The container ship that collided with a major bridge in Baltimore, collapsing it within seconds, suffered two electricity blackouts in the moments before the disaster, a preliminary report by federal investigators released Tuesday said.
The Singapore-flagged Dali also lost power during maintenance twice on the previous day, though the report by the National Transportation Safety Board said it was still probing what impact that may have had.
It had been clear that the ship had lost power in the seconds before the stunning collapse.
But the report is the first detailed examination of the events leading up to the disaster, which killed six construction workers who were making repairs on the bridge, and blocked the busy Port of Baltimore, a key U.S. hub.
In a timeline of the accident, it said the Dali was just 0.6 miles from the bridge when the electrical breakers that fed most of the ship's equipment and lighting unexpectedly tripped, causing the first blackout.
The ship lost propulsion and steering and began to drift off course. The crew managed to restore power briefly, but with the Dali just 0.2 miles from the bridge the lights went out again.
An emergency generator gave the crew some steering and they made a hard turn to port -- but without propulsion, the bridge's fate was sealed.
The report also detailed two blackouts about ten hours before leaving Baltimore.
"The first in-port blackout was caused by the mechanical blocking of the online generator's exhaust gas stack. The second blackout in port was related to insufficient fuel pressure for the online generator," it said.
It also said the crew had been tested multiple times, before and after the disaster, for drugs and alcohol, and that none had showed.
In April, the FBI launched a criminal probe targeting the ship, with its agents boarding the Dali as part of the investigation.
President Joe Biden promised last month to "move heaven and earth" to rebuild the bridge, pledging federal funds and saying a new channel for shipping traffic would open by the end of May.
On Monday, crews demolished part of the bridge in a bid to free the Dali, which has been pinned beneath the wreckage since the collapse.
