The multinational team searching for MH370 and its 239 passengers and crew may widen the hunt using more capable underwater vehicles.
Yesterday, the Bluefin-21 completed its ninth mission scouring the seabed with three more dives expected to wind up the survey of the most likely location of MH370.
Under consideration are the Orion towed search vehicle and the Remus 6000, which found wreckage of Air France 447 in 2011.
The Orion can send real-time data to searchers, giving them far more flexibility. The Remus 6000 autonomous underwater vehicle can dive to 6000m.
Depths in the current search zone range from 1753m to 6000m.
The search area where a beacon was detected is 4500m but falls into trenches on three sides.