmed way points
published zig zag tracks
fuel load on departure
whether the last verbal communication was before or after the initial divergence from the flight plan
satellite ping data and the consequent assumptions about the two arcs of likely location
radar or lack of radar returns
...and several others
are known to be true with any high degree of certainty?
Is international law / convention involved here and if so which is the authority that is charged with bringing all this data together. Is it in fact the Malaysian government/Aviation authority as appears to be the case judging by what we see on the television?
Is there anywhere an unimpeachable peer reviewed and generally acknowledged statement of the known facts as opposed to theories?
For instance do we know with any degree of certainty whether the various statements about:
changes in altitude,
following pre-programmed way points
published zig zag tracks
fuel load on departure
whether the last verbal communication was before or after the initial divergence from the flight plan
satellite ping data and the consequent assumptions about the two arcs of likely location
radar or lack of radar returns
...and several others
are known to be true with any high degree of certainty?
Is international law / convention involved here and if so which is the authority that is charged with bringing all this data together. Is it in fact the Malaysian government/Aviation authority as appears to be the case judging by what we see on the television?
I respectfully disagree with The Economist. Their analysis does not appear to handle the simple matter of "On" / "Off" switches. They seem to have missed a point during editing:
Depends on the options chosen by the airline, doesn't it? I don't think "continuously" is correct, based on what folks who understand these systems have presented in this discussion.
I suspect they meant "HF radio" for planes "far out at sea" since VHF is line of sight. On the other hand, how far from shore "far out at sea" means could depend upon who is reading the article.
Planes far out at sea keep in touch using VHF radio, and the newer ones send ACARS data continuously via satellite.
I suspect they meant "HF radio" for planes "far out at sea" since VHF is line of sight. On the other hand, how far from shore "far out at sea" means could depend upon who is reading the article.
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arearadar said
Per March 11 (I believe it was) press conference said radar hits were corroborated in at least some areas with civilian radar (we have no details of this, just that Daud said this). Hits being a feasible flight path for MH370, approximate rough idea of specs on unidentified blips and process of elimination (how many 777-like 'unidentified' planes are flying around at 2AM?) would lead to a very high degree of certainty, I would imagine.
Also, they (Malaysia) and Vietnam both recognized the turn within moments of it happening, somehow, as both countries said as much in the first couple days. It is possible the turn was before Transponder dropped, or that both countries had secondary on it at that time, but they are just not telling us that.
How did the Malaysians identify supposed MH370 ?
No Secondary, no turn and observe as no communication.
No Secondary, no turn and observe as no communication.
Also, they (Malaysia) and Vietnam both recognized the turn within moments of it happening, somehow, as both countries said as much in the first couple days. It is possible the turn was before Transponder dropped, or that both countries had secondary on it at that time, but they are just not telling us that.
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Inmarsat arcs
The Inmarsat arcs shown at the pcs are for the 8:11 ping only! The others may or may not coincide with them.
To get down where the flotsam has been found the other pings would very likely be coincident.
IF (big if) the flotsam is 370 then there would not have been enough fuel to get there AND do all the Radar returns etc!!
To get down where the flotsam has been found the other pings would very likely be coincident.
IF (big if) the flotsam is 370 then there would not have been enough fuel to get there AND do all the Radar returns etc!!
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really
Where does it say that the a/c was continuously tracked without a break, thus retaining identification ?
I read that a/c disappeared from radar.
After that. primary returns were observed but identification was not confirmed. How could it be ?
As a controller of 33 years experience that wouldn`t satisfy me.
I read that a/c disappeared from radar.
After that. primary returns were observed but identification was not confirmed. How could it be ?
As a controller of 33 years experience that wouldn`t satisfy me.
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Lonewolf, you don't have to be respectful to the Economist, although it does usually provoke some thought at least.
And they do have a point that this repeated misplacing of large airliners is getting to be a bit of an embarrassment.
But, if you want to talk, you need power, and when you most want to talk, you may not have any. A location and direction at last power would at least have been helpful in the cases of AF447 and today.
And they do have a point that this repeated misplacing of large airliners is getting to be a bit of an embarrassment.
But, if you want to talk, you need power, and when you most want to talk, you may not have any. A location and direction at last power would at least have been helpful in the cases of AF447 and today.
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paull
PPMAGENTO's arcs are guesses. Not because I say so. Because he says so. Look closely.
