Malaysian Airlines MH370 contact lost
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yes it is curious. if there has been an explanation I have missed it. aircraft carries ulb. its range is 1 to 2 km in normal conditions. ulb signal is heard so the bearing of it from the tpl is known but not the range but hey we dont need that, it says on the tin it is no more than 2 km away. textbook stuff so far but ulb and aircraft not found. it seems ocean shield and echo together could not establish even a position line. how did this or any other ulb get certificated with such a dismal specification? apparently the number of successful ulb locations via pinger, ever, can be counted on one hand. just another piece of kit to add to the list of recommended upgrades. so its got to be the hard way, the ulb is obviously down there somewhere so its now a long slog to find it a la af 447.
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ULB propagation different from submarine
Concentrating an MH370 sonics search within the immediate area of a few pinger detections was overly optimistic and seems to have disregarded the characteristics of sound in deep water.
Add in the Raytheon claimed discrepancy and it's still a much larger and indefinite search area than those you see on the AMSA/JACC charts. I guess we will see whether this will be reflected in the next phase search zone prognostications.
Add in the Raytheon claimed discrepancy and it's still a much larger and indefinite search area than those you see on the AMSA/JACC charts. I guess we will see whether this will be reflected in the next phase search zone prognostications.
At the 33.5kHz frequency of the assumed pinger detection, the ocean absorbs sound at a rate of about 4.5 dB per kM. This is in addition to r-squared loss. This substantially limits detection range, and is no doubt why the original search area was small. It also leads me to believe that, if the original pinger detect was valid (and I've yet to see another explanation for the signals), the wreckage should still be found close to the detect locations.
It will be interesting to see what the reviewers have to say about this, if any is made public.
See this attenuation calculator: Calculation of absorption of sound in seawater
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Interesting article on detection of ULBs and their practical operating ranges. Apologies if it has been posted previously.
Deep-water Black Box Retrieval - November 2009, Volume 13, Number 09 - Archive - Hydro International
Deep-water Black Box Retrieval - November 2009, Volume 13, Number 09 - Archive - Hydro International
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@Propduffer
Mr Winter seems to have a good Internet presence, e.g.
ATCA Technical Writing Awards
The last radar sighting at 18:22 is shown in the ICAO report maps and in the slides shown at the Beijing meeting a day or so before. Agreed that the lat/long position of the 18:22 sighting seems to have moved West since previous reports.
Who is "Steve Winter", and where does he get the location of the "last radar sighting of MH370 from?
ATCA Technical Writing Awards
The last radar sighting at 18:22 is shown in the ICAO report maps and in the slides shown at the Beijing meeting a day or so before. Agreed that the lat/long position of the 18:22 sighting seems to have moved West since previous reports.
Thank you!
I'm at a loss why People feel so urged to exclude (or to foster on the other Hand) possible causes in this case?
What's the benefit of that?
Does it help improve safety?
Does it make somebody sleep better at night?
Why can't we just wait until they find the boxes?
I'm at a loss why People feel so urged to exclude (or to foster on the other Hand) possible causes in this case?
What's the benefit of that?
Does it help improve safety?
Does it make somebody sleep better at night?
Why can't we just wait until they find the boxes?
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Pingology...
I have made attempted to account for all motion between the aircraft and the satellite..
The Inmarsat 3F1 was moving very slowly westward during the whole flight , this was not enough to significantly change the 'doppler' shift of the signals routed through it....IMHO...
It was also moving northward away from the equator very slowly , reaching a limit at around 18:41UTC , and then moving back toward the equator again . It is this 'wobble' which Inmarsat suggests could help distinguish between an aircraft route in the northern hemisphere , and one in the southern............via subtle differences....
By far the greatest motion is the up and down direction...........although the figures published are relative to the surface straight down and Kuala Lumpur is part of the way around the world , and so lower values would be experienced there .
In the chart the first section is defined with negative values as the satellite is ascending . The latter part as positive values as the satellite is descending . I converted the speeds to feet per minute , as this helps relate it to aircraft motion............
