Voyage Recorder Key to Understanding El Faro Disappearance: NTSB

NTSB Pins Hopes on Recovery of El Faro's Voyage Data Recorder 0:56

Investigators trying to figure out what happened to the doomed cargo ship El Faro are hoping to pull answers from a device that likely remains thousands of feet under the sea.

The vessel's voyage data recorder is built to withstand brutal undersea conditions, National Transportation Safety Board Vice Chairman Bella Dinh-Zarr told NBC News. But once the box hits water, it begins emitting a beacon that lasts only as long as its battery — about 30 days.

NTSB: El Faro's Data Recorder Crucial to Probe 0:31

That leaves about three weeks to find the El Faro's recorder, which is presumed to have gone down with the ship Oct. 1.

The recorder holds all kinds of clues about the ship's demise. It preserves 12 hours of information covering the ship's movements and operations. It also captures conversations that took place on ship, which could help investigators understand what decisions the crew made and why, Dinh-Zarr said.

The NTSB is relying on the Coast Guard and the Navy, which are searching for the ship and the 33 crew members who were aboard when it sank 15,000 feet into the Atlantic while en route to Puerto Rico from Jacksonville, Florida. Searchers have found one body in a survival suit and one battered lifeboat in a 225-mile debris field.

A crew of NTSB investigators showed up in Jacksonville on Tuesday. While they wait for word on the recorder, investigators will collect records on the ship's construction, operation and maintenance, and probe the crew's training and experience, Dinh-Zarr said.

"We want to see how decisions were made in this instance so that we can figure out what happened and, we hope, prevent it from happening again," she said.