Singapore said on Monday that it would volunteer a robotic submersible. So far, no other countries have committed submersibles to the search.
The U.S. Navy-owned Bluefin 21— which is capable of providing recorded video footage and 3-D sonar maps of the ocean floor — was used in the search for the missing Malaysia Airways jetliner.
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Another option is a submersible like the U.S. Navy's Orion, which can descend 20,000 feet and provide live video from the depths of the ocean.
Even though the Java Sea is not deep, the search could benefit from the use of submersibles, Gallo said. He pointed to the Remote Environmental Monitoring UnitS, or REMUS, which are small drones ideal for searching shallow waters.
Their size means that multiple drones can be launched from a single boat, which is makes them convenient for covering large swaths of ocean. The search area in the Java Sea stretches 120,000 square miles, or about the size of New Mexico.
The region's recent stormy weather and sediment dredged up by tidal currents could make spotting signs of wreckage from above — whether from aircraft or satellites — much more difficult.
When a commercial plane crashes, its emergency locator transmitter (ELT) should automatically turn on, broadcasting a signal that can be picked up by passing airplanes. The problem? They can sometimes malfunction, especially when involved in a violent crash.
It's also hard for airplanes and satellites to pick up the ELT signal when the downed plane is underwater, former National Transportation Safety Board investigator Greg Feith said on TODAY after the Malaysia Airlines jetliner went missing.
That is why submersibles are so important, Gallo said. Overall, however, it's the leadership behind the search that will make the biggest difference. Every wasted hour means a growing search radius, as currents carry debris away from the original crash site.
"It's almost like an orchestra," Gallo said. "You can have the right instruments, but you need the right talent and organization to make it work."