(NewsNation) — Six workers are missing and presumed dead after the Francis Scott Key Bridge in Baltimore collapsed Tuesday when a cargo ship lost power and crashed into it.

The focus now shifts to the investigation into what caused the vessel to lose power. 

One focus of the inquiry, investigators say, will be whether contaminated fuel played a role.

One New York ship pilot NewsNation spoke to said this certainly can be an issue — and it’s happened to him before.

Jennifer Homendy, head of the National Transportation Safety Board, said at a news conference that the agency will investigate whether the vessel had any “deficiencies” before it sailed and review in depth the vessel’s safety history and any maintenance it received.

According to a public ship safety database called Equasis, the 985-foot-long vessel was flagged just last year for issues by port officials in Chile, who cited a deficiency in its “propulsion and auxiliary machinery.”

Built in 2015, “Dali” crashed a year later in Antwerp, Belgium.

James Mercante, president of the New York Board of Pilot Commissioners, says if a ship loses propulsion, the pilot is “pretty much a sitting duck.”

“You have to be concerned about the impact of wind, the impact of currents,” he said.

In this situation, the first thing pilots think about is dropping an anchor.

“You have to be concerned with, when you’re going a certain speed, what the effectiveness of your anchor is going to be, when you’re going ahead, and the anchor is deployed and going under your hole, and you’re basically running over your own anchor,” Mercante said. “Hopefully, at some point in time, it grabs, and the anchor grabs on the bottom and then you come to a stop. But without propulsion, also you cannot impact or affect the swing of your ship.”

It could take up to a quarter of a mile to stop a ship like this, Mercante said.

As NTSB officials continue their probe, Mercante said they will want to investigate any interactions between the pilot and captain using a vessel data recorder.

With these recordings, Mercante said, they will have 100% clarity on at least what everyone on board was discussing.

The Associated Press contributed to this report.