etudiant
In US terms, the current guidance is roughly this:
We think an aircraft has crashed about 1100 miles off the coast of California.
Please find the debris. We don't know that there are any afloat, but some may wash ashore, so check the West Coast and the sea bed.
It's a bit more pessimistic than that. Rather, the current detail is "it's somewhere in a 500-mile swath N-S that extends from 1000-2500 miles away". So, keep your eyes open too Hawaii, and watch your beaches Oregon and Mexico.
The Intelsat information is excellent. However, the search guidance seems to be being set by a mix of political grandstanding, and an irrational reaction to satellite photos of freight containers and whitecaps. Tony Abbott says that the search will go on indefinitely: it might need longer than that.
It now seems reasonable to assume that all the satellite information that's going to be available is available, at least to governments, if not to the public, although I find it hard to believe that no-one has some ocean radar satellite data that they can't catch the track of MH370 on. Could its contrail really not be stacked to appear on weather photos taken after dawn over the ocean either? Just a single location enroute would make the search box much much smaller.
If the sonar data recorder detection effort fails, and given the several hundred thousand square kilometer positional uncertainty - that seems likely - it will be a long haul of hoping imaging sonar surveys can locate the wreckage somewhere on the favorably-shaped abyssal plain.
That sonar image in 500N's post shows wreckage, so it's ~100m across with few-cm resolution. If the same can be done with a 5-km swath, and meter resolution, then the wreckage might be found after sailing ~20,000km, which seems to be a bit of a challenge. A spot survey of likely locations based on a coarser survey would seem to be more realistic. Whatever method found the Titanic would seem to be a template, but the location of the Titanic was known to within a few hundred square kilometers: that's about a thousand times better odds for the searchers.