The Inmarsat 3F1 was moving very slowly westward during the whole flight , this was not enough to significantly change the 'doppler' shift of the signals routed through it....IMHO...
It was also moving northward away from the equator very slowly , reaching a limit at around 18:41UTC , and then moving back toward the equator again . It is this 'wobble' which Inmarsat suggests could help distinguish between an aircraft route in the northern hemisphere , and one in the southern............via subtle differences....
By far the greatest motion is the up and down direction...........although the figures published are relative to the surface straight down and Kuala Lumpur is part of the way around the world , and so lower values would be experienced there .
In the chart the first section is defined with negative values as the satellite is ascending . The latter part as positive values as the satellite is descending . I converted the speeds to feet per minute , as this helps relate it to aircraft motion............
Last edited by Robin Clark; 5th May 2014 at 20:35. Reason: problems with image.......
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Australian 14-15 budget
With a very hardline Federal budget due out next Tuesday, I wonder how much pressure the Australian government will find themselves under to wrap up/pass on the associated costs?
I'd like to find the answers with MH370 but at some stage the line has to be drawn. It's great publicity for Australia throughout the world but to fund an indefinite search might be close to political suicide (by a government who are about to implement a debt levy and take an axe to government spending).
Will be interesting to see what questions are asked come Tuesday.
I'd like to find the answers with MH370 but at some stage the line has to be drawn. It's great publicity for Australia throughout the world but to fund an indefinite search might be close to political suicide (by a government who are about to implement a debt levy and take an axe to government spending).
Will be interesting to see what questions are asked come Tuesday.
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Propduffer and Richard,
The last position given for some radar contact, surmised to be MH370, as given to the Chinese families was 200 nm from Butterworth on a 295 radial.
I don't know how you can "move" that point westward unless you possess some additional radar targets that have not been released to the families.
The last position given for some radar contact, surmised to be MH370, as given to the Chinese families was 200 nm from Butterworth on a 295 radial.
I don't know how you can "move" that point westward unless you possess some additional radar targets that have not been released to the families.
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The only possible improvement to safety at this time is to require the transmission of the crash recorder to the ground during the flight. It can be deleted on a flight/daily basis so there is no overload on the recording systems.
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If the aircraft is flown in VNAV (vertical flight path) and is at say 37000 and a way point altitude of 6000 feet is entered at some point down line then the aircraft will descend to reach 6000 feet point in flight idle descent PROVIDED that 6000 has been entered in to the MCP altitude window, the reverse (climb) is true, but unless some one makes a further amendment to the MCP target it won't climb or descend again.
Please correct me if I'm wrong.
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@Datayq1
I have not moved anything. The ICAO report map refers to 'Updated Last Air Defense Radar Point' and the same point is on (a fuzzy copy of) the slide at the 29th April Beijing families meeting.
https://www.documentcloud.org/docume...h370-maps.html
Beijing-4_2014-04-29_zps0977658b.jpg Photo by RichardC10 | Photobucket
I don't know how you can "move" that point westward unless you possess some additional radar targets that have not been released to the families.
https://www.documentcloud.org/docume...h370-maps.html
Beijing-4_2014-04-29_zps0977658b.jpg Photo by RichardC10 | Photobucket
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Transmit the data and we don't have to search for the recorder. Saves a lot of money
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The step climb/descents entered into the FMC are for the FMC to calculate performance and fuel burn
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Well I tried entering our climb level with a step climb at next waypoint and MCP altitude set to cleared level just to see what it would do (in a real 777) and the aircraft did not climb until the ALTSEL was pushed.
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andrekik : They would know ac's last position....
They would have details of lots of other things though, like probably what happened and when.
Unless the data link was switched off, of course, or failed before anything else untoward happened.
Last edited by DrPhillipa; 6th May 2014 at 03:25.
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Thanks for all the replies re FMS VNAV.
