227 pax or 226?
 

Originally was 227 pax and 12 crew, later they mention flight engineer as being there- standby travel? So it comes as 13 from MAS, 226 remaining as Pax

"Inmarsat saying they have used Doppler effect to isolate the southern corridor and tested the theory on known flights. Hence their latest conclusion. Can only give a general location."

Some of us on PPRuNe were discussing the probability of that a couple of days ago.

JakartaDean,

That was my first thought too. But on second thought the single downlink sat -> ground station probably needs as much resources as one link between a/c and sat. To communicate with the a/c the sat has to "illuminate" the whole hemisphere to be receivable by a tiny a/c antenna. In contrast to that the downlink to the ground station can be one concentrated beam and the antenna on the ground can be huge.

Thus the resources spend for the one beamed downlink to the ground station are negligible in comparison to the thousands of unbeamed links to the a/c and ships. So why not use the "cheap" bandwith in the downlink to relay all data available to the ground.

BTW: Newer Aero-C Terminals have automatic doppler comensation. Aero-C - Products - Aero - - Thrane & Thrane
Maybe older terminals required assistance from the satellite for that compensation, which would explain, why the sat "knows" the speed of the terminal.

The fire scenario has been mentioned before but if you think about the radar data indicating a climb to 4x000 feet then a sudden dive(Not sure if this information was validated or not)

Is that the move of a pilot trying to extinguish a fire? Has this happened and knocked out a lot of key systems

No, the flight engineer doesn't work for MAS. He works for a private jet firm.

So the numbers still don't tally. :sad:

Nik4Me

I didn't know that.

There was mention of a "flight engineer" in the early stages.
He was Mohd Khairul working in private aviation as a Flight Mechanic.

The "13th" MAS employee onboard was a "Flight Engineer" ?

4x000 feet?????

This was speculated on several days ago, and an actual 777 pilot dismissed the notion as implausible.

Inmarsat doppler
 

Inmarsat uses 121.5/406.25 MHz tx to find out approximate position using Doppler shift... so why not any other frequency? Accuracy provided by the 406 fx is higher due to the higher frequency and hence more Doppler shift.... I make sense hopefully... or maybe Not...

One of the passengers was MAS staff based in Beijing.

Regarding the INMARSAT contribution, this is on their website:

(emphasis added)

It's not clear that what was announced today was anything beyond this?

Possible analysis of ping data
 

A few days ago Capt Kremin pointed out that if the autopilot was in a mode that maintained a constant magnetic heading, there would be a significant turn to the East at the latitudes of Australia due to the large change in magnetic deviation. I looked at this in the context of the modelling that AAIB, NTSB and others are doing, to understand if the differences could be seen in the INMARSAT ping data that it is believed the authorities have. The answer seems to be not, as the two model tracks in the diagram (great circle in grey and constant magnetic heading in yellow) have very similar ping signatures with average differences of less than 15km (r.m.s. error) in the distances for each ping from the sub-satellite point. This may be less than the noise in the INMARSAT data. The two final southerly points of the tracks are 640km apart (one hour South of the last ping arc). Since a single search area was used by AMSA at the start of their activity, some method must have been used to decide between the track options.

Note: The only publically released data point on the map is the red final arc. The other ping arcs (only two shown) are just modelled results showing they match both tracks. The track direction is just an example that roughly matches the data in the AMSA maps.

http://i60.tinypic.com/2lwobo3.jpg

CodyBlade....

In these unprecedented circumstances when an official statement mentions pax as 226 and "colleagues" as 13, it would not be beyond reason to "query" the situation with regard crew ?

Especially when "openness" appears less than ...... "open" !

BABA99

Of course it does it totally rules out the Northern arc' so they can say with a high degree of certainty all on board are now dead

RichardC10

thanks for that work and the grasp it gives on the required error margin of the arcs. I would expect the great circle solution to turn to the right (west) when getting closer to the pole. Am i wrong or is the turn just too slight to see?

When going west over Malacca Strait in the first part of the track the a/c was heading always directly towards the satellite. Maybe from this part of the track inmarsat could put more constraints on speed.

Wind drift would also play a significant role.

----
Edit: Richards answer was, on southerly tracks and in lower latitudes great circles and rhumb (constant heading) lines are very similar. Wind drift for both solutions is similar too, and would not help to distinguish.

Richard,

Under similar assumptions does that rule out the Northern route? I assume that must require a weird combination of speed and track changes to remain consistent with the timings.

Neither the distance change away from the satellite between the hourly pings nor any potential Doppler information would by itself rule out a Northern location, any better than reasonable assumptions about the aircraft being spotted enroute ruled it out a week ago.

It's also not really clear why today's news, if the better Inmarsat analysis is all there's been, merits the appearance of the Malaysian PM or the move of the victims' families to Perth.

@LLuCCiFeRThe Malaysians are not "claiming" anything. They are reporting the inescapable consequence of what they have been told by the UK AAIB and Inmarsat - both of them highly professional and competent organisations with no axe to grind in the matter. :ugh:

A line of longitude is a great circle. The yellow track, if I read it right is not a small circle.

The grey track is a rhumb line, ie a line of constant heading that cuts all lines of longitude at a constant angle.

I just read that inmarsat said the altitude didnt change and it was 30,000+ constant(bbc)

From what I understood, the Doppler shift of interest was caused not by the aircraft movement, but by the slight movement of the satellite itself. So if the frequency increases when the satellite is moving "south", it means the airplane is in the Southern hemisphere.

But it could as well be a cover for a leak from spysats.

I think a lot more info will come out over the next few days. It seems odd to me that they would announce it at this hour, if they didn't have additional info to back it up.

My hunch is that the crews went out with this "New info" today (local time) and found the wreckage, but details not released until they have a ship on the scene.

We know for certain that there has been a delay with all info, so the fact they announced it at this hour has me believe they have wreckage located that could only be from MH370.

Anyone else of same opinion?

Ps. Regards to fire, have they not confirmed the previously reported irratic altitude changes which had everyone assuming "fire" were incorrect and it held and maintained FL30?