And in all these 6000 odd posts, and all my reading, I have never seen the number for any arc but the 40deg one. If you have, I am eager to hear.
I don't know what gave the impression that I was claiming special knowledge. Quite the opposite.
Now the Washington Post's arcs just may be a horse of another colour. Might be the first flicker of a leak. Good find. I am digesting them.
If you say we do not have it, then the only way you can tell us that PPMAGENTO's map is wrong is if YOU have the data and hence know those are (bad) guesses.
And in all these 6000 odd posts, and all my reading, I have never seen the number for any arc but the 40deg one. If you have, I am eager to hear.
I don't know what gave the impression that I was claiming special knowledge. Quite the opposite.
Now the Washington Post's arcs just may be a horse of another colour. Might be the first flicker of a leak. Good find. I am digesting them.
Last edited by fg32; 20th Mar 2014 at 18:43. Reason: Added: "If you have, I am eager to hear."
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If the two floating objects turn out to be from the 777, they might be the horizontal stab assembly and the vertical fin. Mass media incorrectly reports the vertical to be 20m / 60 feet. This is the height of the tail above the tarmac parked on the ramp, not the size of the vertical itself. I'd estimate the vertical is 10m / 30 feet which is close to the smaller object.
The horizontal stabilizer is a single assembly made up of the left and right surfaces and the carry-through structure. It's not two surfaces bolted to the sides of the fuselage since it obviously needs to be very robust. A severe g-load (in the air or an impact) that caused a horizontal stab failure would likely separate it as a unit. The span is 24m / 71 feet, again close to the reported dimensions of the larger object.
I'm not sure if the stab contains fuel tanks...if it does, they would presumably be empty and further help with floatation. A 777 expert can clarify/correct this point. Recall the AFA447 vertical was afloat for 5 days with no signs of sinking.
Hope the objects are from the 777 and lead to FDR and CVR.
The horizontal stabilizer is a single assembly made up of the left and right surfaces and the carry-through structure. It's not two surfaces bolted to the sides of the fuselage since it obviously needs to be very robust. A severe g-load (in the air or an impact) that caused a horizontal stab failure would likely separate it as a unit. The span is 24m / 71 feet, again close to the reported dimensions of the larger object.
I'm not sure if the stab contains fuel tanks...if it does, they would presumably be empty and further help with floatation. A 777 expert can clarify/correct this point. Recall the AFA447 vertical was afloat for 5 days with no signs of sinking.
Hope the objects are from the 777 and lead to FDR and CVR.
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Not difficult, but expensive.
someone should have known the answers in detail soon after the aircraft went missing.
the Airfrance accident took two years this is likely to never be found.
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Some 2.9 billion people used air transport to help them realize their business and tourism needs in 2012, according to preliminary figures on scheduled services released today by the International Civil Aviation Organization (ICAO).
Per
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Too much data'
Really? How much room does say 12 hours worth of a series of numbers sampled say every 5 seconds really take up.
And if bandwidth is a problem then isn't the answer to add more. Wouldn't a few more satellites paid for by the world's aviation industries cost less than the sorts of monies that are now being expended?
I'd like to see an analysis of the complexities and economics. Has one ever been done?
Really? How much room does say 12 hours worth of a series of numbers sampled say every 5 seconds really take up.
And if bandwidth is a problem then isn't the answer to add more. Wouldn't a few more satellites paid for by the world's aviation industries cost less than the sorts of monies that are now being expended?
I'd like to see an analysis of the complexities and economics. Has one ever been done?
But the suggestions I've seen onTV of real time video streamed from all commercial aircraft in the air, over a satellite communication network, is almost certainly not possible without a whole new satellite system.
You would want at least some reasonable video quality - not like the CCTV footage on crime TV shows, where you can't tell who it is or what they are doing.
Just like home internet connections, satellites data services are optimized for much greater bandwdith down than up, and they are not really designed for video streaming. a satellite connection for streaming is _much_ more expensive than just a regular data connection, and at least for the common services, even streaming is mostly restricted to 256kb/sec or 512/kb/sec, so not very high res. also, the antennas are huge.
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The Washington Post has presumably taken the Australian search box, drawn straight lines - ideally great circles - back from either side of it towards the "last contact", and without too much difficulty plotted circles that are centered on the satellite footprint, and cross the tracks 500 miles back from the 0811 track.
