Thats for the sat com. Would be nice to se the ACARS logs from VHF-com.
Early in investigation it was said that Acars was deliberately shut down.
If so, there should have been some kind of log of on those logs ?

The point that needs to be made here is that any assumption for what happened between 18:29 and 19:41 implies an assumption about whether the plane was travelling east or west when it intersected the 19:41 arc. In turn, this affects the starting point for the long southward track hypothesised to have been flown on auto-pilot. It should be obvious that any constant speed or constant track solution for the later arcs up to 00:19 is rotatable around the satellite location. In other words, the terminal point is very sensitive to assumptions about what happened between 18:29 and 19:41 and the point at which the southerly course was started. The ability to rotate the track around the satellite without disturbing the timings for the southerly leg means that an assumption about the position of either end of the track (the point where it turned south or the terminal location) constrains the possibilities at the other end.

BTW, I have plotted my own ping rings for this and agree with the Australian report that the early rings agree with the submitted Malaysian Radar track.

There is a difference between a clean shut-down and pulling the plug out.

I take issue only with this.
I would agree with USUALLY but in unusual circumstances where all else fails then 'random' maybe a last resort.

Ulric:
We should discuss this and attempt to reach agreement about the ping rings. No conversation can go forth without agreement here.

You plotted your own rings? This means that you calculated distance for each ring using the the BTO data and included the knowledge of the satellite's exact position at that time; did you also compensate for the Earth's oblong shape?

I'm not up for such mathematical gymnastics so I just copied the latest KML version on Duncan Steel's site. Then after being challenged by Nick above I measured the distance between 18:29 and 19:41 rings and the version I'm using matches the expected distance (137nm is close enough to my expectation of 140nm.)

I further checked this against a Richard Cole graphic. I have previously downloaded a drawing labelled "Track_zpse219149d.jpg" (no url) which has the title "Constant Speed path to the final search area" dated may 29th. And the ring plot that I'm using matches this Cole graphic. Although I don't have a url for that jpg I can direct you to page 39 of Richard's data analysis which has a similar graphic with the same information.

Comments from you would be appreciated.

OleOle
That works for me.

Although I can't stop myself from thinking that maybe the 18:22 location was really 6° 0'0.02"N 97°30'0.05"E and the plane flew along the FIR boundary to POVUS from there. Could your BFO numbers support that theory?

If my life (and my passengers') were on a line I very doubt I would be resetting CBs without authorization. This often lead to fires. This makes even less sense with redundancy built into 777. I rather fly with some functionality disabled than with smouldering cockpit.

Just to be clear, I took Duncan Steele's calculated radii for the rings and used a kml circle generator to produce the kml files. I have also produced a set of kml waypoints for Malysian, Indonesian and Australian Airspaces from the data at fallingrain which are useful.
http://www.thesamestory.com/kmlcircle/
http://www.fallingrain.com/world/AS/waypoints.html

Olasek, by 'random' I implied educated rather than random.

You said it would make nonsense of built-in redundancy - true, but when built-in fails then you're on your own.

Holding in a popped CB is one thing, popping CBs is another.

Pretty clearly this accident was outside any foreseen contingency, and while we are considering probabilities, nothing can be ruled out.

Ulric

How did you locate the centerpoints for each of the rings? The satellite wasn't stationary in it's orbit you know.

Would you be so kind as to post your KML file online so that we can all examine it?

I am not aware of any substantiated report that any system on MH370 was 'shut down'. All we know was that various systems were no longer responding at certain times. We also know that the satcom was 'off' at least twice by the fact that it logged on twice. 'Off' in this sense means that the aircraft terminal was not in a logged on status (due to loosing the signal, being shut down, having power lost, etc.) but doesn't tell the reason it was 'off'.

we have a last Transponder return time, a last ACARS message time, a Last RTF time, several missed phone calls times, but not a single logoff or power down message. Nor do I believe any of those systems generate such a logoff messages.

As such, I don't believe there is any information to establish if systems were individually powered down at their normal power controls, by pulling local circuit breakers, by pulling busses, because breakers popped due to overload, because the device was damaged (other than the satcom which clearly was not damaged in that it came back twice).

The two most obvious path's of speculation are
1 - some technical emergency happened which motivated the crew to power down most of the aircraft's systems and after a reasonable time (at minimum I believe the time between loss of transponder and logon of the satcom) power up at least the Satcom, but not use it.

Or

2 - someone (crew, crew forced by passenger, passenger) did the same series of events with the objective of making the aircraft disappear.

It does seem difficult to imagine a technical emergency that would a- be responded to in such a way, b - allow the aircraft to fly for many hours, c - prevent any communication (particularly given that the satcom was back on line for most of the time)

As with Swiss 111, the SATCOM "logged on", but it could not be determined with any accuracy when it "logged off".

