Call me stupid but:
They think it flew faster for the same amount of time, but didn't travel as far!!
Does that sound right, or have they got something the wrong way round?
Previous answers to this question do not make sense either!
Do they mean flew with a higher Fuel flow????
Ok Stupid
(sorry - only joking)
I am sure someone will correct me (or just delete this post) if I am wrong but I think the way this was presented was very confusing. It is my understanding that what was said was that the examination of the data they have from the early part of the flight (radar tracks from various sources I think) has suggested that the plane flew faster FOR THAT PART OF THE FLIGHT which used more fuel in the initial stages. By working with what fuel was on board at take-off and then estimating fuel usage for the initial flight that was tracked they have come up with an estimate of the fuel onboard when radar contact was lost.
They know (or are pretty sure) that the plane was still airborne at the time of the last full ping so they can work out what the endurance was (but not exactly because the plane could have run out of fuel right after the last ping or up to 59 minutes later). Based on the fuel available and endurance you can work out what airspeed would give the correct timing. If the plane had less fuel when it started the track south then in order to still be airborne at the last ping they have now deduced it must have been flying slower than initially thought FOR THAT SOUTHWARD part of the journey - hence the plane has not travelled as far south as their initial estimate.
Also I assume from the pings they have they know what the distance from the satellite was at each ping time so if the plane was travelling slower it was also on a more easterly path to put it on the right distance from the satellite at each point.
Hence why the search area has moved north and east due to the plane flying faster at the start, using more fuel and having to fly slower at the end to make the duration correct.
As an aside can any 777 people give a rough idea of what speed does give you maximum range at cruising altitude? It would seem to me that IF it was intentional and they wanted the plane as far south as possible then they would have gone for max range speed rather than anything else. Although the more easterly track doesn't seem to tie in with that as you would assume you would want to be further away from Australia if possible (unless of course you were aiming for a particular seabed location for the wreckage).