Given the length of time the families (and the rest of the world) have been left hanging, I certainly hope there is slam-dunk evidence that this is the case, and that amendments and alterations won't be forthcoming.
Inmarsat, the UK company that provided the satellite data which indicated the northern and southern corridors, has been performing further calculations on the data. Using a type of analysis never before used in an investigation of this sort, they have been able to shed more light on MH370’s flight path. Based on their new analysis, Inmarsat and the AAIB have concluded that MH370 flew along the southern corridor, and that its last position was in the middle of the Indian Ocean, west of Perth.
Looks like the data was there all along but unextracted.
The data they have isn't position or direction, it is a set of metrics that report on engine performance and conditions.
They never had positional information, except by virtue of the timing signals for those data points to their satellite. Which is how they originally determined the arc shaped corridor.
They must have been able to cross-reference this signal with another satellite (or source) to say with certainty that the plane went down the Southern corridor.
I would be surprised if this was cross-referenced with one of their own satellites given that they could have done that a week ago. I'd speculate that they were supplied with access to some other source that had received the signals, and were able to use that to triangulate the position.
This is not strictly correct. The pings that were being sent to the aircraft and which satellites received confirmations from were to the SATCOM system on board the plane. This is a multi-purpose communications channel. The ACARS is a maintenance reporting system which can send out various information about the aircraft at certain points, and which issued two reports about the Rolls Royce engines, but there were no further engine reports after the aircraft hit cruise altitude (it generally reports at takeoff, cruise, and landing).
http://delorbital.blogspot.com.es/2014/03/how-to-estimate-mh...
Does anyone have any more insight in to this? Was the protocol a one-way ping, or a ping-pong exchange? Previous reports have inferred that the data from the hourly pings were incredibly basic. Obviously timing signal propagation is the basis for GPS, but is it normal or even feasible to collect millisecond or microsecond transmission timings for engineering data fed via satellites like the ones operated by Inmarsat? What other variables would have been used for ranging?
1 millisecond at the speed of light is close to 300km.
edit: Other's have said that they are using Doppler shift.
So it looks like the announcement today is actually old news.
In any case, it's not entirely clear to me how the Doppler effect would distinguish between northerly and southerly passage.
The RR data can optionally be sent via ACARS, which was manually switched off. So no data from that.
"Shortly after the PM's press conference of Mar 24th 2014 Inmarsat reported that the new analysis of their satellite data used to identify the corridor and final location was based on the Doppler effects modifying radio waves and frequencies depending on speed and direction of travel of the aircraft, these data were compared to other flights. The computations are not precise enough to give the accurate position, however, made it possible to identify the general location. The new modelling and comparism were developed after the first discovery of the data on Mar 11th 2014, the work is still in progress."
Perhaps a device utilizing their service was in use on the plane (for in-flight broadband, perhaps?), and Inmarsat was able to review their usage data to help determine the plane's course.