Ship that struck Baltimore bridge had 4 blackouts before disaster. Here’s what we know
The container ship Dali experienced a near-perfect storm of disaster before it struck Baltimore’s Francis Scott Key Bridge in March, killing six people. But Tuesday’s preliminary report by federal security investigators leaves many questions unanswered.
For example, the National Transportation Safety Board described four power outages that affected the 1,000-foot ship. The reasons for three of them have yet to be explained, including two that occurred just before the crash.
Here’s what we know and don’t know about the problems on the ship before the disaster:
The Dali suffered four blackouts in about ten hours: two the day before the crash and two in the minutes before.
The first came after a crew member accidentally closed an exhaust muffler during maintenance, causing one of the ship’s diesel engines to stall, the safety report said. A backup generator arrived, but insufficient fuel pressure soon caused that generator to kick in, resulting in a second blackout. It is unclear why the fuel pressure dropped.
In response, crew members changed the ship’s electrical configuration, which is considered routine. They switched from one transformer and breaker system that had been in use for several months to a different configuration.
The third disruption struck hours later, after the ship left the port of Baltimore and was sailing the Patapsco River. Electrical circuit breakers tripped unexpectedly, causing a power outage. The Dali’s diesel engine was automatically switched off because the cooling pumps no longer had any power.
The pilot’s dispatcher called police and notified the Coast Guard of the power loss. Crew members temporarily restored electricity by manually closing the circuit breakers. Then more breakers tripped, causing another disruption as the ship approached the bridge. The crew restored power, but it was too late.
One of the pilots ordered the rudder to be turned, but because the main engine remained off, there was no propulsion to assist with steering, the report said. The ship struck one of the bridge’s main supports, causing the span to collapse.
The reason behind one power outage is known: the crew member failed to close the muffler. The reason for the second blackout remains unclear, and the two cases of the circuit breakers tripping appear to be complete mysteries.
Jennifer Homendy, chairwoman of the National Transportation Safety Board, told a congressional committee Wednesday that the first two outages were “mechanically distinct” from the second two outages.
She said the tripping of the circuit breakers after the first two outages “could have affected operations as early as the next day during the accident trip.”
Stefano Brizzolara, a professor of ocean engineering at Virginia Tech, pointed out that the crew had switched to a configuration that had not been used for several months. He described it as like putting on a pair of shoes that you haven’t worn in a while. time that has become ‘hard and stiff’.
“Every time you switch to electrical components that are not normally used, the risk of failure increases a little bit,” he said.
But changing a ship’s power configuration is fairly routine, even if it takes several months, says Neil J. Gallagher, a professor at the Webb Institute, a school that teaches naval architecture and naval architecture.
“It shouldn’t change anything,” Gallagher said. “Transformers are a pretty benign item. They’re just wires. It has no moving parts. There isn’t much that breaks. Normally this is not the cause of these types of problems.”
Gallagher added that the fault with the silencer would have caused some concern, but not enough to raise major concerns before leaving port.
“They went for 10 hours and had no problems,” he said. “And honestly, the circuit breakers that tripped while they were underway were not the same as what happened when the engine lost power because they closed the damper.”
Gallagher said freighters do not routinely lose power.
“This is kind of a perfect storm of events that happened at the very worst possible time,” he said.
Brizzolara said crews appeared to have responded quickly to power outages.
“I don’t know if they could do more,” he said. “Unfortunately, these things can happen. Machines are sensitive to errors. And yes, there are layoffs on board ships. But even redundant systems can fail. And this is an example.”
Bradley Martin, a former U.S. Navy captain and senior policy researcher at the RAND Corporation, said limited space in many ports increases the risk of these types of disasters.
“Anyone who has ever been around ships knows that machines break down at inopportune times,” says Martin. “And because we are so close to this infrastructure, there is no good way to respond quickly enough.”
Thomas McKenney, a professor of naval architecture and marine engineering at the University of Michigan, said the Baltimore tragedy raises questions about whether most cargo ships have adequate security.
“I think the relevant question here is how reliable and redundant systems on board ships should be, especially considering that ships have become increasingly larger over time,” McKenney said, adding: “Shipping continues to by far the most efficient way to transport goods. So it’s really about finding the right balance between cost efficiency without compromising safety.”
___
Associated Press reporter Kristin M. Hall in Nashville, Tennessee contributed to this article.