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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 18th Jun 2014, 13:37
  #11081 (permalink)  
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Nice to see Inmarsat explain their reasons for search locations , although still not convincing.
I thought that the 2 guys from Inmarsat were very honest in their explanations, although I admit I would like to have seen the chinagraph images the correct way round.

What more would you like to have for their conclusions to be convincing? Are you referring to the blog post here:

TMF Associates MSS blog MH370: analysis of where to look?

that gives another set of points that seem to be further south west of the Inmarsat estimate? It may be that Inmarsat used different values for the winds aloft, or indeed this group of analysts have used incorrect values from alternative sources. I don't know if there is any really solid wind information for the area in question but added to the IAS uncertainty (has this been resolved?) it might be responsible for these differences.
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Old 18th Jun 2014, 13:47
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Inertial navigation failure, causing a drift in the platform? Perhaps we are drifting away from the ping data which is the subject of this thread. The ping data however interpreted shows the path that was followed. The reasons for that path are a different discussion.
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Old 18th Jun 2014, 15:08
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Originally Posted by uksatcomuk
I'm not refering to the dopler effect "per se" but the effect related to the movement of the satellite itself.
I'm not sure what you mean. They've said several times that satellite motion is the primary source of doppler in the signal because the aircraft attempts to correct for its own motion, but not satellite motion.

If the aircraft wasn't correcting for its motion, we'd have had a much better idea of where it went a long time ago (and, if it was correcting for satellite motion, we'd probably still be arguing about whether it went north or south).
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Old 18th Jun 2014, 15:44
  #11084 (permalink)  
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The search is heading SW, towards the Inmarsat hotspot, apparently.

MH370: Australia to search seafloor of Indian Ocean for missing Malaysian jet - The Economic Times
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Old 18th Jun 2014, 17:53
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Originally Posted by RichardC10
I have written a paper on the analysis, posted here.

https://www.dropbox.com/s/ez4sxffxyl...14_issue_1.pdf

I have tried to be thorough but at the expense of being long. This was a lot of work – my wife thinks I am barmy!
Wow, nice paper ! Can't help thinking your wife is a bit right
Interesting piece of information about the D3 meaning / compensation.
You did not try to model accurately the 1st part of the trajectory and we have no handshakes between 17:10 and 18:30, ok with that, but the trajectories you used frankly cross the Indonesian airspace: shouldn't such trajectories have prompted a reaction from the Indonesian AF as they did in the past ? I think it is possible to reproduce the 3rd of the 3 handshakes at around 18:30: can you visualize the continous underlying time serie D1_aircraft+D2_aircraft ? (not simply its values at the handshake instants).
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Old 18th Jun 2014, 20:35
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Yes and no. The hotspot is a much larger area showed before as a rectangle, the area searched so far is in its extreme north-east corner. Using the word 'hotspot" is misleading because it suggests a small "hot" spot but in fact this is a very large area.

Last edited by porterhouse; 18th Jun 2014 at 21:23.
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Old 19th Jun 2014, 01:31
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Isn't this 'new hotspot' just the same place which has been shown on maps for weeks
Inmarsat vehemently objects to this new area being called a "hotspot", they say it is a pretty large area and the search will be difficult. It may very well be the same area depicted on earlier maps since Inmarsat in this interview says all the relevant calculations were performed within 2-3 weeks of the loss. They also defend actions of the search teams which concentrated on a tiny northern sliver of the area where the pings were believed to be coming from.

