Something which disturbs and saddens me about this, other than the probable loss of life, is the apparent unwillingness of various agencies to share information which may be of help. I'm thinking particularly of the "We didn't tell them because they didn't ask" situation with Thailand. Surely common decency should dictate that any possibly relevant information should be shared as a matter of course without having to be asked and as soon as possible after an event? I appreciate that security needs to be preserved but ways can usually be found of circumventing specific detail which might betray particularly sensitive information which the country of origin might wish to preserve.

@ JG1

It kept pinging and made course changes.

The Imersat Arc
 

The imersat track is shown as an Arc if transposed onto a globe does it become a direct great circle track as normally flown? I assume the track was calculated this way. Perhaps they should release the timing data for others to have a look.
Checking with the search aircraft should give a comparison timing.

How many way-points exist in the southern area that can be programmed into the 777 Internal navigation system?

After depressurization is it possible to open the doors and bale out the 777 did any crew have a unusual carry on bag?

In principle just about anyone would agree with you, but try a Google search.
It is all available on the Internet.
I think ill minded people have Internet too.

But after the initial turn westbound, if it did come back over Malaysia/Indonesia would there not have any cell phone sign in attempts as Mr172 points out? Especially if it, for whatever reason, was at a lower altitude? As was pointed out before, plenty of people leave their phone on after closing the door.

"Ping", which judging from the interview with the Inmarsat VP isn't a term they actually use, clearly implies a ping-and-response sequence in this context. Except in the case of the final ping, of course.

You can create a waypoint anywhere you like so gazzilions! And there and lots of ways to define a waypoint.

The arc isn't a track. :ugh:

It's the set of possibilities for the position at the time of the final exchange with the satellite. And no, it's not a Great Circle.

The other explanation for prioritising the southern arc was that a northerly route would have taken it over several countries' radar systems that - as yet - have drawn a blank. But I guess they may yet come up with something who knows ?

That said, the Malaysian's have continued to say they're keeping their options open, not ruling anything out without a fact-based reason to. There really are still very few facts, that we know of anyway.

ground to sat two fixed positions, sat to aircraft, aircraft to sat one fixed one moving, sat to ground two fixed items.

sat ground and vice versa absolutely irrelevant (the should be a constant). it matters not one jot whether the satellite has an hourly clock or the ground has the hourly clock, the only part that can measure the distance in time and relate it to distance is the sat-aircraft section.

The timing is almost certainly on the satellite why depend on extra transmissions from/to GS which may be down.

You fly into the coverage of a satellite, your presence is detected just like you going to an area of a new phone mast, it knows your there and both of them periodically check to see if you still are. So the satellite has detected a potential service user why tell the ground , it just logs it and checks in an hour

@ JG1

It kept pinging and made course changes.


Pinging because the system which pings is still intact.
Other comms out, some immediately some progressively.
As I said, erratic course because of damaged accelerometers in ADIRU.
That damage might even have caused it to only issue false commands at waypoints.

Depends where you are. In the UK, this is what OFCOM says:

"Although it is not illegal to sell, buy or own a scanning or other receiver in the UK, it must only be used to listen to transmissions meant for GENERAL RECEPTION. The services that you can listen to include Amateur and Citizens' Band transmissions, licensed broadcast radio and weather and navigation broadcasts. It is an offence to listen to any other radio services unless you are authorised by a designated person to do so."

Full text here:

RA 169 - Receive-Only Radio Scanners etc

In practice, of course, I've never heard of someone being prosecuted for listening to, or recording, ATC.

Someone said earlier that the messages are sent in well-defined timeslots, so you wouldn't necessarily have to look at the round-trip delay, but the difference between the time the message was received from the aircraft and the 'ideal' start of the timeslot if the aircraft was directly below the satellite. That's assuming it's fairly well synchronized to the satellite, which you could determine by looking at previous flights that sent position reports.

Imersat Track
 

Thanks Dave
Hate to say your right and cleared my misunderstanding.

If they released the other pings and the last four are possible strait line. I'm sure someone by maths could work a possible track out.

No of course it doesn't! :ugh:

A Great Circle track is a 'segment' originating roughly from the centre of the earth.

These arcs are segments exactly centred at the satellite sending and receiving the 'pings'.

Don't worry, you are not the only one who is having difficulty understanding what these arcs are and why they are not going to add much to the search for either a track flown or the final destination.

Max Nightstop said,

it is a Government owned and Run airline, the Government is effectively the CEO.

Trying to figure out the timeline of recent CEOs, I have run into a handful of confusing "appointments" press releases since 2010. Specifically, it looks as though Anand Selvaratnam and Ahmad Jauhari Yahya may have kind of been switched back and forth a couple times as CEO & Managing Director since April 2011, but who knows for sure. Before that, I am able to figure out

August 2009 - April 2011 - Tengku Datuk Azmil Zahruddin
Archives | The Star Online.

2005 - August 2009 - Idris Jala, current Senator and CEO of the Performance Management and Delivery Unit (Pemandu)
Idris Jala - Wikipedia, the free encyclopedia

In-flight re-fuelling
 

I haven't seen anyone post the other gem from today's press conference when a reporter asked if the SAR aircraft were being air refuelled, where that was technically possible, and had they asked the USA to provide tankers to do the honours. The reply was "no we haven't but I will now, now that you've asked!"

An Australian poster here made the point very clearly, days ago on PPRune, that the RAAF assets could air refuel so they weren't limited to just 2 hours on station in the Southern Indian Ocean. Sad then that they haven't done it.

The Ping, The Satellite and The Ship
 

I am not quite sure if this discussion is about how sat pinging is/was used for a/c positioning (a lot of inputs, harder and harder to follow).

However, pretty clear explained here:
Help from above: Satellite signals can confirm a plane's identity - CNN.com


The probable track was obtained (backwards) starting from the last estimated position, using the know position of the (stationary) sat, the ground reference and the computed angle between the emitter (plane) and receiver (sat) when last ping has been sent - that is, not by time delay means (as GPS works). Which is straightforward...

They also said that's new territory:

regards,

GMM, if I recall correctly, the poster stated that the RAAF Orions were unable to do AAR, however the US Navy Poseidon is capable of it. Of course others have already mentioned the other factors which come into play such as crewing levels and duty times...

SLFplatine said

The problems come in it getting there - or more specifically, back over the peninsula in the manor it did without a crew. Also the issue of ACARS having completely failed to alert anyone to said catastrophic event taking place. (although it appearntly, per Malaysian Press Conferences at least, let them know of WP changes (at least 2) in the last report at 1:07)

Possibility of incapacitated crew after exiting the Straights(/radar) area; very high. Up to that point though; unbelievably low. (and that seems to pretty much be the Official stance of the Investigation team, so...)