Tracer buoys?
The charts by mm43 and greatbear made me think about the role of the currents transporting debris from the impact point.
What if the first search planes on scene would as a standard practice drop, say, twenty tracer buoys (with GPS and a location transmitter) over the search area in order to map out the surface currents as accurately as possible? Then when debris is subsequently found, this "current map" would enable much more accurate pinpointing of the actual impact point.
What do you think, would this be a) useful, b) feasible for future similar crashes ? According to Wikipedia, a Brazilian SAR aircraft spotted debris about 35 hours after the crash. It is not clear if there were other search aircraft in the area before, but even so I'd assume that the more accurate picture is collected about the surface currents, the bigger likelihood of locating the wreckage.
PS: Sorry if this has been mentioned before... I had no time to scan the large number of previous messages.