Inmarsat: 'No hotspot' in search for Flight MH370 | Asia | DW.DE | 18.06.2014
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Old 19th Jun 2014, 06:41
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You did not try to model accurately the 1st part of the trajectory and we have no handshakes between 17:10 and 18:30, ok with that, but the trajectories you used frankly cross the Indonesian airspace: shouldn't such trajectories have prompted a reaction from the Indonesian AF as they did in the past ?
I was trying to use the simplest possible model that will satisfy the data to the level of error in that data, which I estimate to be ~2Hz, one sigma. So I have used two parameters only, the speed of the first leg and the speed of the rest of the legs. As noted in section 7.9, the speeds of the first and second legs can be traded to move the position of the 18:29UT ping North, without affecting the fit. We are on very dodgy statistical ground here. There are only 4 reliable BFO data points at most, and I am fitting two parameters already. If I fit more parameters there is a danger of 'over-fitting', which means any data can be fitted. What the fitting process must avoid (of course the investigation knows this) is to avoid just joining the data dots with a complex model. Such a solution would definitely not be correct, there is noise in the data and this has to addressed.

I have been concerned that presentations (to the families) have made attempts to bend the path round Indonesia. The ping rings in the slides shown were not those derived from the data log (or from the slide of satellite elevations). The precisely defined 18:29UT turning point in the slides seems to be an assumption about the navigation process of the flight - perhaps correct, but not supported by any fact of which I am aware.

Better in the BFO/BTO analysis to avoid using data that cannot be 100% verified. If the data is consistent with the radar data, a consistent track should appear as a statistical acceptable solution.

I think it is possible to reproduce the 3rd of the 3 handshakes at around 18:30: can you visualize the continous underlying time serie D1_aircraft+D2_aircraft ? (not simply its values at the handshake instants).
Yes, I think a course can be generated that will satisfy some of the data around ~18:29UT, but I am not sure it adds any weight to the fit, that is a degree of freedom has to be used up matching the added data point.

On the time data series I will work on that. It will require an assumption about how the course changes between ping-rings (as a function of time) - at the moment I have just modelled one course per leg. That can be done of course, but it is another assumption.
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Old 19th Jun 2014, 08:42
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I will include that in a full run. Effectively that is what I did in section 7.9 of the paper but didn't include much detail. It will need a different average speed from 18:29UT to 19:41UT, but that may be consistent with potential scenarios for the flight. I was trying to keep the model simple, as I said.

I wasn't overwhelmed by the ATSB fact sheet when it was released. The scale is small, but the ping-ring map seems to show the same wrong data as the Malaysian presentations, and there is speculation about possible navigation waypoints on the route. It wasn't clear what level in the investigation it had come from.
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Old 19th Jun 2014, 11:45
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I had missed the fact that the small search area was due to signals picked uo by HMS Echo.


Regarding this larger area that Inmarsat have calculated, can someone confirm my understand below is correct.

A) Some time back there was a diagram showing three segments of the southern arc based on the finalpartialping , if i recall they were called something like the northern section, the middle section and the southern section, and calculations favoured the northern section, which was when they moved from the south of Perth way up north.

B) This section then has to be extended south eastward (approx flight path) to account for the final glide and that is the area they will be searching first. It is also the last area they searched for debris (presumably shifted somewhat to allow for ocean currents/time lapse).

Is that correct.
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Old 19th Jun 2014, 16:16
  #11091 (permalink)  
 
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then (as explained by other posters) that autopilot has two basic modes of operation: either it maintains a selected heading or track (both referenced to the magnetic north),
Point of order/correction that may or may not be of relevance to the greater debate..the 777 autopilot track/heading function can be referenced (by pilot selection) to either magnetic north or True north.

FWIW looking further back in the thread I see some comments regarding a 14 degree/hour track change and..
Inertial navigation failure, causing a drift in the platform?
...Don't forget (?) the Flight Management System uses a mix of both ADIRU and GPS data to perform nav functions. In the real world you'll see a small amount of ADIRU "drift" on every sector and the FMC position will be anchored pretty much on the GPS position.
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Old 19th Jun 2014, 18:34
  #11092 (permalink)  
 
