i WILL say that oceanic flights (or flights going over water more than 50 miles or so) should be equipped with a device to send their GPS coordinates via Iridium. that is very cheap to do (they make handheld devices that do this for a few hunded USD).

At least then you'll get the search started in the right area.

black boxes are almost always recovered. the only thing it would save is a big oceanic search -- how often does that happen?