So, as I understand it, by any of four methods, a live human could climb from 35000ft to 39000ft and level off at 39000ft and, once that had all been achieved:
(1) - Input to FMS any number of existing (or their own) waypoints
(2) - Input to FMS a 5000ft level at a chosen waypoint using a chosen descent method, such as, for example, idle descent
(3) - Enable 5000ft by dialling 5000 in the (MCP?) window, with a press to pre-arm.
After completing (1) to (3), which might require nothing more than 10 minutes after levelling at 39000ft, said live human could then die (by depressurising, or, if already depressurised, by removing their oxygen mask) and the aeroplane would spend the next several hours automatically flying over the waypoints in sequence, descending when it calculated necessary to achieve 5000ft by the location programmed several hours earlier.
Are there any flaws in the above, please?
So, as I understand it, by any of four methods, a live human could climb from 35000ft to 39000ft and level off at 39000ft and, once that had all been achieved:
(1) - Input to FMS any number of existing (or their own) waypoints
(2) - Input to FMS a 5000ft level at a chosen waypoint using a chosen descent method, such as, for example, idle descent
(3) - Enable 5000ft by dialling 5000 in the (MCP?) window, with a press to pre-arm.
After completing (1) to (3), which might require nothing more than 10 minutes after levelling at 39000ft, said live human could then die (by depressurising, or, if already depressurised, by removing their oxygen mask) and the aeroplane would spend the next several hours automatically flying over the waypoints in sequence, descending when it calculated necessary to achieve 5000ft by the location programmed several hours earlier.
Are there any flaws in the above, please?
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Val
To be accurate i fly the 737NG which has a very similar system to the T7
The whole purpose of VNAV is to allow you to fly stepped climbs/descents, but the MCP alt window is king and will not allow you to fly through it in either climb or descent, i understood the T7 was more or less identical in this respect?
What you can do is climb or descend away from the MCP alt with no protection.
So you could be flying along at 1200ft and select 10000 feet in the MCP alt window, this would open up V/S (vertical speed) mode, if you then dialled a positive rate of climb the aircraft would climb away from the MCP alt value with no protection the reverse is also true.
So starting at 12000 ft with 10000 in the MCP and with a +V/S of a 100ft/pm and say a thrust limited climb ceiling of 45000ft it would spend 5 hours 30 minutes slowly climbing, of course as more fuel was used it would be able to climb further and in theory would keep going until it could climb no more and the speed came back to almost min speed, i think? it would probably revert then to level change and with 10000 in the MCP alt window it might descent back there at idle thrust until it captured the 10000 alt (or a 100ft if that was selected?) and that could be below sea level if the QNH was low (1009 or less) with STD (1013) set on the sub scale .
They may be difference between the NG &T7 in the logic but you get the idea, if i get chance i'll try it in the sim.....
The whole purpose of VNAV is to allow you to fly stepped climbs/descents, but the MCP alt window is king and will not allow you to fly through it in either climb or descent, i understood the T7 was more or less identical in this respect?
What you can do is climb or descend away from the MCP alt with no protection.
So you could be flying along at 1200ft and select 10000 feet in the MCP alt window, this would open up V/S (vertical speed) mode, if you then dialled a positive rate of climb the aircraft would climb away from the MCP alt value with no protection the reverse is also true.
So starting at 12000 ft with 10000 in the MCP and with a +V/S of a 100ft/pm and say a thrust limited climb ceiling of 45000ft it would spend 5 hours 30 minutes slowly climbing, of course as more fuel was used it would be able to climb further and in theory would keep going until it could climb no more and the speed came back to almost min speed, i think? it would probably revert then to level change and with 10000 in the MCP alt window it might descent back there at idle thrust until it captured the 10000 alt (or a 100ft if that was selected?) and that could be below sea level if the QNH was low (1009 or less) with STD (1013) set on the sub scale .
They may be difference between the NG &T7 in the logic but you get the idea, if i get chance i'll try it in the sim.....