Investigators reconsidering approach, as underwater drone fails to find Flight 370 wreckage

(CNN) – Another critical point in the search for Malaysia Airlines flight MH370 is approaching, and it seems increasingly as though mission complete may not necessarily mean mission accomplished for the high-tech device scouring the ocean floor for signs of the plane's data recorders.

The Bluefin-21 is on its ninth deep sea dive, having covered more than two thirds of the search area in the Indian Ocean. It may be done with scanning the entire search zone by the end of the week.

So what happens if this painstaking process wraps up without anything turning up?

CNN's Pamela Brown reports.