Perhaps they had some official advice on whether that was appropriate or perhaps not. They do label them as provided by the NTSB, so I guess that's probably true. The Australian box extends East - so maybe that's for currents, or maybe there's something else the Australians are taking into account.
However, assuming the Australian box is right, then to be there at 0811, there isn't much option but to head there in something like a straight line.
Perhaps they had some official advice on whether that was appropriate or perhaps not. They do label them as provided by the NTSB, so I guess that's probably true. The Australian box extends East - so maybe that's for currents, or maybe there's something else the Australians are taking into account.
However, assuming the Australian box is right, then to be there at 0811, there isn't much option but to head there in something like a straight line.
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@arearadar
The only confirmation given regarding radar coverage was that civil radar operating with SSR obviously lost signal from the flight. There never was any communication regarding whether the military ever lost the signal or not. As a former military operator myself I believe that the system never lost track and never reidentified the target since it was recognized as civil / friend or whatever they use in Malaysia.
Command centers and the associated computers do auto-track and target building since the early 1960, so no real tecnological breacktrough. And if the civil system report data into the military one any flight identified by the civil system will be auto-updated to a friendly.
Why would you check a civil target taking a shortcut as long as he does not fly into some active military airspace and most logically the civvies have cleared him direct?
The only confirmation given regarding radar coverage was that civil radar operating with SSR obviously lost signal from the flight. There never was any communication regarding whether the military ever lost the signal or not. As a former military operator myself I believe that the system never lost track and never reidentified the target since it was recognized as civil / friend or whatever they use in Malaysia.
Command centers and the associated computers do auto-track and target building since the early 1960, so no real tecnological breacktrough. And if the civil system report data into the military one any flight identified by the civil system will be auto-updated to a friendly.
Why would you check a civil target taking a shortcut as long as he does not fly into some active military airspace and most logically the civvies have cleared him direct?
I don't own this space under my name. I should have leased it while I still could
Where does it say that the a/c was continuously tracked without a break, thus retaining identification ?
I read that a/c disappeared from radar.
After that. primary returns were observed but identification was not confirmed. How could it be ?
As a controller of 33 years experience that wouldn`t satisfy me.
I read that a/c disappeared from radar.
After that. primary returns were observed but identification was not confirmed. How could it be ?
As a controller of 33 years experience that wouldn`t satisfy me.
As a surveillance operator on the other hand, if I had dots 1, 2, . ,. ,. 4, ., 6
where the spacing accords with the estimated speed allowing for missing returns on a number of sweeps (even where the 'sweep' are not shown on the display) then I would consider that as possibly 'my' track. This is for a non-cooperating track where squawk flash or ident turns could not be requested. If there were no other 'Unknowns' then I would consider I had a coherent track and apply a track number to it.
In this case I think they would have to work on probabilities and not certainties.
PS
I agree with Hunter58. If the military had the primary labelled as Friendly then it would be tracked through the turn back.
PPS, thank you MPN11 ( see we are of an age
)
Last edited by Pontius Navigator; 20th Mar 2014 at 19:43.
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Jindalee Operational Radar Network
If this latest find west of Australia turns out to be the missing aircraft I'm wondering if Australia's over the horizon radar (Radar Jindalee Operational Radar Network) wouldn't have already detected its final flight?
I think its possible that there are military surveillance systems which are capable of detecting large aircraft in this part of the world from a long distance away, and that its possible that government agencies wouldn't want to disclose their technological capabilities publicly for security reasons.
I think its possible that there are military surveillance systems which are capable of detecting large aircraft in this part of the world from a long distance away, and that its possible that government agencies wouldn't want to disclose their technological capabilities publicly for security reasons.
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Economist got it wrong
The Economist got it wrong. The only real reason for a live datastream would be that the TV networks can immediately get crews to the crashsite to sell better pictures.
And in this particular case my gut feeling is that there were too many political hick-hacks pared with absurd levels of paranoia that led to immense amounts of men and material being wasted.
The basic ingredient for any serious investigation or analysis however is missing: the use of the brain.
And in this particular case my gut feeling is that there were too many political hick-hacks pared with absurd levels of paranoia that led to immense amounts of men and material being wasted.
The basic ingredient for any serious investigation or analysis however is missing: the use of the brain.