Satellite is normally assumed to be at the equator and 64.5E. My reading suggested that during the flight of MH370 it's position varied between 0.8 and 1.5N because of it's little elliptical orbit up there. I have centered my rings at 1.2N as a compromise.

I can't remember now where the position information came from but armed with Steele's ring diameters and a circle generator, you can put them anywhere you like. It's a 10 minute job to generate your own rings.

@ Ulric

The circle generator is no big deal, if you have GE pro you don't need a circle generator.

But the satellite position information is kind of a big deal, that "little elliptical orbit" covers a lot of miles. Since you don't have the KML file do you have the distance you used for the 18:28 ring? (I know where the satellite was then.)

I don't think it will help much but here it is
http://www.duncansteel.com/archives/549

If someone hadn't written it, I would have coded my own circle generator - it's easy to do - no need to pay Google for that. The other thing it's useful for is to put range rings around the known and suspected radar installations which might have picked up a trace.

Swissair 111 had a fire on board which disrupted the systems. We don't know what happened on MH370 but the speculation is that circuit breakers were pulled.

Consider your own PC. If you shut it down normally the event is logged, that is quite different from terminating the power by pulling the plug out (or burning the cables). In that case, you won't get a shutdown log but, depending on how the system is configured, you may get a message on reboot saying that the system was not cleanly shutdown.

Ulric

...before we blame a fellow worker.

In Swissair 111, the SATCOM logged on.
There was no "log off" data available from Inmarsat.
The log on was a "renewal".
The time of the "log off" could not be determined.
It was assumed this was due to a "power interruption".

That's the record. I merely am repeating it.

INMARSAT 3-F1 Position Data
 

@Propduffer on 9th Jul 2014, 00:23--

John Zweck, an Australian Ph.D. in math now teaching at UT/Dallas, has posted satellite trajectory data in 1 second steps at:

Aqqa on MH370

About 2/3 down the page:

"The satellite position data from STK in 1 second time steps between March 7th 1100Z and March 8th 1100Z are available in the ECEF (fixed) frame and the WGS 84 frame. The LLA version includes latitude, longitude and altitude (geodetic height) above the WGS 84 ellipsoid and the LLR version includes latitude, longitude and radius from the centre of the WGS 84 ellipsoid."

Followed by links to files in several different formats.

Author's home page:

John Zweck

I'm sorry, I don't mean to imply blame. It's just that the behaviour of systems is different when they are shut down than when they are unplugged.

Confusion over BTO and Ping Angles
 

When the Signaling Unit Logs for 9M-MRO were released, Inmarsat described the BTO as being the round trip delay "relative to a terminal at a nominal fixed location". There were two different interpretations as to where that terminal sat - one had it at a fixed point on the earth, the other had it at a fixed point from Perth (and thus acting as a single constant offset to the round-trip delay.) These two interpretations led to different predictions for ping elevation angle as a function of time, up to 2 degrees.

The first interpretation seemed to make sense because its predictions matched well with the "7 Data Point" graph that showed ping angles for several times during the flight (aside from a puzzling constant offset in angle.) At the time, this graph seemed to provide the most reliable ping angles.

However, it is now clear that this first interpretation is wrong. Equation 1 in the ATSB report can be rewritten to show that the BTO is, indeed, just the round-trip delay plus a constant bias. Tables 1 and 2 of the ATSB report reinforce this view. Table 2, in particular - BTO Calibration at Kuala Lumpur - shows that the BTO and path length were both increasing at a time when the plane was sitting on the ground. The increase in path length was consistent with the increase in round-trip path between Perth and Kuala Lumpur in Table 1, and was due mainly to the satellite-Perth leg.

As a further check, I recomputed ping angles for both the portion of the flight where we have ADS-B data and for the later portion where one can make use of the ping ring plots in Figure 18 of the report. I get consistent agreement between these ping angles and the newly-interpreted BTO, with a spread of 0.2 degrees in elevation angle. These angles differ from those on the 7 Data Point graph by a peak-peak of 2 degrees - ouch!

Thus, we conclude that the "7 Data Point graph" is flawed. Perhaps it was drawn in a rush by someone for one of the family briefings. Its purpose was to show that the plane did not go to Beijing, for which high accuracy was not needed, but was not intended for anything else.

Duncan Steel's Ping Ring radii in message #549 posted on April 5, 2014 are derived from the 7 Data Point graph and thus are wrong. Unfortunately, Richard Cole's BTO model is also the wrong one, and his Appendix B distances are likewise wrong.

For what it's worth, I was following the wrong interpretion as well, until being confounded by the Kuala Lumpur BTO measurements. Since there is interest, I will give my values for BTO and such in a follow-on message.