Originally Posted by
cwatters
No such thing. It's been explained they are designed to generate pings with a defined signal strength for at least 30 days... but they don't suddenly stop at midnight on day 30. They have said they typically last more like 40 days and at gradually reducing signal strength.
As I recall they justified listening for the pinger by saying that "additional analysis" of sat data had narrowed down the search area to make it worth a shot. The details of that additional analysis haven't been released as far as I can tell.
That's not the point. The point is that, if big boys get to the spot and find no trace of a ping, this could still be considered a legitimate finding and absence of the signal could be explained away.
I doubt that the Chinese have access to any useful sat data that is not available to anyone else.
In the light of the recent revelation that MH370 never appeared on Indonesian radars, it looks more likely than ever that the 1827 UTC turn from the Doppler chart was to the northwest, and Indian Ocean is a very expensive dead end.