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Having worked nights at an ATC centre for many years, I must point out that during the wee hours, traffic may be light, but ATC, certainly where I worked, were not "half-asleep".
The charts which were used on the Horizon programme showed the AoRs of both Kuala Lumpur ATCC and that of Ho Chi Min ATCC, but also implied there was a geographical 'gap' between the areas of responsibility of the 2 centres. If this 'gap' really exists, what is it's purpose, and where are the transfer of control/communication points between the 2 ATCCs?
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Old 19th Jun 2014, 19:07
  #11093 (permalink)  
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@zooker, I think it might have been Singapore FIR. IIRC a chart was published earlier.
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Old 19th Jun 2014, 21:33
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The last 8 minutes

Also in the Horizon prog it was stated that in the last 8 minutes, a comms message was sent via Inmarsat that was similar to that sent at the start of a flight, implying that the systems had re-booted after power failure due to running out of fuel; plane dived, fuel re-distributed and there was suffficient to run the engines again

Question:
Would this start-up happen automatically, or would there have had to be intervention from someone on the Flight Deck to attempt to get an engine/generator to power up after having stopped due to running out of fuel?
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Old 19th Jun 2014, 22:51
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Delegated Airspace - Singapore FIR

Singapore leases on a daily basis three small parts of its FIR to Malaysia.

The delegated areas are shown in the Malaysian AIP.
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Old 20th Jun 2014, 04:01
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Virtual terminal location?

First, kudos to RichardC10 for an impressive job and no doubt a lot of hard work.

One item that I find odd is the 718 km altitude of the virtual terminal (VT). This seems a very unlikely choice for humans to make - an altitude of 0 would be far more likely. I suppose that they use a VT plus another unstated constant time correction, and that appears as the VT in RichardC10's analysis, but it is odd.

Is it possible that the VT is zero and some other factor is hidden in there to make things work out as if it were at 718km?

It's most unfortunate that Inmarsat didn't publish the full analysis.
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Old 20th Jun 2014, 07:05
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Mesoman

As you say, there is an additional constant related to the delay in that type of AES (and probably other constants) that cannot be disentangled from the VT virtual altitude with the data available. I don't think a height of zero would be chosen because:
a. it would give negative BTO value for a flight overflying 64.5E,0N
b. they didn't want to log negative numbers even with noise, so applied an offset

They really are just removing an offset, but that offset includes the variable ground station to satellite distance. The explanation does stack up with the graph of satellite elevations that was shown at a briefing, so it must be close.
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Old 20th Jun 2014, 07:13
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HamishMcBush Would this start-up happen automatically, or would there have had to be intervention from someone on the Flight Deck to attempt to get an engine/generator to power up after having stopped due to running out of fuel?
It would probably have been the engines running out of fuel and the APU automatically starting up and using the residual fuel in its fuel line for a short period of time.
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Old 20th Jun 2014, 07:24
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TIME? UTC and System Clocks...

Disclaimer: Non-pilot Librarian at aviation firm.

There seems to have been an analysis of the known and suspected tracks that was performed to determine if the plane was under human control inputs or solely under some mode of auto navigation during the initial period of "Somethings Gone Haywire" in hand off and unusual maneuvers phase.

I would question whether disparate systems of military radars would even be operating at the same system clock settings, particularly when it involves competing military officers.

Consider: System clock for an ATM transaction often differs by several minutes from System Clock for an ATM camera network. So a "noon" withdrawal from an ATM and a "noon" camera snapshot from that same ATM can be off by a few minutes. Also security system at major Miami hotel that displayed time frames on surveillance tapes of hallways, elevators and exit doors was found to be "off" by over fifteen minutes from actual event times.

Therefore, I would have doubts as to timing indications on disparate radar systems, particularly when primary returns are from different radar systems under different military jurisdictions. System clocks vary widely in all complex installations that are essentially a hodge podge of separately designed and separately installed systems.
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Old 20th Jun 2014, 07:36
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Are not all aviation time-dependent systems for ATC etc. systems synchronised to a single unit time source, e.g. the Rugby Atomic Clock or similar?
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