The National Transportation Safety Board’s vice chairman said Tuesday that the top priority in the search for the missing cargo ship El Faro will be to recover its voyage data recorder, but pings from the recorder have not been heard yet.

T. Bella Dinh-Zarr told a news conference on Tuesday the VDR begins pinging when it hits the water if the ship sinks. The recorder collects data from various sensors on the ship and gives information on everything that happened in the 12 hours before it hit the water.

"The voyage data recorder is an instrument that activates upon touching water. So once it is actually in the water, it will begin pinging and it has a battery life of 30 days," Dinh-Zarr said.

Dinh-Zarr said the agency’s investigation is separate from the Coast Guard. Agents are going to examine operations, engineering, human factors and survival factors in determining the cause of the accident. Crews are also going to look at paperwork, interviews and emails, she said.

The 790-foot El Faro had 28 Americans and 5 Polish nationals on board as it traveled in the direct path of Hurricane Joaquin in the Atlantic last week. The ship is believed to have lost power and drifted into the path of the storm during its journey to Puerto Rico. However, the owners of the ship say that may not have happened.

"We don't have all the answers, I'm sorry for that. I wish we did," Anthony Chiarello, president and CEO of ship owner Tote Inc., told reporters. "But we will find out what happened."

The 41-year-old vessel was scheduled to be retired from Caribbean duty and retrofitted in the coming months for service between the West Coast and Alaska, said Phil Greene, a Tote executive.

The El Faro and its equally aged sister vessel were being replaced on the Jacksonville-to-Puerto Rico run by two brand-new ships capable of carrying much more cargo and emitting less pollution.

The crew members were supposed to be doing preparatory work on the engine room, according to Greene. But he gave no further details on their work.

But "I don't believe based on the work they were doing that they would have had anything to do with what affected the propulsion," said Greene, a retired Navy admiral.

Greene said the vessel had no history of engine failure and the company said the ship was modernized in 1992 and 2006. Company records show it underwent its last annual inspection in March.

The American Bureau of Shipping, a nonprofit organization that sets safety and other standards for ships, did a full hull and machinery inspections in February with no red flags, the company said.

F. John Nicoll, a retired captain who spent years piloting the run to Puerto Rico, said he doubts the age of the El Faro was a factor, noting that there are many older ships plying U.S. waters without incident.

He predicted the NTSB will look into whether company pressure to deliver the cargo on time despite the menacing weather played a role in the tragedy — something Tote executives have denied.

"Time and money are an important thing" in the shipping industry, Nicoll said. He said there should be emails and other messages between the captain and the company to help answer the question.

Meanwhile, the Coast Guard continued searching by sea and air for any sign of survivors. The ship is believed to have gone down in 15,000 feet of water after reporting its last known position Thursday. One unidentified body has been found.

Tote executives say the captain, Michael Davidson, planned a heading that would have enabled El Faro to skirt the storm if the ship hadn’t lost power. The ship was left vulnerable to the storm’s 140 mph gusts and battering waves of more than 50 feet.

Davidson attended the Maine Maritime Academy and has a home in Windham, Maine.

"He was a very squared-away sailor, very meticulous with details, very prudent, which is important when you're working on the water. He took his job seriously," said Nick Mavadones, a friend since childhood and general manager of Casco Bay Lines, where he and Davidson worked together.

Still, seafarers who have long experience in the Caribbean say its weather can be treacherous.

"It can go from calm, in a matter of five or six hours, to hell," said Angel Ortiz, who retired as a merchant mariner after 39 years.

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The Associated Press contributed to this report.