By Alexandra Skores

(CNN) — A small label installed on a wire when a giant cargo ship was built may have triggered a chain of events nearly a decade later, causing the ship to slam into a bridge and collapse into the water.

The National Transportation Safety Board held a public meeting Tuesday to determine the probable cause of the container ship Dali crashing into the Francis Scott Key Bridge, and its subsequent collapse, killing six people.

On March 26, 2024, the 213-million-pound cargo vessel Dali lost engine and electrical power as it was leaving the Port of Baltimore and struck a pillar of the Key Bridge.

“The fact is, none of us should be here today,” said Jennifer Homendy, chairwoman of the NTSB, in her opening remarks. “This tragedy should have never occurred. Lives should have never been lost, as with all accidents that we investigate, this was preventable.”

The NTSB said Tuesday it believes a label was put in the wrong place on a signal wire when the ship was built. That sticker, identifying the line, kept the wire from getting a good connection in a circuit breaker – which in turn ultimately caused the first blackout.

As a result, according to Marcel Muse, the NTSB’s investigator in charge, the vessel lost steering, the ability to operate the bow thruster, key water pumps, and most of the vessel’s lighting and equipment essential for operations. That first outage lasted 58 seconds.

The crew onboard the Dali quickly found the tripped breaker, the NTSB said. Power came back within 58 seconds, but restarting a key pump that would have provided fuel to generators had to be done manually, and that didn’t happen. When the generators ran out of gas in their lines, the result was a second blackout.

“To restart it, you would have to go two levels down in near total darkness with a flashlight from the engine control deck to the purifier room on the fourth deck,” Homendy said.

The pump being used was designed to flush out lines for maintenance, but it had been operating for at least seven months. Since it was not intended to be used in this way, it did not have a backup.

When the pump needed to be restarted, the Dali was just three ships’ lengths from the bridge and despite the pilots reacting properly, they couldn’t regain control in time to avoid hitting it, the NTSB said.

About 10 hours earlier, while the ship was still moored, it experienced two onboard blackouts, one caused by a crew error, according to the NTSB.

At the conclusion of Tuesday’s meeting, the board will vote to determine the probable cause of the crash and approve a final report.

A critical minute and 29 seconds

Six construction workers filling potholes on the bridge when the ship slammed into the bridge support might not have been killed if they had been notified to evacuate, the NTSB said in the hearing.

The road crew was in their vehicles on the bridge when it collapsed, sending the trucks tumbling into the water. A seventh worker, who was with them, was injured in the collapse but survived. An inspector, who was outside of his vehicle walking the length of the bridge, ran to safety as it collapsed behind him.

As the Dali veered toward the bridge, the ship notified the Maryland Transportation Authority which shut down traffic on the bridge 48 seconds before impact. The agency also had the inspector’s cell phone number, but did not warn him of the impending collision.

“Had the highway workers been notified of the Dali’s emergency at the same time as the MDTA police officers, there would have been about 1 minute and 29 seconds to evacuate before pier 17 collapsed,” said Scott Parent, a highway factors engineer for the NTSB.

The force of the impact was nearly five times greater than the structural capacity of the pier, investigators said.

One loose wire among thousands

There were thousands of wires on the Dali, and the one loose wire that caused this incident would not have been easily found by the crew.

“The Dali is almost 1,000 feet, and it’s as long as the Eiffel Tower,” Homendy said. “It’s high with miles of wiring and thousands of electrical connections. Locating a single wire that is loose among thousands of wires is like looking for a loose bolt in the Eiffel Tower.”

Over the decade since the ship was built, the wire was exposed to vibrations and movement on the ship, which ultimately caused the disconnection, the NTSB said.

“This was an intermittent electrical issue failure, meaning it didn’t fail all the time,” said Barton Barnum, senior marine engineer with the NTSB.

Barnum said the NTSB left the failed system configured the way it was during the incident. The wire became disconnected again during the investigators’ simulation.

“We’re talking about a very small component here and this is what caused all the problems,” said Thomas Chapman, NTSB board member. “The poor connection within this terminal block is what started the sequence of events that resulted in the blackout.”

It would have been nearly impossible to check every connection, but thermal imaging would have helped identify the problem in a shorter timeframe, the NTSB noted.

Bridge was at risk of collapse in a collision, but no one knew

The Key Bridge had nearly 30 times the acceptable level of risk for critical bridges of collapse if it were hit, based on guidance established by the American Association of State Highway and Transportation Officials, NTSB officials said. But no one knew that before the collapse, because the owner of the bridge, the Maryland Transportation Authority, never evaluated that risk.

Earlier this year, the NTSB also identified 68 other bridges in 19 states spanning waterways frequented by cargo ships that, like the Key Bridge, were built before 1991 and do not have a current vulnerability assessment.

Among those on the list are the Golden Gate Bridge in California; Brooklyn, Manhattan, Williamsburg, George Washington and Verrazzano-Narrows bridges in New York City; the Walt Whitman and Benjamin Franklin bridges in Pennsylvania; the Sunshine Skyway in Florida and the Mackinac Bridge in Michigan.

The Maryland Transportation Authority on Monday said in a release the updated cost estimate to replace the Key Bridge is now projected to be $4.3 billion to $5.2 billion, with an expected opening in late 2030 – a two-year delay from the earlier estimate.

That price tag is more than double the previous expected cost of $1.7 billion to $1.9 billion, which the Maryland Department of Transportation previously confirmed to CNN.

CNN’s Michelle Watson contributed to this report.

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