Ping Ring Data
 

Here are the ping ring data. Ang is the elevation angle. Ang and Arc are computed from BTO using a spherical Earth model. (I do convert geodetic to geocentric positions where appropriate.) The "Measured Ang" is either computed based on the known longitude and latitude at the time during the early phase of the flight or read off of Fig. 18 in the ATSB report. For the latter, I actually create my own graphics with ping rings overlaying an Earth map at the appropriate place and compared them with the Google Earth version in the report.

UT BTO Ang Arc "Measured" Source of "Measured"
deg km "Ang"

16:30 14933 46.90 4134 46.9 long = 101.69, lat = 2.72
17:07 15620 45.69 4253 45.6 long = 102.79, lat = 5.23
18:25 12520 53.31 3504 53.2 Fig 18, ATSB report
18:27 12533 53.28 3507
18:28 12490 53.39 3496
19:41 11500 56.17 3226 56.1 Fig 18, ATSB report
20:41 11740 55.41 3298 55.4 Fig 18, ATSB report
21:41 12780 52.44 3589 52.3 Fig 18, ATSB report
22:41 14540 47.86 4039 47.7 Fig 18, ATSB report
24:11 18040 39.87 4834 39.8 Fig 18, ATSB report
24:19 18400 39.10 4911

Long, lat are geocentric. 17:07 position taken from ATSB report.

@SK999
I don't know who you are and you only have four posts here, but everything you say checks out and you just saved me the trouble of contacting Richard to see what his take on all this is. So I'll go with your number for the 18:28 ring distance: 3496km = 1887.7nm rounded to 1888 nm. For the Satellite location at that time, my location checks with Vinnie Boombatz's link: 18:28:15 at 1.5691n 64.5286e.

So there we have it, AFIK everything is reconciled. We now have a solid Longitude to plot from at 18:28, and the Latitude can't be very far from MEKAR, the southernmost Latitude possible is 6° N - the FIR boundary, (we can be virtually certain the plane didn't cross into the Indonesian FIR there.) The northernmost Latitude is more open to debate; some people here apparently believe the plane went as far north as IGOGU or IGREX, I see the path most likely being IGEBO ---> POVUS , maybe as far north as NOPEK - but that's a separate subject.

So thanks Ulric, Vinnie and SK999 along with MM43 who started this thread.

Are you sure? While we all know PCs routers etc have log files which almost always log a shutdown request, these are only visible if you have access to the PC (or wreckage in this case). I am pretty certain there is nothing detectable outside the aircraft that lets you know if the RT, transponding or ACARS was powered down at the device or lost power. I don't have any specific details on the Satcom, but all of the information so far suggest the link communications are a logon/authenticate and then periodic status checks, but no expectation of a logoff or shutdown message when the system is powered down normally. So that to gives no clue as to why it stopped responding.

I would certainly expect the FDR to be able to answer many of these questions.


In any event, it is moot as I don't think there is any sensible scenario where someone is carfully following a power down protocol.

That sounds like you are done and everyone can move along now nothing to see anymore..thanks for your help

You were quite certain based on one set of KLM that you had a done deal.., and asked for agreements by everyone. Until you were given the set corrected and now you are are sure as God made little green apples that it is a virtual..certainty...

almost a fact..is not the same even as almost the truth..But thank you for your help and take care too.

This man says in item 8 there is a significant degree of inaccuracy..in the whole ping matter to begin with.
Malaysian MH370: SATCOMS 101 (Part One) | Air Traffic Management | Air Traffic Management - ATM and CMS Industry online, the latest air traffic control industry, CAA, ANSP, SESAR and NEXTGEN news, events, supplier directory and magazine
I am just curious if there is any information how defective inmarsat equipment has behaved in the past..spurious bursts ..as they do have a return defective equipment policy and secondly can a defect like that collapse a planes electronics ..


Thank you

JamesGV:
Sorry, I neglected to answer your question. Once logged off, the flight crew would need to log on again through one of the flight deck CDUs. There are two types of log on available - auto, where the system will log on to the best available satellite; or manual (constrained), where the system can be constrained to log on to a particular satellite. I could be wrong, but I think that once the system is manually logged off, it will not log on again until one of those options is selected.

Note: I am only trying to explain how the system works on the flight deck. I am not inferring what may or may not have happened in the case of MH370.

I fly the B777 and SAT COM LOSS is very common, it dates back from B777 rolled out.
After a while datalink will be lost too, then com is re established, datalink follows soon after. This happens several times during any flight. I am amazed nobody mentioned it.

An issue is... there is no notification if ACARS "dumps".
Post ETOPS after oceanic entry, if you don't update, you won't know.

And SATCOM can (and does) go "offline".
The next log on is a "renewal" not "initialisation".

If VHF/HF is required and not attained (as can be in an incident), what do you report ? You simply can't.

Is there an AUTO INIT issue on the B777 (all series), especially earlier series?

@sysconfig
In the same vein of sarcasm I thank you for your comment.
But it should be pointed out to you that the above exchange was needed in order for everyone to "move on" with the same point of reference.

Up until this discussion, there had been no way for any but the most diligent and up to date sat engineer types to know the location of the plane at 18:28, because of a mistake that had been made early on. If you will read sk999's post on the previous page you will learn that Duncan Steel's Ping Ring radii are wrong, as is, Richard Cole's BTO model, and I dare say that without the above conversation mm43's graphic on this page would have carried forth the same error.

I'm glad to see that you made it as far as two posts, but it seems that it's time for you to get a new handle (probably once again.)

:ok: very nice map mm43, as usual. what is the average ground speed of this great circle trajectory ?

I tend to agree with OleOle when he suggests that the 18:40 BFO value of the C-channel Rx (during the Call Progress - Test ) around 90 Hz is strongly indicative of a south bearing at 18:40. It may allow the A/C to fly around the Indonesian air space, crossing it only in a tangential way (flying around Banda Aceh). I am running a new MC simulation assuming the south turn is one minute before 18:40 and taking in account the 88 Hz BFO value at 18:40.

The following are the basic parameters compiled using the Vincenty Ellipsoid formulae:-

Start of track = 6.9752N 93.1072E, 172.4814T 131.144NM from VOCX
End of track = 29.8542S 98.4167E
Initial HDG = 172.3201T
Final HDG = 171.2092T
Dist = 4114660m 2221.739NM
Elapsed Time = 4.6405HRS - 4H 38M 26S
Ground Speed = 478.766KTS

Sorry about the "accuracy";)

Someone else asked for positions crossing each ring. I'll calculate those when I get some time.

As I've previously said, the graphic is just speculation based on the ability to derive a GC track at around 0.84 Mach. With regard to the southward turn at 1830, I assume that any turn or climb taking place at that time could provide the apparent BFO change.

I have created a Google Earth KMZ file with accurate rings and track plots at 20 kt intervals from 490kts to 410 kts and projected where 390 and 370 kts would fall on the 00:11 ring. ( I didn't include the 00:19 ring because I felt it would add more clutter than information.)

I chose a different route than mm43, I plotted what is probably the shortest route possible; I made the route through the strait pass south of MEKAR and from the 18:28 ring the route went direct to IGEBO and POVUS.

I included stuff from east of the 18:28 line, but the purpose of making this kml file available is for the 19:28 line and the southern route.

The KMZ file is at: https://www.dropbox.com/s/jz4d1j674o8g2a3/MH370.kmz

Pictures of the Google Earth presentation are at:
http://i1349.photobucket.com/albums/...psa1a0ba64.jpg

http://i1349.photobucket.com/albums/...ps31397ae3.jpg

Yep, the measurement has the problem of all the BFOs: It could be strongly influenced by vertical speed. In this case, if it the low BFO had been caused by vertical speed, it would have been caused by a vertical speed away from the sat, i.e. a descent.

PS: OTOH looking at appendix 1 of the raw data again: The BFO constantly lies between 86 and 90 in the one minute interval between 18:39:55 and 18:40:56. That is indicative of either a constant descent during this minute or a southerly course. To me the latter has higher probability

@Ole
It wasn't descending at that stage of the flight, but I believe it was headed SSW.

I have looked at the possibility of the flight having hugged the FIR boundary again and I now see that that looks very unlikely - if it did, it would have passed within 5 nm of Pulau We Island, which would have put it in Indonesian sovereign territory.

The main problem I see with the 18:40 BFO is, that it occurs in the C-Channel and not in the R-Channel as all other BFO measurements. Yet the BFO for the 23:14 ground to air call also is in the C-Channel and aligns nicely with the "neighboring" R-Channel measurements, so a big difference between R- and C-Channel BFO doesn't seem to exist. How deterministic this behavior is for this particular terminal we don't know (inmarsat probably does).

Early efter disappearance it was said that it was shut down. I'm finding it hard to know the status of how the investigation looks at this today tough...

Final words from Flight MH370 came after systems shutdown | The Japan Times

BFO value at 22:41
 

Hi Gysbreght,

I tried to double check your above conclusion but come to disagree.

To my interpretation in your graph the red line (calibration) represents

from equation (2) page 55. The difference between red and blue line then represents the remaining

At 22:41 this difference between red and blue line happens to be almost zero.

In richardC10's nomenclature DeltaFup + deltaf_comp is:

with
D1aircraft+D2aircraft : error remaining after imperfect compensation (miscompensation)
D2Satellite ............ : Doppler component caused by sat's motion towards aircraft position

That means D1aircraft+D2aircraft and D2Satellite are of equal size but different sign at 22:41. For an assumed position of 15S 98E at 22:41 I calculate D2Satellite as 3.9 m/s or ~21Hz.

Then the miscompensation also was ~21Hz which leads me to a guestimate of 320+-100 kts for the southward component of the speed.

Some "official" news
 

Blog - Cautious optimism in search for MH370

What is really new is that now you can have some answers from "them"! Very kind!

Whilst we don't know how the 'investigation' looks at this today, we do know that we can't definitively say that ACARS was disabled (neutral term) before the last transmission.

We only know that ACARS did not make it's expected transmission at 17:37. This would place the time of disablement between 17:07 and 17:37.

There is some thought that the disabled transponder event should have triggered an ACARS message (can anyone confirm or refute this?). If this is true, then we would be further able to deduce that ACARS was disabled between 17:07-17:21. However, this would still not definitively place it before the 17:19 last transmission.

Is that right ?

While being on the non civil side of aviation, I don't know all about ACARS. But from what I read, there supposed to be a ACARS over VHF also ? These logs we didnt se?

For the satcom/Inmarsat logs, it seems like ACARS did report stuff on a quite regulary basis, not more than 16 minutes between statusreports ?

Or there was a catastrophic event that was gradually knocking out system after system?